Time-dependent proregenerative effects of exogenous melatonin on the transected sciatic nerve / Efectos proregenerativos dependientes del tiempo de la melatonina exógena en el nervio ciático seccionado

SUMMARY: Microsurgical procedures are the treatment of choice of peripheral nerve injuries, but often fail to reach full functional recovery. Melatonin has neuroprotective actions and might be used as a possible proregenerative pharmacological support. Therefore, the aim of this study was to analyze the time-dependence of the neuroprotective effect of melatonin on the overall fascicular structures of both ends of the transected nerve. Sciatic nerve transection was performed in 34 adult male Wistar rats divided in four groups: two vehicle groups (N=7) treated intraperitoneally for 7 (V7) or 21 (V21) consecutive days with vehicle (5 % ethanol in Ringer solution) and two melatonin groups (N=10) administered intraperitoneally 30 mg/kg of melatonin for 7 (M7) or 21 (M21) consecutive days. At the end of the experiment, proximal stump neuroma and distal stump fibroma were excised and processed for qualitative and quantitative histological analysis. Intrafascicular neural structures were better preserved and the collagen deposition was reduced in the melatonin treated groups than in the vehicle groups. Myelin sheath regeneration observed through its thickness measurement was statistically significantly (p<0,05) more pronounced in the M21 (1,23±0,18 µm) vs. V21 group (0,98±0,13 µm). The mean volume density of the endoneurium was lower in both melatonin treated groups in comparison to the matching vehicle treated groups. Although not statistically different, the endoneural tube diameter was larger in both melatonin groups vs. vehicle groups, and the effect of melatonin was more pronounced after 21 days (24,97 % increase) vs. 7 days of melatonin treatment (18,8 % increase). Melatonin exerts a time-dependent proregenerative effect on nerve fibers in the proximal stump and an anti-scarring effect in both stumps.

Los procedimientos microquirúrgicos son el tratamiento de elección de las lesiones de los nervios periféricos, pero a menudo no logran una recuperación funcional completa. La melatonina tiene acciones neuroprotectoras y podría ser utilizada como un posible apoyo farmacológico proregenerativo. Por lo tanto, el objetivo de este estudio fue analizar la dependencia del tiempo del efecto neuroprotector de la melatonina sobre las estructuras fasciculares generales de ambos extremos del nervio seccionado. La sección del nervio ciático se realizó en 34 ratas Wistar macho adultas divididas en cuatro grupos: dos grupos de vehículo (N=7) tratados por vía intraperitoneal durante 7 (V7) o 21 (V21) días consecutivos con vehículo (5 % de etanol en solución Ringer) y dos grupos grupos de melatonina (N=10) a los que se les administró por vía intraperitoneal 30 mg/kg de melatonina durante 7 (M7) o 21 (M21) días consecutivos. Al final del experimento, se extirparon y procesaron el neuroma del muñón proximal y el fibroma del muñón distal del nervio para un análisis histológico cualitativo y cuantitativo. Las estructuras neurales intrafasciculares se conservaron mejor y el depósito de colágeno se redujo en los grupos tratados con melatonina respecto a los grupos con vehículo. La regeneración de la vaina de mielina observada a través de la medición de su espesor fue estadísticamente significativa (p<0,05) más pronunciada en el grupo M21 (1,23±0,18 µm) vs V21 (0,98±0,13 µm). La densidad de volumen media del endoneuro fue menor en ambos grupos tratados con melatonina en comparación con los grupos tratados con vehículo equivalente. Aunque no fue estadísticamente diferente, el diámetro del tubo endoneural fue mayor en ambos grupos de melatonina frente a los grupos de vehículo, y el efecto de la melatonina fue más pronunciado después de 21 días (aumento del 24,97 %) frente a los 7 días de tratamiento con melatonina (18,8 % de aumento). La melatonina ejerce un efecto proregenerativo dependiente del tiempo sobre las fibras nerviosas del muñón proximal y un efecto anticicatricial en ambos muñones.

Effect of Tacrolimus and Cyclosporine Immunosuppressants on Peripheral Nerve Regeneration: Systematic Review and Meta-analysis / Efeito dos imunossupressores tacrolimus e ciclosporina na regeneração de nervos periféricos: Revisão sistemática e metanálises

Abstract Peripheral nerve damage is an important cause of seeking medical attention. It occurs when the continuity of structures is interrupted and the propagation of nervous impulses is blocked, affecting the functional capacity of individuals. To assess the effects of the immunosuppressants tacrolimus and cyclosporine on the regeneration of peripheral nerves, a systematic review of the literature was carried out. The articles included were published until September 2018 and proposed to evaluate the effects of the immunosuppressants tacrolimus and cyclosporine on nerve regeneration and neuroprotection, available in the MEDLINE, EMBASE, Cochrane Library, Web of Science, Oxford Pain Relief Database, and LILACS databases. The research analysed a total of 56 articles, of which 22 were included in the meta-analysis. Statistical analysis suggests the protective effect of tacrolimus in the regeneration of the number of myelinated axons (95% confidence interval [CI]: 0.93-2.39; p< 0.01); however, such effect was not observed in relation to cyclosporine (95%CI: - 0.38-1.18; p» 0.08) It also suggests that there is a significant relationship between the use of tacrolimus and myelin thickness (95%CI» 2.00-5.71; p< 0. 01). The use of immunosuppressants in the regeneration of peripheral nerve damage promotes an increase in the number of myelinated axons in general, regardless of the administered dose. In addition, it ensures greater myelin thickness, muscle weight and recovery of the sciatic functional index. However, heterogeneity was high in most analyses performed.

