Non-shivering thermogenesis in humans is primarily mediated by brown adipose tissue via which protein?

Non-shivering thermogenesis in humans is primarily mediated by brown adipose tissue via which protein?

• A. Brown adipose tissue via uncoupling protein 1 (UCP1).
• B. White adipose tissue via leptin signaling.
• C. Skeletal muscle via myostatin pathway.
• D. Liver mitochondria via ATP synthase.

Answer: (A)

Non-shivering thermogenesis in humans mainly relies on brown adipose tissue because its mitochondria contain a specialized protein called UCP1 that converts energy from the proton gradient into heat instead of ATP. When cold is sensed, the sympathetic nervous system releases norepinephrine, which triggers a cascade inside brown fat cells, leading to lipolysis and activation of UCP1. UCP1 uncouples oxidative phosphorylation by allowing protons to re-enter the mitochondrial matrix without driving ATP synthase, releasing energy as heat to raise body temperature. This process heats the body without muscle contractions, which is the essence of non-shivering thermogenesis. White fat doesn’t use UCP1 for heat production, and leptin signaling is more about energy balance and appetite than heat generation. Skeletal muscle can contribute to heat via other mechanisms, but non-shivering thermogenesis is primarily brown fat–driven. Liver mitochondria producing ATP would not primarily generate heat in this context.

Non-shivering thermogenesis in humans mainly relies on brown adipose tissue because its mitochondria contain a specialized protein called UCP1 that converts energy from the proton gradient into heat instead of ATP. When cold is sensed, the sympathetic nervous system releases norepinephrine, which triggers a cascade inside brown fat cells, leading to lipolysis and activation of UCP1. UCP1 uncouples oxidative phosphorylation by allowing protons to re-enter the mitochondrial matrix without driving ATP synthase, releasing energy as heat to raise body temperature. This process heats the body without muscle contractions, which is the essence of non-shivering thermogenesis.

White fat doesn’t use UCP1 for heat production, and leptin signaling is more about energy balance and appetite than heat generation. Skeletal muscle can contribute to heat via other mechanisms, but non-shivering thermogenesis is primarily brown fat–driven. Liver mitochondria producing ATP would not primarily generate heat in this context.