A brain scan research conducted by the Psychiatric Imaging group at the MRC LMS describes how the Mu-opioid receptor (MOR) system contributes to the negative symptoms displayed in schizophrenia patients. This is the first study that shows how MOR levels are substantially reduced in the striatum region of the brain. Therefore, insufficient MOR system simulation in the brain adds to the negative feelings experienced by schizophrenia patients. The researchers also used a new analysis method to examine how MORs are connected inside the brain. The team’s findings have been published in the journal Nature Communications.
MORs plays a vital role in the way humans experience pleasure and reward. The human body naturally produces opioid molecules that have endorphins, which are hormones secreted by the brain known to aid pain or stress relief and boost happiness. MORs are the receptors responsible for binding the naturally produced endogenous opioid molecules, and stimulation of the MOR system activates a signaling cascade that can increase motivation to seek reward and increase the motivation to seek reward and food palatability, among other effects. Notably, MORs were found to be reduced in the striatum post-mortem in case of schizophrenia, which made it unclear whether the availability of the receptors was higher when individuals were alive or whether lower MORs could be associated with the negative symptoms of schizophrenia. The analysis unveiled a significant global increase in connection to the brain circuit named cerebello-thalamo-cortical network.
Dr. Abhishekh Ashok, Academic Clinical Fellow, Radiology, of the LMS and Cambridge University Hospital NHS Foundation Trust, and also who conducted the study, says that the negative symptoms in schizophrenia cause significant distress to patients, although there are no existing approved treatments. This is because the nature of changes in brain chemistry that adds to the negative symptoms remains unknown. The PET scan research helps elucidate the changes in brain chemicals in a particular brain circuit that adds to the development of negative symptoms, elaborates Ashok. Oliver Howes, Head, Psychiatric Imaging group, LMS, and senior author of the paper, says that this research is a promising new lead that could help the development of novel treatment.