In vivo characterisation of extracellular dopamine, GABA and acetylcholine from the dorsolateral striatum of awake freely moving rats by chronic microdialysis.

Basal extracellular (EC) DA, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), gamma aminobutyric acid (GABA) and acetylcholine (ACh) were measured in dialysates from the dorsolateral striatum (DLS) of awake rats, every 30 min for 4.5 h each day over a 4-day period. The responsiveness of basal EC DA, DOPAC, HVA and GABA to local perfusion with tetrodotoxin (1 micron) was measured 1 and 4 days after implantation. In addition EC ACh was also measured 4 days after probe implantation. The results of this study indicate that EC levels of DA, DOPAC, HVA, GABA and ACh can be reliably monitored for up to 4 days after probe implantation. In addition, we show that striatal EC levels of DA, GABA and ACh may be regarded as a reflection of ongoing neuronal activity for up to 4 days after implantation of a microdialysis probe.