Increased fat consumption induced by morphine administration in rats

Area of Science:

• Nutritional Neuroscience
• Behavioral Pharmacology
• Animal Nutrition

Background:

• Opioid drugs, such as morphine, are known to affect feeding behavior and appetite regulation.
• Understanding how macronutrient selection is influenced by pharmacological agents is crucial for comprehending food intake control.
• Previous research has indicated that opioids can alter taste preferences and food reward pathways.

Purpose of the Study:

• To investigate the effects of varying doses of morphine sulfate on caloric intake and macronutrient self-selection in male rats.
• To determine if morphine influences the choice between protein, fat, and carbohydrate under different dietary conditions.

Main Methods:

• Male rats were administered different doses of morphine sulfate (0.0, 1.0, 10.0, 20.0 mg/kg).
• Animals had access to either a standard chow or a self-selection diet with high-fat or isocaloric fat options.
• Nutrient intake was measured over a six-hour period post-injection at multiple time points (1, 2, 4, 6 hours).

Main Results:

• Morphine administration led to a significant increase in fat intake across both self-selection dietary regimes.
• Carbohydrate intake was suppressed in a dose-dependent manner following morphine injections.
• Protein intake showed minimal alterations regardless of morphine dose or dietary availability.

Conclusions:

• Morphine sulfate selectively alters macronutrient selection in rats, promoting fat consumption while reducing carbohydrate intake.
• These findings suggest that opioid pathways play a significant role in modulating dietary fat preference and carbohydrate aversion.
• The observed changes in macronutrient choice highlight the complex interplay between opioid signaling and appetite regulation.