Resumo As lesões nervosas periféricas são uma causa importante de busca por atendimento médico. Elas ocorrem quando há a interrupção da continuidade das estruturas e do bloqueio da propagação dos impulsos nervosos, afetando a capacidade funcional dos indivíduos. Para avaliar os efeitos dos imunossupressores tacrolimus e ciclosporina na regeneração de nervos periféricos, foi realizada uma revisão sistemática da literatura. Foram incluídos artigos publicados até setembro de 2018, que se propunham avaliar os efeitos dos imunossupressores tacrolimus e ciclosporina na regeneração nervosa e neuroproteção, disponíveis nas bases de dados MEDLINE, EMBASE, Cochrane Library, Web of Science, Oxford Pain Relief Database e LILACS. A pesquisa analisou um total de 56 artigos, dos quais 22 foram para metanálise. A análise estatística sugere o efeito protetor do tacrolimus na regeneração do número de axônios mielinizados (intervalo de confiança [IC] 95%: 0,93-2,39; p< 0,01); todavia tal efeito não foi observado em relação à ciclosporina (IC95%: - 0,38-1,18; p» 0,08). Ela também sugere haver uma relação significativa entre o uso do tacrolimus e a espessura da mielina (IC95%: 2,00-5,71; p< 0,01). O uso de imunossupressores na regeneração de lesão nervosa periférica promove um aumento no número de axônios mielinizados de forma geral, independentemente da dose administrada. Além disso, garante uma maior espessura da mielina, um maior peso muscular e restabelecimento do índice da função do nervo ciático. Todavia, a heterogeneidade foi alta na maioria das análises realizadas.

Serotonin induces or inhibits neuritic regeneration of leech CNS neurons depending on neuronal identity

Recovery of motor function after central nervous system (CNS) injury is dependent on the regeneration capacity of the nervous system, which is a multifactorial process influenced, among other things, by the role of neuromodulators such as serotonin. The neurotransmitter serotonin can promote neuronal regeneration but there are also reports of it causing restriction, so it is important to clarify these divergent findings in order to understand the direct scope and side effects of potential pharmacological treatments. We evaluated the effect of serotonin on the extent of neuritic outgrowth and morphology of three different neuronal types in the leech Haementeria officinalis during their regeneration in vitro: Retzius interneurons (Rz), annulus erector (AE) motoneurons, and anterolateral number 1 (AL1) CNS neurons. Neurons were isolated and cultured in L15 medium, with or without serotonin. Growth parameters were registered and quantified, and observed differences were analyzed. The addition of serotonin was found to induce AL1 neurons to increase their average growth dramatically by 8.3-fold (P=0.02; n=5), and to have no clear effect on AE motoneurons (P=0.44; n=5). For Rz interneurons, which normally do not regenerate their neurites, the addition of concanavaline-A causes substantial growth, which serotonin was found to inhibit on average by 98% (P=0.02; n=5). The number of primary neurites and their branches were also affected. These results reveal that depending on the neuronal type, serotonin can promote, inhibit, or have no effect on neuronal regeneration. This suggests that after CNS injury, non-specific pharmacological treatments affecting serotonin may have different effects on different neuronal populations.

Effects of ozone therapy on facial nerve regeneration / Efeitos da terapia com ozônio na regeneração do nervo facial

Abstract Introduction: Ozone may promote moderate oxidative stress, which increases antioxidant endogenous systems. There are a number of antioxidants that have been investigated therapeutically for improving peripheral nerve regeneration. However, no previous studies have reported the effect of ozone therapy on facial nerve regeneration. Objective: We aimed to evaluate the effect of ozone therapy on facial nerve regeneration. Methods: Fourteen Wistar albino rats were randomly divided into two groups with experimental nerve crush injuries: a control group, which received saline treatment post-crush, and an experimental group, which received ozone treatment. All animals underwent surgery in which the left facial nerve was exposed and crushed. Treatment with saline or ozone began on the day of the nerve crush. Left facial nerve stimulation thresholds were measured before crush, immediately after crush, and after 30 days. After measuring nerve stimulation thresholds at 30 days post-injury, the crushed facial nerve was excised. All specimens were studied using light and electron microscopy. Results: Post-crushing, the ozone-treated group had lower stimulation thresholds than the saline group. Although this did not achieve statistical significance, it is indicative of greater functional improvement in the ozone group. Significant differences were found in vascular congestion, macrovacuolization, and myelin thickness between the ozone and control groups. Significant differences were also found in axonal degeneration and myelin ultrastructure between the two groups. Conclusion: We found that ozone therapy exerted beneficial effect on the regeneration of crushed facial nerves in rats.

