ADRENALECTOMY INCREASES BICUCULLINE-INDUCED SEIZURE SENSITIVITY IN LONG-SLEEP AND SHORT-SLEEP MICE

Susceptibility to bicuculline-induced seizure onset and tonus was increased in LS and SS mice after adrenaletomy (ADX). Replacement with 10% corticosterone (CCS) in ADX animals resulted in a return to seizure latencies equal to those of sham-operated (SHAM) mice. In SS mice, dexamethasone (DEX) and cholesterol-control replacement was as effective as 10% CCS in returning seizure thresholds to SHAM values. In LS mice, DEX was only effective at a low bicuculline dose. Within the sham-operated group SS mice were more susceptible to bicuculline-induced seizure onset than LS mice; however, after ADX latencies did not differ between the two lines. These results suggest that seizure thresholds are regulated to some extent by the hypothalamic-pituitary-adrenal (HPA) axis. The effects of ADX on GABA-related seizure activity may also be influenced by genotype, such that genetic differences in GABA(A) receptor function and adrenocortical responses in LS and SS mice may be responsible for the differential seizure latencies observed in sham-operated mice.