Central and peripheral temperature changes in sheep following ovariectomy.
OBJECTIVE
To determine if ovariectomized ewes undergo periodic body temperature rises (hot flashes) similar to women at menopause.


METHODS
Eighteen mature ewes were assigned to ovariectomy (OVX), ovariectomy+17 beta-estradiol implant (OVXE) or Sham. Electronic temperature loggers placed subcutaneously over the carotid artery and within the abdomen (core) and subcutaneously in the thigh and axilla (peripheral) were programmed to record body temperatures every 2.5 min for 59 days. Circadian rhythm changes were avoided by dividing readings into 1 h intervals. Hot flashes were defined as a 0.2 or 0.4 degrees C increase over the minimum temperature recorded for a 1 h interval for each sheep.


RESULTS
Logger placement did not reflect core and peripheral temperatures. The carotid and abdominal sites were most useful. The percentage of readings considered HF at the carotid site was 63% OVX, 54% OVXE and 37% Sham (P<0.001), and at the abdominal site were 32% OVX, 15% OVE and 17% Sham (P<0.001). When only the first 7 days after ovariectomy were analyzed, the percentage of readings considered to be HF at the carotid site was 75% OVX, 63% OVXE, and 49% Sham (P<0.001), and at the abdominal site was 35% OVX, 15% OVXE and 17% Sham (P<0.001).


CONCLUSIONS
Ovariectomy in the ewe does illicit changes in body temperature compared with control ewes, which may be interpreted as HF. However, shifts in the circadian rhythm were not apparent. Estradiol treatment led to milder and less frequent HF. Periodic HF in species other than rats have heretofore not been reported.
MacLeay
J M
JM
Department of Clinical Sciences, Colorado State University, Ft. Collins, CO 80523, USA.
Lehmer
E
E
Enns
R M
RM
Mallinckrodt
C
C
Bryant
H U
HU
Turner
A S
AS
D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology*; D004343:Drug Implants; D004958:Estradiol / Q000008:administration & dosage* / Q000494:pharmacology; D005260:Female; D019584:Hot Flashes / Q000503:physiopathology*; D008593:Menopause / Q000502:physiology*; D023421:Models, Animal; D010052:Ovariectomy; D011897:Random Allocation; D012756:Sheep
D004343:Drug Implants; D004958:Estradiol