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1.
J Tissue Eng Regen Med ; 10(12): 1012-1020, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-24677775

RESUMO

Wound healing is a complex process that requires the intervention of cytoactive factors. The one-time application of soluble factors to a wound bed does not maintain a steady, sufficient concentration. Here we investigated the benefits of anchoring a factor in a wound bed via a tether to endogenous collagen. We used a collagen-mimetic peptide (CMP) as a pylon. The CMP binds to damaged but not intact collagen and thus localizes a pendant cytoactive factor in the regions of a wound bed that require intervention. As a model factor, we chose substance P, a peptide of the tachykinin family that promotes wound healing. Using splinted wounds in db/db mice, we found that the one-time application of a CMP-substance P conjugate enhances wound healing compared to unconjugated substance P and other controls. Specifically, all 16 wounds treated with the conjugate closed more thoroughly and, did so with extensive re-epithelialization and mitigated inflammatory activity. These data validate a simple and general strategy for re-engineering wound beds by the integration of beneficial cytoactive factors. Copyright © 2014 John Wiley & Sons, Ltd.


Assuntos
Peptídeos , Substância P/química , Cicatrização/efeitos dos fármacos , Ferimentos e Lesões/terapia , Animais , Materiais Biomiméticos/síntese química , Materiais Biomiméticos/química , Materiais Biomiméticos/farmacologia , Colágeno/química , Modelos Animais de Doenças , Proteínas Imobilizadas/química , Proteínas Imobilizadas/farmacologia , Masculino , Camundongos , Camundongos Mutantes , Peptídeos/síntese química , Peptídeos/química , Peptídeos/farmacologia , Ferimentos e Lesões/metabolismo
2.
Vet Surg ; 44(7): 838-42, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26287445

RESUMO

OBJECTIVE: To evaluate the mechanical properties of locking screw placement in hybrid plating in comparison to all-locked and all nonlocked constructs. STUDY DESIGN: Completely randomized design. Forty-eight synthetic bone cylinders (4th generation composite Sawbones(®)) across 6 construct types (n = 8 each). METHODS: An 8-hole 3.5 mm LCP was placed across a 2 mm cylinder gap to mimic an unstable fracture model. The plates were secured with all locking screws, all nonlocking screws, or a combination of locking screws and nonlocking screws in the hybrid constructs. Constructs were cyclically tested nondestructively in 4-point bending, axial compression, and torsion, and then tested to failure in torsion. The stiffness and strength of each construct were calculated and compared across construct types. RESULTS: Constructs with a locking screw located adjacent to the fracture gap were stiffer in bending and stronger in torsion to failure than constructs without an adjacent locking screw. Hybrid and nonlocking screw constructs more frequently failed by catastrophic breakage of the bone cylinder, compared to all locking screw constructs that failed by plastic deformation of the plate. CONCLUSIONS: Mechanical testing of synthetic bone model constructs shows that hybrid constructs are at least as stiff and strong as entirely nonlocked constructs, and with some screw configurations, are not statistically different from entirely locked constructs.


Assuntos
Placas Ósseas , Parafusos Ósseos , Fixação de Fratura/métodos , Fraturas Ósseas/cirurgia , Animais , Fenômenos Biomecânicos , Cães
3.
J Am Anim Hosp Assoc ; 50(3): 216-20, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24659723

RESUMO

A 3 yr old spayed female mixed-breed German shepherd dog was presented with a right facial swelling that developed after fighting with another dog. A parotid salivary mucocele was diagnosed via physical examination, fine-needle aspirate, and sialography of the parotid and mandibular salivary glands. Surgical excision of the right parotid salivary gland and duct was performed along with drainage of the mucocele. Neither intraoperative nor postoperative complications occurred, and follow-up examination 4 mo later revealed no evidence of recurrence. Case outcome was considered excellent. Sialography was useful for confirming the parotid gland as the source of the mucocele. Surgical excision of the parotid salivary gland is technically challenging, but an effective treatment option for traumatic mucoceles in the dog.


