Selective striatal cell loss is ameliorated by regulated autophagy of the cortex

Abstract

Aims: The harmful cellular environment leads to brain damage, and each brain subregion exhibits a differential vulnerability to its effects. This study investigated the causes of selectively striatal cell loss in systemic 3-nitropropionic acid (3-NP) infused mice.

Main methods: This study was performed in the neuronal cell line, primary neuron, cultured mouse brain, and mice brain tissues. The 3-NP solution was delivered using an osmotic mini-pump system for 7 days. ROS in brain tissue were detected and evaluated with the signals of CM-H2DCFDA for total cellular ROS and MitoSOX Red for mitochondrial ROS. Cellular ROS and the functional status of mitochondria were assessed with a detection kit and analyzed using flow cytometry. To quantify oxidative damaged DNA, apurinic/apyrimidinic (AP) site numbers in DNA were measured. The protein expression level was assessed using Western blotting, and immunohistochemistry was performed. Cleaved caspase-3 activities were measured by using an enzyme-linked immunosorbent assay (ELISA) kit.

Key findings: By 3-NP, mitochondrial dysfunction was higher in the striatum than in the cortex, and mitochondria-derived ROS levels were higher in the striatum than in the cortex. However, autophagy that may restore the energy depletion resulting from mitochondrial dysfunction occurred comparably less in the striatum than in the cortex. Inhibition of ASK1 by NQDI1 regulates MAPK signaling, apoptosis, and autophagy. Regulated autophagy of the cortex improved non-cell autonomously striatal damaged condition.

Significance: This study illustrated that the different vulnerabilities of the brain subregions, striatum or cortex, against 3-NP are rooted in different mitochondria-derived ROS amounts and autophagic capacity.

Keywords: 3-Nitropropionic acid; Apoptosis signal regulating-kinase 1; Autophagy; Neurodegenerative disease.