Cocaine and amphetamine-regulated transcript peptide (CART(62-76))-induced changes in regional monoamine levels in ratbrain

Cocaine- and amphetamine-regulated transcript (CART) is a novel neuropeptide with neurotransmitter-like effects. In the present study we examined the influence of CART peptide fragment, CART(62-76), on the levels of catecholamines (dopamine and norepinephrine), serotonin and their metabolites in five regions of the rat brain. CART(62-76) was administered at 0.5 or 5.0 microg dose intracerebroventricularly. A high-pressure liquid chromatograph coupled to electrochemical array detector was used to analyse the tissue homogenates. In the frontal cortex, CART(62-76) increased the levels of 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of serotonin (5-HT). In the striatum, CART(62-76) decreased the levels of noradrenaline and 5-HT. In the hypothalamus, CART(62-76) increased the levels of 5-HIAA. CART(62-76) had no significant effect in the hippocampus and cerebellum. Our data suggest that CART(62-76) peptide has no major effect on dopaminergic pathways, but it modulates the activity of striatal noradrenergic and corticostriatal and hypothalamic serotoninergic system in the rat brain. These regionally selective neurochemical changes may explain the effects of CART Peptides on appetitive, emotional and locomotor behaviour.