Clodronate changes neurobiological effects of pulsed magnetic field on diabetic rats with peripheral neuropathy

Pulsed magnetic field treatment ameliorates the progression of peripheral neuropathy by modulating the neuronal oxidative stress, apoptosis and angiogenesis in a rat model of experimental diabetes

OBJECTIVE

The present study aimed to investigate the possible anti-neuropathic effects of daily pulsed magnetic field treatments (PMF) in streptozotocin (60 mg/kg) induced 4 weeks diabetic (type-1) wistar rats (6-8 months).

MATERIALS AND METHODS

Body mass, blood glucose and thermal and mechanical sensations were evaluated during the PMF or sham-PMF in diabetic or non-diabetic rats (n = 7/group). After the measurements of motor nerve conduction velocities (MNCV), the levels of several biomarkers for oxidative stress, apoptosis and angiogenesis in spinal cord and sciatic nerve were measured.

RESULTS

PMF for 4 weeks significantly recovered the MCNV (96.9% and 63.9%) and almost fully (100%) restored to the latency and threshold. PMF also significantly suppressed the diabetes induced enhances in biochemical markers of both neuronal tissues.

CONCLUSIONS

Findings suggested that PMF might prevent the development of functional abnormalities in diabetic rats due to its anti-oxidative, anti-apoptotic and anti-angiogenic actions in neuronal tissues.

Advances About Immunoinflammatory Pathogenesis and Treatment in Diabetic Peripheral Neuropathy

Most diabetic patients develop diabetic peripheral neuropathy (DPN). DPN is related to the increase of inflammatory cells in peripheral nerves, abnormal cytokine expression, oxidative stress, ischemia ,and pro-inflammatory changes in bone marrow. We summarized the progress of immune-inflammatory mechanism and treatment of DPN in recent years. Immune inflammatory mechanisms include TNF-α, HSPs, PARP, other inflammatory factors, and the effect of immune cells on DPN. Treatment includes tricyclic antidepressants and other drug therapy, immune and molecular therapy, and non-drug therapy such as exercise therapy, electrotherapy, acupuncture, and moxibustion. The pathogenesis of DPN is complex. In addition to strictly controlling blood glucose, its treatment should also start from other ways, explore more effective and specific treatment schemes for various causes of DPN, and find new targets for treatment will be the direction of developing DPN therapeutic drugs in the future.

A Low-Frequency Pulsed Magnetic Field Reduces Neuropathic Pain by Regulating NaV1.8 and NaV1.9 Sodium Channels at the Transcriptional Level in Diabetic Rats

Low-frequency pulsed magnetic field (LF-PMF) application is a non-invasive, easy, and inexpensive treatment method in pain management. However, the molecular mechanism underlying the effect of LF-PMF on pain is not fully understood. Considering the obvious dysregulations of gene expression observed in certain types of voltage-gated sodium channels (VGSCs) in pain conditions, the present study tested the hypothesis that LF-PMF shows its pain-relieving effect by regulating genes that code VGSCs proteins. Five experimental rat groups (Control, Streptozotocin-induced experimental painful diabetic neuropathy (PDN), PDN Sham, PDN 10 Hz PMF, and PDN 30 Hz PMF) were established. After the pain formation in PDN groups, the magnetic field groups were exposed to 10/30 Hz, 1.5 mT PMF for 4 weeks, an hour daily. Progression of pain was evaluated using behavioral pain tests during the entire experimental processes. After the end of PMF treatment, SCN9A (NaV_1.7 ), SCN10A (NaV_1.8 ), SCN11A (NaV_1.9 ), and SCN3A (NaV_1.3 ) gene expression level changes were determined by analyzing real-time polymerase chain reaction results. We found that 10 Hz PMF application was more effective than 30 Hz on pain management. In addition, NaV_1.7 and NaV_1.3 transcriptions were upregulated while NaV_1.8 and NaV_1.9 were downregulated in painful conditions. Notably, the downregulated expression of the genes encoding NaV_1.8 and NaV_1.9 were re-regulated and increased to control level by 10 Hz PMF application. Consequently, it may be deduced that 10 Hz PMF application reduces pain by modulating certain VGSCs at the transcriptional level. © 2021 Bioelectromagnetics Society.

Aging and the immune response in diabetic peripheral neuropathy

A large proportion of older individuals with diabetes go on to develop diabetic peripheral neuropathy (DPN). DPN is associated with an increase in inflammatory cells within the peripheral nerve, activation of nuclear factor kappa-light-chain-enhancer of activated B cells and receptors for advanced glycation end products/advanced glycation end products pathways, aberrant cytokine expression, oxidative stress, ischemia, as well as pro-inflammatory changes in the bone marrow; all processes that may be exacerbated with age. We review the immunological features of DPN and discuss whether age-related changes in relevant immunological areas may contribute to age being a risk factor for DPN.

Effects of immune cell-targeted treatments result from the suppression of neuronal oxidative stress and inflammation in experimental diabetic rats

In this study, we hypothesized that reduction of immune cell activation as well as their oxidant or inflammatory mediators with minocycline (MCN), liposome-encapsulated clodronate (LEC), or anti-Ly6G treatments can be neuroprotective approaches in diabetic neuropathy. MCN (40 mg/kg) for reduction of microglial activation, LEC (25 mg/kg) for of macrophage inhibition, or anti-Ly6G (150 μg/kg) for neutrophil suppression injected to streptozotocin (STZ)-induced diabetic rats twice, 3 days, and 1 week (half dose) after STZ. Animal mass and blood glucose levels were measured; thermal and mechanical sensitivities were tested for in pain sensations. The levels of chemokine C-X-C motif ligand 1 (CXCL1), CXCL8, and C-C motif ligand 2 (CCL2), CCL3, and total oxidant status (TOS) and total antioxidant status (TAS) were measured in the spinal cord and sciatic nerve tissues of rats. LEC significantly reduced the glucose level of diabetic rats compared with drug control. However, MCN or anti-LY6G did not change the glucose level. While diabetic rats showed a marked decrease in both thermal and mechanical sensations, all treatments alleviated these abnormal sensations. The levels of chemokines and oxidative stress parameters increased in diabetic rats. All drug treatments significantly decreased the CCL2, CXCL1, and CXCL8 levels of spinal cord tissues and ameliorated the neuronal oxidative stress compared with control treatments. Present findings suggest that the neuroprotective actions of MCN, LEC, or anti-Ly6G treatments may be due to the modulation of neuronal oxidative stress and/or inflammatory mediators of immune cells in diabetic rats with neuropathy.