CONICET | Buscador de Institutos y Recursos Humanos

The chronic exposure to oestradiol potentiates the anandamide-induced relaxations in the mesenteric vasculature of the rat. The aim of the present work was to study whether the soy-derived phytoestrogens genistein and daidzein had any effect on the vasodilation caused by anandamide in mesenteric beds isolated from male and female Sprague-Dawley rats. A 3-day oral gavage administration of the phytoestrogen genistein (10 mg/kg), but not of an equivalent dose of the phytoestrogen daidzein, potentiated the reduction of the noradrenaline-induced contractile responses caused by anandamide in mesenteric beds isolated from female but not from male rats. This effect was prevented by the coadministration of the oestrogen receptor antagonist fulvestrant (2.5 mg/kg, s.c., daily during 3 days). The oral treatment with genistein mimicked the reversion caused by oestradiol (450 µg/kg 17â-oestradiol-3-benzoate i.m., daily during 3 days) on the diminution of the anandamide-induced relaxations that occurred after ovariectomy. The endogenous levels of calcitonin gene-related peptide (CGRP), that were reduced by ovariectomy in the mesenteric arteries, were recovered after a 3-day treatment with either 17b-oestradiol or the phytoestrogen genistein. In conclusion, the phytoestrogen genistein potentiates the anandamide-induced relaxations in mesenteries isolated from female but not from male rats. This effect is likely to involve the activation of oestrogen receptors and the consequent increase in the mesenteric content of CGRP.