Resumo Introdução: O ozônio pode promover estresse oxidativo moderado, o que aumenta sistemas endógenos antioxidantes. Há determinado número de antioxidantes sendo investigados terapeuticamente para melhorar a regeneração do nervo periférico. No entanto, nenhum estudo anterior relatou o efeito da terapia com ozônio na regeneração do nervo facial. Objetivo: Nosso objetivo foi avaliar o efeito da terapia com ozônio na regeneração do nervo facial. Método: Ao todo, 14 ratos albinos Wistar foram divididos aleatoriamente em dois grupos com lesões experimentais por esmagamento do nervo: um grupo controle, que recebeu tratamento com solução salina pós-esmagamento; e um grupo experimental, que recebeu tratamento com ozônio. Todos os animais foram submetidos a cirurgia na qual o nervo facial esquerdo foi exposto e esmagado. O tratamento com solução salina ou ozônio se iniciou no dia do esmagamento do nervo. Os limiares de estimulação do nervo facial esquerdo foram medidos antes do esmagamento, imediatamente após o esmagamento e após 30 dias. Depois de medir limiares de estimulação do nervo aos 30 dias pós-lesão, o nervo facial esmagado foi excisado. Todas as amostras foram estudadas por meio de microscopia óptica e eletrônica. Resultados: Após o esmagamento, o grupo tratado com ozônio apresentou menores limiares de estimulação do que o grupo da solução salina. Embora isso não tenha significância estatística, é indicativo de maior melhoria funcional no grupo do ozônio. Foram encontradas diferenças significativas na congestão vascular, macrovacuolização e espessura da mielina entre os grupos do ozônio e controle. Diferenças significativas também foram encontradas na degeneração axonal e ultraestrutura de mielina entre os dois grupos. Conclusão: Verificou-se que a terapia com ozônio teve efeito benéfico sobre a regeneração dos nervos faciais esmagados em ratos.

Effect of ozone and methylprednisolone treatment following crush type sciatic nerve injury

ABSTRACT PURPOSE: To assess and compare the histopathological effects of ozone therapy and/or methylprednisolone (MPS) treatment on regeneration after crush type sciatic nerve injury. METHODS: Forty Sprague-Dawley male rats were randomly allocated into four groups. Four groups received the following regimens intraperitoneally every day for 14 days after formation of crush type injury on sciatic nerve: Group I: ozone (20mcg/ml); Group II: methylprednisolone (2mg/kg); Group III: ozone (20 mcg/ml) and methylprednisolone (2mg/kg); Group IV: isotonic saline (0.9%). The histomorphological evaluation was made after biopsies were obtained from the sites of injury. RESULTS: Significant differences were noted between groups in terms of degeneration (p=0.019), nerve sheath cell atrophy (p=0.012), intraneural inflammatory cellular infiltration (p=0.002), perineural granulation tissue formation (p=0.019), perineural vascular proliferation (p=0.004), perineural inflammatory cellular infiltration (p<0.001) and inflammation in peripheral tissue (p=0.006). Degeneration was remarkably low in Group III, while no change in nerve sheath cell was noted in Group II. CONCLUSION: The combined use of methylprednisolone and ozone treatment can have beneficial effects for regeneration after crush type nerve injury.

Between the foreign and the local: French midwifery, traditional practitioners, and vernacular medical knowledge about childbirth in Lima, Peru / Entre o estrangeiro e o local: obstetrizes francesas, médicos tradicionais e conhecimento médico vernáculo sobre partos em Lima, Peru

This article examines the politics of midwifery and the persecution of untitled female assistants in childbirth in early republican Peru. A close reading of late colonial publications and the works of Benita Paulina Cadeau Fessel, a French obstetriz director of a midwifery school in Lima, demonstrates both trans-Atlantic and local influences in the campaign against untitled midwives. Cadeau Fessel's efforts to promote midwifery built upon debates among writers in Peru's enlightened press, who vilified untrained midwives' and wet nurses' vernacular medical knowledge and associated them with Lima's underclass. One cannot understand the transfer of French knowledge about professional midwifery to Peru without reference to the social, political, and cultural context.

Este artigo analisa as políticas de práticas de parteiras profissionais e a condenação de parteiras leigas nos primórdios do Peru republicano. A leitura atenta de publicações de fins do período colonial e dos trabalhos de Benita Paulina Cadeau Fessel, obstetriz francesa diretora de uma escola de parteiras em Lima, revela influência tanto transatlântica como local na campanha contra as parteiras sem titulação. Cadeau Fessel promovia seu ofício com base em debates veiculados na imprensa peruana ilustrada, que aviltavam o conhecimento tradicional de amas de leite e parteiras leigas e as associavam às classes desfavorecidas. Só é possível compreender a transferência do conhecimento francês sobre trabalho de parteiras profissionais para o Peru relacionando-a ao contexto social, político e cultural.

