This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zhou, H. Articles by Wong, A. O. L. Search for Related Content PubMed PubMed Citation Articles by Zhou, H. Articles by Wong, A. O. L.

Evidence for a Novel Intrapituitary Autocrine/Paracrine Feedback Loop Regulating Growth Hormone Synthesis and Secretion in Grass Carp Pituitary Cells by Functional Interactions between Gonadotrophs and Somatotrophs

Department of Zoology, University of Hong Kong, Hong Kong, People’s Republic of China

Address all correspondence and requests for reprints to: Dr. Anderson O. L. Wong, Associate Professor, Room 4S-12, Kadoorie Biological Sciences Building, Department of Zoology, University of Hong Kong, Pokfulam Road, Hong Kong SAR, People’s Republic of China. E-mail: olwong{at}hkucc.hku.hk.

Gonadotropin (GTH) and GH released from the pituitary are known to interact at multiple levels to modulate the functions of the gonadotrophic and somatotrophic axes. However, their interactions at the pituitary level have not been fully characterized. In this study, autocrine/paracrine regulation of GH synthesis and secretion by local interactions between gonadotrophs and somatotrophs was examined using grass carp pituitary cells as a cell model. Exogenous GTH and GH induced GH release and GH mRNA expression in carp pituitary cells. Removal of endogenous GTH and GH by immunoneutralization with GTH and GH antisera, respectively, suppressed GH release, GH production, and GH mRNA levels. GH antiserum also blocked the stimulatory effects of exogenous GTH on GH release and GH mRNA levels. In reciprocal experiments, GH release and GH mRNA expression induced by exogenous GH was significantly reduced by GTH antiserum. In addition, exogenous GH was found to be inhibitory to basal GTH release and treatment with GH antiserum elevated GTH secretion at low doses but suppressed GTH production at high doses. These results suggest that local interactions between gonadotrophs and somatotrophs may form an intrapituitary feedback loop to regulate GH release and synthesis. In this model, GTH released from gonadotrophs induces GH release and GH production in neighboring somatotrophs. GH secreted maintains somatotroph sensitivity to GTH stimulation, and at the same time, inhibits basal GTH release in gonadotrophs. This feedback loop may represent a novel mechanism regulating GH release and synthesis in lower vertebrates.

This article has been cited by other articles:

				G. C. Bowick, H. M. Spratt, A. E. Hogg, J. J. Endsley, J. E. Wiktorowicz, A. Kurosky, B. A. Luxon, D. G. Gorenstein, and N. K. Herzog Analysis of the Differential Host Cell Nuclear Proteome Induced by Attenuated and Virulent Hemorrhagic Arenavirus Infection J. Virol., January 15, 2009; 83(2): 687 - 700. [Abstract] [Full Text] [PDF]

				K. H. Sze, H. Zhou, Y. Yang, M. He, Y. Jiang, and A. O. L. Wong Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) as a Growth Hormone (GH)-Releasing Factor in Grass Carp: II. Solution Structure of a Brain-Specific PACAP by Nuclear Magnetic Resonance Spectroscopy and Functional Studies on GH Release and Gene Expression Endocrinology, October 1, 2007; 148(10): 5042 - 5059. [Abstract] [Full Text] [PDF]

				L. Huo, G. Fu, X. Wang, W. K. W. Ko, and A. O. L. Wong Modulation of Calmodulin Gene Expression as a Novel Mechanism for Growth Hormone Feedback Control by Insulin-like Growth Factor in Grass Carp Pituitary Cells Endocrinology, September 1, 2005; 146(9): 3821 - 3835. [Abstract] [Full Text] [PDF]