14657608

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Predicate	Object
rdf:type	pubmed:Citation
lifeskim:mentions	umls-concept:C0007613, umls-concept:C0023602, umls-concept:C0034693, umls-concept:C0205307, umls-concept:C0299583, umls-concept:C1280500
pubmed:issue	5
pubmed:dateCreated	2003-12-5
pubmed:abstractText	Neonatal L-monosodium glutamate (MSG) administration in rats induces several neuroendocrine and metabolic disruptions. Leptin, the adipocyte product, modulates several neuroendocrine systems including the hypothalamic-pituitary-gonadal (HPG) axis in mammals. The aim of the present study was to determine whether MSG-induced chronic hyperleptinemia could play any relevant role in the hypogonadism developed by male rats when examined in adulthood. We found that 120-day-old MSG male rats displayed significant hyperleptinemia, hypogonadism, and undisturbed basic testis structure and spermatogenesis. In vitro studies in purified Leydig cells from normal (CTR) and MSG-damaged rats revealed that basal and human chorionic gonadotropin (hCG)-stimulated 17-hydroxy-progesterone (17-HO-P(4)), Delta(4)-androstenedione (Delta(4)A) and testosterone (T) secretions were significantly lower in MSG than in CTR cells. Exposure to murine leptin (Mleptin, 10(-8)M) significantly inhibited hCG-elicited T secretion by CTR cells after 180 min incubation. While Mleptin significantly inhibited hCG-stimulated Delta(4)A output and the Delta(4)A:17-OH-P(4) ratio of secretion, conversely, it failed to modify the ratio T:Delta(4)A release by CTR Leydig cells. Interestingly, the effects of Mleptin found on CTR Leydig cells were absent in MSG Leydig cells. Finally, endogenous hyperleptinemia was associated with a significant decrease in Leydig cell expression of Ob-Rb mRNA in MSG rats. In summary, this study demonstrates that: (1) Mleptin inhibited testicular steroidogenesis in CTR rats; (2) MSG-treated rats showed lower in vitro 17-OH-P(4), Delta(4)A and T production under basal and post-hCG stimulation conditions; (3) purified Leydig cells from MSG-treated rats displayed resistance to the inhibitory action of Mleptin on T release, and (4) endogenous leptin exerts a modulatory effect on Leydig cell Ob-Rb mRNA expression. The inhibitory effect of leptin on testicular function is thus abrogated in MSG-damaged rats. The testicular leptin-resistance developed by MSG rats seems to be due to early chronic exposure of Leydig cells to high leptin circulating levels, which in turn down-regulate testicular Ob-Rb expression. It remains to be determined whether the testicular dysfunction of MSG rats can be reversed after correction of hyperleptinemia or whether it is an irreversible effect of the hypothalamic lesion.
pubmed:language	eng
pubmed:journal	http://linkedlifedata.com/resource/pubmed/journal/0035665
pubmed:citationSubset	IM
pubmed:chemical	http://linkedlifedata.com/resource/pubmed/chemical/Androstenols, http://linkedlifedata.com/resource/pubmed/chemical/Follicle Stimulating Hormone, http://linkedlifedata.com/resource/pubmed/chemical/Leptin, http://linkedlifedata.com/resource/pubmed/chemical/Luteinizing Hormone, http://linkedlifedata.com/resource/pubmed/chemical/RNA, Messenger, http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Cell Surface, http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Leptin, http://linkedlifedata.com/resource/pubmed/chemical/Sodium Glutamate, http://linkedlifedata.com/resource/pubmed/chemical/Testosterone, http://linkedlifedata.com/resource/pubmed/chemical/Thyroxine, http://linkedlifedata.com/resource/pubmed/chemical/androsta-5,16-dien-3 beta-ol, http://linkedlifedata.com/resource/pubmed/chemical/leptin receptor, human, http://linkedlifedata.com/resource/pubmed/chemical/leptin receptor, mouse
pubmed:status	MEDLINE
pubmed:month	Nov
pubmed:issn	0028-3835
pubmed:author	pubmed-author:CalandraRicardo SRS, pubmed-author:FrançaLuiz RLR, pubmed-author:GiovambattistaAndrésA, pubmed-author:NessrallaClaudio C D LCC, pubmed-author:SpinediEduardoE, pubmed-author:SuescunMaría OMO
pubmed:copyrightInfo	Copyright 2003 S. Karger AG, Basel
pubmed:issnType	Print
pubmed:volume	78
pubmed:owner	NLM
pubmed:authorsComplete	Y
pubmed:pagination	270-9
pubmed:dateRevised	2007-11-15
pubmed:meshHeading	pubmed-meshheading:14657608-Analysis of Variance, pubmed-meshheading:14657608-Androstenols, pubmed-meshheading:14657608-Animals, pubmed-meshheading:14657608-Animals, Newborn, pubmed-meshheading:14657608-Blotting, Northern, pubmed-meshheading:14657608-Body Weight, pubmed-meshheading:14657608-Disease Models, Animal, pubmed-meshheading:14657608-Dose-Response Relationship, Drug, pubmed-meshheading:14657608-Female, pubmed-meshheading:14657608-Follicle Stimulating Hormone, pubmed-meshheading:14657608-Hypogonadism, pubmed-meshheading:14657608-Leptin, pubmed-meshheading:14657608-Leydig Cells, pubmed-meshheading:14657608-Luteinizing Hormone, pubmed-meshheading:14657608-Male, pubmed-meshheading:14657608-Mice, pubmed-meshheading:14657608-Organ Size, pubmed-meshheading:14657608-RNA, Messenger, pubmed-meshheading:14657608-Radioimmunoassay, pubmed-meshheading:14657608-Rats, pubmed-meshheading:14657608-Rats, Sprague-Dawley, pubmed-meshheading:14657608-Receptors, Cell Surface, pubmed-meshheading:14657608-Receptors, Leptin, pubmed-meshheading:14657608-Reverse Transcriptase Polymerase Chain Reaction, pubmed-meshheading:14657608-Sodium Glutamate, pubmed-meshheading:14657608-Testis, pubmed-meshheading:14657608-Testosterone, pubmed-meshheading:14657608-Thyroxine
pubmed:year	2003
pubmed:articleTitle	Modulatory effects of leptin on leydig cell function of normal and hyperleptinemic rats.
pubmed:affiliation	Instituto Multidisciplinario de Biología Celular, La Plata, Argentina.
pubmed:publicationType	Journal Article, Comparative Study, Research Support, Non-U.S. Gov't