Abstract |
Obesity in the United States has become a more prevalent issue with increased food accessibility and decreased physical activity. One way to counteract obesity focuses on increasing kilocalories burned through generating heat. Abundant interest focuses on white and brown adipose tissue thermogenesis, while less is know about the regulators of thermogenesis in skeletal muscle. Our laboratory recently found heat production in rat skeletal muscle after exposure to the odor of a natural predator (ferret). The scent of the predator activates the sympathetic nervous system, causing activation of muscle thermogenesis. Thus far, we only demonstrated this effect in male rats and mice. The goal of this study was to establish whether female rats also show predator odor-induced muscle thermogenesis, and to ascertain if it varied over the estrous cycle. Diestrus and proestrus phases were confirmed using cytology, and predator odor-induced thermogenesis was assessed at both phases. Rats were exposed to predator or control odors, and muscle temperatures were measured using transponders implanted in gastrocnemius (leg) muscle. I identified induction of heat in female rat skeletal muscle in response to predator odor compared to control. There was no detectable difference between proestrus and diestrus phases of the estrous cycle. From this, I concluded that predator odor induces a significant increase in muscle thermogenesis in females rats similar to what we have seen in male rats, independent of the female estrous cycle. This increase in muscle thermogenesis, regardless of sex, promotes negative energy balance and can be harnessed to counter obesity.
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Modified Abstract |
Skeletal muscle thermogenesis can be harnessed to increase calories burned and promote weight loss. Our laboratory recently found heat production in male rat skeletal muscle after exposure to the odor of a natural predator (ferret). The scent of the predator activates the sympathetic nervous system, causing activation of muscle thermogenesis. Here, I expanded the investigation to female rats, comparing 2 phases of the estrous cycle—diestrus and proestrus. I identified induction of heat in female rat skeletal muscle in response to predator odor compared to control. There was no detectable difference between proestrus and diestrus phases of the estrous cycle. From this, I concluded that predator odor induces a significant increase in muscle thermogenesis in female as we have seen in male rats, independent of the female estrous cycle.
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