Somatotropic effects of exogenous prolactin and growth hormone in juvenile lizards (Lacerta s. sicula)

Abstract

The somatotropic effects of ovine prolactin and bovine growth hormone (GH) were compared in juveniles of the lizard Lacerta sicula sicula. Both hormones stimulated a marked increase (up to 300%) in food consumption. This effect was associated with a pronounced increase in weight gain which involved some fattening and considerable linear growth: the relative amount of lean growth and fattening were the same with both hormones. GH was slightly more potent on a weight basis, but both were highly effective at a dose of 10 μg/day and some response was evident between 1 and 50 μg/day.

Total lipid storage was the same under both hormone treatments but lipid distributions in the body differed, especially with regard to the liver. GH promoted splanchnomegaly and lipid storage in the liver whereas prolactin decreased hepatic growth and lipid content. When the two hormones were given together, there was no synergism or additive effect with respect to total growth and the effects of prolactin on the liver were antagonized by the GH.