Possible role for endogenous oxytocin in estrogen-facilitated maternal behavior in rats.
Intracerebroventricular (i.c.v.) infusions of oxytocin (OXY) induce short-latency maternal behavior in estrogen-primed virgin rats. To investigate if brain OXY might have a role in the onset of maternal behavior at parturition, we have used both antisera to OXY and an analog antagonist of OXY, d(CH2)5-8-ornithine-vasotocin, to reduce the activity of endogenous OXY in a pregnancy-terminated preparation which yields reliable short-latency maternal behavior. Sprague-Dawley rats with lateral ventricle cannulae were ovariectomized and hysterectomized on day 16 of gestation; maternal behavior was stimulated by a s.c. injection of estradiol benzoate (EB). Effects of the i.c.v. infusion of antisera to OXY or of the i.c.v. infusion of d(CH2)5-8-ornithine-vasotocin on the latency to respond to pups were tested by presenting pups 48 h after surgery and EB treatment. Behavioral observations were made for the next 5 h and periodically over the next 5 days. Groups receiving either the antisera to OXY or the analog antagonist had significantly longer latencies to respond to pups than did control groups. In a separate experiment, i.c.v. infusion of d(CH2)5-8-ornithine-vasotocin was shown to have no effect on the performance of maternal behavior in lactating rats 5 days postpartum. These results suggest that OXY may have a role in promoting short-latency maternal behavior in steroid-primed female rats, but that it is probably not involved in sustaining this behavior during lactation.
D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007106:Immune Sera / Q000494:pharmacology; D007774:Lactation; D008425:Maternal Behavior; D010121:Oxytocin / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000276:immunology / Q000494:pharmacology / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D007106:Immune Sera; D004958:Estradiol; D010121:Oxytocin; C040275:oxytocin, 1-(beta-mercapto-beta, beta-cyclopentamethylenepropionic acid)-Orn(8)-