Correlations between negative symptoms and peripheral G protein levels in mononuclear leukocytes of deficit and nondeficit schizophrenics. Preliminary results.

Receptor-coupled G proteins were measured in mononuclear leukocytes (MNL) of 17 drug-treated patients with deficit schizophrenia (DS) and 16 drug-treated patients with nondeficit schizophrenia (NDS). No significant difference was found in MNL levels of G(alphas), G(alphai), G(alphaq) and G(beta) proteins between the two groups; however, MNL levels of G(alphas) were inversely correlated to the severity of negative symptoms in DS patients, while MNL levels of G(alphaq) were positively correlated to negative symptoms in NDS patients. Since G(alphas) and G(alphaq) are coupled to D-1 and 5-HT(2) receptors, respectively, these findings may support the hypothesis that a prevalent dysfunction of D-1 receptors is involved in the pathophysiology of negative symptoms in DS, whereas a prevalent dysfunction of 5-HT(2) receptors underlies negative symptoms in NDS. These results must be regarded as preliminary because of the possible interference of antipsychotic drugs on the explored parameters.