Assuntos
Doenças do Cão/cirurgia , Mucocele/veterinária , Doenças das Glândulas Salivares/veterinária , Animais , Diagnóstico Diferencial , Doenças do Cão/diagnóstico por imagem , Doenças do Cão/patologia , Cães , Feminino , Mucocele/cirurgia , Glândula Parótida/diagnóstico por imagem , Radiografia , Doenças das Glândulas Salivares/cirurgia
4.
Brain Res ; 1518: 91-103, 2013 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-23623813

RESUMO

The subventricular zone (SVZ) is one of the two major neurogenic regions in the adult mammalian brain. Its close proximity to the striatum suggests that a cell-based therapeutic strategy for the treatment of Huntington's disease (HD) is possible. To achieve this, it is important to understand how adult cell production, migration and differentiation may be altered in the HD brain. In this study, we quantified the number of adult-born striatal cells and characterized their fate in the R6/2 transgenic mouse model of HD. We found that the number of new striatal cells was approximately two-fold greater in R6/2 vs. wild type mice, while SVZ cell proliferation was not affected. Using cell-type specific markers, we demonstrated that the majority of new striatal cells were mature oligodendrocytes or oligodendroglial precursors that were intrinsic to the striatum. We also detected a significant increase in the number of migrating neuroblasts that appeared to be recruited from the SVZ to the striatum. However, these neuroblasts did not mature into neurons and most were lost between 1 and 2 weeks of cell age. Crossing the R6/2 mice with mice the over-expressing brain-derived neurotrophic factor in the striatum increased the numbers of neuroblasts that survived to 2 weeks, but did not promote their differentiation. Together, our data indicate that the potential treatment of HD based on manipulating endogenous progenitor cells should take into consideration the apparent enhancement in striatal oligodendrogliogenesis and the limited ability of recruited SVZ neuroblasts to survive long-term and differentiate in the diseased striatum.


Assuntos
Ventrículos Cerebrais/patologia , Corpo Estriado/patologia , Doença de Huntington/patologia , Células-Tronco Neurais/fisiologia , Oligodendroglia/fisiologia , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Bromodesoxiuridina/metabolismo , Contagem de Células , Diferenciação Celular/genética , Proliferação de Células , Modelos Animais de Doenças , Regulação da Expressão Gênica/genética , Doença de Huntington/genética , Camundongos , Camundongos Mutantes , Células-Tronco Neoplásicas , Proteínas do Tecido Nervoso/metabolismo , Fator de Transcrição 2 de Oligodendrócitos , Oligodendroglia/patologia , Fatores de Tempo
5.
J Burn Care Res ; 34(6): e359-67, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23511285

RESUMO

Silver is a commonly used topical antimicrobial. However, technologies to immobilize silver at the wound surface are lacking, while currently available silver-containing wound dressings release excess silver that can be cytotoxic and impair wound healing. We have shown that precise concentrations of silver at lower levels can be immobilized into a wound bed using a polyelectrolyte multilayer attachment technology. These silver nanoparticle-impregnated polyelectrolyte multilayers are noncytotoxic yet bactericidal in vitro, but their effect on wound healing in vivo was previously unknown. The purpose of this study was to determine the effect on wound healing of integrating silver nanoparticle/polyelectrolyte multilayers into the wound bed. A full-thickness, splinted, excisional murine wound healing model was employed in both phenotypically normal mice and spontaneously diabetic mice (healing impaired model). Gross image measurements showed an initial small lag in healing in the silver-treated wounds in diabetic mice, but no difference in time to complete wound closure in either normal or diabetic mice. Histological analysis showed modest differences between silver-treated and control groups on day 9, but no difference between groups at the time of wound closure. We conclude that silver nanoparticle/polyelectrolyte multilayers can be safely integrated into the wound beds of both normal and diabetic mice without delaying wound closure, and with transient histological effects. The results of this study suggest the feasibility of this technology for use as a platform to affect nanoscale wound engineering approaches to microbial prophylaxis or to augment wound healing.


