Increased Gαq/11 immunoreactivity in postmortem occipital cortex from patients with bipolar affective disorder

As disturbances in guanine nucleotide binding (G) protein-coupled phosphoinositide second messenger systems have been implicated in bipolar disorder, we examined whether the abundance of Gαq/11 and phospholipase C (PLC)-β1 two key transducing proteins in this signaling pathway, are altered in this disorder. Compared with the controls, immunoreactive levels of Gαq/11 were significantly elevated by 62% (p = .047) in occipital cortex of bipolar subjects. A similar increase (52%) in the PLC-β1 immunolabeling was also found in the occipital cortex of the bipolar subjects, but only reached marginal statistical significance (p = .07). In contrast, frontal and temporal cortex Gαq/11 or PLC-β1 immunolabeling did not differ between bipolar and control subjects. Cerebral cortical immunoreactive levels of Gβ1 or Gβ2, included as a negative control, were not different between comparison groups. These findings support and extend earlier observations suggesting that disturbances in G protein-coupled second messenger signaling pathways may play an important role in the pathophysiology of bipolar affective disorder.