Sex impact on daily activity and physiological, metabolic and hormonal responses to different photoperiod regimens in diet-induced obese fischer 344 rats

Résumé fourni par la source

Seasonal variations in terms of light length per day significantly influence physiological, behavioral, and metabolic processes in mammals, which are crucial for adaptation to environmental changes. This study examines the sex-dependent responses to different photoperiods on diet-induced obese Fischer 344 (F344) rats, focusing on body weight, daily activity, metabolism, and hormone levels. Male and female F344 rats were fed a cafeteria diet for 11 weeks and exposed to short (L6, 6 h of light per day) and long (L18, 18 h of light per day) photoperiods to mimic winter and summer conditions during the last 8 weeks.Results indicated that male rats exhibited greater body weight gain compared to females under both photoperiods, with a more pronounced increase in the long photoperiod correlating with testosterone levels. In addition, females displayed different activity distributions than male rats in L6 conditions. Male and female rats had a similar lipid profile in both photoperiods, but females presented a better lipid profile and insulin sensitivity, correlating with increased levels of melatonin. There is a sex-dependent effect on glucose levels only in short photoperiod with reduced levels in female rats. In conclusion, there is an interaction between seasonal rhythms and sex, which results in varying susceptibilities to diet-induced obesity. This research underscores the importance of considering sex differences in obesity studies and metabolic responses to different light conditions.

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