Assuntos
Compostos de Prata/farmacologia , Contenções , Cicatrização/efeitos dos fármacos , Animais , Diabetes Mellitus Experimental , Modelos Animais de Doenças , Masculino , Camundongos , Camundongos Endogâmicos , Nanopartículas , Curativos Oclusivos , Projetos Piloto , Polímeros/farmacologia , Distribuição Aleatória
6.
Exp Neurol ; 241: 125-37, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23261763

RESUMO

The olfactory system continuously incorporates new neurons into functional circuits throughout life. Axons from olfactory sensory neurons (OSNs) in the nasal cavity synapse on mitral, tufted and periglomerular (PG) cells in the main olfactory bulb, and low levels of turnover within the OSN population results in ingrowth of new axons under normal physiological conditions. Subpopulations of bulb interneurons are continually eliminated by apoptosis, and are replaced by new neurons derived from progenitors in the adult forebrain subventricular zone. Integration of new neurons, including PG cells that are contacted by sensory axons, leads to ongoing reorganization of adult olfactory bulb circuits. The mechanisms regulating this adaptive structural plasticity are not all known, but the process is reminiscent of early nervous system development. Neurotrophic factors have well-established roles in controlling neuronal survival and connectivity during development, leading to speculation that trophic interactions between OSNs and their target bulb neurons may mediate some of these same processes in adults. A number of different trophic factors and their cognate receptors are expressed in the adult olfactory pathway. Neurotrophin-3 (NT3) is among these, as reflected by beta-galactosidase expression in transgenic reporter mice expressing lacZ under the NT3 promoter. Using a combination of approaches, including immunocytochemistry, real-time PCR of laser-captured RNA, and adenovirus-mediated gene transfer of NT3 fusion peptides in vivo, we demonstrate that OSNs express and anterogradely transport NT3 to the olfactory bulb. We additionally observe that in mice treated with adenovirus encoding NT3 tagged with hemagglutinin (HA), a subset of bulb neurons expressing the TrkC neurotrophin receptor are immunoreactive for HA, suggesting their acquisition of the fusion peptide from infected sensory neurons. Our results therefore provide evidence that OSNs may serve as an afferent source of trophic signals for the adult mouse olfactory bulb.


Assuntos
Neurônios Aferentes/metabolismo , Neurotrofina 3/metabolismo , Condutos Olfatórios/metabolismo , Animais , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Células COS , Células Cultivadas , Chlorocebus aethiops , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Corantes Fluorescentes , Gânglios Espinais/citologia , Proteínas de Fluorescência Verde/genética , Hipocampo/metabolismo , Técnicas In Vitro , Microdissecção e Captura a Laser , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Imunoeletrônica , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neuritos/metabolismo , Neuroblastoma/patologia , Neurônios Aferentes/citologia , Neurônios Aferentes/ultraestrutura , Neurotrofina 3/genética , Transporte Proteico/fisiologia , RNA Mensageiro/metabolismo , Ratos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Secretogranina II/metabolismo , Transfecção
7.
Ann Surg ; 256(2): 371-7, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22609841

