title: Prolactin in maintenance of the corpus luteum of early pseudopregnancy in the golden hamster.
abstract: The role of prolactin in the maintenance of the corpus luteum of pseudopregnancy was studied in the golden hamster. Nine groups of seven to fourteen animals each received 1 mg bromocriptine at 11.00 h on days 1, 2 or 3 of pseudopregnancy (three groups for each day). On each day of treatment with bromocriptine, one group of hamsters was injected with bovine prolactin 4 h before bromocriptine, and one group received prolactin 4 h before bromocriptine for three consecutive days following treatment with bromocriptine. One group received bromocriptine only. These nine groups were compared with a control group of animals given 0.85% saline instead of bromocriptine and prolactin. Peripheral blood samples were taken from all hamsters at 11.00 h on days 3, 4, 5 and 6 of pseudopregnancy and plasma levels of progesterone were determined by radioimmunoassay. Luteolysis, indicated by a decline in progesterone level by 24 or 48 h after treatment with bromocriptine, occurred in all hamsters given bromocriptine alone, whether it was administered on day 1, 2 or 3. Pretreatment with a single dose of prolactin did not mitigate the bromocriptine-induced fall in progesterone. In the majority of cases, pretreatment with prolactin plus daily doses of prolactin maintained the progesterone at levels not different from saline-treated hamsters. These data suggest that prolactin is a necessary luteotrophin during early pseudopregnancy without which luteolysis ensues.
mesh_terms: D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology; D003340:Corpus Luteum Maintenance / Q000187:drug effects; D006224:Cricetinae; D005260:Female; D008647:Mesocricetus; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011388:Prolactin / Q000494:pharmacology / Q000502:physiology*; D011555:Pseudopregnancy
chemical_list: D001971:Bromocriptine; D011374:Progesterone; D011388:Prolactin