The importance of human brown adipose tissue volume

NGS Sequencing Reveals New UCP1 Gene Variants Potentially Associated with MetS and/or T2DM Risk in the Polish Population—A Preliminary Study

The number of people suffering from metabolic syndrome (MetS) including type 2 diabetes (T2DM), hypertension, and obesity increased over 10 times through the last 30 years and it is a severe public health concern worldwide. Uncoupling protein 1 (UCP1) is a mitochondrial carrier protein found only in brown adipose tissue involved in thermogenesis and energy expenditure. Several studies showed an association between UCP1 variants and the susceptibility to MetS, T2DM, and/or obesity in various populations; all these studies were, however, limited to a few selected polymorphisms. The present study aimed to search within the entire UCP1 gene for new variants potentially associated with MetS and/or T2DM risk. We performed NGS sequencing of the entire UCP1 gene in 59 MetS patients including 29 T2DM patients, and 36 controls using the MiSeq platform. An analysis of allele and genotype distribution revealed nine variations which seem to be interesting in the context of MetS and fifteen in the context of T2DM. Altogether, we identified 12 new variants, among which only rs3811787 was investigated previously by others. Thereby, NGS sequencing revealed new intriguing UCP1 gene variants potentially associated with MetS and/or T2DM risk in the Polish population.

[11C]carfentanil PET imaging for studying the peripheral opioid system in vivo: effect of photoperiod on mu-opioid receptor availability in brown adipose tissue

PURPOSE

Photoperiod determines the metabolic activity of brown adipose tissue (BAT) and affects the food intake and body mass of mammals. Sympathetic innervation of the BAT controls thermogenesis and facilitates physiological adaption to seasonal changes, but the exact mechanism remains elusive. Previous studies have shown that central opioid signaling regulates BAT thermogenesis, and that the expression of the brain mu-opioid receptor (MOR) varies seasonally. Therefore, it is important to know whether MOR expression in BAT shows seasonal variation.

METHODS

We determined the effect of photoperiod on BAT MOR availability using [11C]carfentanil positron emission tomography (PET). Adult rats (n = 9) were repeatedly imaged under various photoperiods in order to simulate seasonal changes.

RESULTS

Long photoperiod was associated with low MOR expression in BAT (β =  - 0.04, 95% confidence interval: - 0.07, - 0.01), but not in muscles. We confirmed the expression of MOR in BAT and muscle using immunofluorescence staining.

CONCLUSION

Photoperiod affects MOR availability in BAT. Sympathetic innervation of BAT may influence thermogenesis via the peripheral MOR system. The present study supports the utility of [11C]carfentanil PET to study the peripheral MOR system.

TIGAR deficiency enhances skeletal muscle thermogenesis by increasing neuromuscular junction cholinergic signaling

Cholinergic and sympathetic counter-regulatory networks control numerous physiological functions, including learning/memory/cognition, stress responsiveness, blood pressure, heart rate, and energy balance. As neurons primarily utilize glucose as their primary metabolic energy source, we generated mice with increased glycolysis in cholinergic neurons by specific deletion of the fructose-2,6-phosphatase protein TIGAR. Steady-state and stable isotope flux analyses demonstrated increased rates of glycolysis, acetyl-CoA production, acetylcholine levels, and density of neuromuscular synaptic junction clusters with enhanced acetylcholine release. The increase in cholinergic signaling reduced blood pressure and heart rate with a remarkable resistance to cold-induced hypothermia. These data directly demonstrate that increased cholinergic signaling through the modulation of glycolysis has several metabolic benefits particularly to increase energy expenditure and heat production upon cold exposure.