RESUMO

OBJECTIVE: To investigate the antibacterial effect of augmenting a biological dressing with polymer films containing silver nanoparticles. BACKGROUND: Biological dressings, such as Biobrane, are commonly used for treating partial-thickness wounds and burn injuries. Biological dressings have several advantages over traditional wound dressings. However, as many as 19% of wounds treated with Biobrane become infected, and, once infected, the Biobrane must be removed and a traditional dressing approach should be employed. Silver is a commonly used antimicrobial in wound care products, but current technology uses cytotoxic concentrations of silver in these dressings. We have developed a novel and facile technology that allows immobilization of bioactive molecules on the surfaces of soft materials, demonstrated here by augmentation of Biobrane with nanoparticulate silver. Surfaces modified with nanometer-thick polyelectrolyte multilayers (PEMs) impregnated with silver nanoparticles have been shown previously to result in in vitro antibacterial activity against Staphylococcus epidermidis at loadings of silver that are noncytotoxic. METHODS: We demonstrated that silver-impregnated PEMs can be nondestructively immobilized onto the surface of Biobrane (Biobrane-Ag) and determined the in vitro antibacterial activity of Biobrane-Ag with Staphylococcus aureus. In this study, we used an in vivo wound infection model in mice induced by topical inoculation of S aureus onto full-thickness 6-mm diameter wounds. After 72 hours, bacterial quantification was performed. RESULTS: Wounds treated with Biobrane-Ag had significantly (P < 0.001) fewer colony-forming units than wounds treated with unmodified Biobrane (more than 4 log10 difference). CONCLUSIONS: The results of our study indicate that immobilizing silver-impregnated PEMs on the wound-contact surface of Biobrane significantly reduces bacterial bioburden in full-thickness murine skin wounds. Further research will investigate whether this construct can be considered for human use.


Assuntos
Curativos Biológicos , Materiais Revestidos Biocompatíveis/uso terapêutico , Curativos Oclusivos , Engenharia Tecidual/métodos , Animais , Materiais Revestidos Biocompatíveis/química , Modelos Animais de Doenças , Nanopartículas Metálicas , Camundongos , Polímeros/química , Prata/química , Cicatrização
8.
Exp Neurol ; 228(2): 270-82, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21310147

RESUMO

The adult forebrain subventricular zone contains neural stem cells that produce neurons destined for the olfactory bulb, where interneuron populations turnover throughout life. Forebrain injuries can stimulate production of these cells, and re-direct migrating precursors from the olfactory system to areas of damage, where their region-appropriate differentiation and long-term functional integration remain a matter for debate. Paradoxically, little is known about the ability of these progenitors to replace olfactory neurons lost to injury. Their innate capacity to generate bulb neurons may give them an advantage in this regard, and using injections of N-methyl-d-aspartate to kill mature olfactory bulb neurons, combined with bromodeoxyuridine labeling to monitor the fate of adult-born cells, we investigated the potential for injury-induced neurogenesis in this system. Widespread degeneration of bulb neurons did not affect the rate of cell proliferation in the subventricular zone, or cause neuroblasts to divert from their normal migratory route. However migration was slowed by the injury, leading to the accumulation and differentiation of neuroblasts as NeuN+ cells in the rostral migratory stream within 2 weeks of their birth. Despite this, a subset of new neurons successfully invaded the damaged bulb tissue, where they expressed neuronal markers including NeuN, calretinin, GABA, and tyrosine hydroxylase, with some surviving here for as long as 6 months. To test for functional integration of cells born post-injury, we also performed smaller NMDA lesions in restricted portions of the bulb granule cell layer and observed adult-born NeuN+ cells in these areas within 5 weeks, and BrdU+ cells that expressed the immediate-early gene c-fos following odor stimulation. These data suggest that the normal neurogenic capacity of the adult subventricular zone can be adapted to replace subsets of olfactory neurons lost to injury.


Assuntos
Diferenciação Celular/fisiologia , Movimento Celular/fisiologia , Genes fos/fisiologia , Regeneração Nervosa/fisiologia , Células-Tronco Neurais/fisiologia , Neurogênese/fisiologia , Plasticidade Neuronal/fisiologia , Bulbo Olfatório/lesões , Animais , Diferenciação Celular/genética , Movimento Celular/genética , Proliferação de Células , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Regeneração Nervosa/genética , Células-Tronco Neurais/patologia , Neurogênese/genética , Plasticidade Neuronal/genética , Bulbo Olfatório/patologia
9.
Adv Funct Mater ; 21(10): 1863-1873, 2011 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-25558188