Propentofylline reverses delayed remyelination in streptozotocin-induced diabetic rats

Objective The diabetic state induced by streptozotocin injection is known to impair oligodendroglial remyelination in the rat brainstem following intracisternal injection with the gliotoxic agent ethidium bromide (EB). In such experimental model, propentofylline (PPF) recently showed to improve myelin repair, probably due to its neuroprotective, antiinflammatory and antioxidant effects. The aim of this study was to evaluate the effect of PPF administration in diabetic rats submitted to the EB-demyelinating model. Materials and methods Adult male rats, diabetic or not, received a single injection of 10 microlitres of 0.1% EB solution into the cisterna pontis. For induction of diabetes mellitus the streptozotocin-diabetogenic model was used (50 mg/kg, intraperitoneal route – IP). Some diabetic rats were treated with PPF (12.5 mg/kg/day, IP route) during the experimental period. The animals were anesthetized and perfused from 7 to 31 days after EB injection and brainstem sections were collected for analysis of the lesions by light and transmission electron microscopy. Results Diabetic rats injected with EB showed larger amounts of myelin-derived membranes in the central areas of the lesions and considerable delay in the remyelinating process played by surviving oligodendrocytes and invading Schwann cells after the 15th day. On the other hand, diabetic rats that received PPF presented lesions similar to those of non-diabetic animals, with rapid remyelination at the edges of the lesion site and fast clearance of myelin debris from the central area. Conclusion The administration of PPF apparently reversed the impairment in remyelination induced by the diabetic state. Arch Endocrinol Metab. 2015;59(1):47-53 .

Effect of Macrophage Migration Inhibitory Factor on Corneal Sensitivity after Laser In Situ Keratomileusis in Rabbit

PURPOSE: To investigate the effect of macrophage migration inhibitory factor (MIF) on corneal sensitivity after laser in situ keratomileusis (LASIK) surgery. METHODS: New Zealand white rabbits were used in this study. A hinged corneal flap (160-microm thick) was created with a microkeratome, and -3.0 diopter excimer laser ablation was performed. Expressions of MIF mRNA in the corneal epithelial cells and surrounding inflammatory cells were analyzed using reverse transcription polymerase chain reaction at 48 hours after LASIK. After LASIK surgery, the rabbits were topically given either 1) a balanced salt solution (BSS), 2) MIF (100 ng/mL) alone, or 3) a combination of nerve growth factor (NGF, 100 ug/mL), neurotrophine-3 (NT-3, 100 ng/mL), interleukin-6 (IL-6, 5 ng/mL), and leukemia inhibitory factor (LIF, 5 ng/mL) four times a day for three days. Preoperative and postoperative corneal sensitivity at two weeks and at 10 weeks were assessed using the Cochet-Bonnet esthesiometer. RESULTS: Expression of MIF mRNA was 2.5-fold upregulated in the corneal epithelium and 1.5-fold upregulated in the surrounding inflammatory cells as compared with the control eyes. Preoperative baseline corneal sensitivity was 40.56 +/- 2.36 mm. At two weeks after LASIK, corneal sensitivity was 9.17 +/- 5.57 mm in the BSS treated group, 21.92 +/- 2.44 mm in the MIF treated group, and 22.42 +/- 1.59 mm in the neuronal growth factors-treated group (MIF vs. BSS, p < 0.0001; neuronal growth factors vs. BSS, p < 0.0001; MIF vs. neuronal growth factors, p = 0.815). At 10 weeks after LASIK, corneal sensitivity was 15.00 +/- 9.65, 35.00 +/- 5.48, and 29.58 +/- 4.31 mm respectively (MIF vs. BSS, p = 0.0001; neuronal growth factors vs. BSS, p = 0.002; MIF vs. neuronal growth factors, p = 0.192). Treatment with MIF alone could achieve as much of an effect on recovery of corneal sensation as treatment with combination of NGF, NT-3, IL-6, and LIF. CONCLUSIONS: Topically administered MIF plays a significant role in the early recovery of corneal sensitivity after LASIK in the experimental animal model.

Señalización de la angiotensina II, a través de la producción de radicales libres en estructuras del sistema nervioso: papel en el estres agudo y crónico / Angiotensin II signaling, through the production of free radicals in structures of the nervous system: role in acute and chronic stress

