Appetitive and consummatory sexual behaviors of female rats in bilevel chambers II. Patterns of estrus termination following vaginocervical stimulation

Copulation with intromission or manual vaginocervical stimulation (VCS) sho rtens the duration that intact female rats maintain lordosis responding dur ing estrus. The present study examined whether VCS could shorten the durati on of both appetitive and consummatory measures of female sexual behavior, and whether these effects occur differentially in time and across different hormone priming intervals. Ovariectomized, sexually experienced female rat s were administered subcutaneous injections of estradiol benzoate 48 h and progesterone 4 h, before receiving 50 manual VCSs with a lubricated glass r od distributed over 1 h. Control females received sham VCSs distributed ove r the same time. The females were then tested for sexual behavior in bileve l chambers with two sexually vigorous males (to one ejaculatory series or 1 0 min with each male, separated by 5 min) 12, 16, and 20 h after VCS. Prior to the final hormone treatment, different groups of females had been given the same hormone treatment either 28, 14, 7, or 4 days before. In females tested at 28- and 14-day hormone intervals, VCS induced both active and pas sive rejection responses at 12, 16, and 20 h. In contrast, females that rec eived sham VCS displayed relatively normal sexual behavior at 12 h, althoug h by 16 and 20 h these females displayed active and passive rejection. Fema les tested at 7- or 4-day intervals displayed normal levels of lordosis at all testing times, regardless of VCS treatment. These data indicate that VC S facilitates rejection responses that precede the decrease in lordosis res ponsiveness. However, the effects of VCS are dependent on the frequency of hormone priming, suggesting that hormone treatment may block some of the lo ng-term inhibitory effects of VCS on female sexual behavior. (C) 2000 Acade mic Press.