Regional differences in concentrations of LHRH receptors,LH and FSH in the bovine adenohypophysis

Pituitaries from intact luteal phase (INT) and ovariectomized (OVX) cows were collected at slaughter to determine whether differences exist among regions of the bovine adenohypophysis in the concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH) and receptors for luteinizing hormone releasing hormone (LHRH). Each adenohypophysis was divided into three paired regions (anterior, AT; medial, M; posterior, PT) by first making a midsagittal cut followed by two transverse cuts of approximately equal size. Values for all variables were similar between paired regions. Mean LHRH receptor, LH and FSH concentrations were greater in OVX than INT adenohypophyseal regions. Receptor and gonadotropin concentrations differed among all three regions and were greatest in the AT, intermediate in the M and lowest in the PT regions of the adenohypophysis. There were significant correlations between LHRH receptor concentrations and concentrations of LH and FSH among the three adenohypophyseal regions for both INT and OVX cows. Therefore, to accurately characterize LHRH receptors from the bovine adenohypophysis, a midsagittal-half of the gland should be used for analysis.