Serotonin-mediated behavior in rats chronically treated with (-) deprenyl.

Area of Science:

• Neuropharmacology
• Serotonergic system research

Background:

• (-) Deprenyl is a monoamine oxidase B inhibitor.
• Its effects on the serotonergic system at low doses require further elucidation.

Purpose of the Study:

• To investigate the impact of low-dose (-) deprenyl on the rat serotonergic system.
• To assess changes in serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels.
• To evaluate 5-HT receptor responsiveness and the effects on p-chloroamphetamine (PCA)-induced behaviors.

Main Methods:

• Rats were administered daily low doses (0.25 mg/kg) of (-) deprenyl for 30 days.
• Serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels in the striatum were measured.
• Postsynaptic 5-HT receptor responsiveness was assessed using 5-methoxy-N,N-dimethyl-tryptamine (5-MeODMT).
• The p-chloroamphetamine (PCA)-induced 5-HT syndrome was evaluated, including after reserpine-induced 5-HT depletion.

Main Results:

• Low-dose (-) deprenyl did not alter striatal 5-HT or 5-HIAA levels.
• Postsynaptic 5-HT receptor responsiveness to 5-MeODMT remained unchanged.
• (-) Deprenyl significantly enhanced the PCA-induced 5-HT syndrome.
• This enhancement persisted even when 5-HT stores were depleted by reserpine.

Conclusions:

• Low-dose (-) deprenyl does not directly affect basal serotonergic neurotransmission or postsynaptic receptor sensitivity.
• (-) Deprenyl potentiates the effects of releasing agents like PCA, suggesting an indirect mechanism.
• This potentiation may involve mechanisms independent of presynaptic serotonin storage.