Electrical stimulation (ES) is emerging as a non-pharmacological neuromodulation strategy, but its direct impact on human dopaminergic neurons and its relationship to rapid-acting antidepressant mecha Show more
Electrical stimulation (ES) is emerging as a non-pharmacological neuromodulation strategy, but its direct impact on human dopaminergic neurons and its relationship to rapid-acting antidepressant mechanisms remain unclear. This study aimed to investigate whether brief biphasic low-frequency low-intensity (LF-LI) ES can induce structural and molecular plasticity in human induced pluripotent stem cell (iPSC)-derived mesencephalic dopaminergic neurons, identify the underlying signaling mechanisms, and evaluate its potential to rescue cortisol-induced impairments as in-vitro endocrine model of depression. iPSC-derived dopaminergic neurons were exposed to LF-LI ES using a custom culture-compatible stimulator, and structural plasticity was quantified three days later by computer-assisted morphometry. Pharmacological blockers, quantitative PCR and Western blot analyses were employed to assess calcium influx, brain-derived neurotrophic factor (BDNF)-TrkB-extracellular signal-regulated kinase (ERK)-mTOR signaling, and dopamine D3 auto-receptor roles in mediating LF-LI ES effects. A single 1h LF-LI ES session at 4 mA induced robust increases in maximal dendrite length, primary dendrite number, and soma area, comparable to 1 μM ketamine. LF-LI ES rapidly enhanced ERK and p70-S6K phosphorylation and required L-type voltage-gated calcium channels, TrkB and mTOR, as their inhibition prevented structural remodeling. LF-LI ES increased dopamine D3 auto-receptors mRNA, and its antagonism attenuated LF-LI ES-induced plasticity. In cortisol-treated neurons, LF-LI ES fully reversed dendritic hypotrophy and soma shrinkage. In conclusion, brief LF-LI ES elicits long-lasting, ketamine-like structural and molecular plasticity in human dopaminergic neurons and rescues stress hormone-induced impairments, supporting LF-LI ES-based neuromodulation approaches targeting dopaminergic circuits in major depressive disorder and treatment-resistant depression. Show less
Brain-derived neurotrophic factor (BDNF) plays an important role in the survival of dopaminergic neurons. Clinical studies have suggested that serum BDNF levels are reduced in patients with Parkinson' Show more
Brain-derived neurotrophic factor (BDNF) plays an important role in the survival of dopaminergic neurons. Clinical studies have suggested that serum BDNF levels are reduced in patients with Parkinson's disease (PD). However, no study has investigated peripheral BDNF levels and BDNF Val66Met polymorphism in the prodromal stage of PD and their relationship with disease conversion. In total, 120 patients with video-polysomnography confirmed isolated REM sleep behavior disorder (iRBD) and 120 healthy controls (HCs) were enrolled. Genetic analyses were performed, and plasma levels of BDNF were measured. All patients with iRBD underwent comprehensive clinical testing, and 107 iRBD patients were prospectively followed up. Plasma BDNF levels were significantly lower in the iRBD group than in HCs (18,878.85 pg/mL vs. 24,649.85 pg/mL, p = 0.002), but no differences were observed in BDNF Val66Met carrier rates between the two groups. Plasma BDNF levels did not differ significantly between BDNF Val66Met carriers and noncarriers. Notably, higher plasma BDNF levels were associated with an increased risk of short-term disease conversion (hazard ratio = 3.418, 95% CI: 1.520-7.684, p = 0.003), whereas BDNF Val66Met carrier rates showed no such association. Our findings suggest that plasma BDNF is significantly associated with iRBD and may likely serve as a prognostic biomarker for the development of neurodegenerative disease. However, the BDNF Val66Met polymorphism may not be involved in the pathogenesis of iRBD as well as phenoconversion in the studied population. Show less