Antiserum to LH reverses the abortifacient effect of Bromergocryptine treatment in early rat pregnancy.
In vivo experiments showed that anti-bovine luteinizing hormone rabbit serum (a-LH) reversed the abortifacient effect of Bromergocryptine (BEC) on day 6 of pregnancy in 13 of 19 rats when injected 5-15 h after the initial BEC administration. Radioreceptor assay studies revealed that BEC treatment entailed an 85% drop of ovarian LH-receptor (LH-rec) concentration and a drastic decrease in progesterone serum levels. a-LH restored both the ovarian LH-rec content and progesterone serum levels in those rats that were found to have macroscopically intact implantations. A time course study of LH serum levels after BEC treatment showed a trend for BEC to stimulate LH secretion with a maximum 12-18 h after the initial BEC injection. These experiments indicate that (i) BEC terminates early rat pregnancy primarily by inducing a process of desensitization of ovarian LH-rec by blocking prolactin (PRL) secretion and possibly also by additionally stimulating LH secretion, which in the absence of endogenous PRL causes HL-rec and serum progesterone levels to drop; (ii) a-LH administration without simultaneous PRL substitution may rescue LH-rec of BEC treated rats from being desensitized as well as prevent fetuses from being resorbed. It is suggested that the contribution of PRL in the luteotropic complex is permissive for the luteotropic action of LH and/or for keeping the corpus luteum in a functional state rather than being luteotropic by itself.
D000019:Abortifacient Agents / Q000494:pharmacology*; D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology*; D002417:Cattle; D006063:Chorionic Gonadotropin / Q000378:metabolism; D010064:Embryo Implantation / Q000187:drug effects; D005260:Female; D007106:Immune Sera / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000276:immunology* / Q000378:metabolism; D008297:Male; D009929:Organ Size / Q000187:drug effects; D010053:Ovary / Q000033:anatomy & histology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface; D011974:Receptors, LH; D013997:Time Factors
D000019:Abortifacient Agents; D006063:Chorionic Gonadotropin; D007106:Immune Sera; D011956:Receptors, Cell Surface; D011974:Receptors, LH; D001971:Bromocriptine; D007986:Luteinizing Hormone