Abstract

The medial preoptic area (mPOA) is critical in the control of male sexual behaviour, and dopamine (DA) plays an important role within it However, both the roles of DA and the mPOA in female sexual behaviour are not fully understood, with few studies producing consistent data. In the present set of experiments the role of DA within the mPOA on the full cascade of female sexual behaviour is investigated. Ovariectomized female rats were bilaterally cannulated into the mPOA and hormonally primed either fully, with estradiol benzoate (EB) and progesterone (P), or partially with EB-alone. Since it was hypothesized that DA plays a facilitative role in female sexual behaviour, a nonselective DA receptor, and selective DA Dl and D2 receptor agonists (apomorphine, SKF 38393 and quinpirole, respectively) were infused to EB-alone females and nonselective DA receptor, and selective DA Dl and D2 receptor antagonists (flupenthixol, SCH 23390, and raclopride, respectively) were infused to EB+P rats. Copulatory behaviour was then immediately tested over a period of thirty minutes in a bilevel chamber with a sexually experienced male. Precopulatory behaviours were increased in EB-alone females following infusions of a low dose (0.25 æg) of apomorphine and both a low (0.05 æg) and a high dose (0.2 æg) of quinpirole. Hops and/or darts were decreased following infusion of a low dose (0.05 æg) of SKF 38393. In EB+P females, precopulatory behaviours were decreased following infusions of a high dose (4.0 æg) of SCH 23390, but were increased following infusions of a high dose (4.0 æg) of raclopride. Flupenthixol had no effect on sexual behaviour. These results suggest that the ratio of DA Dl/D2 activity within the mPOA of female rats is critical for the expression of precopulatory behaviours, and may work within brain areas responsible for stimulating lordosis to control the timing of female sexual behaviour.