Absence of a prenidatory effect of luteinizing hormone releasing hormone (LHRH) in hamsters.

Luteinizing hormone releasing hormone at high doses will terminate gestation in rats during early and midpregancy (ED50 approximately equal to 100 microgram/day) and rabbits during early pregnancy. Early pregnancy in hamsters, in contradistinction, seems refractory to this effect. Administration of LHRH up to massive doses (10 mg/day) over the first 3 or 7 days of pregnancy failed to affect the pregnancies in meaningful fashion. Further, a single injection (100 mg) on day 5 had no effect on pregnancy; this system has been employed for the assay of prostaglandins because hamsters are remarkably sensitive to PG's (PGF2alpha, ED50 approximately equal to 17 microgram, PGE2, ED50 approximately equal to 210 microgram). The absence of response of hamsters to LHRH cannot be interpreted at present.