Abstract Body: Background: The stellate ganglia (SG), comprising of sympathetic postganglionic neurons and satellite glial cells (SGCs), regulate cardiac sympathetic output. Heightened cardiac sympathetic activation contributes to ventricular arrhythmias (VAs) in chronic heart failure (CHF). Optogenetics, a neuromodulatory technique that uses light-sensitive opsins to precisely depolarize or hyperpolarize targeted cells, provides a powerful and highly selective approach to manipulate SG excitability. The cell type specific control makes it an ideal tool to investigate and potentially modulate pathological sympathetic activation in CHF.
Aim: Our objective is to assess whether optogenetic silencing of SGCs can suppress sympathetic ganglionic neuronal excitation in CHF rats.
Methods: HF was induced by left coronary artery ligation. At 12 weeks post-ligation, AAV5-vector control or AAV5-GFAP promoter driven eArch3.0-EYFP gene (an inhibitory light-sensitive proton pump) was microinjected into the SG in HF rats and an Optogenetic probe with green light (566 nm) was implanted on the SG for Optogenetic SGC silencing. After 1 week of gene transfection, rat SGs were stimulated by Optogenetics. Following 3 weeks of stimulation (10Hz, 5 mW/mm2, 30 min, twice/day), neuronal electrophysiological recordings and western analysis were performed to explore SGCs role in sympathetic ganglionic neuronal excitation in CHF.
Results: Whole-cell Patch-clamp recordings demonstrated that Optogenetic stimulation produced an outward current and induced cell hyperpolarization in isolated SGCs with AAV-eArch3.0 gene transfection, indicating that Optogenetic stimulation can cause SGC silencing. After 3-week Optogenetic SGC silencing in conscious CHF rats, N-type Ca⁺⁺ currents (34±1.3 pA/pF)) and cell excitability (19.5±1.5 spikes/s for action potentials and 28 ±1.9 pA for current threshold) were attenuated, compared to rats with CHF alone (47.5±3.1 pA/pF, 26.8±1.1 spikes/s, and 19.8±0.9 pA, respectively). Western analysis revealed that Optogentic SGC silencing reduced expression of Connexin43 (Cx43), PKC-α, MAPK14, and TNFα converting enzyme (TACE) in the SG from CHF rats.
Conclusion: Optogenetic SGC silencing reduced sympathetic ganglionic neuronal excitability through downregulating SGC mediated CX43 -PKC/MAPK-TACE signaling pathways, which could be a therapeutic target to mitigate sympathetic overactivation and suppress VAs in CHF.