Maximum thermogenesis in hibernators: Magnitudes and seasonal variations

Brown fat and nonshivering thermogenesis in the gray mouse lemur (Microcebus murinus)

“…In gray mouse lemurs, NST was stimulated by the ␤-adrenergic agonist isoproterenol. The dose-response curve appeared very similar to those obtained in rodents (17,53). Maximum oxygen consumption obtained with the highest dose of isoproterenol used to give maximum thermogenesis was about three times higher than the resting MR.…”

“…The thermogenic response to intramuscular injection of two doses of a ␤-adrenergic agonist (isoproterenol) was measured in the same way for 60 min (53). The injection of 20 and 200 g/100 g of isoproterenol in 200 l of saline vehicle and a control injection of vehicle were performed in the same four normothermic animals (2 males and 2 females) on a different day, during the diurnal rest, at least 6 h of daylight.…”

“…The tissue specificity of UCP1 in BAT has been widely used as a sensitive marker to identify whether BAT is present or not (21). NST has been shown to be induced by the sympathoadrenal system, and injection of norepinephrine or ␤-adrenergic agonist (isoproterenol) has been used to induce NST experimentally (17,23,24,26,53).…”

The Cytologic Investigation of Brown Adipose Tissue of D.laniger (Felten & Storch, 1968) (Mammalia: Rodentia) in Hibernation

“…The color of this tissue is coming from blood vessels and cytochromes in mitochondria those it contains. Although white adipose tissue spreads throughout the body, brown adipose tissue is concentrated in the body's specific locations (20). In our study, the BAT has attracted markedly great attention as the brown color on the back of the animal in hibernation.…”

Mammalian Hibernation: An Escape from the Cold

“…This implies that the contribution of heat production by BAT is probably minor in these rodents for arousal from hibernation. However, since peak heat production during arousal from hibernation in some ground squirrels is only about 60 -70070 of their maximum thermogenic capability elicited by severe cold (Wang and Abbotts 1981), there remains the possibility that shivering thermogenesis could have increased to compensate for the heat deficit created by the removal of the BAT. 1n this regard it is interesting to note that in the Richardson's ground squirrel, the maximum thermogenic capacity does not vary seasonally but the NST is, however, significantly elevated from 20.6% of total thermogenesis in animals sampled in June to 45.6070 sampled in the hibernating phase (Abbotts and Wang 1980).…”