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Effect of naloxone and beta-casomorphin on the hypothalamic-pituitary-luteinizing hormone axis in vitro.
- Source :
-
Life sciences [Life Sci] 1992; Vol. 51 (12), pp. 899-907. - Publication Year :
- 1992
-
Abstract
- The effect of naloxone and beta-casomorphin on luteinizing hormone (LH) release from pituitary cell aggregates, obtained by three-dimensional culture, with or without mediobasal hypothalamic fragments was studied in vitro. Short-term naloxone perifusion at a concentration of 10(-5)M did not modify either basal or LHRH-stimulated LH release from the pituitary cell aggregates. In contrast, a 12-min naloxone perifusion at the same concentration caused an increase in LH release in the mediobasal hypothalamic-pituitary cell aggregate axis. This increase was rapid (12-16 min after time pulse), marked [up to 10 times (p less than 0.004) the initial base line], short (return to the base line secretion 32-40 min after the beginning of the time pulse) and dose-dependent, with a rise greater than 1000% at a concentration of 10(-4) (p less than 0.006). The same effect was observed when a second pulse was applied 48 min after the first one. LH release induced by naloxone was antagonized 56 +/- 2% (p less than 0.03) by beta-casomorphin (an exogenous opiate) at a concentration of 10(-5) M. beta-casomorphin alone did not modify LH basal secretion, but inhibited 25.1 +/- 2.4% (p less than 0.008) LH release enhanced by LHRH. These results indicate that naloxone, an opiate antagonist, markedly increases LH release via a mu-type opioid receptor mechanism at the hypothalamic level only, during short-term exposure.
- Subjects :
- Animals
Caseins
Cells, Cultured
Gonadotropin-Releasing Hormone pharmacology
Hypothalamus, Middle drug effects
Male
Perfusion
Pituitary Gland, Anterior cytology
Pituitary Gland, Anterior drug effects
Radioimmunoassay
Rats
Rats, Inbred Strains
Statistics as Topic
Endorphins pharmacology
Hypothalamo-Hypophyseal System drug effects
Luteinizing Hormone metabolism
Naloxone pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 0024-3205
- Volume :
- 51
- Issue :
- 12
- Database :
- MEDLINE
- Journal :
- Life sciences
- Publication Type :
- Academic Journal
- Accession number :
- 1518367
- Full Text :
- https://doi.org/10.1016/0024-3205(92)90397-8