Estradiol administration suppresses body temperature elevation induced by application of menthol to ovariectomized rats.

The aim of the present study was to investigate the effect of estradiol (E2 ) on thermoregulatory responses induced by menthol in ovariectomized rats. Wistar rats were ovariectomized, and implanted with a silastic tube with or without E2 (E2 (+) and E2 (-) groups). L-menthol (10%) or vehicle was applied to the skin of the whole trunk in selected animals, which were then exposed to 27 °C or 16 °C for 2 h. Continuous body temperature (Tb ), tail skin temperature (Ttail ), and treatment-associated behaviors were measured. cFos immunoreactive (cFos-IR) cells in the median preoptic area, paraventricular nucleus (PVN), medial preoptic area, posterior hypothalamus, and dorsomedial hypothalamus were counted. At 27 °C, in the E2 (+) and E2 (-) groups, the Tb and Ttail were greater in rats applied menthol than that in rats applied vehicle. In rats applied menthol, the Tb in the E2 (+) group was lower than that in the E2 (-) group. In the E2 (+) and E2 (-) groups, the number of cFos-IR cells in the PVN was greater in rats applied menthol than that in rats applied vehicle. These results suggested that menthol treatment increased Tb in ovariectomized rats with or without E2 at 27 °C, and that activation of the PVN might be involved in this response. E2 administration suppresses Tb elevation induced by application of menthol to ovariectomized rats.