DISSOCIATION OF ACTIVE FROM IMMOBILITY COMPONENTS OF SEXUAL-BEHAVIOR IN FEMALE RATS BY CENTRAL 6-HYDROXY-DOPAMINE - IMPLICATIONS FOR CA INVOLVEMENT IN SEXUAL-BEHAVIOR AND SENSORIMOTOR RESPONSIVENESS

Ovariectomized female rats were given a hormone treatment (2 .times. 8 .mu.g/kg estradiol benzoate) that normally supports only low levels of lordosis response and no soliciting behavior in tests with sexually active males. When subjected to an intraventricular 6-hydroxydopamine (6-OHDA) procedure (with pargyline pretreatment) that produced 85% and 95% depletions of caudate dopamine and cortical norepinephrine, respectively, these females exhibited dramatic increase in intensity and frequency of lordotic response but no soliciting behavior over 3 weekly tests. The increase in lordosis was not due to drug or stress-induced adrenal progesterone release, since dexamethasone suppressed progesterone levels, as documented by radioimmunoassay, but not higher receptivity of 6-OHDA treated females. In other ovariectomized females given a hormone regimen (2 .times. 50 .mu.g/kg estradiol benzoate plus 500 .mu.g progesterone) that supported maximal levels of lordosis and soliciting, the same 6-OHDA treatment prolonged average lordosis duration while decreasing incidence and duration of soliciting. Differential effects of interfering with catecholamine, and the more likely dopamine function on soliciting and lordosis components of female sexual behavior might best be understood as dissociation between mutually antagonistic behavior patterns, such that responsiveness involving active orientation and forward locomotion is suppressed, while responses requiring immobility are augmented.