Positive feedback relationship between progesterone and daily change of prolactin secretion that develops functional corpora lutea in PMSG-induced first oestrous cycle in prepubertal rats.
1. Mechanisms regulating the appearance of the pseudopregnancy (PSP)-like dioestrus induced by pregnant mare serum gonadotrophin (PMSG, 5 i.u.) treatment in prepubertal rats were studied. 2. The appearance rate of PSP-like dioestrus in the PMSG-induced first oestrous cycle was low in rats treated at 22 days of age. All rats treated at 28 or 31 days of age showed PSP-like dioestrus. 3. The daily change in plasma prolactin levels observed in rats treated at 28 days of age disappeared after ovariectomy. The implantation of Silastic tubings containing progesterone at ovariectomy maintained the change. 4. These results indicate that the PSP-like dioestrus can be induced by the positive feedback relationship which is established between progesterone and prolactin by 28 days of age.
Tomogane
H
H
Department of Animal Science, School of Agriculture, Nagoya University, Japan.
Yokoyama
A
A
D000818:Animals; D003338:Corpus Luteum / Q000187:drug effects* / Q000502:physiology; D004031:Diestrus / Q000187:drug effects; D004971:Estrus / Q000187:drug effects*; D005246:Feedback / Q000502:physiology*; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology*; D011374:Progesterone / Q000097:blood*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012741:Sexual Maturation / Q000187:drug effects*
D006064:Gonadotropins, Equine; D011374:Progesterone; D011388:Prolactin