Release of a prolactin-like substance by bovine granulosa cells in vitro: effects of ovarian steroids.

The time-dependent accumulation of prolactin (PRL) immunoreactivity in serum-free and in serum-supplemented cultures of bovine granulosa cells was observed. Blockade of endogenous progesterone by specific antiserum had no significant influence on PRL immunoreactivity, but progesterone addition (10-10,000 ng/ml) lead to a dose-dependent decrease. Antisera against testosterone and against estradiol-17 beta were inhibitors, and additions of these hormones (100-10,000 ng/ml) stimulated the release of PRL immunoreactivity.

[Hydrolysis of prolactin by a serine proteinase from mammary gland secretory cell mitochondria].

Mitochondrial proteinase isolated from secretory cells of the mammary gland of lactating rats able to hydrolyze 125I-labeled and native prolactin (PRL) has been studied. The enzyme represents a serine proteinase and is localized in the inner mitochondrial membrane. The molecular mass of the enzyme is 17-18 kDa, pH optimum is at 8.

Growth hormone alters metabolic effects and proteolysis of insulin in adipose tissue during lactation.

To study the regulation of lipogenesis in adipose tissue by insulin and growth hormone during lactation, tissue was biopsied from primiparous bovines at 30 days antepartum and 60 days postpartum. Tissue was cultured for 24 hr or 48 hr in M199 with acetate and glucose, with a change of medium at 24 hr. The three in vitro treatments were: insulin and hydrocortisone at 10 and 50 ng/ml, respectively (IH); IH + 10 ng/ml of growth hormone (G10); and IH + 100 ng/ml of growth hormone (G100).

[Pancreatic juice peptides as possible regulators of reparative processes in the pancreas in acute and chronic pancreatitis].

The experiments were performed on 34 dogs. The subcutaneous injection of boiled pancreatic juice was established to increase the survival of dogs in acute destructive pancreatitis (p < 0.001) and to decrease the specific volume damage to acinar (p < 0.

[Heterogeneous forms of prolactin in the blood and colostrum of ruminants].

The monomer form of prolactin prevailed in the blood of cows and she-goats in the physiological conditions associated with an intensive prolactin secretion. The dimer's content increased at the final stage of lactation and in pregnancy. High level of prolactin was found in the colostrum, a form of the prolactin with the milk mass over 100000 having been identified in the soluble fraction of milk.