Estrous cycle irregularities in overfed rats

Area of Science:

• Reproductive Endocrinology
• Metabolic Physiology
• Animal Models of Obesity

Background:

• Obesity in rodents often correlates with reproductive dysfunction, but the exact causes remain unclear due to associated metabolic disturbances.
• Existing animal models for obesity-induced reproductive issues are confounded by metabolic abnormalities.

Purpose of the Study:

• To investigate the relationship between diet-induced obesity, brown adipose tissue (BAT) thermogenesis, and estrous cycle regularity in metabolically intact rats.
• To determine if increased BAT thermogenesis during overfeeding contributes to reproductive impairments.

Main Methods:

• Rats were fed either a cafeteria-type diet (obesity group) or standard Purina chow (control group).
• Body weight, caloric intake, and estrous cycle length were monitored.
• Brown adipose tissue (BAT) thermogenesis was assessed in relation to dietary intake and reproductive parameters.

Main Results:

• Cafeteria feeding resulted in hyperphagia, increased body weight, and prolonged estrous cycles, primarily due to a longer diestrous phase.
• Increased brown adipose tissue (BAT) thermogenesis was observed in cafeteria-fed rats.
• Switching back to a standard diet normalized caloric intake, body weight, and estrous cycle regularity.

Conclusions:

• Diet-induced obesity in rats is associated with disruptions in the estrous cycle.
• Increased brown adipose tissue (BAT) thermogenesis during overfeeding may be a key factor contributing to reproductive cycle irregularities.
• Reproductive function appears to be sensitive to changes in body temperature regulated by BAT thermogenesis.