High levels of Gs alpha in platelets of euthymic patients with bipolar affective disorder.

OBJECTIVE

Previous investigations have suggested the involvement of signal-transducing guanine-nucleotide-binding proteins (G proteins) both in the mechanism of action of lithium and in the pathophysiology of bipolar affective disorder. To determine whether such G protein abnormalities are a trait phenomenon, the authors investigated the levels of G protein alpha subunits in platelets and lymphocytes of euthymic patients with bipolar affective disorder.

METHOD

Selective antibodies were used to quantitate levels of G protein alpha subunits regulating adenylylcyclase activity (Gs alpha-both 45- and 52-kDa forms- and Gil-2 alpha) and those regulating phosphoinositide turnover (Gq/11 alpha) in both platelets and lymphocytes of 44 euthymic patients with bipolar affective disorder and 27 matched comparison subjects.

RESULTS

Levels of both Gs alpha 45 and Gs alpha 52 were higher in the platelets of the euthymic bipolar patients (both bipolar I and bipolar II) than in those of the comparison subjects.

CONCLUSIONS

These findings are consistent with previous reports of high Gs alpha levels in bipolar affective disorder and, furthermore, suggest that such levels may be a trait abnormality for this condition.