Increased thermogenic capacity of brown adipose tissue under low temperature and its contribution to arousal from hibernation in Syrian hamsters

Kitao, Naoya; Hashimoto, Masaaki

doi:10.1152/ajpregu.00053.2011

Cited by 19 publications

(23 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Animals hibernating at temperatures below their hypothalamic set-point may be particularly dependent on heat generated by brown adipose tissue. While electromyographic activity from shivering has been observed at T b 's as low as 47C (Tøien et al 2001), shivering is not thought to be an effective heat generator at this temperature (Kitao and Hashimoto 2012). Brown adipose tissue, on the other hand, upregulates UCP-1 upon cold exposure, and the highest levels are found in hibernators that are actively generating heat (Barger et al 2006), indicating functionality at very low temperatures.…”

Section: Discussionmentioning

confidence: 98%

Thermogenic Capacity at Subzero Temperatures: How Low Can a Hibernator Go?

Richter¹,

Williams²,

Lee³

et al. 2015

Physiological and Biochemical Zoology

View full text Add to dashboard Cite

Hibernation in mammals is a physiological and behavioral adaptation to survive intervals of low resource availability through profound decreases in metabolic rate (MR), core body temperature (Tb), and activity. Most small mammalian hibernators thermoconform, with Tb approximating ambient temperature (Ta); arctic species are an exception, since they must actively defend what can be large thermal gradients between Tb and Ta. Here we compare the thermogenic capacity of the arctic ground squirrel (Urocitellus parryii) to that of the golden-mantled ground squirrel (Callospermophilus lateralis), a temperate-zone montane hibernator. We allowed animals to reenter torpor at sequentially lower Ta's and found that arctic ground squirrels maintained steady state torpor at Ta's as low as -26°C, through a 36-fold increase in torpid MR (TMR), compared to their minimum TMR, exhibited at a Ta of 0°C. Golden-mantled ground squirrels are able to maintain steady state torpor at Ta's at least as low as -8°C, through a 13.5-fold increase in MR, compared to their minimum TMR at a Ta of 2°C. In a second experiment, torpid animals were exposed to continuously decreasing Ta's (0.25°C/30 min); individuals of both species increased their metabolism while remaining torpid at low Ta's (as low as -30°C for arctic ground squirrels and -10°C for golden-mantled ground squirrels). Although the capacity to hibernate at subfreezing Ta's is not unique to arctic ground squirrels, their large body size, greater torpid metabolic scope, and previously ascribed capacity to supercool allow them to occupy much colder hibernacula for prolonged seasons of hibernation.

show abstract

Section: Discussionmentioning

confidence: 98%

Thermogenic Capacity at Subzero Temperatures: How Low Can a Hibernator Go?

Richter¹,

Williams²,

Lee³

et al. 2015

Physiological and Biochemical Zoology

View full text Add to dashboard Cite

show abstract

“…Forskolin activates the adenylyl cyclase enzyme directly and increases the intracellular levels of cAMP with a Kd=14.8×10 −9 M [8]. Forskolin is known as an inducer of thermogenic response in BAT [9]. …”

Section: Introductionmentioning

confidence: 99%

Adrenergic pathway activation enhances brown adipose tissue metabolism: A [18F]FDG PET/CT study in mice

