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dc.contributor.authorSteiner, Robert A.en_US
dc.contributor.authorClifton, Donald K.en_US
dc.contributor.authorMarks, Daniel L.en_US
dc.contributor.authorSmith, M. Susanen_US
dc.date.accessioned2008-10-17T20:40:06Z
dc.date.available2008-10-17T20:40:06Z
dc.date.issued1993-09en_US
dc.identifier.citationEndocrinology. 1993 Sep;133(3):1450-8en_US
dc.identifier.urihttp://hdl.handle.net/1773/4286
dc.description.abstractGalanin is colocalized with GnRH, and its expression in these neurons is enhanced at proestrus, a time of activation of GnRH neurons. We tested the hypothesis that the expression of both the GnRH and galanin mRNAs in GnRH neurons decrease during lactation in the rat, a reproductive state characterized by reduced gonadotropin secretion. For double label in situ hybridization, GnRH mRNA was detected with an antisense cRNA probe labeled with the hapten digoxigenin, whereas galanin mRNA was detected with a cRNA probe labeled with 35S. The number of silver grains deposited over a digoxigenin-labeled cell body provided an index of galanin mRNA levels in GnRH cells. We observed a 60% reduction in signal (grains per cell) for galanin mRNA in GnRH neurons of lactating animals compared with those of diestrus animals (P < 0.004), with no difference in the number of GnRH neurons between groups. To compare cellular GnRH mRNA content between groups, we used single label in situ hybridization and image analysis. Signal levels (grains per cell) for GnRH mRNA were not different between diestrus and lactating animals in either an initial (diestrus, 121.4 +/- 5.9; lactation, 117.3 +/- 8.0; P > 0.7) or in a subsequent trial (diestrus, 184.0 +/- 10.4; lactation, 197.5 +/- 13.0; P > 0.7). To confirm and extend these findings, we used a RNAse protection assay to measure and compare the content of GnRH mRNA in hypothalamic fragments between diestrus and lactating animals. The concentration of GnRH mRNA (picograms of mRNA per 25 micrograms total RNA) was not different between the two groups (diestrus, 1.21 +/- 0.25; lactation, 1.25 +/- 0.13; P > 0.7). A determination of the total GnRH peptide content by RIA in a separate set of hypothalamic dissections revealed no difference between groups in the level of GnRH content (nanograms) per hypothalamus (diestrus, 6.0 +/- 0.6; lactation, 5.7 +/- 0.4; P > 0.4). We conclude that galanin mRNA expression in GnRH neurons of the rat is diminished during lactation, whereas GnRH expression continues unabated. This decrease in galanin gene expression associated with lactation may lead to decreased synthesis and secretion of galanin, which, in turn, could diminish the pulsatile secretion of GnRH or reduce its activity at the pituitary.en_US
dc.language.isoen_USen_US
dc.publisherEndocrine Societyen_US
dc.subjectin situ hybridizationen_US
dc.subjectgonadotropin-releasing hormoneen_US
dc.subjectgalaninen_US
dc.subjectraten_US
dc.subject.meshIn Situ Hybridizationen_US
dc.subject.meshHypothalamus, metabolismen_US
dc.subject.meshNeurons, metabolismen_US
dc.subject.meshRNA Probesen_US
dc.subject.meshLactation, physiologyen_US
dc.subject.meshAnimalsen_US
dc.subject.meshFemaleen_US
dc.subject.meshRats, Sprague-Dawleyen_US
dc.subject.meshRNA, Antisenseen_US
dc.subject.meshRNA, Messenger, analysis, metabolismen_US
dc.subject.meshComparative Studyen_US
dc.subject.meshRibonucleasesen_US
dc.subject.meshPeptides, geneticsen_US
dc.subject.meshGene Expression Regulationen_US
dc.subject.meshGonadorelin, geneticsen_US
dc.subject.meshGalaninen_US
dc.subject.meshRatsen_US
dc.subject.meshDiestrus, metabolismen_US
dc.subject.meshDigoxigeninen_US
dc.subject.meshResearch Support, U.S. Gov't, P.H.S.en_US
dc.titleRegulation of gonadotropin-releasing hormone (GnRH) and galanin gene expression in GnRH neurons during lactation in the rat [published erratum appears in Endocrinology 1994 Jan;134(1):498]en_US
dc.typeArticleen_US


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