In vivo effects of local and systemic phencyclidine on the extracellular levels of catecholamines and transmitter amino acids in the dorsolateral striatum of anaesthetized rats

The dose‐dependent effects of systemically and locally administered phencyclidine (PCP) on the extracellular levels of dopamine, dihydroxyphenylacetate (DOPAC), homovanillate (HVA), 5‐hydroxyindolacetate (5‐HIAA), γ‐aminobutyrate (GABA), glutamate and aspartate in the dorsolateral striatum of anaesthetized rats were studied by in vivo microdialysis. Both local (1, 5, 50 and 100 µM) and systemic (2 and 10 mg kg^‐1 i.p.) PCP caused a dose‐dependent increase in the extracellular levels of dopamine. The lowest PCP doses caused only a moderate but long‐lasting increase in the extracellular levels of dopamine, while the highest PCP doses caused a massive but transient increase followed by a rebound decrease. The low doses of both systemic and local PCP tended to increase the levels of DOPAC, while those of HVA were not changed. The extracellular levels of 5‐HIAA were increased only by the lowest (1 µM) locally administered dose of PCP. GABA levels were increased when PCP was administered locally at two doses. None of the treatments affected the extracellular levels of glutamate and aspartate. The results show that the effects of local and systemic PCP administration are dissimilar on the extracellular levels of 5‐HIAA and GABA and thus provide new information on the neurochemical effects of PCP.