Painful diabetic neuropathy leads to functional CaV3.2 expression and spontaneous activity in skin nociceptors of mice
| Autor: | Peter W. Reeh, Tal Hoffmann, Slobodan M. Todorovic, Susanne K. Sauer, Katrin Kistner, Sonja Lj. Joksimovic |
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| Rok vydání: | 2021 |
| Předmět: |
Male
medicine.medical_specialty Gene Expression Calcitonin gene-related peptide Article Diabetes Mellitus Experimental Calcium Channels T-Type Mice Organ Culture Techniques Diabetic Neuropathies Developmental Neuroscience Diabetes mellitus Internal medicine medicine Animals Skin Mice Knockout business.industry Calcium channel Cutaneous nerve Nociceptors Streptozotocin medicine.disease Mice Inbred C57BL Endocrinology Neurology Nociceptor Neuralgia Cold sensitivity Female Sciatic nerve medicine.symptom business medicine.drug |
| Zdroj: | Exp Neurol |
| ISSN: | 0014-4886 |
| DOI: | 10.1016/j.expneurol.2021.113838 |
| Popis: | Painful diabetic neuropathy occurs in approximately 20% of diabetic patients with underlying pathomechanisms not fully understood. We evaluated the contribution of the Ca(V)3.2 isoform of T-type calcium channel to hyperglycemia-induced changes in cutaneous sensory C-fiber functions and neuropeptide release employing the streptozotocin (STZ) diabetes model in congenic mouse strains including global knockouts (KOs). Hyperglycemia established for 3 – 5 weeks in male C57BL/6J mice led to major reorganizations in peripheral C-fiber functions. Unbiased electrophysiological screening of mechanosensitive single-fibers in isolated hairy hindpaw skin revealed a relative loss of (polymodal) heat sensing in favor of cold sensing. In healthy Ca(V)3.2 KO mice both heat and cold sensitivity among the C-fibers seemed underrepresented in favor of exclusive mechanosensitivity, low-threshold in particular, which deficit became significant in the diabetic KOs. Diabetes also led to a marked increase in the incidence of spontaneous discharge activity among the C-fibers of wildtype mice, which was reduced by the specific Ca(V)3 blocker TTA-P2 and largely absent in the KOs. Evaluation restricted to the peptidergic class of nerve fibers - measuring KCl-stimulated CGRP release - revealed a marked reduction in the sciatic nerve by TTA-P2 in healthy but not diabetic wildtypes, the latter showing CGRP release that was as much reduced as in healthy and, to the same extent, in diabetic Ca(V)3.2 KOs. These data suggest that diabetes abrogates all Ca(V)3.2 functionality in the peripheral nerve axons. In striking contrast, diabetes markedly increased the KCl-stimulated CGRP release from isolated hairy skin of wildtypes but not KO mice, and TTA-P2 reversed this increase, strongly suggesting a de novo expression of Ca(V)3.2 in peptidergic cutaneous nerve endings which may contribute to the enhanced spontaneous activity. De-glycosylation by neuraminidase showed clear desensitizing effects, both in regard to spontaneous activity and stimulated CGRP release, but included actions independent of Ca(V)3.2. However, as diabetes-enhanced glycosylation is decisive for intra-axonal trafficking, it may account for the substantial reorganizations of the Ca(V)3.2 distribution. The results may strengthen the validation of Ca(V)3.2 channel as a therapeutic target of treating painful diabetic neuropathy. |
| Databáze: | OpenAIRE |
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