CHANGES IN ENZYMIC ACTIVITY, CHEMICAL COMPOSITION AND HISTOLOGY OF THE MAMMARY GLANDS AND METABOLITES IN THE BLOOD OF LACTATING RABBITS AFTER HYPO- PHYSECTOMY AND REPLACEMENT THERAPY WITH SHEEP PROLACTIN, HUMAN GROWTH HORMONE OR BOVINE GROWTH HORMONE

Five groups of five lactating rabbits each were used. Milk yield was recorded from the 8th day of lactation onwards and on the 10th day of lactation the rabbits received the following treatments: Group S, sham\x=req-\ operation with saline (1 ml/12 h); Group P, hypophysectomy with sheep prolactin (1 mg/12 h); Group H, hypophysectomy with human growth hormone (1 mg/12 h); Group B, hypophysectomy with bovine growth hor-mone (1 mg/12 h) and Group C, hypophysectomy with saline (1 ml/12 h). The injections of saline or hormones were continued for 5 days and at the end of this period a blood sample was taken, the animals were killed and their mammary glands removed for histological examination and assay of the following enzymes: 6-phosphogluconate dehydrogenase (EC 1.1.1.44), phosphofructokinase (EC 2.7.1.11), phosphoglucomutase (EC 2.7.5.1), UDP-glucose pyrophosphorylase (EC 2.7.7.9), acetyl-CoA carboxylase(EC 6.4.1.2), acetyl-CoA synthetase (EC 6.2.1.1) and ATP-citrate lyase(EC 4.1.3.8). On the 5th day after surgery the concentrations of blood L\x=req-\ lactate and pyruvate and plasma free fatty acids and protein were similar in all groups, whereas plasma glucose was higher in groups S, B and H than i