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dc.contributor.authorSteiner, Robert A.en_US
dc.contributor.authorClifton, Donald K.en_US
dc.contributor.authorRossmanith, Winfried G.en_US
dc.contributor.authorMarks, Daniel L.en_US
dc.date.accessioned2008-10-17T20:40:47Z
dc.date.available2008-10-17T20:40:47Z
dc.date.issued1996-03en_US
dc.identifier.citationJ Neuroendocrinol. 1996 Mar;8(3):185-91en_US
dc.identifier.urihttp://hdl.handle.net/1773/4322
dc.description.abstractOn the day of proestrus in the rat, rising plasma levels of estradiol (E) act in concert with progesterone (P) to trigger a preovulatory release of gonadotropins. Cellular levels of galanin mRNA in GnRH neurons are increased in association with the proestrous surge of gonadotropin secretion; however, the relative contribution made by E and P to the induction of galanin mRNA expression in GnRH neurons is unknown. We investigated the role of E and P in the induction of galanin gene expression in GnRH neurons by examining the effects of different combinations of E (estradiol benzoate; 50 micrograms and P (5 mg)) on the LH surge and the concomitant induction of galanin mRNA in GnRH neurons. We sacrificed ovariectomized adult rats after 1 of 4 treatments: Group 1: vehicle control (n = 6); Group 2: P alone (n = 7) Group 3: E alone (n = 7); Group 4: combined E/P (n = 6); the animals were killed at 18.00 h at the time of the LH surge. The brains from these animals were processed by double-label in situ hybridization to allow measurement of galanin mRNA levels in GnRH neurons. GnRH neurons were identified with a digoxigenin-labeled cRNA probe for GnRH mRNA, and galanin mRNA was detected and measured simultaneously with an 35S-labeled cRNA probe coupled with computerized grain counting. Estimation of cellular levels of GnRH mRNA was accomplished with single-label in situ hybridization, an 35S-labeled GnRH cRNA probe and computerized grain counting. We observed a 3-fold induction of galanin mRNA in the GnRH neurons of animals treated with E alone compared with those treated with the vehicle alone (vehicle: 13 +/- 2 vs E: 42 +/- 4 grains/cell (g/c); P < 0.01); LH levels in the E-treated animals were elevated, albeit moderately, with respect to the vehicle controls. Compared with vehicle-treated animals, those treated with the combination of E and P showed a 5-fold induction of galanin mRNA in GnRH neurons (68 +/- 9 g/c), which was significantly (P < 0.01) greater than that observed in the animals treated with E alone; in addition, the magnitude of the LH surge was much greater (P < 0.05) in the E/P-treated group compared with the E alone group. In contrast, compared to the vehicle controls, animals treated with P alone (15 +/- 2 g/c) showed no discernable effect on galanin mRNA levels; moreover, no LH surge occurred in the P alone group. Neither the number of identified GnRH cells nor their content of GnRH mRNA differed significantly among the experimental groups (GnRH mRNA signal: vehicle controls: 153 +/- 6 vs E: 159 +/- 6 vs E/P: 153 +/- vs P: 148 +/- 8 g/c). We conclude that while E is the primary ovarian signal inducing galanin mRNA expression in GnRH neurons and the LH surge itself, P plays a facilitatory role in both of these processes.en_US
dc.language.isoen_USen_US
dc.publisherBlackwell Publishingen_US
dc.subjectgalanin mRNAen_US
dc.subjectgonadotropin-releasing hormone (GnRH) estradiolen_US
dc.subjectprogesteroneen_US
dc.subjectin situ hybridizationen_US
dc.subjecthypothalamusen_US
dc.subject.meshIn Situ Hybridizationen_US
dc.subject.meshImage Processing, Computer-Assisteden_US
dc.subject.meshNeurons, drug effects, metabolismen_US
dc.subject.meshProgesterone, pharmacologyen_US
dc.subject.meshLuteinizing Hormone, blooden_US
dc.subject.meshEstradiol, pharmacologyen_US
dc.subject.meshResearch Support, Non-U.S. Gov'ten_US
dc.subject.meshRNA Probesen_US
dc.subject.meshRNA, Messenger, biosynthesisen_US
dc.subject.meshAnimalsen_US
dc.subject.meshOvariectomyen_US
dc.subject.meshGalanin, biosynthesisen_US
dc.subject.meshGonadorelin, physiologyen_US
dc.subject.meshFemaleen_US
dc.subject.meshRats, Sprague-Dawleyen_US
dc.subject.meshBrain, cytologyen_US
dc.subject.meshBrain Chemistry, drug effectsen_US
dc.subject.meshResearch Support, U.S. Gov't, P.H.S.en_US
dc.titleInduction of galanin mRNA in GnRH neurons by estradiol and its facilitation by progesteroneen_US
dc.typeArticleen_US


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