LONG-TERM MONITORING OF EXTRACELLULAR DOPAMINE CONCENTRATION IN THE RAT STRIATUM BY A REPEATED MICRODIALYSIS PROCEDURE

This study examined a protocol for repeated measurement of the extrace llular dopamine (DA) concentration in the rat striatum by microdialysi s. Rats were implanted with a guide cannula in the striatum and the pr obe was inserted on each dialysing day, i.e. over a 23 day period. Dur ing this period the animals were submitted to a control saline treatme nt. DA concentration was measured using the no-net-flux method. In the se conditions, DA concentration remained remarkably constant over the 23 day period. The histological analysis using glial fibrillary acidic protein (GFAP), dopamine (DA) and tyrosine hydroxylase (TH) immunocyt ochemistry showed a moderate gliosis and a discrete increase of immuno reactivity of catecholaminergic fibres around the probe implantation s ite. This increase is probably related to a plasticity of the dopamine rgic system in response to the lesion due to the probe implantations. This study shows that such a paradigm makes possible to measure the wh ole time course of the DA concentration in the rat striatum during chr onic treatments with psychoactive drugs such cocaine or other compound s acting in the nigrostriatal system. (C) 1997 Elsevier Science B.V.