Inhibition of growth of a prolactin-secreting pituitary tumor in rats by analogs of luteinizing hormone-releasing hormone and somatostatin.
We investigated the effects of [D-Trp6]LH-RH [agonistic analog of luteinizing hormone-releasing hormone (LH-RH)], N-Ac-[D-p-Cl-Phe1,2,D-Trp3,D-Phe6,D-Ala10]LH-RH (antagonistic analog), and [D-5-methoxy-Trp8]somatostatin (somatostatin analog) on the growth of the prolactin and corticotropin-secreting pituitary tumor 7315a in female Buffalo rats. Chronic administration of [D-Trp6]LH-RH in a dose of 25 micrograms/day, starting 18 days after inoculation with the tumor, inhibited the growth of the pituitary tumor. Tumor weight and volume also were reduced when this agonist was administered 3 days after inoculation. The antagonistic LH-RH analog, injected in a dose of 50-100 micrograms for 14-24 days, also significantly inhibited the growth of pituitary tumor. Chronic administration of the somatostatin analog in a dose of 25 micrograms twice a day likewise decreased tumor weights in comparison with controls. The inhibition of pituitary tumor growth by LH-RH agonist, LH-RH antagonist, and somatostatin analog was accompanied by a decrease in serum prolactin levels. It was concluded that LH-RH agonist, LH-RH antagonist, and somatostatin analog can inhibit the growth of estrogen-dependent prolactin/corticotropin-secreting pituitary tumor in rats.
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D008186:Luteolytic Agents / Q000494:pharmacology*; D009374:Neoplasms, Experimental / Q000378:metabolism / Q000503:physiopathology; D010911:Pituitary Neoplasms / Q000378:metabolism / Q000503:physiopathology*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011915:Rats, Inbred BUF; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000494:pharmacology; D017329:Triptorelin Pamoate
D008186:Luteolytic Agents; D017329:Triptorelin Pamoate; D007987:Gonadotropin-Releasing Hormone; D013004:Somatostatin; C038201:somatostatin, 5-methoxy-Trp(8)-; C033265:LHRH,(N)-Ac-(4-Cl-Phe)(1)-(4-Cl-Phe)(2)-Trp(3)-Phe(6)-AlaNH2(10)-; D011388:Prolactin