Existen evidencias que apoyan la participación de las especies reactivas de oxígeno en las cascadas de señalización y transducción intracelular de la angiotensina II. La ANG II es importante en el mantenimiento de la homeostasis corporal, regulando la presión arterial y el metabolismo de fluidos y electrolitos. Se sabe que en la periferia, la ANG II es capaz de estimular a la NAD(P)H oxidasa con la subsiguiente producción de ERO. El anión superóxido es metabolizado secuencialmente por las enzimas antioxidantes como la superóxido dismutasa, la catalasa y la glutatión peroxidasa. A su vez, las especies reactivas de oxígeno son capaces de activar a las proteínas kinasas activadas por mitógenos, las cuales se encuentran asociadas al crecimiento y la diferenciación celular. Se evaluó la posible participación de las especies reactivas de oxígeno en el mecanismo de señalización intracelular mediado por el receptorAT1en el hipotálamo, el órgano subfornicaly médula suprarrenal de la rata. Nuestros resultados demostraron que la estimulación del tejido nervioso con ANG II in vitroincrementó la actividad de la enzimas antioxidante. Al evaluar el papel del receptor AT1, la NAD(P)H oxidasa, el anión superóxido y la proteína kinasa C; así como la activación de las ERK1/2 en la señalización de la ANG II en el hipotálamo, OSF y MSR, demostramos que el bloqueo del receptor AT1con losartán, la interferencia del ensamblaje de la NAD(P)H oxidasa con apocinina, el secuestro de anión superóxido empleando un mimético de la SOD, tempol,y la inhibición de la PKC con cheleritrina, bloquearon completamente el efecto que produce la ANG II sobre las enzimas antioxidantes in vitro.Igualmente, la activación de la ERK1/2 inducida por la ANG II fue reducida por APO y LOS a nivel hipotalámico. Adicionalmente, el bloqueo del receptor AT2hipotalámico con PD123319, no bloqueo sino que mas bien potenció la respuesta de las enzimas antioxidantes y la activación de las ERK1/2 inducida por la ANG II, lo que desenmascaró el efecto contra regulatorio del receptor AT2sobre la acción de la ANG II mediada por el receptor AT1. Se sabe que durante el estrés el sistema renina angiotensina circulante y cerebral se encuentra estimulado, por lo tanto el incremento de la ANG II endógena debería desencadenar vías de señalización similares a las reportadas in vitro. Efectivamente, nuestros hallazgos demostraron que tanto,el estrés agudo inducido por la inmovilización forzada,como el estrés crónico en ratas espontáneamente hipertensas incrementaron la actividad de las enzimas antioxidantes en las tres estructuras cerebrales estudiadas. Este efecto es mediado por la vía del receptor AT1, la estimulación de la NAD(P)H oxidasa y la producción de anión superóxido ya que el tratamiento in vivo con LOS, APO y TEM fue capaz de bloquear completamente el incremento de la actividad de las enzimas antioxidantes inducidas por el estrés y por ende por la ANG II endógena.A nivel de la MSR demostramos, por primera vez, que la estimulación del receptor AT2 esta asociada a la estimulación de la NAD(P)H oxidasa, ya que la APOy el PD 123319 fueron capaces de bloquear el incremento de la actividad de las enzimas antioxidantes inducida por la ANG II. Demostrando así, que el receptor AT1en la MSR contrarregula la acción de la ANG II a través del receptor AT2.En conclusión, nuestros resultados indican que a nivel del sistema nervioso las especies reactivas de oxígeno participan en la cascada de señalización intracelular de la ANG II, y ejercen un importante papel en la respuesta al estrés y la hipertensión.

Nerve growth factor with fibrin glue in end-to-side nerve repair in rats / Fator de crescimento nervoso em cola de fibrina no reparo término-lateral de nervos em ratos

PURPOSE: To determine the effects of end-to-side nerve repair performed only with fibrin glue containing nerve growth in rats. METHODS: Seventy two Wistar rats were divided into six equal groups: group A was not submitted to nerve section; group B was submitted to nerve fibular section only. The others groups had the nerve fibular sectioned and then repaired in the lateral surface of an intact tibial nerve, with different procedures: group C: ETS with sutures; group D: ETS with sutures and NGF; group E: ETS with FG only; group F: ETS with FG containing NGF. The motor function was accompanied and the tibial muscle mass, the number and diameter of muscular fibers and regenerated axons were measured. RESULTS: All the analyzed variables did not show any differences among the four operated groups (p>0.05), which were statistically superior to group B (p<0.05), but inferior to group A (p>0.05). CONCLUSION: The end-to-side nerve repair presented the same recovery pattern, independent from the repair used, showing that the addition of nerve growth factor in fibrin glue was not enough for the results potentiating.

OBJETIVO: Determinar os efeitos do reparo nervoso término-lateral realizado apenas com cola de fibrina contendo fator de crescimento nervoso em ratos. MÉTODOS: Setenta e dois ratos Wistar foram distribuídos em seis grupos: A - não submetido à secção nervosa; B - secção do nervo fibular (sem reparo); Os outros grupos tiveram o nervo fibular seccionado e então reparado na superfície lateral do nervo tibial intacto, com diferentes procedimentos: C - RNTL com suturas; D - RNTL com suturas e FCN; E - RNTL apenas com CF; F - RNTL com CF contendo FCN. A função motora foi acompanhada e a massa do músculo tibial, o número e o diâmetro das fibras musculares e axônios regenerados foram medidos. RESULTADOS: Não houve diferença entre as variáveis avaliadas nos quatro grupos operados (p>0,05), os quais foram superiores ao grupo B (p<0,05), mas inferiores ao grupo A (p>0,05). CONCLUSÕES: O reparo nervoso término-lateral mostrou o mesmo padrão de recuperação, independente do tipo de reparo utilizado, evidenciando que a adição de fator de crescimento nervoso na cola de fibrina não foi suficiente para a potencialização dos resultados.

Effect of neurotrophic factor, MDP, on rats’ nerve regeneration

Our objective was to determine the immune-modulating effects of the neurotrophic factor N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) on median nerve regeneration in rats. We used male Wistar rats (120-140 days of age, weighing 250-332 g) and compared the results of three different techniques of nerve repair: 1) epineural neurorrhaphy using sutures alone (group S - 10 rats), 2) epineural neurorrhaphy using sutures plus fibrin tissue adhesive (FTA; group SF - 20 rats), and 3) sutures plus FTA, with MDP added to the FTA (group SFM - 20 rats). Functional assessments using the grasp test were performed weekly for 12 weeks to identify recovery of flexor muscle function in the fingers secondary to median nerve regeneration. Histological analysis was also utilized. The total number and diameter of myelinated fibers were determined in each proximal and distal nerve segment. Two indices, reported as percentage, were calculated from these parameters, namely, the regeneration index and the diameter change index. By the 8th week, superiority of group SFM over group S became apparent in the grasping test (P = 0.005). By the 12th week, rats that had received MDP were superior in the grasping test compared to both group S (P < 0.001) and group SF (P = 0.001). Moreover, group SF was better in the grasping test than group S (P = 0.014). However, no significant differences between groups were identified by histological analysis. In the present study, rats that had received MDP obtained better function, in the absence of any significant histological differences.

