Background: Dendritic structural features, such as spine density and volume, are dynamically regulated by glutamate signaling to the actin cytoskeleton. Spine growth and retraction result from enhanced polymerization and depolymerization of F-actin. Decreased spine density has been observed in layer 3 of multiple cortical areas in schizophrenia while genetic and pharmacological studies support a role for glutamate signaling to F-actin in disease pathology. However, the mechanics by which spine signaling is impaired and the effect this impairment has on homeostasis of spine formation and retraction is currently unknown. To begin to address this question in human postmortem brain tissue we have utilized orthogonal approaches of confocal microscopy and targeted mass spectrometry to investigate spine density, volume, and protein expression.
Methods: Primary auditory cortex tissue from 20 pairs of SCZ and matched control subjects, in which we have previously evaluated the expression of 155 synaptic proteins, were utilized. Dendritic spines were identified by co-localization of spinophilin and F-actin (defined by binding of phalloidin). This approach is innovative as it allows for an estimate of spine F-actin content and volume in human postmortem tissue.
