Spontaneous skin flushing episodes in the aging female rat

It is well known that with the loss of gonadal function most women experience hot flushes, characterized by a rapid regional increase in cutaneous blood flow. Animal models for this vasomotor syndrome have been elusive, thus hampering efforts to evaluate the endocrine and neuronal substrates of the hot flush. In this report, evidence is reported for the occurrence in aging female rats of spontaneous tail skin temperature (TST) fluctuations which are similar in amplitude, duration and frequency to hot flushes reported for peri-menopausal women. Paradoxically, these TST pulses occur in animals with senescent reproductive states in which serum estrogen levels are moderately elevated and ovariectomy eliminates these rat flushing episodes. This demonstration of steroid-dependent, spontaneous flushing episodes indicates that the aging female rat can be used to evaluate the neuronal and hormonal basis of vasomotor instability.