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Dopamine is required for hyperphagia in Lep(ob/ob) mice
M S Szczypka1, M A Rainey, R D Palmiter
1Howard Hughes Medical Institute and Department of Biochemistry, Box 357370, University of Washington, Seattle, Washington, USA.
Nature Genetics
|May 10, 2000
Summary
Dopamine is essential for feeding initiation and sensorimotor functions. Even in leptin-deficient mice, dopamine is required for food intake, highlighting its critical role in regulating appetite and feeding behaviors.
Area of Science:
- Neuroscience
- Neurobiology
- Behavioral Neuroscience
Background:
- Feeding is a complex behavior influenced by sensory cues, reward pathways, and hormonal signals.
- Dopamine plays a crucial role in reward, motivation, motor control, and sensorimotor integration, all vital for feeding.
- Leptin is a key hormone regulating appetite and metabolism via the hypothalamic leptin-melanocortin pathway.
Purpose of the Study:
- To investigate the role of dopamine in feeding behavior, particularly in the context of leptin deficiency.
- To determine if leptin deficiency can overcome the aphagia observed in dopamine-deficient mice.
Main Methods:
- Utilized dopamine-deficient (DD) mice and leptin-null (Lep(ob/ob)) mice.
- Generated double mutant mice lacking both dopamine and leptin (DD x Lep(ob/ob)).
- Administered L-3,4-dihydroxyphenylalanine (L-DOPA) to restore dopamine levels and observed feeding and movement behaviors.
Main Results:
- Dopamine-deficient mice become aphagic and die without L-DOPA treatment.
- Leptin-null mice exhibit obesity and hyperphagia.
- Double mutant DD x Lep(ob/ob) mice became obese with L-DOPA treatment but ceased feeding upon its termination, despite retaining motor function.
Conclusions:
- Dopamine is indispensable for initiating feeding behavior.
- Dopamine's role in feeding is critical, even in the absence of functional leptin signaling.
- These findings underscore the necessity of dopamine for sensorimotor aspects of food consumption.