Increased hippocampal supragranular Timm staining in subjects with bipolar disorder

Biochemical and structural abnormalities have been reported in hippocampus of subjects with mood disorders. This study examined the organization of mossy fibers in anterior hippocampus of subjects obtained from the Stanley Neuropathology Consortium. Frozen postmortem hippocampal sections from subjects with major depression, bipolar disorder, schizophrenia and non-psychiatric controls were stained using the Neo-Timm procedure, which selectively stains mossy fibers. Increased Timm staining in the supragranular layer was found in subjects with bipolar disorder relative to control subjects. These results are suggestive of neuronal sprouting in hippocampus of subjects with bipolar disorder. There were no significant associations between supragranular Timm staining and suicide, length illness or drug treatment at the time of death.