Studies of gene co-expression networks of the frontal cortex and striatum (post mortem study) of individuals with OCD and controls

Obsessive compulsive disorder (OCD) is a psychiatric disorder, characterized by the presence of obsessions and/or compulsions. Functional neuroimaging studies indicate that OCD is a heterogeneous disorder related the cortical-striatal thalamic circuitry (CSTC) and the areas that compose this circuitry include the nucleus accumbens (NAC), putamen (PT), caudate nucleus (CN), orbitofrontal cortex (OFC) and subgenual cingulate gyri (ACC). The main characteristics of CSTC is the innervation of the frontal cortex in direction of the striatum and each small circuitries have specific characteristics in the affective, dorsal cognitive and ventral cognitive motor. In this work we compared the cases and controls transcriptome of the three striatal areas (CN, NAC and PT) separately from post mortem brain tissue and the co-expression networks of the striatum and of two circuits involved in the disorder. Results showed that different biological process as well as networks connectivity deregulation were specific for each striatum region according to the striatum tripartite model and contribute in different ways to OCD pathophysiology. Specifically, regulation of neurotransmitter levels, presynaptic process involved in chemical synaptic transmission were shared between NAC and PT. Cellular response to chemical stimulus, response to external stimulus, response to organic substance, regulation of synaptic plasticity, and modulation of synaptic transmission were shared between CN and PT. Most genes harboring common and/or rare variants previously associated with OCD that are differentially expressed or part of a least preserved co-expression modules in our study also suggest striatum sub regions specificity. The co-expression modules preserved and least preserved in affective and ventral cognitive circuitry corroborate with transcriptional signatures of each area and each circuitry in OCD and controls. This is the first work with the proposal to evaluate the gene expression in striatum areas individually, involved with OCD as well evaluate the coexpression networks in striatum and each circuitry (AU)