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

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 (T_b), tail skin temperature (T_tail), 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 T_b and T_tail were greater in rats applied menthol than that in rats applied vehicle. In rats applied menthol, the T_b 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 T_b 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 T_b elevation induced by application of menthol to ovariectomized rats.