RESUMO

We report the design of polyelectrolyte multilayers (PEMs) that can be prefabricated on an elastomeric stamp and mechanically transferred onto biomedically-relevant soft materials, including medical-grade silicone elastomers (E'~450-1500 kPa; E'-elastic modulus) and the dermis of cadaver-skin (E'~200-600 kPa). Whereas initial attempts to stamp PEMs formed from poly(allylamine hydrochloride) and poly(acrylic acid) resulted in minimal transfer onto soft materials, we report that integration of micrometer-sized beads into the PEMs (thicknesses of 6-160 nm) led to their quantitative transfer within 30 seconds of contact at a pressure of ~196 kPa. To demonstrate the utility of this approach, PEMs were impregnated with a range of loadings of silver-nanoparticles and stamped onto the dermis of human cadaver-skin (a wound-simulant) that was subsequently incubated with bacterial cultures. Skin-dermis stamped with PEMs that released 0.25±0.01 µg cm-2 of silver ions caused a 6 log10 reduction in colony forming units of Staphylococcus epidermidis and Pseudomonas aeruginosa within 12 h. Significantly, this level of silver release is below that which is cytotoxic to NIH 3T3 mouse fibroblast cells. Overall, this study describes a general and facile approach for the functionalization of biomaterial surfaces without subjecting them to potentially deleterious processing conditions.

10.
J Comp Neurol ; 515(6): 696-710, 2009 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-19496176

RESUMO

Life-long addition and elimination of neurons within the adult olfactory epithelium and olfactory bulb allows for adaptive structural responses to sensory experience, learning, and recovery after injury. The interdependence of the two structures is highlighted by the shortened life span of sensory neurons deprived of bulb contact, and has prompted the hypothesis that trophic cues from the bulb contribute to their survival. The specific identity and source of these signals remain unknown. To investigate the potential role of target neurons in this support, we employed a neurotoxic lesion to selectively remove them while preserving the remaining nerve projection pathway, and examined the dynamics of sensory neuron proliferation and survival. Pulse-labeling of progenitors with bromodeoxyuridine showed that, as with surgical bulb removal, increased apoptosis in the epithelium triggered accelerated production of new neurons after chemical depletion of target cells. Rather than undergoing premature death, a large subpopulation of these neurons survived long term. The combination of increased proliferation and extended survival resulted in essentially normal numbers of new sensory neurons surviving for as long as 5 weeks, with an accompanying restoration of olfactory marker protein expression. Changes in neurotrophic factor expression levels as measured by quantitative polymerase chain reaction (Q-PCR), and in bulb cell populations, including the addition of new neurons generated in the subventricular zone, were observed in the injured bulb. These data indicate that olfactory sensory neurons can adapt to reductions in their normal target field by obtaining sufficient support from remaining or alternative cell sources to survive and maintain their projections.


Assuntos
Sobrevivência Celular/fisiologia , Bulbo Olfatório/citologia , Mucosa Olfatória/citologia , Neurônios Receptores Olfatórios/fisiologia , Animais , Apoptose/fisiologia , Proliferação de Células , Regeneração Nervosa/fisiologia , Bulbo Olfatório/patologia , Neurônios Receptores Olfatórios/citologia , Neurônios Receptores Olfatórios/patologia , Ratos , Células-Tronco/citologia , Células-Tronco/fisiologia
11.
Behav Brain Res ; 198(2): 388-96, 2009 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-19084559

RESUMO

Tolerance to the hypophagic effect of psychostimulants is contingent on having access to food while intoxicated. Rats given chronic injections of such drugs with access to food learn to suppress stereotyped movements, which interfere with feeding. In contrast, controls given the drug after food access do not learn to suppress stereotypy and, therefore, do not become tolerant. To determine the role of the basal ganglia in this phenomenon, we used in situ hybridization to measure the expression of c-fos mRNA, a marker for neural activation, in the brains of tolerant and nontolerant rats. Rats given chronic amphetamine injections prior to food access learned to suppress stereotyped movements, whereas yoked controls given the drug after feeding did not. Following an acute injection of amphetamine, both of these groups had higher levels of c-fos mRNA than saline-treated controls throughout the striatum, in the nucleus accumbens core, the ventral pallidum and layers V-VI of the motor cortex. In contrast, tolerant rats, which had learned to suppress stereotypy, had higher levels of c-fos mRNA than both amphetamine- and saline-treated controls in the entopeduncular nucleus, globus pallidus, subthalamic nucleus, pedunculopontine nucleus, nucleus accumbens shell, olfactory tubercle, somatosensory cortex, and layers II-IV of motor cortex. These data suggest that the learned suppression of amphetamine-induced stereotypy involves the activation of dorsal striatal pathways previously implicated in response selection as well as the ventral striatum, long implicated in appetitive motivation and reinforcement.


