Abstract
Summary
(1) We have investigated the effect of growth hormone (GH) and oxytocin alone, and in combination, upon lactation in the rat. Amount of milk obtained by a litter of 6 during 30 minutes nursing on day 14 postpartum, expressed as percent litter body weight, was used as the index of response. (2) Control yields averaged 3.8% with normal distribution. Removal of milk with aid of .1 USP unit/kg oxytocin i.v. resulted in 50% higher yield with more uniformity among individual values. (3) GH injected subc., from days 7-13 at dose of 1 mg/rat/day evoked a 41.1% increase in milk yield. Yields obtained in GH-treated lactating rats with aid of oxytocin were greater and more uniform than with GH or oxytocin alone. The significance of this is discussed. (4) GH had no effect upon pituitary, thyroid or adrenal weight/100 g body weight. GH caused a significant increase in percent weight gain of mothers but not their litters. Litter growth rate as an index of lactation in the rat is discussed.
Get full access to this article
View all access options for this article.