Inert gas narcosis is a neurological syndrome inducing several
psychomotor disorders.
Nitrogen narcosis represents the major cause of performances decrease concerning divers, in the depth range of 30 to 90 meters (0.3 to 0.9 MegaPascal). As
narcosis affects motor functions, we chose to study the nigro-striatal dopaminergic pathway owing to its involvement in
psychomotor disorders. The aim of this study is to compare, in the Sprague-Dawley rats striatium, changes in extracellular concentrations of
Dopamine and its metabolites: Dihydroxyphenylacetic
Acid (
DOPAC) and
Homovanillic Acid (HVA) under a normobaric
narcosis (20; 40, and 60% of
Nitrous Oxide (N2O)) on one hand, and under 0.9 MegaPascal of
Nitrox (
Nitrogen Oxygen normoxic mixture) on the other hand. In fact, if these two conditions are similar, normobaric
narcosis would allow us to explain
nitrogen narcosis mechanisms without any pressure effect. The first emergence of
Dopamine and metabolites variations occurs around 40% of N2O.
Dopamine decreases by 45% and is accompanied by a
DOPAC diminution of 7% while HVA concentrations remain constant. Under 60% N2O, these decrease have a greater amplitude. The
Dopamine variations obtained under 0.9 Mpa of
Nitrox are closed to alterations induced by 60% of N2O (DA decreases by 70%).