Dopamine receptor sensitive effect of dizocilpine on feeding behaviour

Area of Science:

• Neuroscience
• Behavioral Pharmacology
• Endocrinology

Background:

• Endogenous excitatory amino acids (EAAs) are implicated in regulating food intake.
• Adrenal corticotropic hormone (ACTH) can induce anorexia, a stress-related feeding behavior.
• The role of dopamine in mediating these effects requires further elucidation.

Purpose of the Study:

• To investigate the effects of dizocilpine on feeding behavior and ACTH-induced anorexia.
• To explore the involvement of dopamine pathways in dizocilpine's effects on feeding.
• To examine dizocilpine's ability to reverse ACTH-induced anorexia in an elevated plus maze model.

Main Methods:

• Rats were administered dizocilpine intracerebroventricularly (i.c.v.) to assess effects on food intake.
• Dopamine receptor antagonists (SCH 23390, pimozide, haloperidol) and dopamine depletors (reserpine, alpha-methyl-p-tyrosine) were used to investigate mechanisms.
• ACTH was administered to induce anorexia, and dizocilpine's reversal effects were evaluated in an elevated plus maze.

Main Results:

• Dizocilpine administration dose-dependently increased food intake in food-deprived rats.
• Dopamine receptor antagonists and dopamine depletion blocked or reversed dizocilpine-induced hyperphagia.
• Dizocilpine reversed ACTH-induced anorexia and associated behavioral changes in the elevated plus maze, an effect also blocked by dopamine antagonists.

Conclusions:

• Endogenous excitatory amino acids play a significant role in controlling food intake.
• Dizocilpine-induced hyperphagia and its reversal of ACTH-induced anorexia are mediated by dopaminergic pathways.
• These findings support the hypothesis that EAAs influence feeding behavior through dopaminergic mechanisms.