Weight change affects serum leptin and corticosterone in the collared lemming

Area of Science:

• Animal physiology
• Endocrinology
• Seasonal biology

Background:

• Photoperiod is a key environmental cue influencing seasonal adaptations in many species.
• Hormones like leptin and corticosterone play roles in regulating energy balance and stress responses.
• Understanding these hormonal changes is crucial for comprehending seasonal weight fluctuations.

Purpose of the Study:

• To investigate the relationship between photoperiod, body mass, fat mass, and serum concentrations of leptin and corticosterone in collared lemmings.
• To determine if photoperiod-induced changes in body composition are associated with altered leptin and corticosterone levels.
• To elucidate the hormonal mechanisms underlying seasonal weight changes in this rodent model.

Main Methods:

• Male collared lemmings were exposed to either long day (LD) or short day (SD) photoperiods post-weaning.
• Animals were subjected to photoperiod shifts (LD-LD, LD-SD, SD-SD, SD-LD) and sampled at 10 and 21 days post-switch.
• Serum leptin and corticosterone levels were measured, alongside carcass analysis for body composition.

Main Results:

• Lemmings exposed to SD-LD photoperiods exhibited significant weight loss, while LD-SD groups showed weight gain.
• SD-LD lemmings displayed lower leptin levels relative to fat mass and higher corticosterone levels compared to SD-SD controls.
• Weight gain in LD-LD and LD-SD groups did not result in significant changes in relative leptin or corticosterone levels.

Conclusions:

• Photoperiod significantly influences body weight and fat mass in collared lemmings, mimicking seasonal adaptations.
• Corticosterone and leptin are strongly associated with photoperiod-induced weight loss, but not significantly with weight gain.
• These findings suggest distinct hormonal regulation for seasonal weight loss versus weight gain in lemmings.