The latter possibility is not likely, however, because contrary to the situation in human and rat ovaries, in which the gene for LHRH receptor is expressed, this gene is not expressed in the CL of cattle. Apparently the gene encoding for LHRH, however, is expressed in cumulus-oocyte complexes of cattle.
LHRH can be involved in regulation of FSH secretion in some physiological states, and FSH has been reported to have a cooperative luteotropic function with LH in hamsters. Suppression of FSH secretion may, therefore, have contributed to the suppressed luteal function of the treated females as compared with luteal function of the control females in the present study. In females treated with the LHRH antagonist from Days 2 through 7 of the estrous cycle in a previous study, concentrations of FSH between Days 2 and 12 of the estrous cycle were not different from those of untreated control females.
In the present study, concentrations of FSH from Days 2 through 12 of the es-trous cycle in females treated with LHRH antagonist from Days 2 through 7 (data not reported) were also not different from those of control females. There was suppressed luteal function in both the previous and present studies of females treated with LHRH antagonist from Days 2 to 7 of the estrous cycle as compared with untreated control females in the absence of suppressed concentrations of FSH in blood.