Effects of appetite regulating nuropeptides on somatotroph axis of cattle

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Expression and affects of appetite regulating nuropeptides (orexin : OX, Galanin : Gal, leptin : Lep, nuropeptide Y : nero Y) on somatotrophs were detailed in bovine adenohypophysis. Prepro-OX mRNA and OX1-receptor (OX1R) mRNA were expressed and their partial DNA and amino acid sequences were determined in bovine adenohypophysis. OX-A was localized in PRL cells and OX1R was also detected in the identical cell type. However, OX-A was not effective on the release of GH and PRL in the primary cultures of the adenohypophysial cells. Gal mRNA and immunoreactive Gal were localized in ACTH cells. The Gal expression was mainly mediated by testosterone. Gal producing cells also expressed both of androgen receptor (AR) and estrogen receptor (ER). It was demonstrated that the Gal expression in ACTH cells was regulated by ER-binding signals of estrogen derived from testosterone by P450 aromatase in another type cells of the adenohypophysis, so called, intracrinology fashion Lap mRNA were expressed in the adenohypophysis and immunoreactive Lep was mainly localized in GH cells although was immunoreactive in a small number of PRL, TSH and GTH cells. Since cytokines are known to exert important roles in nuroendocrine system, the expression of interleukin 18 (IL-18) and its receptor (IL-18R) in the adenohypophysial cells was examined in detail. IL-18 mRNA and immunoreactive IL-18 were localized in GH cells. The partial DNA sequence of bovine IL-18R α was determined and immunoreactive IL-18Rα was also localized in GH cells. These findings indicate that IL-18 may plays GH secretion or the differentiation of somatotrophs in autocrine fashion. Furthermore, bovine adenohypophysial cell line that presents IL-18 and IL-18Rα,and can passages for long time was established. New findings in the present study are ordering to submit international Journals as four publications.