Effects of diet and photoperiod on NE turnover and GDP binding in Siberian hamster brown adipose tissue

Abstract

This experiment examined the effects of diet and photoperiod on food intake, body weight, and brown adipose tissue (BAT) activity in female Siberian hamsters (Phodopus sungorus sungorus). BAT function was assessed by measuring both the sympathetic nervous system activity of BAT [estimated by the rate of norepinephrine (NE) turnover] and BAT thermogenic activity (estimated by GDP binding to BAT mitochondria). Nineteen weeks of high-fat feeding in long photoperiod [16:8 light-dark cycle (LD)] caused a 20% increase in food intake but did not affect body weight. Both NE turnover rate and GDP binding in interscapular BAT (IBAT) were increased four- to eightfold relative to that from chow-fed controls. Thus it appears that in Siberian hamsters BAT can serve the same energy-dissipating function during diet-induced overeating previously established in rats and mice. Nineteen-week exposure to a short photoperiod (LD 8:16) produced a reduction in body weight but did not affect food intake. Both NE turnover rate and GDP binding in IBAT were increased two- to fourfold relative to that from long-photoperiod controls. Thus it appears that in Siberian hamsters the photoperiod-induced improvements in thermogenic capacity are mediated via the same mechanisms as are cold- or diet-induced thermogenesis.

Dual effects of fibroblast growth factor 21 on hepatic energy metabolism

“…The Siberian hamsters are a natural model of adiposity that, when fed a high-fat diet, do not increase their caloric intake and so do not gain additional weight. Even in longterm high-fat diet studies where some increase in food intake can be observed in Siberian hamsters, this does not result in weight gain, rather the animals increase thermogenesis via increased sympathetic nervous system (SNS) activation of brown fat (McElroy et al 1986). Although hamsters have a different biology from mice and rats, which is a reflection of their evolution and ecology, they cannot be considered to be any less valid as a model for understanding fundamental mechanisms of action of hormones than other rodents; indeed, using a variety of animal models has overall translational benefits (Ebling 2014).…”

Effects of central or peripheral leptin administration on norepinephrine turnover in defined fat depots

“…Physiological stimuli promote SNS activity in a tissue-specific manner; therefore, activation of SNS outflow to one organ does not necessarily represent outflow to all organs (29). Measurements of norepinephrine turnover (NETO) in specific tissues has been used as a measure of site-specific sympathetic activity in conditions such as fasting (28) and seasonal changes in energy balance in hibernating animals (27). Collins et al (7) found only a small nonsignificant increase in NETO to retroperitoneal (RP) white adipose tissue of mice given an intraperitoneal injection of leptin, despite a significant increase in intrascapular brown adipose tissue (IBAT) NETO.…”

Diet induced obesity inApodemus chevrieri(Mammalia: Rodentia: Muridae)

“…Additionally, there might be a different response to a high-fat diet for the animals exhibiting resistance to diet-induced obesity Peacock et al 2004). For example, a high-fat diet increased activity in Bank voles (Peacock & Speakman 2001;Peacock et al 2004) and meadow voles (Dark & Zucker 1983;Meek et al 1995), and thermogenic capacity in Siberian hamsters (McElroy et al 1986). These results suggest that the resistance to diet-induced obesity observed in photoperiodic animals is likely due to the increases in energy expended on metabolism and/or activity.…”

“…In the present study, we determined the effect of short day and high-fat diet on body-weight gain, thermogenesis, body fat mass, body compositions, energy budgets and BAT UCP1 expression to test the hypothesis that A. chevrieri showing short-day induced decreases in body mass and body fat mass, similar with Siberian hamsters (Phodopus sungorus) (Pallas, 1773) (McElroy et al 1986), Shaw's jird (Meriones shawi) (Milne-Edwards, 1867) (El-Bakry et al 1999) and meadow voles (Microtus pennsylvanicus) (Pallas, 1773) , should be resistant to the high-fat diet-induced obesity.…”