DIFFERENTIAL INVOLVEMENT OF PKC AND PKA IN GHRELIN-INDUCED GROWTH HORMONE AND GONADOTROPIN RELEASE FROM PRIMARY CULTURES OF DISPERSED GOLDFISH PITUITARY CELLS.
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1
University of Alberta, Biological Sciences, Canada
Ghrelin (GRLN) stimulates feeding and the release of pituitary growth hormone (GH) and maturational gonadotropin (LH) in goldfish, thus providing a possible link between energy balance and reproduction. Previous work shows that mRNAs for GRLN and its receptors are expressed in the goldfish pituitary. Extracellular Ca2+ entry through L-type voltage-sensitive Ca2+ channels and increases in intracellular Ca2+ are important signaling components leading to goldfish (g)GRLN19-elicited GH and LH release. In this study, we examined the role of protein kinase C (PKC) and A (PKA) in gGRLN19-induced hormone secretion via column perifusion of dispersed goldfish pituitary cells, and single cell Ca2+-imaging of identified goldfish somatotropes and gonadotropes. PKC inhibitors (bisindolylmaleimide-II and Gö 6976) attenuated gGRLN19-stimulated hormone secretion and associated Ca2+ signals. gGRLN19-induced hormone release and Ca2+ signals were not observed when cells were already stimulated by a PKC agonist (DiC8). PKA inhibitors (H-89 and KT5720), however, only inhibited gGRLN19-induced hormone release and Ca2+ responses in LH cells. On the other hand, an adenylate cyclase activator (forskolin) enhanced gGRLN19-induced GH, but not LH, release. Ca2+ signals elicited by combined forskolin and gGRLN19 treatment were not different from those to either treatment alone in either cell type. These results suggest that while PKC and PKA mediate GRLN actions on LH release by actions upstream of Ca2+ signals, similar responses in GH cells only involve PKC. In addition, activation of PKA may enhance GRLN-stimulated GH secretion by actions downstream of Ca2+ changes. (Supported by NSERC.)
Acknowledgements
NSERC
University of Alberta, Biological Sciences
Province of Alberta
Keywords:
calcium imaging,
Goldfish ghrelin,
Goldfish pituitary,
identified gonadotropes,
identified somatotropes,
perifusion,
PKA,
PKC
Conference:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011.
Presentation Type:
Oral Presentation
Topic:
Neuroendocrine control of reproduction
Citation:
Grey
CL and
Chang
JP
(2011). DIFFERENTIAL INVOLVEMENT OF PKC AND PKA IN GHRELIN-INDUCED GROWTH HORMONE AND GONADOTROPIN RELEASE FROM PRIMARY CULTURES OF DISPERSED GOLDFISH PITUITARY CELLS..
Front. Endocrinol.
Conference Abstract:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology.
doi: 10.3389/conf.fendo.2011.04.00135
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Received:
22 Jul 2011;
Published Online:
09 Aug 2011.
*
Correspondence:
Dr. John P Chang, University of Alberta, Biological Sciences, Edmonton, Canada, john.chang@ualberta.ca