Abstract
BACKGROUND AND OBJECTIVES: Studies have demonstrated that the cannabinoid CB1 receptor is involved in the modulation of pain, mainly by activating the descending pain control pathway. However, the role of photobiomodulation in this process is not well elucidated. Thus, the present study aimed to investigate the involvement of the CB1 receptor in the supraspinal photobiomodulation-induced antinociception. METHODS: Male albino swiss mice were submitted to chronic constriction injury and treated with photobiomodulation. To evaluate the supraspinal involvement of the CB1 receptor in the photobiomodulation-induced antinociception, the cannabinoid CB1 receptor antagonist AM251 (0.1µg/vol 0.2µL) was injected 5 minutes before the photobiomodulation treatment. The photobiomodulation treatment was performed on the fifth day after the stereotactic surgery and chronic constriction injury at a dose of 50J/cm2 in acute condition. The hot plate and von Frey monofilaments tests were performed to evaluate the thermal and mechanical pain sensitivity, respectively. RESULTS: The thermal and mechanical nociceptive threshold was higher in mice with chronic constriction injury, injected with saline and treated with photobiomodulation at the dose of 50J/cm2 in both the hot plate (p<0.001) and von Frey (p>0.001) tests. These antinociceptive effects were not detected in mice with chronic constriction injury pre-treated with AM251. CONCLUSION: The present study suggests that CB1 receptors located in Supraspinal structures, participate in the control of neuropathic pain following photobiomodulation treatment in animals undergoing chronic constriction injury.
Highlights
Neuropathic pain is defined as the pain arising as a direct consequence of a lesion or disease affecting the somatosensory system either at the peripheral or central level, even in the absence of nociception[1,2]
The present study suggests that cannabinoid receptors 1 (CB1) receptors located in Supraspinal structures, participate in the control of neuropathic pain following photobiomodulation treatment in animals undergoing chronic constriction injury
The objective of our study is to identify the influence of the CB1 receptor on the dorsolateral column of the periaqueductal gray in mice treated with photobiomodulation after chronic constriction injury (CCI) of the sciatic nerve
Summary
Neuropathic pain is defined as the pain arising as a direct consequence of a lesion or disease affecting the somatosensory system either at the peripheral or central level, even in the absence of nociception[1,2]. The CB1 receptors are present mainly in the central nervous system, especially in regions related to transmission and pain modulation, such as PAG, RVM, the dorsal horn of the spinal cord, and other motor and limbic structures. The objective of our study is to identify the influence of the CB1 receptor on the dorsolateral column of the periaqueductal gray (dlPAG) in mice treated with photobiomodulation after chronic constriction injury (CCI) of the sciatic nerve. RESULTS: The thermal and mechanical nociceptive threshold was higher in mice with chronic constriction injury, injected with saline and treated with photobiomodulation at the dose of Gabriela Xavier Santos – https://orcid.org/0000-0002-6366-0909; Giovane Galdino de Souza – https://orcid.org/0000-0002-1898-1973; Suélen Santos Alves – https://orcid.org/0000-0001-6705-233X; Gabriela Nagai Ocamoto – https://orcid.org/0000-0001-5496-3548; Nivaldo Antonio Parizzoto – http://orcid.org/0000-0003-1774-9053; Luciana Maria dos Reis – https://orcid.org/0000-0002-0672-7804
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