Sarcolipin Makes Heat, but Is It Adaptive Thermogenesis?

Campbell, Kevin L.; Dicke, Alysha A.

doi:10.3389/fphys.2018.00714

Cited by 35 publications

(44 citation statements)

References 32 publications

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“…The importance of mitochondrial thermogenesis is uncertain because evidence has been reported both for [63][64][65] and against such thermogenesis. 67 The main evidence is impaired thermogenesis in mice with sarcolipin (Sln) knocked out, 24,25 Sln being a regulator of Serca. 67 The main evidence is impaired thermogenesis in mice with sarcolipin (Sln) knocked out, 24,25 Sln being a regulator of Serca.…”

Section: Nst In Skeletal Musclesmentioning

confidence: 99%

“…27,66 The role of thermogenesis by "slippage" of Ca 2+ back into the cytosol at the site of Ca 2+ transport into SR by the ATPase Serca 25 also appears uncertain. 67 The main evidence is impaired thermogenesis in mice with sarcolipin (Sln) knocked out, 24,25 Sln being a regulator of Serca. Thus, Sln -/mice die within a few hours of exposure to 4°C if their interscapular BAT (iBAT) is also ablated, whereas iBAT ablation alone has no such effect.…”

Section: Nst In Skeletal Musclesmentioning

confidence: 99%

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Body temperature control in rats by muscle tone during rest or sleep

et al. 2019

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Aim To explore the role of tonic motor unit activity in body temperature control. Methods Motor unit activity in soleus and several other skeletal muscles was recorded electromyographically from adult rats placed in a climate chamber on a load sensitive floor, which, together with video monitoring, allowed detection of every successive period of movement and no movement. Results In the absence of movements during rest or sleep, motor unit activity was exclusively tonic and therefore equivalent to muscle tone as defined here. The amount of tonic activity increased linearly in the soleus as the ambient temperature decreased from 32°C to below 7°C, owing to progressive recruitment and increased firing rate of individual units. Brief movements occurred randomly and frequently during rest or sleep in association with brief facilitation or inhibition of motor neurons that turned tonic motor unit activity on or off, partitioning the tonic activity among the available motor units. Shivering first appeared when a falling ambient temperature reached ≤7°C in several muscles except soleus, which was as active between shivering bursts as during them. Conclusion Muscle tone and overt shivering are strikingly different phenomena. Tonic motor unit activity in the absence of movements evokes isometric contractions and, therefore, generates heat. Accordingly, when the amount of tonic activity increases with falling ambient temperature, so must heat production. Consequently, graded muscle tone appears as an important and independent mechanism for thermogenesis during rest or sleep at ambient temperatures ranging from <7°C to at least 32°C.

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Section: Nst In Skeletal Musclesmentioning

confidence: 99%

Section: Nst In Skeletal Musclesmentioning

confidence: 99%

Body temperature control in rats by muscle tone during rest or sleep

et al. 2019

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“…It remains unknown whether, in humans, the expression of SLN is influenced by loading and energy balance. Although it has been suggested that enhancing SLN activity could be an effective mechanism to increase energy expenditure and control weight gain, the role that SLN may play in the regulation of fat mass is unknown in humans …”

Section: Introductionmentioning

confidence: 99%

“…Although it has been suggested that enhancing SLN activity could be an effective mechanism to increase energy expenditure and control weight gain, 5 the role that SLN may play in the regulation of fat mass is unknown in humans. 6 Skeletal muscle accounts for 15%-17% of resting metabolic rate (RMR). 7 The majority of the energy expended by resting skeletal muscles is used to maintain the resting membrane potential and cytosolic [Ca 2+ ], through the action of the Na + -K + ATPase and the sarcoplasmic reticulum Ca 2+ -ATPase (SERCA).…”

Section: Introductionmentioning

confidence: 99%

Sarcolipin expression in human skeletal muscle: Influence of energy balance and exercise

Morales-Álamo

Martinez‐Canton²,

Gelabert‐Rebato

et al. 2019

Scandinavian Med Sci Sports

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Sarcolipin (SLN) is a SERCA uncoupling protein associated with exercise performance and lower adiposity in mice. To determine SLN protein expression in human skeletal muscle and its relationship with adiposity, resting energy expenditure (REE), and performance, SLN was assessed by Western blot in 199 biopsies from two previous studies. In one study, 15 overweight volunteers underwent a pretest followed by 4 days of caloric restriction and exercise (45‐minute one‐arm cranking + 8‐hour walking), and 3 days on a control diet. Muscle biopsies were obtained from the trained and non‐exercised deltoid, and vastus lateralis (VL). In another study, 16 men performed seven sessions of 4‐6 × 30‐sec all‐out sprints on the cycle ergometer with both limbs, and their VL and triceps brachii biopsied pre‐ and post‐training. SLN expression was twofold and 44% higher in the VL than in the deltoids and triceps brachii, respectively. SLN was associated with neither adiposity nor REE, and was not altered by a severe energy deficit (5500 kcal/day). SLN and cortisol changes after the energy deficit were correlated (r = .38, P = .039). SLN was not altered by low‐intensity exercise in the overweight subjects, whereas it was reduced after sprint training in the other group. The changes in SLN with sprint training were inversely associated with the changes in gross efficiency (r = −.59, P = .016). No association was observed between aerobic or anaerobic performance and SLN expression. In conclusion, sarcolipin appears to play no role in regulating the fat mass of men. Sprint training reduces sarcolipin expression, which may improve muscle efficiency.

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“…7 Furthermore, as shown by Lømo et al, any adjustments in thermogenesis must closely track the minute-to-minute variations in ambient temperature and also heat from activity and feeding. It is clear that the absence of overt shivering is not evidence for the absence of contractile thermogenesis in muscle.…”

Section: Editorialmentioning

confidence: 98%