Semi-quantitative analysis of the effects of cyclosporine on remyelination following gliotoxic injection in the brainstem / Análise semiquantitativa dos efeitos da ciclosporina na remielinização após injeção gliotóxica no tronco encefálico

The use of cyclosporine (CsA) has shown to induce an increase in the density of oligodendrocytes near remyelinating areas following the injection of ethidium bromide (EB), a demyelinating agent, in the rat brainstem. This study was designed in order to evaluate if CsA has the capacity of increasing remyelination. In this context, a comparison between the final balance of myelin repair in CsA treated and non-treated rats was assessed using a semi-quantitative method developed for documenting the extent and nature of remyelination in gliotoxic lesions. Wistar rats were submitted to intracisternal injection of 10 microliters of 0.1 percent EB. Some were treated during 31 days with CsA (group III - 10 mg/kg/day by 7 days and, thereafter, 3 times a week, with a minimal interval of 48 hours) by intraperitonial route. Others were not treated with CsA (group I). A control group was planned receiving into the cisterna pontis 10 microliters of 0.9 percent saline solution and following after that the same CsA administration protocol (group II). Results clearly demonstrate that in vivo administration of CsA after EB-demyelinating lesions stimulated oligodendrocyte remyelination (mean remyelination scores of 3.72±0.25 for oligodendrocytes and 1.04±0.39 for Schwann cells) compared to non-treated animals (3.13±0.71 and 1.31±0.62, respectively), although the mechanisms by which this positive CsA effect occurs are unclear.

O uso de ciclosporina (CsA) mostrou induzir um aumento na densidade de oligodendrócitos próximos a áreas de remielinização após injeção de brometo de etídio (EB), um agente desmielinizante, no tronco encefálico de ratos. Este estudo foi desenvolvido a fim de avaliar se a CsA possui a capacidade de acelerar a remielinização. Neste contexto, foi feita uma comparação entre o balanço final de reparo mielínico em ratos tratados ou não com CsA usando-se um método semiquantitativo desenvolvido para documentação da extensão e natureza da remielinização em lesões gliotóxicas. Ratos Wistar foram submetidos à injeção intracisternal de EB a 0,1 por cento. Alguns foram tratados durante 31 dias com CsA (grupo III - 10 mg/kg/dia por 7 dias e, após, 3 vezes por semana, com um intervalo mínimo de 48 horas entre as aplicações) por via intraperitoneal. Outros não foram tratados com CsA (grupo I). Um grupo controle foi desenvolvido recebendo, na cisterna pontina, 10 microlitros de solução salina e seguindo após o mesmo protocolo de administração de CsA (grupo II). Os resultados mostram claramente que a administração in vivo de CsA após lesões desmielinizantes induzidas pelo EB estimulou a remielinização por oligodendrócitos (escores médios de remielinização de 3,72±0,25 para oligodendrócitos e 1,04±0,39 para células de Schwann) em comparação aos animais não-tratados (3,13±0,71 e 1,31±0,62, respectivamente), embora os mecanismos pelos quais este efeito positivo da CsA ocorre sejam desconhecidos.

End-to-side nerve repair using fibrin glue in rats / Anastomose nervosa término-lateral usando cola de fibrina em ratos

Purpose: To evaluate axonal regeneration after end-to-side nerve repair with fibrin glue in rats. Methods: Forty-five Wistar rats were divided into three groups: group A (n=15), were not submitted to surgery (control group); group B (n=15) were submitted to fibular transection without repair; and group C (n=15), were submitted to fibular transection with end-to-side nerve anastomosis using fibrin glue, in the lateral surface of an intact tibial nerve. The three groups were submitted to walking track (30 and 90 days) and posterior morphometrical analysis (90 days). Results: The functional tests demonstrated that there was no difference in the walking track during the study in group A (p>0.05). The group B had walking pattern impairment in the two tests (p>0.05). The group C had walking pattern impairment in the first test, with important recovery in the second test (p<0.05). The morphometrical assessment revealed significantly higher number of regenerated mielinates axons in group C, compared to group B (p<0.05). Conclusion: The end-to-side nerve repair with fibrin glue shows axonal recovery, demonstrated through functional and morphometrical ways in rats.

Objetivo: Avaliar a regeneração axonal após anastomose nervosa término-lateral (ATL) usando cola de fibrina em ratos. Métodos: Quarenta e cinco ratos Wistar distribuídos em três grupos: os animais do grupo A (n=15) não foram submetidos à secção nervosa (grupo controle); os animais do grupo B (n=15) foram submetidos apenas à secção do nervo fibular, sem posterior anastomose; e os animais do grupo C (n=15) foram submetidos à secção do nervo fibular e à ATL com cola de fibrina no nervo tibial. Posteriormente, os animais foram submetidos a dois testes de marcha (30 e 90 dias) e à análise morfométrica (90 dias). Resultados: A análise estatística dos testes de marcha demonstrou que o grupo A não apresentou alteração no padrão de caminhada durante o estudo (p>0,05). O grupo B apresentou prejuízo motor no primeiro e no segundo teste (p>0,05). O grupo C apresentou um padrão de atrofia no primeiro teste, com recuperação da marcha no segundo teste (p<0,05). Na análise morfométrica, o grupo C apresentou regeneração axonal significativamente superior ao grupo B (p<0,05). Conclusão: A ATL realizada com cola de fibrina resultou em regeneração axonal no rato, demonstrada tanto histologicamente quanto funcionalmente.

