Possible Negative Ultra-Short Loop Feedback of Luteinizing Hormone Releasing Hormone (LHRH) in the Ovariectomized Rat

dc.contributor.authorde Castro, J.C. Bedran
dc.contributor.authorKhorram, O.
dc.contributor.authorMccann, S. M.
dc.contributor.institutionUniversidade do Estado de Sao Paulo
dc.contributor.institutionUniversity of Texas Health Science Center
dc.date.accessioned2022-04-29T08:42:16Z
dc.date.available2022-04-29T08:42:16Z
dc.date.issued1985-01-01
dc.description.abstractTo determine if LHRH might act within the brain to modify its own release, repeated blood samples were removed from conscious ovariectomized rats and minute doses of LHRH were injected into the third ventricle (3V). The effect of these injections on plasma LH and FSH was measured by radioimmunoassay (RIA). The higher dose of intraventricular LHRH (10 ng in 2 yl) induced an increase in plasma LH within 10 min after its injection. Plasma LH decreased for the next 60 min. This was followed by restoration of LH pulses characteristic of the ovariectomized rat. This dose of LHRH slightly elevated plasma FSH concentrations. In stark contrast, a 10 fold lower dose of 1 ng of LHRH injected into the ventricle resulted in a highly significant decrease of plasma LH at 10 min following injection, followed by return of LH pulsations. There was no effect on the pulsatile release of FSH. The results are interpreted to mean that at the higher dose, sufficient LHRH reached the site of origin of the hypophyseal portal vessels in the median eminence so that it diffused into portal vessels and was delivered to the gonadotrophs to induce LH release. In contrast, the lower dose provided sufficient hypothalamic concentrations of the peptide to suppress the discharge of the LHRH neurons, thereby leading to a decline in plasma LH, indicative of an ultrashort-loop negative feedback of LHRH to suppress its own release. © 1985, SAGE Publications. All rights reserved.en
dc.description.affiliationDepartamento de Ciencias Fisiologicas Universidade do Estado de Sao Paulo Campus de Aracatuba, Aracatuba
dc.description.affiliationDepartment of Physiology University of Texas Health Science Center, Dallas, Texas 75235
dc.format.extent132-135
dc.identifierhttp://dx.doi.org/10.3181/00379727-179-1-RC2
dc.identifier.citationProceedings of the Society for Experimental Biology and Medicine, v. 179, n. 1, p. 132-135, 1985.
dc.identifier.doi10.3181/00379727-179-1-RC2
dc.identifier.issn1535-3699
dc.identifier.issn0037-9727
dc.identifier.scopus2-s2.0-0021814309
dc.identifier.urihttp://hdl.handle.net/11449/230819
dc.language.isoeng
dc.relation.ispartofProceedings of the Society for Experimental Biology and Medicine
dc.sourceScopus
dc.titlePossible Negative Ultra-Short Loop Feedback of Luteinizing Hormone Releasing Hormone (LHRH) in the Ovariectomized Raten
dc.typeArtigo
unesp.campusUniversidade Estadual Paulista (Unesp), Faculdade de Odontologia, Araçatubapt
unesp.departmentCiências Básicas - FOApt

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