The effect of progesterone on prolactin stimulation of fatty acid synthesis, glycerolipid synthesis and lipogenic-enzyme activities in mammary glands of pseudopregnant rabbits, after explant culture or intraductal injection.
The activities of lipogenic enzymes, such as acetyl-CoA carboxylase, fatty acid synthetase and glucose-6-phosphate dehydrogenase, and glycerolipid synthesis increased significantly in mammary explants of 11-day-pseudopregnant rabbits in response to prolactin, in the presence of near-physiological concentrations of insulin and corticosterone in culture. Increasing the concentration of progesterone in culture resulted in suppression of glycerolipid synthesis and activities of acetyl-CoA carboxylase and fatty acid synthetase, but not the pentose phosphate dehydrogenases. However, at near-physiological concentration of progesterone, only acetyl-CoA carboxylase activity was decreased. Injection of prolactin intraductally into 11-day-pseudopregnant rabbits stimulated glycerolipid synthesis, fatty acid synthesis and enzymes involved in fatty acid synthesis, after 3 days. Intraductal injection of progesterone separately or together with prolactin had no significant effect on basal or stimulated lipogenesis in mammary glands. Intramuscular injection of progesterone at 10 mg/day did not suppress fatty acid synthesis stimulated when prolactin was injected intraductally, but a significant inhibition was observed at a higher dose (80 mg/day).
D000818:Animals; D046508:Culture Techniques; D005227:Fatty Acids / Q000096:biosynthesis; D005260:Female; D005994:Glycerophosphates / Q000378:metabolism; D008055:Lipids / Q000096:biosynthesis*; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology*; D011388:Prolactin / Q000494:pharmacology*; D011555:Pseudopregnancy / Q000378:metabolism; D011817:Rabbits
D005227:Fatty Acids; D005994:Glycerophosphates; D008055:Lipids; D011374:Progesterone; D011388:Prolactin