ABSTRACT
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.
Subject(s)
Animals , Male , Rats , Sciatic Nerve/drug effects , Melatonin/pharmacology , Nerve Regeneration/drug effects , Peripheral Nerves , Sciatic Nerve/physiology , Time Factors , Rats, Wistar , Myelin Sheath/drug effects , Nerve Regeneration/physiologyABSTRACT
The blood-nerve barrier (BNB) is a barrier system similar to blood-brain barrier (BBB), which can selectively limits the interchange of materials between the blood and the peripheral nervous system. It has been reported that the change of BNB permeability occurs in nerve lesions, and further research on BNB is of great significance for the treatment of those diseases. This paper mainly introduced the structure and function of BNB, progress of BNB cellular biology, changes and significance of BNB under pathological conditions, and the possible association between BNB and drug effects.
ABSTRACT
There is a great variety of injuries that affect peripheral nerves derived from acquired or congenital degenerative diseases affecting the central nervous system that cause loss of sensorimotor functions. The objective of this work was to perform an end-to-side or side-to-side experimental axonal stereological study in order to compare volume density of axons, endouneuro and myelin sheath (and muscle mass) in peroneal and tibial nerves, with anastomosis contact from 0.25 cm to 0.50 cm. After approval of the Ethics Committe, 20 male Wistar rats were divided into four groups of five rats each (G1= end-to-side neurorrhaphy; G2= side-to-side neurorrhaphy of 0.25 cm; G3= side-to-side neurorrhaphy of 0 cm and G4= Control of normality). After 180 days, fragments of peroneal and tibial nerves were collected for histological and stereological study. In comparative stereological experimental study between neurorraphies, the volume density of axons, myelin sheath of tibial and fibular nerves, as well as the post-surgical muscle mass, remains the same in end-to-side and side-to-side neurorraphies, regardless of contact area of anastomosis. It can be inferred, as surgical repair options, both end-to-side neurorrhaphy to recover and prevents atrophy of the endplate as side-to-side neurorraphy that is independent of the distance between the nerve stumps.
Gran variedad de lesiones atingen a los nervios periféricos, derivadas de enfermedades adquiridas o degenerativas congénitas que afectan la parte central del sistema nervioso y que ocasionan pérdida de funciones sensoriomotoras. El objetivo de ese trabajo fue realizar un estudio experimental estereológico axonal post neurorrafias termino-lateral o latero-lateral para comparar densidad de volumen de axones, endoneuro y vaina de mielina (así como masa muscular) en nervios fibular y tibial, con unión de contacto entre 0,25 cm y 0,50 cm. Tras la aprobación del comité de ética, fueran utilizados 20 ratones machos de la raza Wistar divididos en cuatro grupos de 5 ratones cada uno (G1= Neurorrafia término lateral; G2= Neurorrafia latero lateral de 0,25 cm; G3= Neurorrafia latero lateral de 0,50 cm y G4= Control). Posteriormente, fragmentos de los nervios tibiales y fibulares fueron procesados para estudios histológicos y estereológicos. En el estudio experimental estereológico comparativo entre neurorrafias termino-lateral y latero-lateral, la densidad de volumen de axones, endoneuro y vaina de mielina de nervios tibial y fibular y también la masa muscular post quirúrgica se mantuvo equitativa, independientemente del área de unión de contacto. Podemos inferir como opciones de reparación quirúrgica, que el tratamiento de la neurorrafia termino-lateral y latero-lateral previnen la atrofia de placa motora, independiente de la distancia entre los muñones nerviosos.
Subject(s)
Animals , Male , Rats , Neurosurgical Procedures/methods , Peroneal Nerve/pathology , Peroneal Nerve/surgery , Tibial Nerve/pathology , Tibial Nerve/surgery , Axons/pathology , Myelin Sheath/pathology , Nerve Regeneration , Peripheral Nerves/pathology , Peripheral Nerves/surgery , Rats, WistarABSTRACT
The perineurial cells of the small nerve branch of the normal human abdominal wall are observed with electron microscope. The fibrous long-spacing bodies (FLS) are found within the interstitial substance of the endoneurium. 1. 2-5 layers of the perineurial cells surround the nerve fasciculus. The perineurial cells are squamous in shape and the cytoplasm contains microfilaments and pinocytotic vesicles. Each perineurial cell has an obvious basement membrane on its basal surface but the fibroblasts, whatever situated in the endoneurium or on the outer surface of the perineurium, has no basement membrane. Numerous desmosome and some gap junctions between the close attached perineurial cells are demostrated. The collagen fibrils between perineurial cells can be often shown. FLS bodies and collagen fibrils about 45 nm in diameter in the interstitial substance of endoneurium inside perineurial cells are demonstrated. In the connective tissue surrounding the outside of perineurial cells, the collagen fibrils of 80 nm in diameter can be seen, but no FLS bodies present there. 2. FLS bodies in the endoneurial matrix can be demostrated. Most of them closely associated with the basement membrane of the Schwann cells surrounding the unmyelinated nerves but no FLS bodies are found associate with those of the myelinated nerves. A few FLS bodies do not relate to basement membrane and they are invested only with the collagen fibrils. In the longitudinal sections, most of FLS bodies are in spindle shape of various sizes, their longitudinal axes parallel to that of the adjoining collagen fibrils. Sometimes the FLS bodies continue with the collagen fibrils are found. Occasionally, FLS body like a bridge locate between two Schwann cells and its dark bands continue to the basement membrane of the Schwann cells. Two or three FLS bodies may fuse together but their cross bands do not registered at the same level. In the oblique sections, FLS bodies are nearly rectangular in shape, with the cross bands shown, and their appearance do not show greaty difference from those in longitudinal sections. The periodicity of FLS bodies is about 133nm in length; the dark band in it is about 53 nm, which is made of the dense granular substance; the light band is about 80 nm, which is made of a network with approximated parallel microfilaments. There are no further crossstriated structures within the periods. Some problems, such as the role of the perineurial cells, the relationship of FLS bodies with basement membrane, are briefly discussed.