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Registro Completo |
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Biblioteca(s): |
Embrapa Caprinos e Ovinos. |
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Data corrente: |
11/01/2000 |
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Data da última atualização: |
09/08/2023 |
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Autoria: |
CICERO, T. J.; ADAMS, M. L.; O'CONNOR, L. H.; NOCK, B. |
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Título: |
In vivo evidence for a direct effect of naloxone on testicular steroidogenesis in the male rat. |
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Ano de publicação: |
1989 |
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Fonte/Imprenta: |
Endocrinology, v. 125, n. 2, p. 957-963, Aug. 1989. |
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DOI: |
https://doi.org/10.1210/endo-125-2-957 |
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Idioma: |
Inglês |
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Conteúdo: |
Abstract: It has been suggested that endogenous opioid peptides (EOP) exert paracrine or autocrine effects in the testes. To assess this hypothesis, we examined whether naloxone, by blocking the effects of EOP, influenced serum testosterone levels, apart from its effects on LHRH/LH, in the intact male rat. We found that naloxone increased serum LH and testosterone levels over essentially the same time course and produced dosedependent increases in serum testosterone levels even though LH levels were maximally elevated at all doses. These data are not consistent with the view that naloxone exerts its effects on testosterone exclusively by altering LHRH/LH release. Additional, perhaps more definitive, evidence of a direct effect of naloxone on testosterone's biosynthesis was provided by our observations that 1) naloxone generated increases in serum testosterone levels in male rats in which the naloxone-induced surge in LH was blocked by nembutal; and 2) intratesticular injections of naloxone increased serum testosterone levels without increasing LH. Although these data suggest that naloxone influences steroidogenesis independently of its effects on LH, we found that the antagonist failed to increase serum testosterone levels in hypophysectomized animals or when serum LH levels were allowed to reach undetectable levels in nembutalblocked animals. Consequently, our data are consistent with the hypothesis that naloxone facilitates the effects of LH on testosterone's biosynthesis rather than exerting an independent effect of its own. Whether the effects observed in these studies represent a negative autocrine effect of EOP on Leydig cells or a paracrine effect on Sertoli cells remains to be determined. Nevertheless, our results provide, to our knowledge, the first in vivo evidence that EOP modulate testicular steroidogenesis in the intact animal. MenosAbstract: It has been suggested that endogenous opioid peptides (EOP) exert paracrine or autocrine effects in the testes. To assess this hypothesis, we examined whether naloxone, by blocking the effects of EOP, influenced serum testosterone levels, apart from its effects on LHRH/LH, in the intact male rat. We found that naloxone increased serum LH and testosterone levels over essentially the same time course and produced dosedependent increases in serum testosterone levels even though LH levels were maximally elevated at all doses. These data are not consistent with the view that naloxone exerts its effects on testosterone exclusively by altering LHRH/LH release. Additional, perhaps more definitive, evidence of a direct effect of naloxone on testosterone's biosynthesis was provided by our observations that 1) naloxone generated increases in serum testosterone levels in male rats in which the naloxone-induced surge in LH was blocked by nembutal; and 2) intratesticular injections of naloxone increased serum testosterone levels without increasing LH. Although these data suggest that naloxone influences steroidogenesis independently of its effects on LH, we found that the antagonist failed to increase serum testosterone levels in hypophysectomized animals or when serum LH levels were allowed to reach undetectable levels in nembutalblocked animals. Consequently, our data are consistent with the hypothesis that naloxone facilitates the effects of LH on testosterone's biosynthesis ... Mostrar Tudo |
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Palavras-Chave: |
Drug effects; Esteroidogenese; Rato macho. |
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Thesagro: |
Testículo. |
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Thesaurus Nal: |
Gonadotropin-releasing hormone; Hypophysectomy; Luteinizing hormone; Males; Naloxone; Pentobarbital; Rats; Testes; Testosterone. |
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Categoria do assunto: |
L Ciência Animal e Produtos de Origem Animal |
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Marc: |
LEADER 02790naa a2200325 a 4500
001 1524078
005 2023-08-09
008 1989 bl uuuu u00u1 u #d
024 7 $ahttps://doi.org/10.1210/endo-125-2-957$2DOI
100 1 $aCICERO, T. J.
245 $aIn vivo evidence for a direct effect of naloxone on testicular steroidogenesis in the male rat.$h[electronic resource]
260 $c1989
520 $aAbstract: It has been suggested that endogenous opioid peptides (EOP) exert paracrine or autocrine effects in the testes. To assess this hypothesis, we examined whether naloxone, by blocking the effects of EOP, influenced serum testosterone levels, apart from its effects on LHRH/LH, in the intact male rat. We found that naloxone increased serum LH and testosterone levels over essentially the same time course and produced dosedependent increases in serum testosterone levels even though LH levels were maximally elevated at all doses. These data are not consistent with the view that naloxone exerts its effects on testosterone exclusively by altering LHRH/LH release. Additional, perhaps more definitive, evidence of a direct effect of naloxone on testosterone's biosynthesis was provided by our observations that 1) naloxone generated increases in serum testosterone levels in male rats in which the naloxone-induced surge in LH was blocked by nembutal; and 2) intratesticular injections of naloxone increased serum testosterone levels without increasing LH. Although these data suggest that naloxone influences steroidogenesis independently of its effects on LH, we found that the antagonist failed to increase serum testosterone levels in hypophysectomized animals or when serum LH levels were allowed to reach undetectable levels in nembutalblocked animals. Consequently, our data are consistent with the hypothesis that naloxone facilitates the effects of LH on testosterone's biosynthesis rather than exerting an independent effect of its own. Whether the effects observed in these studies represent a negative autocrine effect of EOP on Leydig cells or a paracrine effect on Sertoli cells remains to be determined. Nevertheless, our results provide, to our knowledge, the first in vivo evidence that EOP modulate testicular steroidogenesis in the intact animal.
650 $aGonadotropin-releasing hormone
650 $aHypophysectomy
650 $aLuteinizing hormone
650 $aMales
650 $aNaloxone
650 $aPentobarbital
650 $aRats
650 $aTestes
650 $aTestosterone
650 $aTestículo
653 $aDrug effects
653 $aEsteroidogenese
653 $aRato macho
700 1 $aADAMS, M. L.
700 1 $aO'CONNOR, L. H.
700 1 $aNOCK, B.
773 $tEndocrinology$gv. 125, n. 2, p. 957-963, Aug. 1989.
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Registro original: |
Embrapa Caprinos e Ovinos (CNPC) |
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