Linked Life Data

9195472

Source:http://linkedlifedata.com/resource/pubmed/id/9195472

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1997-8-22
pubmed:abstractText
The present study deals with the effects of withdrawal of dopamine (DA) on the translocation of protein kinase C (PKC) isozymes and release of prolactin (Prl) in resting- and substance P (SP)-stimulated cultures of enriched rat pituitary lactotrophs. Following a brief tonic input (10 min), DA withdrawal induced a redistribution of PKC alpha- and beta-immunoreactivity (IR) to the particulate fraction with maximal levels, attained after 5 min, remaining translocated for 20 min. DA withdrawal prolonged the effect of SP-induced translocation of PKC alpha- and beta-IR. Similar effects were detected when the catalytic activity of PKC in response to DA withdrawal was evaluated. Thus, DA washout redistributed PKC catalytic activity and prolonged the effect of SP on catalytical PKC translocation to the particulate fraction. Pretreatment of cells with the protein kinase A inhibitor, rp-adenosine-3',5'-cyclic monophosphothionate (rp-cAMP), reduced the amount of PKC alpha- and beta-IR redistributed after DA withdrawal. Furthermore, this treatment also reduced the DA withdrawal effect on SP-mediated translocation of PKC alpha- and beta-IR. Methoxyverapamil, a blocker of voltage-gated Ca2+ channels, completely inhibited the redistribution of PKC isozymes after DA withdrawal, but also reduced the potentiating effect of DA withdrawal on SP-induced redistribution of PKC isozyme-IR. In perifused enriched lactotrophs, DA withdrawal induced a release of Prl that lasted 45-55 min and prolonged the effect of SP on Prl secretion. rp-cAMP did not significantly affect Prl release due to DA removal, but the prolonging effect of DA withdrawal on SP-induced Prl secretion was abolished. Methoxyverapamil completely abolished the rebound release of Prl after DA withdrawal, and the potentiating effect of DA removal on SP-mediated Prl release was also diminished. Readdition of DA after DA withdrawal was able to suppress the translocation of PKC isozyme-IR and catalytic activity and to reduce the release of Prl to baseline levels. Moreover, readdition of DA reduced the potentiating effects of DA withdrawal on the same parameters after SP-stimulation of cells. On the basis of these results it is concluded that in resting cells following DA withdrawal prolactin is released and specific PKC isozymes and concomitant catalytic activity are translocated to the particulate fraction in enriched lactotrophs. While cAMP/PKA and influx of Ca2+ seem to work in concert in translocating PKC, influx of Ca2+ is the primary mechanism responsible for the rebound release of Prl after DA withdrawal. DA withdrawal exerts a potentiating effect on SP-induced PKC translocation and Prl release. It is suggested that the biochemical events involved in these processes are cAMP/PKA and Ca2+ influx.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/Calcium, http://linkedlifedata.com/resource/pubmed/chemical/Calcium Channel Blockers, 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/Gallopamil, http://linkedlifedata.com/resource/pubmed/chemical/Isoenzymes, http://linkedlifedata.com/resource/pubmed/chemical/Prolactin, http://linkedlifedata.com/resource/pubmed/chemical/Protein Kinase C, http://linkedlifedata.com/resource/pubmed/chemical/Substance P, http://linkedlifedata.com/resource/pubmed/chemical/Thionucleotides, http://linkedlifedata.com/resource/pubmed/chemical/adenosine-3',5'-cyclic...
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0952-5041
pubmed:author
pubmed:issnType
Print
pubmed:volume
18
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
181-91
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed-meshheading:9195472-Animals, pubmed-meshheading:9195472-Biological Transport, Active, pubmed-meshheading:9195472-Calcium, pubmed-meshheading:9195472-Calcium Channel Blockers, pubmed-meshheading:9195472-Cells, Cultured, pubmed-meshheading:9195472-Cyclic AMP, pubmed-meshheading:9195472-Cyclic AMP-Dependent Protein Kinases, pubmed-meshheading:9195472-Dopamine, pubmed-meshheading:9195472-Enzyme Inhibitors, pubmed-meshheading:9195472-Gallopamil, pubmed-meshheading:9195472-Isoenzymes, pubmed-meshheading:9195472-Male, pubmed-meshheading:9195472-Pituitary Gland, Anterior, pubmed-meshheading:9195472-Prolactin, pubmed-meshheading:9195472-Protein Kinase C, pubmed-meshheading:9195472-Rats, pubmed-meshheading:9195472-Rats, Wistar, pubmed-meshheading:9195472-Subcellular Fractions, pubmed-meshheading:9195472-Substance P, pubmed-meshheading:9195472-Thionucleotides
pubmed:year
1997
pubmed:articleTitle
Effects of withdrawal of dopamine on translocation of protein kinase C isozymes and prolactin secretion in rat lactotroph-enriched pituitary cells. Modulation of substance P-mediated responses.
pubmed:affiliation
Department of Physiology, Panum Institute, University of Copenhagen, Denmark.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't