Influência do AMP cíclico na regeneração do nervo facial em ratos / Influence of cyclic AMP on facial nerve regeneration in rats

Estimular a regeneração do nervo facial é ainda hoje um desafio. OBJETIVO: Estudar a possível influência neurotrófica do nucleotídeo cíclico adenosina monofosfato (AMPc) na regeneração do nervo facial de ratos Wistar. MÉTODO: Trinta e dois animais foram submetidos à transecção completa com sutura imediata do nervo facial direito, sendo divididos em expostos ou não expostos à aplicação tópica de AMPc, com análises comportamentais (movimentação de vibrissas e fechamento da rima palpebral) e histométrica (contagem de fibras mielinizadas) em dois períodos, 14 e 28 dias após a lesão. RESULTADO: Encontramos diferenças estatísticas (p<0,05) nas análises comportamental e histométrica no 14º dia, sugerindo uma precocidade na regeneração do nervo facial exposto ao AMPc. CONCLUSÃO: Nosso estudo constatou uma possível ação neurotrófica do AMPc na regeneração do nervo facial em ratos.

Promoting facial nerve regeneration is a significant challenge. AIM: To evaluate the possible neurotrophic influence of cyclic AMP on facial nerve regeneration of Wistar rats. METHOD: The right facial nerve of thirty-two animals were completely transected and immediately sutured, followed by exposure or not to topical cyclic AMP. Behavioral and histometric analyses were done at 14 and 28 days. RESULTS: Statistical differences (p<0.05) were found in the behavioral and histometric analyses on the 14th day, suggesting an early regenerative response of the facial nerve to cAMP exposure. CONCLUSION: This study demonstrates a possible neurotrophic effect of cAMP on facial nerve regeneration in rats.

Histopathological analysis of gangliosides use in peripheral nerve regeneration after axonotmesis in rats / Análise histopatológica da regeneração nervosa periférica com uso de gangliosídeos após axonotmese em ratos

PURPOSE: To analyze the action of gangliosides in peripheral nerve regeneration in the sciatic nerve of the rat. METHODS: The sample was composed of 96 male Wistar rats. The animals were anaesthetized and, after identification of the anaesthesic plane, an incision was made in the posterior region of the thigh, followed by skin and muscle divulsion. The right sciatic nerve was isolated and compressed for 2 minutes. Continuous suture of the skin was performed. The animals were randomly divided into two groups: the experimental group (EG), which received subcutaneous injection of gangliosides, and the control group (CG), which received saline solution (0.9 percent) to mimic the effects of drug administration. RESULTS: No differences were observed between the experimental and control groups evaluated on the eighth day of observation. At 15 and 30 days the EG showed an decrease in Schwann cell activity and an apparent improvement in fibre organization; at 60 days, there was a slight presence of Schwann cells in the endoneural space and the fibres were organized, indicating nerve regeneration. At 15 and 30 days, the level of cell reaction in the CG had diminished, but there were many cells with cytoplasm in activity and in mitosis; at 60 days, hyperplastic Schwann cells and mitotic activity were again observed, as well as nerve regeneration, but to a lesser extent than in the EG. CONCLUSION: The administration of exogenous gangliosides seems to improve nerve regeneration.

OBJETIVO: Avaliar os efeitos de gangliosídeos na regeneração nervosa periférica em nervo isquiático de ratos após axonotmese. MÉTODOS: Foram utilizados 96 ratos machos albinos (Wistar). Os animais foram anestesiados e após constatação do plano anestésico, foi realizada incisão na face posterior da coxa direita do animal. Em seguida, foi realizada a dissecção cirúrgica da pele e do músculo e divulsão dos músculos. O nervo isquiático direito foi isolado e sofreu compressão por 2 minutos. Efetuou-se a sutura contínua da pele. Os animais foram distribuídos aleatoriamente em 2 grupos: experimental (GE) que receberam gangliosídeos pela via sub-cutânea e controle (GC) que receberam soro fisiológico 0,9 por cento com a finalidade de mimetizar os efeitos de administração da droga de estudo. A análise histopatológica foi realizada em 8, 15, 30 e 60 dias. RESULTADOS: Não se evidenciaram diferenças significantes entre os grupos controle e experimental avaliados com 8 dias. Nos grupos experimentais de 15 e 30 dias observou-se uma diminuição da atividade das células de Schwann e aparente melhora na organização das fibras nervosas; com 60 dias havia discreta presença células de Schwann no espaço endoneural e as fibras nervosas estavam organizadas sinalizando a regeneração nervosa. Nos grupos controles de 15 e 30 dias o padrão de reação celular diminuiu, entretanto havia muitas células com citoplasmas em atividade e mistose; com 60 dias observou-se ainda a presença de hiperplasia de células de Schwann, atividade mitótica ainda presente e regeneração nervosa presente, porém em menor grau comparando-se com aquele visto no grupo experimental. CONCLUSÃO: A administração de gangliosídeos exógenos parece incrementar a regeneração nervosa.

