Effect of ephedrine on neuronal plasticity of hypoxic-ischemic brain damage in neonatal rats

Study the effect of ephedrine on neural plasticity of hypoxic ischemic brain damaged (HIBD) in neonatal rats, and explore the underlying molecular mechanism.

60 Sprats suffered from HIBD (7 days old) were randomly divided into ephedrine group, D-amphetamine (D-AMPH) group, cytidine triphosphate (CTP) group, ganglioside (GM1) group, and spontaneous recovery group. Using immunohistochemical method to test the expression of growth-associated protein-43(GAP-43) and synaptophysin (SYP) on one side of hippocampal CA3 area, then, 4 weeks later, Morris Water Maze test was performed for five days.

(1) The expression levels of GAP-43 and SYP on hippocampal CA3 area in ephedrine group were higher than that in spontaneous recovery group (P<0.05). However, there was no statistical difference in ephedrine groups, CTP group, and D-AMPH group. (2) The average time of escape latency was significantly shorter in treating groups than that in spontaneous recovery group (P<0.05), and the frequency of original platform passing was higher than that in spontaneous recovery group (P<0.01). The average time of escape latency was longer in ephedrine group than that in GM1 group. The frequency of original platform passing was significantly less in ephedrine group than that in GM1 group, No statistical difference found in ephedrine groups, CTP group, and D-AMPH group.

Ephedrine may enhance memory, the abilities of spatial orientation and learning in HIBD rats. This protective effect may be associated with increasing synaptic connectivity, as assessed by increased expression of GAP-43 and SYP after HIBD. Ephedrine triggered similar protection against HIBD as treatment of D-AMPH and CTP. However, the amelioration of ability of spatial orientation, learning and memory by ephedrine on HIBD rats in later stage is slightly weaker than that by GM1, which may be related with ephedrine dosage.