TRPV1 Properties in Thoracic Dorsal Root Ganglia Neurons are Modulated by Intraperitoneal Capsaicin Administration in the Late Phase of Type-1 Autoimmune Diabetes

• Published in: Cellular and molecular neurobiology 2013-03, Vol.33 (2), p.187-196
• Main Authors: Radu, Beatrice Mihaela, Iancu, Adina Daniela, Dumitrescu, Diana Ionela, Flonta, Maria Luisa, Radu, Mihai
• Format: Article
• Language: English
• Subjects: Animals; Autoimmune diseases; Biomedical and Life Sciences; Biomedicine; Blood Glucose - metabolism; Capsaicin - administration & dosage; Capsaicin - pharmacology; Capsaicin - therapeutic use; Cell Biology; Cells, Cultured; Diabetes Mellitus, Type 1 - blood; Diabetes Mellitus, Type 1 - complications; Diabetes Mellitus, Type 1 - drug therapy; Fluorescent Antibody Technique; Ganglia, Spinal - drug effects; Ganglia, Spinal - metabolism; Ganglia, Spinal - pathology; Hyperglycemia - blood; Hyperglycemia - complications; Hyperglycemia - drug therapy; Injections, Intraperitoneal; Ion Channel Gating - drug effects; Mice; Mice, Inbred BALB C; Mice, Transgenic; Neurobiology; Neurosciences; Original Research; Sensory Receptor Cells - drug effects; Sensory Receptor Cells - metabolism; Sensory Receptor Cells - pathology; Thorax - innervation; TRPV Cation Channels - metabolism
• ISSN: 0272-4340; 1573-6830; 1573-6830
• DOI: 10.1007/s10571-012-9883-6

Pharmacological therapies in type 1 diabetes for efficient control of glycemia and changes in pain alterations due to diabetic neuropathy are a continuous challenge. Transient receptor potential vanilloid type 1 (TRPV1) from dorsal root ganglia (DRG) neurons is one of the main pharmacological targets in diabetes, and its ligand capsaicin can be a promising compound for blood-glucose control. Our goal is to elucidate the effect of intraperitoneal (i.p.) capsaicin administration in type 1 diabetic mice against TRPV1 receptors from pancreatic DRG primary afferent neurons. A TCR +/− /Ins-HA +/− diabetic mice (dTg) was used, and patch-clamp and immunofluorescence microscopy measurements have been performed on thoracic T 9 –T 12 DRG neurons. Capsaicin (800 μg/kg, i.p. three successive days) administration in the late-phase diabetes reduces blood-glucose levels, partly reverses the TRPV1 current density and recovery time constant, without any effect on TRPV1 expression general pattern, in dTg mice. A TRPV1 hypoalgesia profile was observed in late-phase diabetes, which was partly reversed to normoalgesic profile upon capsaicin i.p. administration. According to the soma dimensions of the thoracic DRG neurons, a detailed analysis of the TRPV1 expression upon capsaicin i.p. treatment was done, and the proportion of large A-fiber neurons expressing TRPV1 increased in dTg capsaicin-treated mice. In conclusion, the benefits of low-dose capsaicin intraperitoneal treatment in late-phase type-1 diabetes should be further exploited.