Follicle-stimulating hormone within and secreted from anterior pituitaries of female golden hamsters during the estrous cycle and after ovariectomy.

Anterior pituitary (AP) glands were removed from groups of female golden hamsters at 0900 h on estrus (E), diestrus I (DI), and diestrus II (DII) and at 1200 h and 1500 h on proestrus (P12 and P15), as well as at 0900 h from ovariectomized hamsters (OVX). Hemipituitaries were incubated in culture medium with or without 10(-8) M luteinizing hormone-releasing hormone (LHRH) for 3 h at 37 degrees C to determine the magnitude of basal and LHRH-stimulated follicle-stimulating hormone (FSH) release. All samples were assessed for FSH activity by radioimmunoassay and radioreceptor assay. In a second set of experiments, AP were removed from E, DII, and OVX hamsters and bisected. One hemipituitary was homogenized in 10 mM Tris-HCl and the other half was incubated for 3 h. Follicle-stimulating hormone forms present within pituitary extracts or secreted into medium were separated by an isoelectric focusing technique, chromatofocusing. Basal FSH release was lowest in AP collected on DII and P12, higher in AP collected on E and DI, and highest in AP from OVX. Luteinizing hormone-releasing hormone-stimulated release of FSH was highest in AP obtained on DII and P12, lower in AP collected on E and DI, and lowest in AP from OVX. Radio-receptor-to-radioimmunoassay ratio of secreted FSH was greatest when basal FSH secretion was low and LHRH sensitivity was high (DII and P12) and least when basal FSH secretion was high and LHRH sensitivity low (E and after OVX).(ABSTRACT TRUNCATED AT 250 WORDS)