Expression of estrogen receptor subtypes and neuronal nitric oxide synthase in neutrophils from women and men: regulation by estrogen.

Objectives: (a) To identify the subtype of estrogen receptor (ER) expressed in neutrophils from premenopausal women and in neutrophils from men under different estrogen conditions and (b) to analyze the association between the modifications in the expression of ER subtypes and neuronal nitric oxide synthase (nNOS) expression induced by estrogen.

Methods: Neutrophils were isolated from pre-menopausal women during different stages of the menstrual cycle and from ten men for in vitro estrogen incubations.

Results: Neutrophils from premenopausal women expressed both ERalpha and ERbeta subtypes which were increased in the ovulatory phase of the menstrual cycle. Neutrophils derived from men also expressed ERalpha and ERbeta but only ERalpha expression was enhanced by in vitro incubation with 17beta-estradiol (10(-8) mol/l). In vitro incubation of neutrophils from women with 17beta-estradiol enhanced expression of both ER-alpha and ER-beta subtypes. nNOS protein was overexpressed in neutrophils from premenopausal women during the ovulatory phase. 17beta-Estradiol (10(-8) mol/l) also increased nNOS protein expression in neutrophils derived from men. Mithramycin A (10(-6) mol/l) and curcumin (10(-6) mol/l), prevented the upregulation of nNOS and ERalpha in neutrophils derived from men, suggesting the involvement of AP-1 and Sp-1 transcription factors.

Conclusions: Although the in vivo levels of circulating estrogen concentrations seem to be associated with overexpression of both ERalpha and ERbeta in neutrophils from premenopausal women, which was further confirmed by the in vitro experiments with neutrophils from women, in vitro incubation of neutrophils from men with 17beta-estradiol only increased ERalpha protein expression which was associated with enhanced expression of nNOS protein.