A translational approach for NMDA receptor profiling as a vulnerability biomarker for depression and schizophrenia

Andrographolide improves PCP-induced schizophrenia-like behaviors through blocking interaction between NRF2 and KEAP1

Schizophrenia is one of the foremost psychological illness around the world, and recent evidence shows that inflammation and oxidative stress may play a critical role in the etiology of schizophrenia. Andrographolide is a diterpenoid lactone from Andrographis paniculate, which has shown anti-inflammation and anti-oxidative effects. In this study, we explored whether andrographolide can improve schizophrenia-like behaviors through its inhibition of inflammation and oxidative stress in Phencyclidine (PCP)-induced mouse model of schizophrenia. We found that abnormal behavioral including locomotor activity, forced swimming and novel object recognition were ameliorated following andrographolide administration (5 mg/kg and 10 mg/kg). Andrographolide inhibited PCP-induced production of inflammatory cytokines, decreased p-p65, p-IκBα, p-p38 and p-ERK1/2 in the prefrontal cortex. Andrographolide significantly declined the level of MDA and GSH, as well as elevated the activity of SOD, CAT and GCH-px. In addition, andrographolide increased expression of NRF-2, HO-1 and NQO-1, promoted nuclear translocation of NRF-2 through blocking the interaction between NRF-2 and KEAP1, which may be associated with directly binding to NRF-2. Furthermore, antioxidative effects and anti-schizophrenia-like behaviors of andrographolide were compromised by the application of NRF-2 inhibitor ML385. In conclusion, these results suggested that andrographolide improved oxidative stress and schizophrenia-like behaviors induced by PCP through increasing NRF-2 pathway.

Role of Grina/Nmdara1 in the Central Nervous System Diseases

Glutamate receptor, ionotropic, N-methyl-D-aspartate associated protein 1 (GRINA) is a member of the NMDA receptors (NMDARs) and is involved in several neurological diseases, which governs the key processes of neuronal cell death or the release of neurotransmitters. Upregulation of GRINA has been reported in multiple diseases in human beings, such as major depressive disorder (MDD) and schizophrenia (SCZ), with which the underlying mechanisms remain elusive. In this review, we provide a general overview of the expression and physiological function of GRINA in the central nervous system (CNS) diseases, including stroke, depression, epilepsy, SCZ, and Alzheimer’s disease (AD).

Early Identification and Intervention of Schizophrenia: Insight From Hypotheses of Glutamate Dysfunction and Oxidative Stress

Schizophrenia is a severe mental disorder which leads to functional deterioration. Early detection and intervention are vital for better prognosis. However, the diagnosis of schizophrenia still depends on clinical observation to date. Without reliable biomarkers, schizophrenia is difficult to detect in its early phase. Further, there is no approved medication for prodromal schizophrenia because current antipsychotics fail to show satisfactory efficacy and safety. Therefore, to develop an effective early diagnostic and therapeutic approach for schizophrenia, especially in its prodromal phase, is crucial. Glutamate signaling dysfunction and dysregulation of oxidative stress have been considered to play important roles in schizophrenic prodrome. The N-methyl-D-aspartate receptor (NMDAR) is one of three types of ionotropic glutamate receptors. In this article, we reviewed literature regarding NMDAR hypofunction, oxidative stress, and the linkage between both in prodromal schizophrenia. The efficacy of NMDAR enhancers such as D-amino acid oxidase inhibitor was addressed. Finally, we highlighted potential biomarkers related to NMDAR and oxidative stress regulation, and therefore suggested the strategies of early detection and intervention of prodromal schizophrenia. Future larger-scale studies combining biomarkers and novel drug development for early psychosis are warranted.