Increased levels of SNAP-25 and synaptophysin in the dorsolateral prefrontal cortex in bipolar I disorder.

In order to identify whether the mechanisms associated with neurotransmitter release are involved in the pathologies of bipolar disorder and schizophrenia, levels of presynaptic [synaptosomal-associated protein-25 (SNAP-25), syntaxin, synaptophysin, vesicle-associated membrane protein, dynamin I] and structural (neuronal cell adhesion molecule and alpha-synuclein) neuronal markers were measured in Brodmann's area 9 obtained postmortem from eight subjects with bipolar I disorder (BPDI), 20 with schizophrenia and 20 controls. Determinations of protein levels were carried out using Western blot techniques with specific antibodies. Levels of mRNA were measured using real-time polymerase chain reaction. In BPDI, levels of SNAP-25 (p < 0.01) and synaptophysin (p < 0.05) increased. There were no changes in schizophrenia or any other changes in BPDI. Levels of mRNA for SNAP-25 were decreased in BPDI (p < 0.05). Changes in SNAP-25 and synaptophysin in BPDI suggest that changes in specific neuronal functions could be linked to the pathology of the disorder.