calpain and Diabetic-Neuropathies

Calpain plays an important role in the pathophysiology of neurological and cardiovascular complications, but its functional association in diabetic neuropathy is not yet elucidated. Therefore, we investigated the role of calpain in modulation of tetrodotoxin-resistant sodium channels (TTX-R Na(+) channels) in dorsal root ganglion (DRG) neurons using a pharmacological approach. The effects of a calpain inhibitor, MDL 28170 (3 and 10 mg/kg, i.p.) on TTX-R Na(+) channels in DRG neurons of streptozotocin-induced diabetic rats were assessed by using whole-cell patch-clamp technique. In addition to this biochemical, functional and behavioral deficits were also measured. Diabetic rats demonstrated the mechanical allodynia and thermal hyperalgesia with reduced nerve perfusion and conduction velocity as compared to control. MDL 28170 treatments significantly recovered these functional and nociceptive deficits. Moreover, diabetic rats exhibited increased calpain activation, lipid peroxidation and proinflammatory cytokines as compared to control. Drug treatment significantly improved these biochemical deficits. Additionally, DRG neurons from diabetic rats illustrated a significant increase in TTX-R sodium current (INa) density as compared to control. MDL 28170 treatments in diabetic rats significantly blocked the altered channel kinetics with hyperpolarizing shift in voltage-dependence of steady-state activation and inactivation curves. All together, our study provides evidence that calpain activation is directly associated with alterations in TTX-R Na(+) channels and triggers functional, nociceptive and biochemical deficits in experimental diabetic neuropathy. The calpain inhibitor, MDL 28710 have shown beneficial effects in alleviating diabetic neuropathy via modulation of TTX-R Na(+) channel kinetics and reduction of oxidative stress and neuro-inflammation.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Calpain; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Dipeptides; Ganglia, Spinal; Glycoproteins; Hyperalgesia; Male; Membrane Potentials; Neuroimmunomodulation; Neurons; Nociceptive Pain; Oxidative Stress; Patch-Clamp Techniques; Rats, Sprague-Dawley; Sodium Channels

The association of the gene encoding calpain 10 with type 2 diabetes mellitus (T2DM) has been reported. In this study we aimed to evaluate the association of SNP-19,-44, and -63 polymorphisms of calpain 10 with type 2 diabetes and diabetic-related conditions, such as diabetic retinopathy, nephropathy, and neuropathy in a Turkish population. The study group included 202 patients (133 female and 69 male) with T2DM, while the control group included 80 nondiabetic people (44 female and 36 male). Genotyping was done by the polymerase chain reaction and restriction fragment length polymorphism method. Calpain 10 SNP-44 TC genotype was found to be significantly frequent in type 2 diabetic patients with respect to the control group (p < 0.01). Body mass index (BMI) was found to be significantly high in TC genotype with type 2 diabetic patients (p < 0.05). SNP-44 T allele frequency was found to be lower in type 2 diabetic patients compared with the controls (p < 0.01). We conclude that the calpain 10 SNP-44 gene polymorphism may be accepted as a risk factor in the development of T2DM and elevated BMI in type 2 diabetic patients in a Turkish population.

Topics: Alleles; Calpain; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Female; Gene Frequency; Genetic Predisposition to Disease; Genotype; Humans; Male; Middle Aged; Polymerase Chain Reaction; Polymorphism, Genetic; Polymorphism, Restriction Fragment Length; Risk Factors; Turkey