Differential astroglial responses in the spinal cord of rats submitted to a sciatic nerve double crush treated with local injection of cultured Schwann cell suspension or lesioned spinal cord extract: implications on cell therapy for nerve repair

PURPOSE: Reactive astrocytes are implicated in several mechanisms after central or peripheral nervous system lesion, including neuroprotection, neuronal sprouting, neurotransmission and neuropathic pain. Schwann cells (SC), a peripheral glia, also react after nerve lesion favoring wound/repair, fiber outgrowth and neuronal regeneration. We investigated herein whether cell therapy for repair of lesioned sciatic nerve may change the pattern of astroglial activation in the spinal cord ventral or dorsal horn of the rat. METHODS: Injections of a cultured SC suspension or a lesioned spinal cord homogenized extract were made in a reservoir promoted by a contiguous double crush of the rat sciatic nerve. Local injection of phosphate buffered saline (PBS) served as control. One week later, rats were euthanized and spinal cord astrocytes were labeled by immunohistochemistry and quantified by means of quantitative image analysis. RESULTS: In the ipsilateral ventral horn, slight astroglial activations were seen after PBS or SC injections, however, a substantial activation was achieved after cord extract injection in the sciatic nerve reservoir. Moreover, SC suspension and cord extract injections were able to promote astroglial reaction in the spinal cord dorsal horn bilaterally. Conclusion: Spinal cord astrocytes react according to repair processes of axotomized nerve, which may influence the functional outcome. The event should be considered during the neurosurgery strategies.

OBJETIVO: Astrócitos reativos participam de vários mecanismos após lesões do sistema nervoso central e periférico, os quais incluem neuroproteção, brotamento neuronal, neurotransmissão e dor neuropática. As células de Schwann (CS), um tipo de glia periférica, também reagem com a lesão do nervo, podendo interferir com o reparo e cicatrização, crescimento de fibras e regeneração neuronais. Investigamos aqui a possibilidade da terapia celular para o reparo do nervo ciático poder alterar o padrão da ativação astrocitária nos cornos anterior e posterior da medula espinal do rato. MÉTODOS: Suspensão de CS cultivadas ou extrato homogeneizado de medula espinal lesada de rato foram inoculados num reservatório feito a partir de dois esmagamentos aplicados no nervo ciático do rato distantes 0,5mm entre si. Injeção local de salina tamponada serviu como controle. Os ratos foram mortos uma semana após e os astrócitos da medula espinal marcados por método imunohistoquímico e quantificados por análise de imagem. RESULTADOS: No corno anterior da medula, ipsilateral à lesão, ativação astrocitária leve foi vista após as injeções de tampão ou CS, entretanto, ativação celular intensa foi observada nesta região com a inoculação neural do extrato homogeneizado de tecido medular lesado. Adicionalmente, as inoculações de CS e de extrato homogeneizado de tecido medular promoveram forte reação astrocitária no corno dorsal da medula espinal, bilateralmente. CONCLUSÕES: Os astrócitos da medula espinal reagem em função do processo de reparo do nervo lesado, o que pode influenciar o resultado funcional esperado, algo que deve ser considerado durante o planejamento da estratégia neurocirúrgica.

Screening of brain-derived neurotrophic factor-like compounds / 中国药理学通报

Aim To apply simple combined models to screen small molecule BDNF-like compounds for potential pharmacotherapy of central nerve degenerative diseases.Methods BDNF-like bioactivities were dentified with effects against apoptosis induced by serum withdrawal in turn in cultured human SH-SY5y cells,rat NIH3T3/trkB cells vs NIH3T3 cells,using MTT technique.Results More than 400 compounds were tested by using these methods.11 of them presented protective effects on apoptosis induced by serum withdrawal in SH-SY5y cells.2 of them also provided selective protection against apoptosis induced in NIH3T3/trkB cells versus in NIH3T3 cells,which were identified as BDNF-like compounds.Further study showed that these 2 compounds could withstand SH-SY5y cell injuries induced by 6-OHDA.Conclusion All the above studies provide a useful series of simple models for BDNF-like drug screen and some compound candidates for further study of neuroprotection.

Effects of Insulin, 2-Deoxyglucose and Dichloroacetate on Acute Focal Cerebral Ischemia in Rats

Hyperglycemia has been reported to worsen the tolerance of the brain to ischemia, and it has therefore been recommended that patient undergoing neurosurgical procedures not receive glucose-containing solutions. Since ischemic events lead to increased lactate production and accumulation and hence neuronal damage, the present study was designed to test the effect of insulin-induced hypoglycemia and decreased lactate by 2-Deoxyglucose and Dichloroacetate on focal cerebral ischemia in rats. Although the pre and post-ischemic blood glucose levels of control group and Dichloroacetate group showed no change, the blood glucose level of 2-Deoxyglucose group showed a significant increase(p=0.001), and insulim group a significant decrease(p=0.004). The reducing effects on the infarct zone in these three treated groups were found with statistical significance. As compared with control group, the tissue lactate levels of treated groups were decreased in both infarct zone and border zone but these data did not show statistical significance. From these observations, it is suggested that reduction of lactate production and accumulation could be beneficial by affording neuronal protection in ischemic tissues.