Neuroprotective Effects of a Hydrogen Sulfide Donor in Streptozotocin-Induced Diabetic Rats

Diabetic neuropathy is an important long-term complication of diabetes. This study explored the hypothesis that hydrogen sulfide (H₂S) ameliorates neuropathic pain by controlling antiapoptotic and pro-apoptotic processes. The effects of a slow-releasing H₂S donor, GYY4137, on the expression of antiapoptotic and pro-apoptotic genes and proteins, such as B-cell lymphoma 2 (Bcl2) and Bcl-2-like protein 4 (Bax), as well as caspases, cyclooxygenase (COX)-1 and COX-2, monocytes/macrophages, and endothelial cells, in the spinal cord of male Sprague-Dawley rats with streptozotocin-induced peripheral diabetic neuropathy, were investigated using reverse transcription-PCR, western blot and immunohistochemistry. The antihypoalgesic activities of GYY4137 on diabetic rats were evaluated using the tail flick test. Treatment of diabetic rats with GYY4137 attenuated thermal hypoalgesia and prevented both the diabetes-induced increase in Bax mRNA expression (p = 0.0032) and the diabetes-induced decrease in Bcl2 mRNA expression (p = 0.028). The GYY4137-treated diabetic group had increased COX-1 (p = 0.015), decreased COX-2 (p = 0.002), reduced caspase-7 and caspase-9 protein expression (p < 0.05), and lower numbers of endothelial and monocyte/macrophage cells (p < 0.05) compared to the non-treated diabetic group. In summary, the current study demonstrated the protective properties of H₂S, which prevented the development of neuropathy related behavior, and suppressed apoptosis activation pathways and inflammation in the spinal cord. H₂S-releasing drugs could be considered as possible treatment options of diabetic peripheral neuropathy.