Objectives: 

Many temperate-zone animals use changes in photoperiod to time breeding. Shorter term cues, like food availability, are integrated with photoperiod to adjust reproductive timing. Golden hamster (Mesocricetus auratus) breed in long days. We examined the effects of day or night food restriction on daily food intake, body weight, blood glucose levels and hormone (leptin, estrogen, testosterone) parameters.

Materials: 

Feeding in male and female hamsters were restricted to day time (DT) or night time (NT) for 30 days. Body weight and the amount of food intake were measured daily. Food consumption was calculated daily. There were one animal per cage. Control animals had free access at all times. Blood glucose levels were measured at 19:00, 02:00, 06:00 and 12:00 h once a week for four weeks. At the end of the experiment animals were dissected and bloods were taken for hormone (leptin, estrogen, testosterone ) measurements in ELISA. Brains were removed and hypothalamic cuts were made and stored at -80 °C for hypothalamic gene expression (for further analyses of NPY and AGRP)

Results: 

In the ad libitum feeding, hamsters had similar levels of glucose, food intake and body weights. Variations in this pattern were observed under food-restricted conditions. The DT-restricted animals exhibited decreased body weight in both genders, higher levels of glucose and more food intake. A significant increase, however, was observed in the glucose levels in NT-restricted animals at 02:00. Estrogen levels in NT- restricted animals dropped significantly compared to ad libitum and DT-restricted animals. The testosterone levels were similar in DT and NT-restricted animals. The leptin levels were also similar in DT and NT-restricted groups but were lower compared to ad libitum group.

Conclusions: 

These results show that adult male and female hamsters are more sensitive to NT and DT food restriction and multiple potential environmental cues can be utilized to affect metabolic and hormonal status in adult golden hamsters.