Effects of prolactin and experimental handling on liver, fat body and ovary lipid contents and their daily variations in Rana esculenta (L.)

Three groups of females of R. esculenta were kept under constant temperature and photoperiod conditions (L:D = 12:12). One group consisted of intact frogs, while the remainder were given saline or prolactin (PRL) injections 6 hours after light onset. After 5 days of such treatment examination was made every 6 hours over a 24-hour period of lipid content in the liver, fat bodies (FBs) and ovaries and the level and composition of plasma lipids. Both the experimental handling and PRL treatment caused in animals a decrease in weight of the liver and mobilization of lipid metabolism, inducing a shift in lipids and a change in their distribution within the organs examined. In animals injected with saline lipids were transported chiefly to FBs, whereas in frogs given PRL the whole, combined lipid content in these organs decreased considerably, suggesting that they had been transported to the tissues and that their catabolism had been intensified. It is suggested also that PRL has sparing effect on the ovarian lipid pool. In both groups, especially in frogs given PRL, there was a marked increase in plasma lipid concentration and the contents in percentages of its different classes. Increase in concentration of phospholipids (3X) and cholesterol (10X) in animals given PRL is particularly distinct. Both experimental handling and PRL administration affected the pattern of diurnal fluctuations in the lipid content of the organs examined.