Sex differences in the neuroprotective effect of insulin against chemically-induced convulsions in mice

Insulin, an important regulator of peripheral metabolism, has been reported to interact with many neurotransmitter systems including those associated with convulsion. The effect of insulin against pentylenetetrazole and strychnine-induced convulsions in mice, as well as possible sex differences, were evaluated in this study. Mice of both sexes weighing between 20 and 25 g were administered insulin intraperitoneally at doses of 1, 2, 4 and 8 IU/kg. Each mouse received a convulsive dose of pentylenetetrazole (100 mg/kg, i.p.) or strychnine (2 mg/kg, i.p.) and was observed for the onset of convulsions and occurrence of death. Against pentylenetetrazole-induced convulsions, all the doses of insulin used significantly (p < 0.05) prolonged the onset of convulsions and significantly delayed the time of death in male mice when compared with control. However, in female mice, only insulin 8 IU/kg significantly prolonged the onset of convulsions, while insulin 4 IU/kg significantly delayed the time of death. Against strychnine-induced convulsions, insulin at the doses of 2 and 4 IU/kg significantly (p < 0.05) prolonged the onset of convulsions in male mice relative to control, while 8 IU/kg insulin significantly prolonged the time of death in male mice compared to control. However, none of the doses of insulin administered to female mice were effective against strychnine-induced convulsions. These results show that insulin produced sex-related protective effects against chemically-induced convulsions in mice. Keywords: Insulin, convulsion, pentylenetetrazole, strychnine, male mice, female mice.