Evidence for adrenal medulla involvement in cold adaptation of preoptic-lesioned rats.
The cold-adaptation process was examined in preoptic-lesioned (PO, 18 rats) and adrenaldemedullated-preoptic-lesioned rats (ADPO, 16 rats). PO rats and ADPO female Wistar rats were cold acclimatized to 5 degrees C for 2 operated and then treated exactly like the lesioned rats. Lesions in the PO region caused a decrease in the ability to maintain normal body temperature in a cold environment (5 degrees C for 2 h). Their colonic temperature fell even by the end of the 2nd h of cold exposure (-1.1 degrees C for PO rats and -1.25 degrees C for ADPO rats, P less than 0.01). However, after 2 weeks of cold acclimation the PO rats, but not the ADPO rats were able to thermoregulate in the cold and showed a normal increase in interscapular brown adipose tissue weight (79%, P less than 0.01). These data suggest that the PO is not an essential link for cold adaptation when a mild cold-adaptation method is used. Furthermore, the data show that increased adrenal medullary activity is required for the cold adaptation process in PO rats.
Martins
A N
AN
Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil.
Blom
M V
MV
Reis
A M
AM
Coimbra
C C
CC
D000222:Adaptation, Physiological; D000313:Adrenal Medulla / Q000502:physiology*; D000818:Animals; D001833:Body Temperature Regulation; D003080:Cold Temperature; D005260:Female; D011301:Preoptic Area / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains