Regional cerebral glutamate concentrations and chronic tobacco consumption

Increasing evidence indicates a crucial role of glutamate in the brain reward system and nicotine addiction. Because the pertinent models involve frontal and hippocampal glutamatergic projections, our goal was to investigate cerebral glutamate concentrations in healthy subjects with different smoking behavior.

Glutamate was measured with proton magnetic resonance spectroscopy at 3 tesla in the left hippocampus and anterior cingulate cortex (ACC) in 13 chronic tobacco smokers, 9 former smokers, and 16 never-smokers using a dedicated quantification method.

Glutamate concentrations did not differ between groups in either voxel ( F=1.151, DF=2, P=0.340). No significant correlations between glutamate concentrations and age of smoking onset, daily cigarette consumption, or lifetime exposure to tobacco smoke (pack-years) were observed.

Our findings do not support a crucial role of cingulate or hippocampal glutamate concentration in chronic tobacco consumption. Besides group differences potentially gone unnoticed due to the limited sample size, however, these results cannot rule out dysfunctional glutamatergic neurotransmission or glutamate dysfunctions in other brain regions of smokers.