Assuntos
Anfetamina/farmacologia , Gânglios da Base/metabolismo , Estimulantes do Sistema Nervoso Central/farmacologia , Comportamento Alimentar/efeitos dos fármacos , Movimento/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-fos/genética , Comportamento Estereotipado/efeitos dos fármacos , Anfetamina/administração & dosagem , Animais , Gânglios da Base/efeitos dos fármacos , Corpo Estriado/metabolismo , Expressão Gênica/efeitos dos fármacos , Globo Pálido/metabolismo , Hibridização In Situ , Masculino , Córtex Motor/metabolismo , Núcleo Accumbens/metabolismo , Condutos Olfatórios/metabolismo , RNA Mensageiro , Ratos , Ratos Sprague-Dawley , Córtex Somatossensorial/metabolismo , Núcleo Subtalâmico/metabolismo , Fatores de Tempo
12.
Cell Immunol ; 235(2): 122-35, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16243300

RESUMO

Tumor-associated chemokines, including CC chemokine ligand 2/monocyte chemoattractant protein-1 (CCL2), are thought to play many roles in cancer progression. Here we demonstrate the novel finding that during growth of the D1-7,12-dimethylbenzanthracene-3 mammary tumor in BALB/c mice, there is a dramatic up-regulation of CCL2 in splenic T cells at both the mRNA and protein levels upon stimulation. Of particular relevance is the finding that tumor-infiltrating T cells also produce high levels of CCL2. While a variety of tumor cell lines have been found to produce CCL2, we found no detectable levels of CCL2 protein in supernatants of the cultured mammary tumor cells. Investigation of the mechanisms involved in CCL2 induction showed that treatment of splenic T cells with the tumor-derived factors GM-CSF and phosphatidyl serine (PS) resulted in increased CCL2 production. This increased production may be involved in the downregulation of IFN-gamma by the T cells of tumor-bearing mice previously reported in this model, as treatment of splenic T lymphocytes with CCL2 resulted in a decreased secretion of IFN-gamma by those cells.


Assuntos
Neoplasias da Mama/imunologia , Neoplasias da Mama/metabolismo , Quimiocina CCL2/metabolismo , Regulação Neoplásica da Expressão Gênica , Fator Estimulador de Colônias de Granulócitos e Macrófagos/metabolismo , Fosfatidilserinas/metabolismo , Linfócitos T/metabolismo , Animais , Neoplasias da Mama/induzido quimicamente , Células Cultivadas , Quimiocina CCL2/genética , Regulação para Baixo/efeitos dos fármacos , Interferon gama/farmacologia , Camundongos , Camundongos Endogâmicos BALB C , Linfócitos T/efeitos dos fármacos
13.
Brain Res Dev Brain Res ; 157(2): 162-71, 2005 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-15882910

