Effect of an LHRH analog on growth and hormone receptor levels in DMBA-induced mammary tumors in the rat.
Dimethylbenz(a)anthracene (DMBA)-induced mammary tumors in the rat are well known to be hormono-dependent. Daily injections of an LHRH agonist, [D-Ala6, des-Gly-NH2(10)]LHRH ethylamide (LHRH-A), 1 microgram daily, for 38 days results in a 35% decrease in the number of tumors present at the beginning of the experiment compared to a decline of 45% after ovariectomy and of 8% in the control group. This is accompanied by a marked reduction in ovarian LH and FSH receptors. LHRH-A treatment also resulted in reduction in the number of progesterone and prolactin receptors in the tumors. In addition, an increase in plasma LH and FSH and a decline in plasma prolactin (PRL) concentrations are observed. The mechanisms by which the LHRH agonist induces its antitumoral effect probably relate to an ovarian desensitization to LH and FSH with a concomitant decrease in circulating levels of estrogen and prolactin, two well known stimuli for the growth of DMBA-induced mammary tumors.
D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D001551:Benz(a)Anthracenes; D002369:Castration; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D006728:Hormones / Q000494:pharmacology; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000503:physiopathology*; D010053:Ovary / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism; D011962:Receptors, FSH; D011974:Receptors, LH; D011980:Receptors, Progesterone / Q000378:metabolism; D011981:Receptors, Prolactin; D014599:Uterus / Q000378:metabolism
D001551:Benz(a)Anthracenes; D006728:Hormones; D011956:Receptors, Cell Surface; D011960:Receptors, Estrogen; D011962:Receptors, FSH; D011974:Receptors, LH; D011980:Receptors, Progesterone; D011981:Receptors, Prolactin; D007987:Gonadotropin-Releasing Hormone; C010661:surfagon; D015127:9,10-Dimethyl-1,2-benzanthracene