The effect of growth hormone and prolactin preparations on the intermediary metabolism of rat adipose tissue

Abstract

1.1. The effects of a bovine growth hormone preparation and three ovine prolactin preparations (PLR, PLC and PLF) on adipose tissue metabolism were compared with those of insulin and adrenalin. PLR and PLC were prepared using a DEAE-cellulose column, whereas PLF was prepared using Sephadex G-75. PLF contains two minor components which are largely absent from PLC. Adrenalin, bovine growth hormone, PLC and PLR increased (a) CO2 production from [6-14C]glucose; (b) glyceride-glycerol production from [I-14C]glucose to a greater extent than from [6-14C]glucose; (c) inhibited lipogenesis and (d) stimulated lipolysis. Dilution of PLC resulted in a diminution of lipolysis with a corresponding decrease in effect upon glucose metabolism. It was concluded that the effect of these pituitary hormones on glucose metabolism by rat adipose tissue is dependent upon their stimulation of lipolysis. Conversely, insulin and PLF stimulated (a) CO2 production from [I-14C]glucose; (b) lipogenesis; and (c) more glyceride-glycerol production from [6-14C]glucose than from [I-14C]glucose. PLC and bovine growth hormone reversed the stimulation of glycogen synthesis by insulin.2.2. PLC, PLF and insulin stimulated protein synthesis from [I-14C]leucine by adipose tissue taken from either normal or hypophysectomized rats. However, bovine growth hormone stimulated leucine incorporation only in tissues taken from hypophysectomized animals.3.3. It is concluded that the mode of action of prolactin on carbohydrate and lipid metabolism is dependent upon the mode of its purification, whereas its action upon protein synthesis is common to all preparations.