PEC-60 INCREASES DOPAMINE BUT NOT GABA RELEASE IN THE DORSOLATERAL NEOSTRIATUM OF THE HALOTHANE-ANESTHETIZED RAT - AN IN-VIVO MICRODIALYSISSTUDY

The effect of striatal perfusion with the intestinal peptide PEC-60 on endogenous dopamine (DA) and gamma-aminobutyric acid (GABA) release i n the dorsolateral striatum and GABA release in the globus pallidus wa s monitored using in vivo microdialysis in the halothane anaesthetized rat. The results show that PEC-60 (100 nM) increases DA release in th e dorsolateral striatum without influencing GABA release in the dorsol ateral striatum or in the globus pallidus. In addition. PEC-60 failed to influence the extracellular striatal 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels. The PEC-60 induced increa se in striatal D4 was abolished by the addition of tetrodotoxin (1 mu M) to the perfusion medium. These data suggest that PEC-60 plays a rol e in modulating striatal DA release but not DA metabolism and that thi s effect is primarily targeted on the presynaptic DA terminals of the nigrostriatal DA pathway rather than on the postsynaptic striatopallid al GABA projection neurons in the dorsolateral striatum.