Figure 1.

Stimulation of the main striatal projections involved in nitrogen narcosis. Two microdialysis probes are presented on the diagram to point out the stimulation points on the glutamatergic ways. The aim is to enhance neurotransmitters release and their metabolites in the striatum. A probe is schematized in the striatum and the second one is in the prefrontal cortex. Measures of citrulline arginine dopamine and glutamate are performed in the striatum. SNr/iGP projects to thalamus with GABA-ergic neurons. Thalamus essentially projects to striatum and cortex with glutamatergic neurons. The compilation of these both pathways virtually results in an inhibitory pathway, represented on the diagram. Cortex and especially prefrontal cortex (PFC) essentially project to striatum with glutamate as (excitatory) transmitter. SNc projects to striatum using dopamine, but the effect on striatum (inhibitory or excitatory) depends on the type of receptor: D1-like (direct pathway; inhibitory) or D2-like (indirect pathway not shown: excitatory). Using the direct pathway, striatum project to SNr/iGP with GABA. DA, dopamine; GABA, gamma aminobutyric acid; Glu, glutamate;PFC, prefrontal cortex; SNc, subtantia nigra pars compacta; SNr/iGP, substantia nigra pars reticulata and internal globus pallidus. Dotted arrows mark inhibitory pathways. Solid arrows mark excitatory pathways.