RESUMO

Cholinergic axons originating from the septum form a characteristic layer of preterminal axons and apparent termination in the molecular layer of the hippocampal dentate gyrus. The present study explored the specificity of this characteristic axonal pattern, through the use of organotypic slice co-cultures. Slices of hippocampus were co-cultured with a slice from one of a variety of other potential sources of afferents, and the afferent axons were labeled histochemically or immunocytochemically to determine which afferents distribute within the dentate molecular layer in a pattern similar to that formed by septal cholinergic projections. Acetylcholinesterase (AChE) histochemistry demonstrated that cholinergic axons from septum, substantia innominata, and striatum all consistently targeted the inner molecular layer of the dentate gyrus. AChE-labeled cholinergic axons from dorsal lateral pontine tegmentum and from spinal cord sometimes formed this pattern, while axons from the habenula failed to extend into the dentate gyrus. Immunocytochemically identified monoaminergic axons from the substantia nigra, locus coeruleus, and raphe extended into co-cultured hippocampus; each of these afferent systems displayed a prominent axonal plexus within the hilus of the dentate, but only the raphe axons projected prominently to the molecular layer. These data demonstrate that the molecular layer of the dentate gyrus provides an attractive target zone for some cholinergic and monoaminergic afferents, but not all. Commonalities between neuronal populations that preferentially project to the molecular layer in vitro may offer clues regarding the axon guidance mechanisms that normally direct cholinergic axons to target sites in the dentate gyrus molecular layer.


Assuntos
Diferenciação Celular/fisiologia , Fibras Colinérgicas/metabolismo , Giro Denteado/crescimento & desenvolvimento , Cones de Crescimento/metabolismo , Vias Neurais/crescimento & desenvolvimento , Núcleos Septais/crescimento & desenvolvimento , Acetilcolina/metabolismo , Acetilcolinesterase/metabolismo , Animais , Animais Recém-Nascidos , Tronco Encefálico/citologia , Tronco Encefálico/crescimento & desenvolvimento , Tronco Encefálico/metabolismo , Catecolaminas/metabolismo , Comunicação Celular/fisiologia , Técnicas de Cocultura , Sinais (Psicologia) , Giro Denteado/citologia , Giro Denteado/metabolismo , Histocitoquímica , Imuno-Histoquímica , Vias Neurais/citologia , Vias Neurais/metabolismo , Técnicas de Cultura de Órgãos , Ratos , Ratos Sprague-Dawley , Núcleos Septais/citologia , Núcleos Septais/metabolismo , Serotonina/metabolismo , Substância Inominada/metabolismo
14.
J Comp Neurol ; 455(1): 56-71, 2003 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-12454996

RESUMO

Behavioral evidence indicates that altricial mammals possess olfactory function at early developmental ages, before the olfactory bulb has matured anatomically. We monitored the early anatomic and functional development of the olfactory bulb in rat pups stimulated with odors using in situ localization of c-fos mRNA to identify responsive postsynaptic neurons. Odor-specific spatial patterns of neuronal activation in the glomerular layer were evident from birth, were sharply defined rather than diffuse, and remained relatively unchanged in terms of their bulbar distribution during the first 3 postnatal weeks. In neonates, focal postsynaptic responses in the glomerular layer occurred in the form of clusters of activated tufted neurons. Broad zones of activated mitral cells were located beneath these cell clusters, with scattered neurons in the underlying granule cell layer also expressing c-fos. The cellular composition of these functional neuronal groups shifted from predominantly output neurons at the earliest ages, to increasing incorporation of interneurons as they developed postnatally. The characteristic distribution of activated neurons in the mature glomerular layer, in which the boundaries of individual glomeruli are precisely defined by cells expressing c-fos, emerged near the end of the first week. Broad zones of cRNA hybridization in the mitral cell layer became increasingly restricted as the size of the activated granule cell population increased postnatally, correlating with the functional maturation of inhibitory circuitry. These results provide evidence that the types and distributions of neurons collectively activated by sensory input to glomeruli change as the rat olfactory bulb matures and that distinct, functional odor maps in the glomerular layer are established from birth.


Assuntos
Mapeamento Encefálico/métodos , Neurônios/fisiologia , Bulbo Olfatório/fisiologia , Olfato/fisiologia , Animais , Animais Recém-Nascidos , Feminino , Masculino , Neurônios/química , Odorantes , Bulbo Olfatório/química , Bulbo Olfatório/crescimento & desenvolvimento , Gravidez , Ratos , Ratos Wistar
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