Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 3, 1995
Publication Date: N/A
Interpretive Summary: Recent work indicated that treatment of newborn pigs with vitamin A for two weeks increased uterine gland tissue in the developing uterus. Uterine glands are responsible for producing several substances known to be required by developing unborn piglets during pregnancy. Therefore, we tested whether treatment of pigs during the prepubertal period with vitamin nA would cause a permanent increase in uterine gland tissue and improve survival of unborn piglets during pregnancy in treated pigs as adults. To improve our test of the effect of vitamin A treatment on the ability of the uterus to carry unborn piglets and also to examine the development of the uterus during and after the treatment period, one uterine horn and ovary were removed on either d 28, 84 or 112 of age for each gilt. Pigs were subsequently raised to adulthood, mated and killed on day 44-47 of pregnancy to obtain the number of unborn piglets present in the remaining uterine horn. In contrast to previous results, vitamin A treatment during the prepubertal period did not affect the amount of gland tissue in the uterus and instead decreased uterine smooth muscle content. Vitamin A treated pigs had longer remaining uterine horns as adults but despite this increase, no increase in litter size was obtained. Thus, prepubertal treatment of pigs with vitamin A did not increase litter size during subsequent pregnancy.
The effect of prepubertal retinyl palmitate (RP) treatment on uterine development and adult uterine capacity was determined. Gilts remained intact or were unilaterally hysterectomized-ovariectomized (UHO) on d 28, 84 or 112 of age. Starting at birth, half of the gilts in each UHO group were treated with RP (14,000 IU/kg*wk) and half received control solution. All intact gilts received control solution. Blood samples were collected on d 28, 56 84 and 112 of age and were measured for retinoid and retinol binding protein (RBP). At UHO, the removed uterine horn was weighed, a 1 cm piece was processed for morphometric analysis of the uterine wall and tissues were also incubated in minimal essential medium (MEM) plus 3H-leucine to assess total protein and RBP production. After puberty, gilts were mated, killed on d 44 to 47 of pregnancy, and uterine length, number of CL and fetuses, and fetal, placental and empty uterine weights were recorded. To assess adult endometrial function, endometrial tissues were incubated in MEM plus 3H-leucine and nondialyzable radioactivity, acid phosphatase and RBP production were measured. During the prepubertal period, RP treatment decreased myometrial area but had no effect on other components of the uterine wall. Treatment with RP also did not effect production of nondialyzable radioactivity or secretion of RBP by uterine tissue. During subsequent pregnancy, prepubertal RP treatment increased uterine length, but did not affect uterine weight, number of fetuses, placental or fetal weights, or endometrial production of nondialyzable radioactivity, acid phosphatase or RBP. Therefore, prepubertal RP treatment at the dosage administered did not affect uterine capacity.