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      Specific Release of a Novel Pituitary Polypeptide, 7B2, from Rat Anterior Pituitary Cells in vitro by Luteinizing Hormone-Releasing Hormone

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      S. Karger AG

      7B2, Pituitary-gonadotrophs, LHRH-release

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          We have recently purified a novel pituitary polypeptide, designated 7B2. Subsequently, we developed a sensitive and specific radioimmunoassay (RIA) for this novel polypeptide. Our aim in the present study was to investigate the release of 7B2 from rat pituitary induced by various hypothalamic factors [luteinizing hormone-releasing factor (LH-RH), corticotropin-releasing factor (CRF), and growth hormone-releasing factor (GRF)]. The anterior pituitaries were removed from rats and immediately dispersed enzymatically (a mixture of collagenase/dispase/deoxyribonuclease/chicken serum) and plated on collagen-coated multiwell plates in culture medium containing 10% fetal bovine serum. After 2 days of attachment period, the medium was replaced with fresh medium every 24 h. The primary cell culture was incubated with various concentrations of LH-RH, CRF or GRF. Subsequently, the concentrations of IR-7B2, IR-LH, IR-FSH, and IR-ACTH released into the medium were quantified by specific RIA. LH-RH, at a concentration as low as 7.5 ng/ml (6 × 10<sup>–9</sup> M; dose range 7.5–60 ng/ml) stimulated the release of IR-7B2, IR-LH, and IR-FSH, by 2- to 3-fold, 17- to 18-fold, and 3-fold, respectively, over basal levels. No significant increase of IR-7B2 was observed when stimulated by CRF or GRF at doses as high as 100 ng/ml. In addition, K+ (50 m M) stimulated the release of all the peptides measured. In conclusion, our studies suggest that the novel peptide 7B2 is under LH-RH control and indirectly confirm the immunohistochemical results of its cellular co-localization in FSH and LH cells.

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          Author and article information

          S. Karger AG
          01 April 2008
          : 44
          : 3
          : 373-377
          Laboratories of Biochemical and Molecular Neuroendocrinology, Clinical Research Institute of Montreal (affiliated with the University of Montreal), Montreal, Canada
          124671 Neuroendocrinology 1986;44:373–377
          © 1986 S. Karger AG, Basel

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          Pages: 5
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