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

Abstract

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.

Phenylthiocarbamide (PTC) perception in patients with schizophrenia and first-degree family members: Relationship to clinical symptomatology and psychophysical olfactory performance

“…It is notable that previous work investigating deficit and non-deficit patients for peripheral G protein levels found a significant relationship between these assays and degree of negative symptoms in both groups of patients (Monteleone et al 2002). We speculate that the difference in PTC tasting status reflects underlying G protein-coupled signal transduction abnormalities that have some contribution to the clinical symptoms of the illness.…”

Impairments of working memory in schizophrenia and bipolar disorder: the effect of history of psychotic symptoms and different aspects of cognitive task demands

“…In our study, we observed the lack of association between WM performance in SZ patients with positive and general symptoms as well as apathy in the presence of a correlation with negative symptoms. These findings may be attributed to the fact that while negative symptomatology is believed to result from decreased dopaminergic activity in the prefrontal cortex directly involved in WM (Okubo et al, 1997 ; Heckers et al, 1999 ; Monteleone et al, 2002 ). Positive and general symptoms as well as apathy are associated with possibly altered activity in the areas less crucial to WM performance, such as the hippocampus (Krieckhaus et al, 1992 ; Tamminga et al, 2010 ) and the basal ganglia (Pankow et al, 2012 ; Khadka et al, 2013 ; Sorg et al, 2013 ).…”

Phenylthiocarbamide Perception in Patients With Schizophrenia and First-Degree Family Members

“…Although nontaster status has been linked to a variety of medical disorders, there have been few investigations of PTC taster status in schizophrenia (6)(7)(8). Abnormalities in the function and/or expression of G protein signaling pathways have been reported in patients with schizophrenia and appear to be implicated in prepulse inhibition of the startle reflex and negative symptoms (9,10). Therefore, we anticipated that patients would show a differential pattern of PTC tasting status relative to healthy comparison subjects and that a similar pattern would be observed in their non-ill firstdegree relatives.…”