Transient Receptor Potential Canonical 5 (TRPC5) Channels Activator, BTD [N-{3-(adamantan-2-yloxy)-propyl}-3-(6-methyl-1,1-dioxo-2H-1λ6,2,4- benzothiadiazin-3-yl)-propanamide)] Ameliorates Diabetic Cardiac Autonomic Neuropathy in Rats

Background: Diabetic cardiac autonomic neuropathy (DCAN) is a serious diabetic complication with no approved pharmacological agents for its treatment. Parasympathetic system dysfunction characterized by vagal nerve damage is one of the major drivers of DCAN. The TRPC5 or transient receptor potential canonical 5 channel is a promising target in autonomic dysfunction; however, its role in vagal nerve damage and subsequent DCAN has not yet been elucidated. The present study investigated the role of the TRPC5 channel in DCAN using [N-{3-(adamantan-2-yloxy)-propyl}-3-(6-methyl-1,1-dioxo-2H-1λ6,2,4-benzothiadiazin-3-yl) propanamide)] or BTD, which is a potent TRPC5 activator. Objective: The role of the TRPC5 channel and its activator, BTD, was investigated in the treatment of parasympathetic dysfunction associated with DCAN. Methods: Type 1 diabetes was induced in male Sprague-Dawley rats using streptozotocin. The alterations in cardiac autonomic parameters in diabetic animals were assessed by heart rate variability, hemodynamic parameters, and baroreflex sensitivity. TRPC5's role in DCAN was investigated by treating diseased rats with BTD (1 and 3 mg/kg, i.p. for 14 days). BTD's beneficial effects in parasympathetic dysfunction were assessed by western blotting, estimating oxidative stress and inflammatory markers in the vagus nerve. Results: BTD treatment (3 mg/kg, i.p.) once daily for 14 days ameliorated heart rate variability, hemodynamic dysfunction, and baroreflex sensitivity in diseased rats. BTD treatment down regulated TRPC5 expression by increasing the activity of protein kinase C in the vagus nerve. It also down-regulated the apoptotic marker CASPASE-3 and also exerted potent anti-inflammatory action on pro-inflammatory cytokines levels in the vagus. Conclusion: BTD ameliorated parasympathetic dysfunction associated with DCAN by virtue of its TRPC5 modulatory, anti-inflammatory, and anti-apoptotic properties.