The experiments reported here add further evidence in support of the view that sex steroids may influence the binding characteristics of brain opioid receptors. In particular, it has been shown that: (a) the number of μ-opioid receptors varies in the hypothalamus of regularly cycling female rats according to the different phases of the estrous cycle, which are characterized by fluctuations of circulating levels of sex steroids; (b) the number of μ-opioid receptors decreases in the hypothalamus and in the corpus striatum when ovariectomized rats are submitted to treatments with estradiol and progesterone able to induce a "positive" feedback effect on LH release. A treatment with estrogen alone able to induce a "negative" feedback effect on LH release brings about an increase of the number of μ-opioid receptors in the thalamus and in the hippocampus; (c) in addition to the μ-receptors, receptors of the delta type may also be involved in the control of gonadotropin secretion; recent results here presented indicate that a line of immortalized hypothalamic cells (GT1 cells), which synthesize and secrete LHRH, present δ opioid receptors on their membranes; these are apparently involved in the control of LHRH release from these cells.

Effects of steroids on the brain opioid system / F. Piva, P. Limonta, D. Dondi, F. pimpinelli, L. Martini, R. Maggi. - In: JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY. - ISSN 0960-0760. - 53:1-6(1995), pp. 343-348. ((Intervento presentato al IX. convegno International Congress on Hormonal Steroids tenutosi a Dallas, USA nel 1994.

Effects of steroids on the brain opioid system

F. Piva;P. Limonta;D. Dondi;L. Martini;R. Maggi
1995

Abstract

The experiments reported here add further evidence in support of the view that sex steroids may influence the binding characteristics of brain opioid receptors. In particular, it has been shown that: (a) the number of μ-opioid receptors varies in the hypothalamus of regularly cycling female rats according to the different phases of the estrous cycle, which are characterized by fluctuations of circulating levels of sex steroids; (b) the number of μ-opioid receptors decreases in the hypothalamus and in the corpus striatum when ovariectomized rats are submitted to treatments with estradiol and progesterone able to induce a "positive" feedback effect on LH release. A treatment with estrogen alone able to induce a "negative" feedback effect on LH release brings about an increase of the number of μ-opioid receptors in the thalamus and in the hippocampus; (c) in addition to the μ-receptors, receptors of the delta type may also be involved in the control of gonadotropin secretion; recent results here presented indicate that a line of immortalized hypothalamic cells (GT1 cells), which synthesize and secrete LHRH, present δ opioid receptors on their membranes; these are apparently involved in the control of LHRH release from these cells.
Settore BIO/13 - Biologia Applicata
Settore BIO/09 - Fisiologia
JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/182340
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