Rat tail skin temperature regulation by estrogen, phytoestrogens and tamoxifen.

ABSTRACT

OBJECTIVE: Develop a rat model for the evaluation of estrogenic agents on estrogen deficiency-induced changes in thermoregulation. METHODS: OVX rats are impaired in thermoregulation which manifests itself as an elevation in basal tail skin temperature (TST) and are less able to respond to temperature changes than intact rats. RESULTS: Administration of estrogen subcutaneously to estrogen-depleted rats either as depot formulation, biodegradable pellets, or daily injections, suppressed the increased TST. OVX rats maintained on a diet devoid of phytoestrogens had a higher TST by several degrees than OVX rats fed normal chow, offering greater ability to test estrogenic agents on thermoregulation. Depletion of estrogen in intact rats via chronic administration of leuprolide acetate, a GnRH agonist, also increased TST, which was in turn suppressed by estrogen. In intact rats, tamoxifen exhibited estrogen antagonistic activity elevating TST, while in OVX rats, tamoxifen acted as an agonist by suppressing TST. CONCLUSION: OVX rats kept on a diet devoid of phytoestrogens are a sensitive model for estrogen-dependent thermoregulation.