Effect of ganglioside on cognitive function in rats with diabetic encephalopathy

Abstract

Objective To evaluate the effect of ganglioside on cognitive function in rats with diabetic encephalopathy and investigate its mechanism.Methods Sixty Wistar rats were equally randomized into control group (A),diabetic encephalopathy group (B) and diabetic encephalopathy+ganglioside treatment group (C); each group was further divided into two subgroups according to the time points of 1 and 3 months (n=10).Ganglioside was injected intraperitoneally at 10 mg/kg daily in rats of the C1 and C3 groups.The cognitive function was investigated by Morris water maze test.Immunohistochemistry and RT-PCR were performed to determine the protein and mRNA expressions of neuron-specific enolase (NSE) and S-100B.Results (1) By Morris water maze test,the performances of A1,B1 and C1 groups were (6.7±0.5) s,(14.1±1.7) s and (6.9±0.6) s,while those of A3,B3 and C3 groups were (7.0±0.5) s,(26.6±2.1) s and (14.3±1.7) s.Mild dysfunction of learning and memory was detected in B1 group,and the dysfunction became worse in B3 group; while it was greatly improved in ganglioside-treatment groups.(2) Immunohistochemistry showed that the NSE protein expressions of A1,B1 and C1 groups were (0.081±0.009),(0.292±0.034) and (0.090±0.011),while those of A3,B3 and C3 groups were (0.089±0.013),(0.402±0.068) and (0.184±0.028); as compared with control groups,significant increases were noted in B1 and B3 groups,and dramatic reduces were noted in C1 and C3 groups; the tendency of S-100B protein expression was similar with NSE.(3) By RT-PCR,the NSE mRNA expressions of A1,B1 and C1 groups were (0.121±0.011),(0.532±0.047) and (0.130±0.019),while those of A3,B3 and C3 groups were (0.135±0.024),(1.178±0.128) and (0.371±0.039); as compared with control groups,significant increases were noted in B1 and B3 groups,and dramatic reduces were observed in C1 and C3 groups; the tendency of S-100B protein expression was similar with NSE.(4) Similarly,both NSE and S-100B expressions were positively correlated with Morris water maze test results.Conclusion Diabetic encephalopathy may be closely related to the hippocampal NSE and S-100B super-expressions; ganglioside has a protective effect by inhibiting NSE and S-100B expressions. Key words: Diabetic encephalopathy; Ganglioside; Cognitive function; Neuron-specific enolase; S-100B