The effect of prolactin pretreatment on prostaglandin F2 alpha-associated structural changes in membranes from rat corpora lutea.
The ability of prolactin treatment to antagonize the luteolytic effect of prostaglandin F2 alpha (PGF2 alpha) was examined in the rat. Animals were superovulated, treated with PGF2 alpha and various doses of prolactin. Plasma progesterone concentrations were measured to assess luteal function. Microsomes were prepared from ovarian homogenates and examined by wide-angle x-ray diffraction for evidence of structural changes in the cellular membranes during luteolysis. In addition, the concentrations of various lipids were analyzed for alterations in membrane lipid composition. In preparations from control animals, all of the membrane lipid was in the liquid-crystalline phase at body temperature. However, in samples from PGF2 alpha-treated rats, portions of the bilayer underwent a structural alteration from liquid-crystalline to gel phase. This phase transition was not accompanied by significant changes in the relative concentrations of various lipids. Prolactin treatment was effective in inhibiting this membrane breakdown in a dose-dependent manner. These results suggest that PGF2 alpha and prolactin may control luteal function by affecting membrane structure.
D000818:Animals; D003338:Corpus Luteum / Q000187:drug effects*; D015237:Dinoprost; D004305:Dose-Response Relationship, Drug; D005260:Female; D008055:Lipids / Q000097:blood; D008566:Membranes / Q000187:drug effects; D008861:Microsomes / Q000187:drug effects; D010053:Ovary / Q000187:drug effects; D010060:Ovulation / Q000187:drug effects; D010743:Phospholipids / Q000097:blood; D011374:Progesterone / Q000097:blood; D011388:Prolactin / Q000494:pharmacology*; D011460:Prostaglandins F / Q000037:antagonists & inhibitors*; D051381:Rats; D011919:Rats, Inbred Strains; D014961:X-Ray Diffraction
D008055:Lipids; D010743:Phospholipids; D011460:Prostaglandins F; D011374:Progesterone; D011388:Prolactin; D015237:Dinoprost