Study of pre-synaptic internalisation in human schizophrenia brains

Aims: Efficient synaptic communication is crucial to maintain healthy behavioural and cognitive processes. Individuals affected by schizophrenia present behavioural symptoms and alterations in decision-making, suggesting altered synaptic integrity as the support of the illness. It is currently unknown how this synaptic change is mediated in schizophrenia, but microglia have been proposed to act as the culprit, actively removing synapses pathologically. Here, we aimed to explore the interaction between microglia and synaptic uptake in human post-mortem tissue. Methods: We assessed microglial activation and synaptic internalisation by microglia in a post-mortem human tissue of 10 control and 10 schizophrenia cases. Immunohistochemistry was performed to identify microglia (Iba1 and CD68) and the presynaptic terminals (synapsin I). Results: We found no difference in microglial expression, nor a difference in pre-synaptic protein level phagocyted by microglia between the two groups. Conclusions: Our findings are consistent with the brain imaging studies in schizophrenia implying that microglia play a role mainly during the early phases of the disease, by example in active synapse remodelling, which is not detected in the chronic stage of the illness.