Dietary self-selection in chronically insulin-treated golden hamsters

Area of Science:

• Metabolic research
• Animal physiology
• Nutritional science

Background:

• Insulin is a key metabolic hormone regulating glucose homeostasis.
• Dietary composition influences metabolic responses to hormonal changes.
• Understanding macronutrient selection under hormonal influence is crucial for metabolic health.

Purpose of the Study:

• To investigate the impact of insulin on caloric consumption and body weight in golden hamsters.
• To determine how dietary self-selection of macronutrients (protein, carbohydrate, fat) is affected by insulin administration.
• To analyze the macronutrient distribution of excess calorie intake during insulin treatment.

Main Methods:

• Adult male golden hamsters were fed either a standard chow diet or a self-selection diet (protein, carbohydrate, fat).
• Animals received daily injections of long-acting insulin (escalating doses) or saline over 12 consecutive days.
• Caloric consumption, body weight, and dietary intake of specific macronutrients were monitored.

Main Results:

• Insulin-injected hamsters showed significantly increased total caloric consumption (up to 33%) and weight gain compared to controls.
• Hamsters on the self-selection diet increased fat intake in response to higher insulin doses (60 and 100 U/kg).
• Carbohydrate and protein intake increased only at the highest insulin dose (100 U/kg), with fat comprising ~65% of excess calories.

Conclusions:

• Insulin significantly stimulates appetite and promotes weight gain in golden hamsters, irrespective of diet type.
• When presented with dietary choices, hamsters modulate macronutrient intake, prioritizing fat consumption under insulin stimulation.
• These findings highlight the complex interplay between hormonal regulation and dietary selection in energy balance.