Hysterectomy-induced maternal behavior pregnancy in the rat

Performed hysterectomies between the 10th and 19th day of pregnancy, and tested females with pups for the onset of maternal behavior starting 0, 24, 48, or 72 hr after surgery. Ss were 394 Charles River female rats. Pups remained with females overnight, and testing was repeated daily with fresh pups until females exhibited maternal behavior. Latencies for the onset of maternal behavior were shorter after hysterectomy on the 10th and 16th days of pregnancy than in intact pregnant Ss at the same stages of pregnancy; latencies become shorter, the later the termination of pregnancy. When the ovaries were removed along with hysterectomy during pregnancy, short-latency maternal behavior no longer was exhibited. Pregnant Ss were tested during the last 40 hr of pregnancy: nest building began at 34 and retrieving at 28 hr prepartum. The effect of hysterectomy during pregnancy on ovarian secretion of estrogen and progesterone is reviewed, and it is concluded that the rise in estrogen secretion, which follows hysterectomy during pregnancy, is most likely the cause of the rapid onset of maternal behavior after hysterectomy. A similar proposal is made for the prepartum onset of maternal behavior in intact pregnant females. (50 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).