Sexual dimorphic porcine pituitary response to growth hormone-releasing hormone

The aim of this study was to compare growth hormone (GH) response of barrows and gilts to porcine growth hormone-releasing hormone (pGRH) at the pituitary level. Anterior pituitary cells from barrows and gilts responded to pGRH in a dose-dependent manner. The median effective pGRH concentration (EC50) which stimulated GH release from cells of barrows was greater (P less than .05) than that for cells obtained from intact female siblings. Maximal pGRH mediated GH secretion from barrows was not different (P greater than 0.05) than that from gilt stimulated cells. These data demonstrate that somatotrophs of growing peripubertal gilts are more responsive to pGRH stimulation than are cells from their castrated male siblings. This difference could be caused by castration of the neonatal male.