title: Cholecystokinin stimulates and inhibits lordosis behavior in female rats.
abstract: Recently, IP CCK-8 has been shown to inhibit lordosis in sexually experienced, estradiol benzoate (EB) and progesterone (P) primed rats. However, receptivity is influenced by prior sexual experience and/or exposure to sex steroids, as well as the steroid dosage administered before testing. Thus, we examined the effect of CCK-8 (3 micrograms/kg; IP) on lordosis in rats with different degrees of receptivity. Three weeks after ovariectomy, females were treated with EB followed 48 hr later with P, or with EB alone. CCK-8 significantly facilitated lordosis in rats given 5 micrograms EB. Following a 5 week nonexperimental period, animals were more receptive and CCK-8 significantly inhibited lordosis in the 5 or 10 micrograms EB groups. In a separate experiment, rats were ovariectomized, adrenalectomized, and treated with EB alone. As in the first experiment, CCK-8 facilitated and inhibited lordosis. CCK-8's effects were highly dependent on the female's receptivity, facilitating lordosis when receptivity was low and inhibiting lordosis when receptivity was high (but not maximal). In conclusion, IP CCK-8 modulates lordosis behavior independent of P, but its effects depend on the female's degree of receptivity.
mesh_terms: D000315:Adrenalectomy; D000818:Animals; D002766:Cholecystokinin / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D010052:Ovariectomy; D011374:Progesterone / Q000378:metabolism / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D013268:Stimulation, Chemical
chemical_list: D011374:Progesterone; D004958:Estradiol; D002766:Cholecystokinin