engleski

The effects of adrenalectomy and gonadectomy on sex and stress-induced differences in the sensitivity of rats to bicuculline

The effects of adrenalectomy, gonadectomy and combined adrenalectomy plus gonadectomy on previously described sex-dependent anticonvulsive effect of swim stress was studied in rats. The convulsive signs (myoclonic twitch, generalized convulsions, tonic hindlimb extension) were produced by constant i.v. infusion of GABAA antagonist bicuculline, which started 15 min after termination of swim stress (10-min swim at 18-19 0 C). Adrenalectomy decreased the threshold doses of bicuculline producing the first myoclonic twitch and the onset of generalized convulsions only in females. In adrenalectomized females, but not in males, swim stress enhanced the threshold dose of bicuculline producing generalized convulsions, but unlike in adrenal-intact animals, it failed to enhance the dose of bicuculline producing tonic hindlimb extension. In gonadectomized stressed and unstressed animals all sex differences disappeared, and swim stress enhanced in both sexes only the threshold doses of bicuculline producing tonic hindlimb extension. Adrenalectomized plus gonadectomized animals displayed clear sex differences in doses of bicuculline necessary to produce all convulsive signs. In the same animals swim stress postponed, especially in females, the onset of the first myoclonic twitch and generalized convulsions, but not the onset of tonic hindlimb extension. In summary, our results suggest that hormones of the adrenal and gonadal glands are only partly responsible for decreased susceptibility, especially of female rats, to GABAA antagonist bicuculline. Moreover, they have demonstrated that stress produces gender-specific anticonvulsive effect even in the animals completely deprived of steroid hormones of the peripheral origin.

bicuculline-induced convulsions; sex differences; swim stress; adrenalectomy; gonadectomy

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