[Effects of estrogen and remifemin on neuronal nitric oxide synthase and transient receptor potential vanilloid 1 in submandibular gland of ovariectomized rats].

To investigate the effects of estrogen and remifemin on the expression of neuronal nitric oxide synthase (nNOS), transient receptor potential vanilloid 1 (TRPV1), muscarinic acetylcholine receptor, member 1 and 3 (M1 and M3 receptor) and acetylcholinesterase (AChE) in the submandibular gland of rats. Forty SD female adult rats were divided into SHAM group (sham operation), OVX group (ovarian removal), OVX+E group (ovarian removal + estrogen treatment) and OVX+ICR group (ovarian removal + remifemin treatment), 10 per group. The rats were recovered for 2 weeks after operation. The SHAM group and the OVX group were treated with distilled water, the OVX+E group and the OVX+ICR group were treated with β-estradiol and remifemin respectively. After 4 weeks, the location and expression of nNOS, TRPV1, M1 and M3 receptors in the submandibular gland were evaluated by immunohistochemistry. The changes of AChE expression in rat submandibular gland were observed by AChE staining. Compared with SHAM group (0.23±0.02, 0.28±0.01, 0.25±0.03, 0.19±0.03), the expression of nNOS, TRPV1, M1 and M3 receptors in OVX group (0.16±0.01, 0.21±0.01, 0.15±0.02, 0.09±0.02) were significantly lower (0.05); there were no significant difference between OVX+E group (0.23±0.01, 0.28±0.02, 0.23±0.03, 0.19±0.01) and SHAM group (0.05). But compared with OVX group, the expression of nNOS, TRPV1 and M3 receptors in OVX+ICR group were no significantly changed (0.05), and only M1 receptor expression (0.22±0.03) was significantly increased (0.05). The expression of AChE in OVX group (0.14±0.01) was significantly higher than that in SHAM group (0.10±0.01) (0.05). The expression of AChE in OVX+E group (0.15±0.01) was significantly higher than that in SHAM group (0.05). The expression of AChE in OVX+ICR group (0.09±0.01) was not significantly different from that in SHAM group (0.05). Estrogen can significantly increase the expression of nNOS and TRPV1 in the submandibular gland of rats, suggesting that estrogen may regulate the salivary secretion function of the submandibular gland through nNOS and TRPV1. The mechanism of remifemin is different from that of estrogen, and remifemin does not play a regulatory role by nNOS and TRPV1.