Effects of REM deprivation on the lordosis response induced by gonadal steroids in ovariectomized rats.

Ovariectomized rats were submitted to REM sleep deprivation (REMd) using the water tank technique and their behavioral responsiveness (lordosis) to gonadal steroids was tested. In Experiment 1, animals received 2 micrograms of estradiol benzoate (EB) followed by 2 mg of progesterone (P) 44 hours later. Several REMd periods (12, 72, 96 and 120 hr) were applied, all ending four hr after P. REMd animals showed significantly lower lordosis quotients (LQ) than undisturbed sleep animals regardless of the duration of the deprivation period. In Experiment 2, animals received a single dose of EB (2 micrograms) and were REMd for 120 hours. Animals were tested daily to evaluate their LQ. EB, at this dose level, failed to elicit significant lordosis behavior in undisturbed sleep rats. REMd rats gradually increased their LQ values reaching maximal levels at 72 hours. Adrenalectomized control groups receiving the same hormonal treatment responded similarly to the experimental groups, thus discarding the participation of adrenal steroids in these effects. The present results show that REMd differentially affects the response to E and P in ovariectomized rats, enhancing the former and inhibiting the latter.