There is evidence that endogenous opioid peptides exert an inhibitory effect on pituitary luteinizing hormone (LH) secretion both in animals and in humans, by interacting with μ-opioid receptors. However, a role for δ-opioid receptors in the regulation of gonadotrophin releasing hormone (GnRH) secretion has recently been suggested. In the present study, we evaluated the effect of the highly selective δ-opioid receptor agonist deltorphin on the LH and follicle stimulating hormone (FSH) responses to naloxone in six healthy fertile women during the luteal phase of the menstrual cycle. Deltorphin infusion alone (7 μg/kg/min for 60 min) did not significantly change the basal serum concentrations of LH in this group of women. The intravenous (i.v.) bolus administration of naloxone (15 mg) induced a significant (P < 0.001) increase in serum LH concentrations (from a mean basal value of 4.24 ± 1.10 IU/l to a peak of 13.27 ± 1.8 IU/l). The LH response to naloxone was significantly (P < 0.001) blunted by preinfusion of deltorphin (13.27 ± 1.80 IU/l versus 4.80 ± 1.18 IU/l). No significant changes in FSH concentrations were observed during deltorphin, naloxone or deltorphin plus naloxone administration. These data indicate that activation of δ-opioid receptors can reduce naloxone-induced LH release, suggesting a possible role of δ receptors in opioidergic modulation of LH secretion in women.
Effect of delta-opioid receptor agonist deltorphin on circulating concentrations of luteinizing hormone and follicle stimulating hormone in healthy fertile women
BONDANELLI, Marta;AMBROSIO, Maria Rosaria;FRANCESCHETTI, Paola;GUERRINI, Remo;DEGLI UBERTI, Ettore
1998
Abstract
There is evidence that endogenous opioid peptides exert an inhibitory effect on pituitary luteinizing hormone (LH) secretion both in animals and in humans, by interacting with μ-opioid receptors. However, a role for δ-opioid receptors in the regulation of gonadotrophin releasing hormone (GnRH) secretion has recently been suggested. In the present study, we evaluated the effect of the highly selective δ-opioid receptor agonist deltorphin on the LH and follicle stimulating hormone (FSH) responses to naloxone in six healthy fertile women during the luteal phase of the menstrual cycle. Deltorphin infusion alone (7 μg/kg/min for 60 min) did not significantly change the basal serum concentrations of LH in this group of women. The intravenous (i.v.) bolus administration of naloxone (15 mg) induced a significant (P < 0.001) increase in serum LH concentrations (from a mean basal value of 4.24 ± 1.10 IU/l to a peak of 13.27 ± 1.8 IU/l). The LH response to naloxone was significantly (P < 0.001) blunted by preinfusion of deltorphin (13.27 ± 1.80 IU/l versus 4.80 ± 1.18 IU/l). No significant changes in FSH concentrations were observed during deltorphin, naloxone or deltorphin plus naloxone administration. These data indicate that activation of δ-opioid receptors can reduce naloxone-induced LH release, suggesting a possible role of δ receptors in opioidergic modulation of LH secretion in women.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
