| Autor: |
Lengyel, A. M. J., Grossman, A., Bouloux, P.-M. G., Rees, L. H., Besser, G. M. |
| Zdroj: |
Journal of Endocrinology; September 1985, Vol. 106 Issue: 3 p317-322, 6p |
| Abstrakt: |
Dopamine and morphine modulate GH and LH release, probably at a hypothalamic locus. To investigate this in more detail, we studied the influence of these substances on somatostatin and LH-releasing hormone (LHRH) release from rat hypothalamic fragments in vitro. Hypothalamic fragments were incubated in Earle's medium. After 60 min of preincubation, medium from two 20-min incubations was collected and somatostatin and LHRH levels measured by radioimmunoassay. Dopamine (10 nmol/l–0·1 mmol/l) induced a progressive increase (r= 0·41; P<0·01) in basal somatostatin levels. K +(30 mmol/l)-induced somatostatin release was also increased (r= 0·54; P<0·01) by increasing doses of dopamine. Metoclopramide (10 μmol/l) blocked the dopamine (1 μmol/l)-induced increase in somatostatin release. No significant relationship between dopamine and LHRH was found either basally or after K +(30 mmol/l) stimulation. Basal somatostatin was negatively correlated (r= −0·63; P<0·01) with morphine concentrations. No significant correlation was found after K+(30 mmol/l) depolarization. Basal LHRH release was not influenced by morphine, while K +(30 mmol/l)-induced release was significantly lower than controls only at a concentration of 10 nmol/l. These results suggest that dopamine and morphine act at a hypothalamic level to modulate GH release through alterations in somatostatin secretion. Dopamine and morphine have no consistent effect on hypothalamic LHRH release.J. Endocr. (1985) 106, 317–322 |
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