Effects of age, reproductive status and ambient temperature on skin temperature regulation in the female rat.
In the present study, we evaluated a large population of aged Long-Evans female rats for the occurrence of spontaneous tail skin temperature (TST) surges. Young (5-7 months) normally cycling (NC) rats and aged (19-29 months), repeated pseudopregnant (PP) and constant estrous (CE) rats were placed in an environmentally controlled room with ambient temperatures of 24-25 degrees C or 29-30 degrees C and TST was monitored at 5 min intervals for 2 h. In young NC and aged PP rats, the incidence of TST surges (flushes) was 8-17% at low and 28-33% at high ambient temperature. Old CE rats exhibited a flushing incidence of 21% and 74% at ambient temperatures of 24-25 degrees C and 29-30 degrees C, respectively. The observed flushing episodes did not differ in their duration or amplitude among the three groups of rats. However, at both low and high ambient temperature, the frequency of flushes were significantly higher in old CE rats. Collectively, these data indicate that reproductive status, rather than age, is the important determinant of TST stability in the female rat. Further, elevated estrogen associated with the CE state may compromise, while elevated progesterone associated with the PP state has a protective effect on the stability of TST in the female rat.
Simpkins
J W
JW
Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville 32610, USA.
D000375:Aging / Q000502:physiology*; D000818:Animals; D001833:Body Temperature Regulation; D004971:Estrus / Q000502:physiology*; D005260:Female; D005483:Flushing / Q000503:physiopathology; D011555:Pseudopregnancy / Q000503:physiopathology*; D051381:Rats; D012881:Skin Temperature