Immunocytochemical Identification of Pit-1 Containing Cells in the Anterior Pituitary of Hens

Prolactin (PRL) is a hormone mainly secreted by the anterior pituitary gland. In birds, PRL exerts a variety of physiological functions in target tissues expressing the PRL receptor (PRLR). In chicken, the PRLR mRNA is abundant in the anterior pituitary gland, but its regional and cellular localization are unknown. In the present study, we investigated the expression of the PRLR mRNA in cephalic and caudal lobes of the chicken anterior pituitary gland. Real-time polymerase chain reaction (PCR) revealed high levels of PRLR mRNA in both cephalic and caudal lobes. In situ hybridization revealed that the PRLR mRNA was distributed in a wide area of both lobes, and co-localized with the PRL and growth hormone (GH) mRNAs in the cephalic and caudal lobes, respectively. These results suggest that PRL exerts autocrine/paracrine effects through PRLR on PRL-producing lactotrophs and GH-producing somatotrophs in the chicken anterior pituitary gland.

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Glucocorticoid-Inducible Glutamine Synthetase in GH Cells of Chick Embryos, <I>Gallus domesticus</I>: Ontogeny of Glutamine Synthetase, GH, and Pit-1 Protein in the Pituitary Gland

Shirasawa

Yingjie

Tsuruo³

et al. 2006

J. Poult. Sci.

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It has been known that glutamine synthetase (GS, L-glutamate ammonia ligase) is an enzyme that catalyzes ATP-dependent condensation of glutamate and ammonia to form glutamine, and that GS and growth hormone (GH) are proteins that are induced by glucocorticoid-treatment during the development of animals. To understand the relationship between these glucocorticoid-inducible proteins, we studied pituitary GS and GH cells during the development of chick embryos, Gallus domesticus. GS cells were immunohistochemically identified in epithelia of Rathke's pouch as early as embryonic day . (E.) following corticosterone-treatment. The population of GS cells and GS activity gradually increased by E+., and then rose sharply after E+0. Pituitary GS activity was precociously induced by corticosterone-treatment starting around E1. GH cells were first demonstrable in the pituitary gland on E++, and then increased until hatching. Corticosterone-treatment also caused premature induction of GH in the pituitary cells after E2, but not before. Dual-fluorescence immunohistochemistry showed a large population of GS cells in the cephalic lobe that was identical to the ACTH cells, and in the caudal lobe of the gland they were the same as the GH cells. Ontogeny of pituitary Pit-+ protein, an important transcription factor of GH, was also studied by immunohistochemistry. Pit-+ positive cells appeared at E0 and increased in number by E+, of development. The population of Pit-+ cells was, however, not a#ected by corticosterone-treatment. These result demonstrate that glucocorticoid receptors are present in pituitary GS cells even before day 2 when GH cells start to di#erentiate, and that a large population of GS cells may have some physiological roles in the gland. This is the first report showing that pituitary GS is a glucocorticoid-inducible marker protein to regulate pituitary functions.

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Immunocytochemical Identification of Pit-1 Containing Cells in the Anterior Pituitary of Hens

Cited by 3 publications

References 19 publications

Role of chicken Pit-1 isoforms in activating growth hormone gene

Role of chicken Pit-1 isoforms in activating growth hormone gene

Expression of Prolactin Receptor mRNA in Lactotrophs and Somatotrophs of the Chicken Anterior Pituitary Gland

Glucocorticoid-Inducible Glutamine Synthetase in GH Cells of Chick Embryos, <I>Gallus domesticus</I>: Ontogeny of Glutamine Synthetase, GH, and Pit-1 Protein in the Pituitary Gland

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