Netrin Inhibits Regenerative Axon Growth of Adult Dorsal Root Ganglion Neurons in Vitro

Netrin is a neuronal guidance molecule implicated in the development of spinal commissural neurons and cortical neurons. The attractive function of netrin requires the receptor, Deleted in Colorectal Cancer (DCC), while the receptor Unc5h is involved in the repulsive action of netrin during embryonic development. Although the expression of netrin and its receptor has been demonstrated in the adult nervous system, the function of netrin in adult neurons has not yet been elucidated. Here, we show that netrin treatment inhibited neurite outgrowth of adult dorsal root ganglion (DRG) neurons in explant and dissociated cultures. In addition, unc5h1-3 mRNAs, but not the dcc mRNA, are abundantly expressed in the adult DRG. An in situ hybridization study demonstrated that unc5h mRNAs were expressed in DRG neurons. This finding indicates that netrin/Unc5h signaling may play a role in the neurite outgrowth of adult DRG neurons and that netrin may be involved in the regulation of peripheral nerve regeneration.

Spinal cord regeneration: the action of neurotrophin-3 in spinal cord injury in rats

OBJECTIVE: For many years, it was believed that medullary regeneration could not occur, although currently there are many trials using neurotrophic factors, stem cells, fetal medulla grafts, peripheral nerve grafts, and antibodies against myelin-associated proteins that demonstrate the existence of the possibility of spinal cord regeneration. The purpose of this study was to investigate the action of neurotrophin-3, a novel neurotrophic factor. METHODS: The New York University impactor, a standardized device for delivery of spinal cord injuries was used on 33 rats, which were divided into 2 groups: a control group receiving distilled water intraperitoneally and a treatment group receiving neurotrophin-3 intraperitoneally. RESULTS: Using the Basso, Beattie, and Bresnahan scale, the locomotor recovery curve for the neurotrophin-3 treated group was superior to that of the control group (P < 0.05); the administration of neurotrophin-3 was associated with the absence of deaths, while the control group showed a 28.5 percent (P = 0.026) mortality rate. Other parameters (hematuria rate and histological analysis) showed no significant differences. CONCLUSIONS: Based on these results, it appears that a strong relationship exists between the use of neurotrophin-3 in rats with spinal cord injury and better functional recovery.

OBJETIVO: Por muitos anos acreditou-se que a regeneração medular não fosse factível. Atualmente porém, existem várias experiências utilizando fatores neurotróficos, células troncos, enxerto de medula fetal, enxerto de nervo periférico e anticorpos contra proteínas associadas a mielina que sugerem o contrário. Esta pesquisa estudou a ação de um dos mais novos neurotróficos, o Neurotrophin-3. MÉTODOS: As lesões medulares foram realizadas através do New York University impator, método experimental de produção de lesão medular padronizada. Foram utilizados 33 ratos divididos em 2 grupos. Um grupo controle com administração intraperitoneal de água destilada e um grupo tratamento, tratado com Neurotrophin-3 por via intraperitoneal. RESULTADOS: Observamos que a curva de recuperação locomotora, segundo a escala de Basso, Beattie e Bresnahan, do grupo Neurotrophin-3 foi superior à do grupo controle (p < 0,05); a administração de Neurotrophin-3 determinou ausência de mortes no grupo tratamento, enquanto o grupo controle apresentou taxa de mortalidade de 28,5 por cento (p = 0,026). Os outros parâmetros (taxa de hematúria e análise histológica) não apresentaram diferenças estatisticamente significantes. CONCLUSÕES: Existe forte relação entre a aplicação de Neurotrophin-3 em ratos com lesão medular e melhor recuperação funcional.

Effect of caffeine administration on latent learning ability of male rats in a simple maze task

The proximal and distal stumps of severed mouse sciatic nerves were inserted into opposite ends of polyethylene tubes. The tubes were implanted either empty ofr filled with collagen alone or in combination with interleukin-1 (IL1). Six weeks later, neurons in the L3-L5 dorsal root ganglia were back-filled with HRP. The number of HRP reactive sensory neurons detected in the IL1-treated animals was significantly greater than that seen in the other experimental groups. Thus, exogenous IL1 may partially mimic the effects obtained with in vivo administration of nerve growth factor in protecting sensory neurons from lesion-induced death

Exogenous ganglioside stimulation of axonal regeneration after new transection and entubulation repair

Adult male mice received sciatic nerve transection at the midthigh level and both nerve stumps were sutured into a polythylene tube (PT) to bridge a nerve gap of 4 mm. The tubes were implanted either empty, or filled with collagen alone or in combination with gangliosides (GM1, GD1a, GD1b, anhd GT1b). Following a survival time of 6 weeks, the PT with the regenerating nerve cables were processed for plastic embedding, and morphometric measurements were made on myelinated and unmyelinated axons. The data suggest that local application of exogenous gangliosides causes a stimulation of axonal sprouting in vivo with no effefct on the rate of axonal maturation