Objective:
This study investigated the chronic (oral) and acute (hypothalamic infusion) effects of L-arginine supplementation on feed intake, body composition, and behavioral changes in rats.
Methods:
Twenty rats were divided into two groups treated orally for 60 days; one group received L-arginine (1 g/kg body weight) and one group received saline (1 mL/NaCl 0.9%). Daily consumption of water and food were evaluated, and weight monitored. After the oral treatment, the rats underwent stereotactic biopsy and a group was injected with 2 µL of L-arginine (0.5 mM) and another received an injection of saline (0.9% NaCl), in the hypothalamic route, through micro infusion. Immediately after micro infusion, the animal behavior was evaluated through tests in the open field. Food and water consumption were evaluated at 12 and 24 hours after the micro infusion. Daily water consumption and weight gain evolution were evaluated. At the end of treatments, rats were euthanized and blood was collected for glucose, glycerol, and cholesterol evaluation, and histological analysis of vital organs.
Results:
Oral supplementation with L-arginine increased water intake (11%, p<0.05) and promoted weight gain (3%, p<0.05). However, hypothalamic infusion promoted a significant increase in chow intake (30%, p<0.05) after 24 hours of L-arginine administration.
Conclusion:
Chronic oral treatment with L-arginine was not effective on appetite modulation; however, an effect was observed when L-arginine was administered directly into the hypothalamus, suggesting a central regulation on appetite through nNOS sensitization. Chronic use of L-arginine did not cause substantial changes in anthropometric, biochemical, behavioral, or histological variables.
Central nervous system; Eating; Feeding behavior
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