Activation of capsaicin receptors in the periaqueductal gray does not alter pain tolerance in a diabetic neuropathy model

Document Type : Original Research

Authors
T. Shirafkan 1
A. Komaki 2
A. Sarihi 3
1 Department of Biology, Faculty of Basic Sciences, Islamic Azad University of Hamadan, Iran
2 Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
3 Department of Neuroscience, School of Sciences and Advanced Technology in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
Abstract
Introduction: To date, a multitude of neural circuits within the central nervous system have been recognized for their roles in pain modulation. Notably, the ventrolateral periaqueductal gray (vlPAG) region of the midbrain emerges as a pivotal element within the supraspinal pain modulation network. This region’s significance has been thoroughly documented across diverse animal pain models. In our study, we concentrated on exploring the functions of capsaicin receptors in this specific area, particularly their involvement in mediating antinociceptive effects.

Methods: In this study, male Wistar rats were utilized to examine the antinociceptive effects of capsaicin when directly administered into the ventrolateral periaqueductal gray (vlPAG) region of the midbrain. The efficacy of this intervention was evaluated using the tail-flick test, conducted five minutes after injection. The research compared the outcomes of intra-vlPAG capsaicin administration between healthy control rats and those with diabetes.

Results: In the control groups, capsaicin induced a swift and temporary analgesic effect, but it did not produce antinociceptive effects in diabetic rats.

Conclusion: Acute microinjections of capsaicin failed to elicit significant antinociceptive effects in the diabetic animal group. To derive more precise conclusions, it is advisable to also examine the long-term impacts of these compounds.

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Pathobiology Reserach
Volume 26, Issue 3
September 2023
Pages 31-36