Effect of exogenous hydrogen sulfide on hippocampal neuronal damage induced by epilepsy

Objective To explore the effects of exogenous supplier of hydrogen sulfide (H2S) sodium hydrosulfide (NaHS) on hippocampal neuronal damage in immature rats with status epilepticus (SE) induced by lithium-pilocarpine. Methods Three or four weeks old Sprague Dawley rats were divided into five groups according to random number table: normal group, normal + NaHS group, epilepsy group, epilepsy+NaHS group and epilepsy+hydroxylamine (HA) group (n=6). SE models were induced by lithium-pilocarpine in immature rats of epilepsy group, epilepsy+NaHS group and epilepsy+ HA group; meanwhile, NaHS (10 mg/kg) or hydroxylamine (1 mg/kg) or equivalent normal saline were given by intraperitoneal injection, respectively. Hippocampus tissues and plasma were collected, and the concentrations of H2S in the plasma and hippocampus were detected by spectrophotometer. The cystathionine beta synthase (CBS) mRNA expression in the hippocampus was assayed by real-time PCR. Hippocampal neurons were observed by Nissl staining. The neuron-specific enolase (NSE) expression in the hippocampus was assayed by Western blotting. Results Spectrophotometer and real-time PCR results showed that the concentration of H2S in the plasma and hippocampus and the CBS mRNA levels in the hippocampus of the epilepsy group were significantly lower than those in the normal group (P< 0.05); these indexes in the epilepsy+ NaHS group were up-regulated as compared with those in the epilepsy group, while those in the epilepsy+HA group were significantly lower than those in the epilepsy group (P<0.05). Nissl staining showed that decreased number of nissl bodies and disordered arrangement of pyramidal cells in the hippocampus CA3 area of epilepsy group were noted as compared with those in the normal group; the loss of nissl bodies and the disordered arrangement of pyramidal cells in the hippocampus in epilepsy + NaHS group were improved as compared with those in the epilepsy group. Western blotting showed that the NSE expression in the epilepsy group was significantly higher than that in normal group, and NSE expression in epilepsy+NaHS group was significantly lower than that in the epilepsy group, while NSE expression in epilepsy+ HA group was significantly higher than that in the epilepsy group (P<0.05). Conclusion Exogenous H2S supplier NaHS could significantly up-regulate the CBS mRNA level in the hippocampus, increase the hydrogen sulfide content in the plasma and hippocampus, decrease the NSE expression in the hippocampus, and eventually attenuate neurons damage of hippocampus caused by epilepsy in rats. Key words: Hydrogen sulfide; Status epilepticus; Hippocampus; Neuron