Source:http://linkedlifedata.com/resource/pubmed/id/12446588
Switch to
| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:dateCreated |
2002-11-26
|
| pubmed:abstractText |
Orexins are recently discovered neuropeptides that play an important role in the regulation of hormone secretion, and their receptors have been recently demonstrated in the pituitary. The effects of orexin-A on voltage-gated Ca2+ currents and GH release in primary cultured ovine somatotropes were examined. The expression of orexin-1 receptor was demonstrated by RT-PCR in ovine somatotropes, from which Ca2+ currents were also isolated as L, T, and N currents. Application of orexin-A (100 nM) significantly and reversibly increased only the L current, and coadministration of orexin-A and GHRH (10 nM) showed an additive effect on this current, but no effect of orexin-A was observed on either T or N current. Furthermore, the orexin-A-induced increase in the L current was completely abolished by the inhibition of protein kinase C (PKC) activity using calphostin C (100 nM), phorbal 12,13-dibutyrate pretreatment (0.5 micro M) for 16 h or specific PKC inhibitory peptide PKC(19-36) (1 mM). However, the increase in L current by orexin-A was sustained when cells were preincubated with a specific protein kinase A blocker H89 (1 micro M) or a specific intracellular Ca2+ store depleting reagent thapsigargin (1 micro M). Finally, orexin-A alone did not significantly increase GH release, but coadministration of orexin-A and GHRH showed a synergistic effect on GH secretion in vitro. Our results therefore suggest that orexin-A may play an important role in regulating GHRH-stimulated GH secretion through the enhancement of the L-type Ca2+ current and the PKC-mediated signaling pathway in ovine somatotropes.
|
| pubmed:language |
eng
|
| pubmed:citationSubset |
AIM
|
| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Calcium,
http://linkedlifedata.com/resource/pubmed/chemical/Calcium Channels,
http://linkedlifedata.com/resource/pubmed/chemical/Calcium Channels, L-Type,
http://linkedlifedata.com/resource/pubmed/chemical/Carrier Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Cyclic AMP,
http://linkedlifedata.com/resource/pubmed/chemical/Cyclic AMP-Dependent Protein Kinases,
http://linkedlifedata.com/resource/pubmed/chemical/Enzyme Inhibitors,
http://linkedlifedata.com/resource/pubmed/chemical/Growth Hormone,
http://linkedlifedata.com/resource/pubmed/chemical/Growth Hormone-Releasing Hormone,
http://linkedlifedata.com/resource/pubmed/chemical/Intracellular Signaling Peptides...,
http://linkedlifedata.com/resource/pubmed/chemical/Neuropeptides,
http://linkedlifedata.com/resource/pubmed/chemical/Protein Kinase C,
http://linkedlifedata.com/resource/pubmed/chemical/RNA,
http://linkedlifedata.com/resource/pubmed/chemical/Receptors, G-Protein-Coupled,
http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Neuropeptide,
http://linkedlifedata.com/resource/pubmed/chemical/orexin receptors,
http://linkedlifedata.com/resource/pubmed/chemical/orexins
|
| pubmed:status |
MEDLINE
|
| pubmed:author | |
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
4609-19
|
| pubmed:dateRevised |
2007-11-15
|
| pubmed:articleTitle |
Orexin-A augments voltage-gated Ca2+ currents and synergistically increases growth hormone (GH) secretion with GH-releasing hormone in primary cultured ovine somatotropes.
|
| pubmed:affiliation |
Prince Henry's Institute of Medical Research, Clayton, Victoria 3168, Australia.
|