The effect of anti-hypertensive drug treatment on brown adipocyte diameter and locule distribution in rats

Effects of aging, phenotype and carbohydrate feeding on caloric efficiency and adiposity in the LA/Ntul//-cp (corpulent) rat

“…21,22,29 Brown adipose tissue [BAT] is a major thermogenic tissue of man and animals, and can be stimulated by CHO feeding, cafeteria overfeeding, cold exposure and noradrenergic stimulation. [29][30][31][32][33][34][35] In mammalian animals, including humans, BAT normally becomes activated soon after birth and is responsible for heat generation via uncoupling of oxidative phosphorylation, which assists in maintaining body temperature during the early life of the newborn of the species. 34 BAT depots remain histologically present well into adulthood in many mammalian species studied.…”

“…[29][30][31][32][33][34][35] In mammalian animals, including humans, BAT normally becomes activated soon after birth and is responsible for heat generation via uncoupling of oxidative phosphorylation, which assists in maintaining body temperature during the early life of the newborn of the species. 34 BAT depots remain histologically present well into adulthood in many mammalian species studied. Histologically, brown adipocytes differ markedly from white 2 adipocytes on the basis of their smaller size, numerous mitochondria, a centrally located nucleus, and multiple small lipid locules, and sympathetic neuroregulation while in contrast, white adipocytes contain a larger single lipid droplet, a small peripherally located nucleus, few mitochondria, and lack direct neural stimulation.…”

“…Histologically, brown adipocytes differ markedly from white 2 adipocytes on the basis of their smaller size, numerous mitochondria, a centrally located nucleus, and multiple small lipid locules, and sympathetic neuroregulation while in contrast, white adipocytes contain a larger single lipid droplet, a small peripherally located nucleus, few mitochondria, and lack direct neural stimulation. 36 BAT has been proposed as contributing to an energy balancing mechanism for energy balance especially during caloric overnutrition 34 while in addition to thyroidal mechanisms that have been demonstrated to respond to both over-and undernutrition by switching from T4 deiodination from the active form (T3) to the inactive form, reverse T3 (rT3). 24 The T3 as the active form of the thyroid hormone presumably contributes to a number of metabolic processes including protein turnover, carbohydrate oxidation, and others including the energy wasting hepatic mitochondrial α-glycerophosphate dehydrogenase shuttle, which has been shown to correlate with circulating T3 concentrations 37 and to diminish with aging in activity with advancing age in rats 37,38 and the metabolism of α-glycerophosphate was also reported to be decreased in subcutaneous adipose tissue samples obtained from obese subjects.…”

Effect of adrenalectomy and glycemic status on caloric efficiency and adiposity in the congenic LA/Ntul//-cp (corpulent) rat

“…Numerous studies indicate that carbohydrate rich and energy dense dietary supplements may enhance net energy intake, often associated with greater energy deposition and thermogenic energy expenditure 13 in normally lean rats, but result in greater adiposity in the obese phenotype of this and other genetically obese rat strains. [14][15][16][17][18] Schlafani et al investigated a broad range of dietary carbohydrate sources and reported that introduction of a 16% sucrose solution (w/v) as a drinking water supplement could stimulate adaptive thermogenesis in lean rats with only a minimal impact on overall caloric intake, [19][20][21][22] and Stock and Rothwell 14 and Tulp et al, 1,23,24 found that CHO enrichment resulted in increases in energy expenditure mechanisms in lean but not in obese rats. Tulp and Carlin 25 demonstrated that the complex CHO Polycose, a form of partially hydrolized cornstarch, resulted in greater energy intakes and adiposity than the sucrose solutions referred to above in this strain suggesting that the perceptions or preferences for sweetness in rats may differ from those as perceived by humans.…”

“…In contrast, white adipocytes contain a larger single lipid droplet focused on mechanisms of energy deposition and storage, a small peripherally located nucleus within a cytoplasmic ring surrounding the adipocyte lipid droplet, fewer mitochondria, and lack direct neural or β3-adrenergic stimulation. [18][19][20]22 The lipid locule size of adipocytes is believed to play an important role in BAT mediated energy expenditure as the smaller lipid locule size in BAT vs White adipose tissue (WAT) adipocytes results in a greater net surface area to lipid mass, in the smaller lipid droplets thereby enabling a more efficient process of fatty acid mobilization, oxidation and resultant heat generation than is possible in WAT adipocytes. [26][27][28][29][30][31][32][33][34][35][36] BAT has been proposed as contributing factor to an energy balancing mechanism for energy balance especially during caloric overnutrition 21 while in addition to thyroidal mechanisms that have been demonstrated to respond to both over-and undernutrition by switching from outer ring T4 deiodination from the active form (T3) during abundant caloric availability and cold exposure to the inner ring inactive form, reverse T3 (rT3) during periods of caloric restriction, food depravation or starvation.…”