[Changes in expression levels of PV, GAD67 and KCC2 in the brain tissue of rats with schizophrenia induced by MK-801]

Abstract

Objective: To study changes in the expression levels of parvalbumin (PV), glutamate decarboxylase 67 (GAD67) and K+-Cl- cotransporter 2 (KCC2) in the brain tissue of rats with schizophrenia (SZ) induced by dizocilpine (MK-801), and to investigate the mechanism involving gamma-aminobutyric acid (GABA) by which NMDA receptor blocker induces SZ in the perinatal period.

Methods: Thirty-six neonatal male Sprague-Dawley rats were randomly assigned to two batches on postnatal day 6. Each batch was divided into normal control (treated by 0.9% normal saline), SZ-development model (treated by subcutaneous injection of 0.1 mg/kg MK-801 on postnatal days 7-10; bid), and SZ-chronic medication model groups (treated by intraperitoneal injection of 0.2 mg/kg MK-801 on postnatal days 47-60; qd). On postnatal day 63, the brain tissue of the first batch of rats was obtained and then fixed with paraform for histological sections; expression levels of PV and GAD67 in the medial prefrontal cortex (mPFC) and hippocampus CA1 were measured by immunohistochemistry. Simultaneously, the second batch of rats was sacrificed and the mPFC and hippocampus were obtained and homogenized; expression levels of KCC2 in the mPFC and hippocampus were measured by Western blot.

Results: Expression levels of PV and GAD67 in the mPFC and hippocampus CA1 were significantly lower in the SZ-development and chronic medication model groups than in the normal control group (P<0.05). Expression levels of KCC2 in the mPFC and hippocampus were significantly lower in the SZ-development model group than in the SZ-chronic medication model and normal control groups (P<0.05).

Conclusions: The expression changes of PV and GAD67 in SZ can be simulated using the SZ development model induced by MK-801, which might affect the development of the GABA system in the PFC and hippocampus by downregulating KCC2 expression.