IMBALANCE OF THE G(S) AND G(I O) FUNCTION IN POSTMORTEM HUMAN BRAIN OF DEPRESSED-PATIENTS/

The amounts of various G protein subunits in postmortem brain samples from the parietal and temporal cortices were the same in controls and depressive patients as demonstrated by immunoblotting. However, photoa ffinity GTP labeling (AAGTP) of G(i/o)alpha but not G(s)alpha was sign ificantly increased in depressives in both cortex regions. Furthermore , the ratio of G(a)/G(i/o) AAGTP incorporation revealed a significant reduction in depressives in these regions. The present findings sugges t that an imbalance of second messengers via G protein function may be involved in the pathophysiology of depression.