ERRγ Ligand Regulates Adult Neurogenesis and Depression-like Behavior in a LRRK2-G2019S-associated Young Female Mouse Model of Parkinson's Disease

Adult neurogenesis, a process controlling the proliferation to maturation of newly generated neurons in the post-developmental brain, is associated with various brain functions and pathogenesis of neuropsychological diseases, such as Parkinson's disease (PD) and depression. Because orphan nuclear receptor estrogen-related receptor gamma (ERR gamma) plays a role in the differentiation of neuronal cells, we investigated whether an ERR gamma ligand enhances adult neurogenesis and regulates depressive behavior in a LRRK2-G2019S-associated mouse model of PD. Young female LRRK2-G2019S mice (7-9 weeks old) showed depression-like behavior without dopaminergic neuronal loss in the nigrostriatal pathway nor motor dysfunction. A significant decrease in adult hippocampal neurogenesis was detected in young female LRRK2-G2019S mice, but not in comparable male mice. A synthetic ERR gamma ligand, (E)-4-hydroxy-N'-(4-(phenylethynyl)benzylidene)benzohydrazide (HPB2), ameliorated depression-like behavior in young female LRRK2-G2019S mice and enhanced neurogenesis in the hippocampus, as evidenced by increases in the number of bromodeoxyuridine/neuronal nuclei-positive cells and in the intensity and number of doublecortin-positive cells in the hippocampal dentate gyrus (DG). Moreover, HPB2 significantly increased the number of spines and the number and length of dendrites in the DG of young female LRRK2-G2019S mice. Furthermore, HPB2 upregulated brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) signaling, one of the important factors regulating neurogenesis, as well as phosphorylated cAMP-response element binding protein-positive cells in the DG of young female LRRK2-G2019S mice. Together, these results suggest ERR gamma as a novel therapeutic target for PD-associated depression by modulating adult neurogenesis and BDNF/TrkB signaling.

Automated summary

By studying a mouse model of PD associated with LRRK2-G2019S mutation, researchers found that a synthetic ERRγ ligand can enhance adult neurogenesis and improve depression-like behavior. Furthermore, the ERRγ ligand also increased the number of cell spines and dendrites, and upregulated the BDNF/TrkB signaling pathway, suggesting its potential as a novel therapeutic target for PD-related depression.