Experimental models of Parkinson's disease: Dopamine neurons in the substantia nigra, pars compacta, are lesioned following the stereotaxic injection of the neurotoxin 6-hydroxydopamine in anesthetized rats. Fresh-frozen brain sections are cut on a cryostat and processed for in situ hybridization histochemistry or immunohistochemistry.

Behavioral observations of motor activity are performed on adult rodent experimental models of Parkinson's disease in observation chambers.

Immunohistochemistry or immunofluorescence is used on fresh-frozen tissue sections with antibodies directed against specific neurotransmitters or their receptors. This technique is used to study the distribution and expression of molecules involved in cell signaling in the basal ganglia.

In situ hybridization histochemistry is used on fresh-frozen tissue sections using riboprobes or oligonucleotide probes to study the distribution and expression of genes involved in cell metabolism and cell signaling.

Light microscopy is used to examine the distribution of immunostaining or mRNAs on tissue sections processed for immunohistochemistry or in situ hybridization histochemistry, respectively.

Quantitative image analysis of immunostaining is performed by computerized densitometry. Measurements of mRNA levels are performed at the single cell level on radioautographs by counting silver grains with a computerized image analysis system.

Microdialysis is used to assess changes in GABA levels in various regions of the basal ganglia induced by agonists of dopamine receptors in a rodent model of ParkinsonŐs disease. Separation of GABA is performed by HPLC followed by electrochemical detection of GABA derivative.