Estrous cycle modulates fasting-induced torpor propensity via hypothalamic estrogen signalling

Area of Science:

• Physiology
• Neuroendocrinology
• Metabolic Regulation

Background:

• Torpor is a survival strategy involving reduced metabolism and body temperature during scarcity.
• The hypothalamus, specifically the preoptic area (POA), plays a role in regulating torpor.
• Estrogens, like estradiol, are known to influence energy balance and thermogenesis via central mechanisms.

Purpose of the Study:

• To investigate the role of estrogen signaling within the POA in mediating fasting-induced torpor in mice.
• To determine if estradiol modulates torpor depth, duration, and propensity.

Main Methods:

• Monitoring torpor patterns across the estrus cycle in female mice.
• Administering exogenous estradiol to male and female mice.
• Utilizing ERα (estrogen receptor alpha) knockdown in the POA of female mice.

Main Results:

• Torpor depth and duration varied with the estrus cycle, peaking during diestrus when estradiol is highest.
• Exogenous estradiol extended torpor bouts in females but not males.
• ERα knockdown in the POA significantly reduced torpor in female mice.

Conclusions:

• Estradiol signaling through ERα in the POA is crucial for regulating fasting-induced torpor in female mice.
• Cyclical variations in torpor propensity may be an adaptive mechanism to balance energy conservation and reproduction.