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Similarities in feeding behavior of chronic methamphetamine treated and withdrawn rats to VMH lesioned rats
Abstract:
During chronic methamphetamine (M) administration and after drug withdrawal, total daily food intake, water consumption and body weight increase was measured. Additionally, food intake in the early light phase provided an index of normal circadian rhythmicity. A parallel development of tolerance to the anorexic effect of M and increased feeding in the early light phase occurred. A further abnormal behavior of both chronic M-treated and withdrawn rats was the lack of preference reversal when given free access to concentrated vs. diluted glucose solutions. Both disturbed circadian feeding rhythmicity and inhibition of the glucose preference reversal are found in rats with ventromedial hypothalamic (VMH) lesions. Reduced food intake and diminished body weight increase is a characteristic of lateral hypothalamic lesions. By analogy, chronic M-treatment could be considered to induce a functional state similar to lesions of the medial and lateral hypothalamus, each with a different time course.
Insights
Chronic methamphetamine (M) use and withdrawal disrupt rat feeding patterns and glucose preference, mimicking hypothalamic damage. These changes suggest M affects brain regions regulating appetite and circadian rhythms.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Pharmacology
Background:
- Chronic methamphetamine (M) use is associated with significant physiological and behavioral changes.
- Understanding the neurobiological underpinnings of M's effects on appetite and circadian rhythms is crucial.
Purpose of the Study:
- To investigate the effects of chronic methamphetamine administration and withdrawal on food intake, water consumption, body weight, and circadian feeding patterns in rats.
- To assess behavioral changes related to glucose preference following chronic M exposure.
Main Methods:
- Rats were administered methamphetamine chronically, and their food intake, water consumption, and body weight were monitored.
- Circadian rhythmicity was assessed by measuring food intake during the early light phase.
- Glucose preference was evaluated by offering rats concentrated versus diluted glucose solutions.
Main Results:
- Tolerance to the anorexic effect of methamphetamine developed with chronic administration.
- Increased feeding during the early light phase indicated disrupted circadian rhythms.
- Rats exhibited a lack of preference reversal for glucose solutions, suggesting impaired reward processing or appetite regulation.
- These behavioral changes in M-treated rats showed similarities to effects observed in rats with ventromedial (VMH) or lateral hypothalamic lesions.
Conclusions:
- Chronic methamphetamine administration and withdrawal induce significant disruptions in feeding behavior, circadian rhythms, and glucose preference in rats.
- These findings suggest that methamphetamine may induce functional states analogous to hypothalamic lesions, impacting appetite regulation and reward pathways.
- Further research is warranted to elucidate the specific neural circuits involved and the long-term consequences of M-induced neuroadaptations.