Mirbolooki

Upadhyay

Constantinescu

et al. 2014

Nuclear Medicine and Biology

View full text Add to dashboard Cite

Objective Pharmacologic approaches to study brown adipocyte activation in vivo with a potential of being translational to humans are desired. The aim of this study was to examine pre- and postsynaptic targeting of adrenergic system for enhancing brown adipose tissue (BAT) metabolism quantifiable by [18F]fluoro-2-deoxyglucose ([18F]FDG) positron emission tomography (PET)/ computed tomography (CT) in mice. Methods A β3-adrenoreceptor selective agonist (CL 316243), an adenylyl cyclase enzyme activator (forskolin) and a potent blocker of presynaptic norepinephrine transporter (atomoxetine) were injected through the tail vein of Swiss Webster mice 30 minutes before intravenous (iv) administration of [18F]FDG. The mice were placed on the PET/CT bed for 30 min PET acquisition followed by 10 min CT acquisition for attenuation correction and anatomical delineation of PET images. Results Activated interscapular (IBAT), cervical, periaortic and intercostal BAT were observed in 3-dimentional analysis of [18F]FDG PET images. CL 316243 increased the total [18F]FDG standard uptake value (SUV) of IBAT 5-fold greater compared to that in placebo-treated mice. It also increased the [18F]FDG SUV of white adipose tissue (2.4-fold), and muscle (2.7-fold), as compared to the control. There was no significant difference in heart, brain, spleen and liver uptakes between groups. Forskolin increased [18F]FDG SUV of IBAT 1.9-fold greater than that in placebo-treated mice. It also increased the [18F]FDG SUV of white adipose tissue (2.2-fold) and heart (5.4-fold) compared to control. There was no significant difference in muscle, brain, spleen, and liver uptakes between groups. Atomoxetine increased [18F]FDG SUV of IBAT 1.7-fold greater than that in placebo-treated mice. There were no significant differences in all other organs compared to placebo-treated mice except liver (1.6 fold increase). A positive correlation between SUV levels of IBAT and CT hounsfiled unit (HU) (R2=0.55, p<0.001) and between CT HU levels of IBAT and liver (R2=0.69, p<0.006) was observed. Conclusions The three pharmacologic approaches reported here enhanced BAT metabolism by targeting different sites in adrenergic system as measured by [18F]FDG PET/CT.

show abstract

“…Likewise, social separation alone suppressed muscularity and adiposity with female biases. Consistent with greater bioenergetic depletion [86, 87], social separation reduced the sizes of brown adipose depots in males, but not in females. Social separation decreased adrenal weights in females only, and we have reported that this effect was more robust in females than in males [36].…”

Section: Discussionmentioning

confidence: 98%

Sex differences in motivational responses to dietary fat in Syrian hamsters

Shannonhouse

Grater

York

et al. 2015

Physiology & Behavior

View full text Add to dashboard Cite

Women are more likely than men to exhibit motivational disorders (e.g., anhedonia and anxiety) with limited treatment options, and to overconsume high-fat “comfort foods” to improve motivational disruptions. Unfortunately, neurobiological underpinnings for sex differences in motivational disruptions and their responses to dietary fat are poorly understood. To help bridge these fundamental knowledge gaps, we assessed behavioral and neurobiological responses to dietary fat in a hamster model of female-biased motivational lability. Relative to social housing, social separation reduced hedonic drive in a new behavioral assay, the reward investigational preference (RIP) test. Fluoxetine or desipramine treatment for 21, but not 7, days improved RIP test performance. Pharmacologic specificity in this test was shown by non-responsiveness to diazepam, tracazolate, propranolol, or naltrexone. In the anxiety-related feeding/exploration conflict (AFEC) test, social separation worsened latency to eat highly palatable food under anxiogenic conditions, but not in home cages. Social separation also reduced weight gain, food intake, and adiposity while elevating energy expenditure, assessed by caloric efficiency and indirect calorimetry. Furthermore, chronic high-fat feeding improved anhedonic and anxious responses to separation, particularly in females. In the motivation-influencing nucleus accumbens, females, but not males, exhibited a separation-induced anxiety-related decrease in Creb1 mRNA levels and an anhedonia-related decrease in ΔFosb mRNA levels. Consistent with its antidepressant- and anxiolytic-like effects on behavior, high-fat feeding elevated accumbal Creb1 and ΔFosb mRNA levels in females only. Another accumbal reward marker, Tlr4 mRNA, was elevated in females by high-fat feeding. These results show that social separation of hamsters provides a novel model of sex-dependent comorbid anhedonia, anxiety, and anorexia, and implicate accumbal CREB, ΔFosB, and TLR4. Moreover, the results validate a new assay for chronic anti-depressant efficacy.

show abstract

Increased thermogenic capacity of brown adipose tissue under low temperature and its contribution to arousal from hibernation in Syrian hamsters

Cited by 19 publications

References 44 publications

Thermogenic Capacity at Subzero Temperatures: How Low Can a Hibernator Go?

Thermogenic Capacity at Subzero Temperatures: How Low Can a Hibernator Go?

Adrenergic pathway activation enhances brown adipose tissue metabolism: A [18F]FDG PET/CT study in mice

Sex differences in motivational responses to dietary fat in Syrian hamsters

Contact Info

Product

Resources

About