[Sex differences in the cholinergic status of white rats]

Female rats injected with organophosphate inhibitor of acetylcholinesterase chlorophose at doses of 10 mg/kg and 360 mg/kg showed less considerable decrease in blood acetylcholinesterase activity than did male animals. Females compared with males also demonstrated less expressed clinical symptoms of poisoning (salivation, convulsion) after injection of chlorophose at dose of 360 mg/kg. The value of LD50 in female rats was 860 mg/kg, whereas the comparable value in male animals was 700 mg/kg. Following the injection of atropine at doses of 0.1, 0.3, 0.6 mg/100 g female rats showed 2-3 fold increases in basal adrenal and plasma corticosterone levels, but significant decreases in stress-induced corticosterone levels. As for males, the basal and stress-induced values of corticosterone were not significantly affected by atropine administration. These results suggest that functional reserves of cholinergic system and responsiveness of the hypothalamic-pituitary-adrenal axis to cholinergic influence are greater in females than in males. It is concluded that cholinergic status is significantly higher in female rats than in male ones.