Cold-induced developmental changes in fat cell size and number in brown adipose tissue of the rat

Abstract

Seven-week-old Long-Evans rats were acclimated to a constant temperature of either 28 degrees C (control group) or 5 degrees C (cold-acclimated group). Cold acclimation induced a 70% increase in the interscapular brown adipose tissue (IBAT) relative mass, a 35% increase in DNA content, and a 44% decrease in triglyceride (TG) content, which resulted in a 51% decrease of the TG/DNA ratio. A procedure is described by which brown fat cells were isolated, with a yield of 21% from the IBAT of the control group and of 38% in the cold-acclimated group. In both groups, the brown fat cells accounted for 35-37% of the total cells in the tissue. Cold acclimation induced decreases in the mean fat cell diameter (about 20%), the mean fat cell TG content (50%), and the fat cell TG/DNA ratio (50%). The total number of IBAT fat cells was significantly increased in cold-acclimated rats. It is concluded that cold acclimation involves a hyperplasia of the IBAT, associated with a decrease of fat cell size without any alteration of the fat cell-to-nonfat cell ratio.

The lipid profile of brown adipose tissue is sex-specific in mice

“…Given the high mitochondrial content of this tissue, the sex-specific phospholipid composition of BAT likely reflects differences in the composition of mitochondrial membranes which may, in turn, be related to the increased mitochondrial size and cristae density of BAT mitochondria from female rats described by Rodriguez-Cuenca et al [30] who found these to resemble the morphological changes of mitochondria from cold-acclimated rats [30,34]. Similarly, a lower rate of TAG to phospholipids, as observed in female BAT in our study, also has been detected in BAT following cold acclimation [35,36]. These findings suggest a higher thermogenic activity of female BAT, and at least in rats this could, indeed, be the case [37].…”

In vivo morphometry and functional morphology of brown adipose tissue by magnetic resonance imaging

“…The main drawback (beside the costs for the basic instrumentation) is that resolution is relatively low in comparison with light microscopy; however, when higher spatial resolution is needed, exploitation of high-field magnets coupled with a mini-imaging system can give good results (Osculati et al, 1991;Sbarbati et al, 1991). The lipid content of the brown fat cell roughly mirrors its functional status, being larger in the relatively quiescent cell and reduced in the actively thermogenetic cell (Senault et al, 1981). In a previous paper we showed that MRI differentiates areas of prevailing monovacuolar or multivacuolar brown adipocytes (Osculati et al, 1991).…”

The effects of rearing environment on pup development

“…Further, the animals may have responded differentially to the stress of the procedure, such that differences in thermoregulatory behavior were masked. On the other hand, it may be that while nest-reared animals have a lower quantity of brown adipose tissue, the quality of the tissue also differs (e.g., Senault, Cherqui, Cadot, & Portet, 1981).…”