Thiadiazine-thione derivatives ameliorate STZ-induced diabetic neuropathy by regulating insulin and neuroinflammatory signaling.

Diabetes Mellitus is accompanied by chronic hyperglycemia, inflammation, and related molecular processes, which leads to diabetic neuropathy. In this work, we tested Thiadiazine-thione (TDT) synthetic derivatives TDT1 and TDT2 against streptozotocin (STZ)-induced diabetic neuropathy. Sprague Dawley's rats, SH-SY5Y neuronal and BV2 microglial cells were employed in this work, followed by behavioral, biochemical, and morphological studies utilizing RT-qPCR, ELISA, Immunoblotting, immunohistochemistry, Immunofluorescence, and in silico analyses. TDT1 and TDT2 abolished STZ-induced allodynia and hyperalgesia. Next, we examined IRS1/PI3K/AKT signaling to assess TDT1 and TDT2's impact on diabetic neuropathy. STZ downregulated IRS1, PI3K, AKT mRNA and protein expression in rat spinal cord and SH-SY5Y neuronal cells. TDT1 and TDT2 improved IRS1, PI3k, and AKT mRNA and protein expression. STZ elevated GSK3β mRNA and protein expression in vivo and in vitro, whereas TDT1 and TDT2 mitigated it. STZ increased the expression of inflammatory mediators such as p-NF-κB, TNF-α, and COX-2 in rat spinal cord lysates. TDT1 and TDT2 co-treatment with STZ decreased inflammatory cytokine expression by ameliorating astrocytosis (revealed by increased GFAP) and microgliosis (indicated by increased Iba1). TDT1 and TDT2 reduced STZ-induced JNK, Iba1, and COX-2 upregulation in BV2 microglial cells validating our in vivo findings. In silico molecular docking and MD simulations analyses suggested that TDT1 and TDT2 have IRS binding affinity, however, both compounds had an identical binding affinity, but distinct interaction pattern with IRS protein residues. Overall, these findings demonstrate that TDT derivatives mitigated STZ-induced neuropathy through modulating the insulin and inflammatory signaling pathways.