Ms. Blumberg et G. Sokoloff, DYNAMICS OF BROWN FAT THERMOGENESIS IN WEEK-OLD RATS - EVIDENCE OF RELATIVE STABILITY DURING MODERATE COLD-EXPOSURE, Physiological zoology, 70(3), 1997, pp. 324-330
Neonates of many mammalian species, including humans, depend primarily
on thermogenesis by brown adipose tissue as a defense against cold ch
allenge. Although the steady-state thermogenic responses of brown adip
ose tissue to various air temperatures are well known, the dynamic res
ponses have received relatively little attention. In this article, we
examine the relative stability of brown adipose tissue thermogenesis d
uring brief perturbations of air temperature. Specifically, week-old r
ats were allowed to settle at one of two levels of cold exposure. Thes
e two levels were defined on the basis of previous work as being moder
ate (30.5 degrees C) or extreme (23 degrees C). After pups had settled
at these temperatures, they were exposed to positive or negative air
temperature perturbations of approximately 3.7 degrees C. Pups experie
ncing perturbations hum the moderate air temperature, unlike those exp
osed to the extreme air temperature, exhibited organized thermogenic r
esponses that allowed them to return quickly to their preperturbation
conditions. These data suggest that brown adipose tissue thermogenesis
is more stably controlled than has previously been suspected.