Ketanserin and anxiety levels: influence of gender, estrous cycle, ovariectomy and ovarian hormones in female rats.

The influence of gender, estrous cycle, ovariectomy and ovarian hormones on the behavioral effects of the 5-HT2 receptor antagonist, ketanserin (KET), was studied. Intact males, female rats in the four stages of the estrous cycle and ovariectomized (OVX) female rats 14 days after surgery were used. The OVX rats received progesterone [PROG, 25 mg/kg, subcutaneously (SC)] and/or estradiol benzoate (EB, 10 micrograms/kg, SC). KET (3 mg/kg, SC) was injected 30 min before testing. All the animals were subjected to the following behavioral tests: exploration of an elevated plus-maze and retention of a passive-avoidance response. KET enhanced the exploration of the open arms in diestrous female rats but inhibited this behavior during the other stages of the cycle and in OVX rats injected either with oil or EB. This dose of KET was ineffective in males and in OVX rats injected with PROG. Furthermore, KET inhibited the retention of the passive avoidance response in males, in diestrous and metestrous female rats and in OVX rats injected with oil. In estrous females and in OVX rats injected with EB, KET enhanced the passive-avoidance response. These results demonstrate that the sensitivity to KET differs with the gender, estrous cycle and hormonal treatment and suggest that central serotonergic activity is influenced by the hormonal status of the animal.