Effects of 5‐HT₁ and 5‐HT₂ Receptor Agonists on Electromagnetic Field‐Induced Analgesia in Rats

Abstract

Much evidence demonstrates the antinociceptive effect of magnetic fields (MFs). However, the analgesic action mechanism of the electromagnetic field (EMF) is not exactly understood. The aim of the present study was to investigate the effects of 5‐HT1 and 5‐HT2 receptor agonists (serotonin HCl and 2,5‐dimethoxy‐4‐iodoamphetamine [DOI] hydrochloride) on EMF‐induced analgesia. In total, 66 adult male Wistar albino rats with an average body mass of 225 ± 13 g were used in this study. The animals were subjected to repeated exposures of alternating 50 Hz and 5 mT EMF for 2 h a day for 15 days. Prior to analgesia tests, serotonin HCl (5‐HT1 agonist) 4 mg/kg, WAY 100635 (5‐HT1 antagonist) 0.04 mg/kg, DOI hydrochloride (5‐HT2 receptor agonist) 4 mg/kg, and SB 204741 (5‐HT2 antagonist) 0.5 mg/kg doses were injected into rats. For statistical analysis of the data, analysis of variance was used and multiple comparisons were determined by Tukey’s test. Administration of serotonin HCl MF (5 mT)‐exposed rats produced a significant increase in percent maximal possible effect (% MPE) as compared with EMF group (P < 0.05). On the contrary, injection of WAY 100635 to MF‐exposed rats produced a significant decrease in analgesic activity (P < 0.05). Similarly, the administration of DOI hydrochloride significantly increased % MPE values as compared with the EMF group while SB 204741 reduced it (P < 0.05). In conclusion, our results suggested that serotonin 5‐HT1 and 5‐HT2 receptors play an important role in EMF‐induced analgesia; however, further research studies are necessary to understand the mechanism. Bioelectromagnetics. 2019;40:319–330. © 2019 Bioelectromagnetics Society.

Investigation of Analgesic Effects of Venlafaxine, Atomoxetine and Trazodone Alone and in Combination in Acute Pain Models of the Rats

“…Activation of 5-HT1 and 5-HT2 receptors leads to pain inhibition, but activation of 5-HT3 receptors leads to pain facilitation (Cortes-Altamirano et al, 2018). The increase in the antinociceptive effect of the combination of Venlafaxine and Trazodone may be due to increased serotonin levels (Ozdemir et al, 2019). In the tail flick and hot plate tests, the combination of Venlafaxine and Atomoxetine increased the antinociceptive effect more than Venlafaxine alone or Atomoxetine alone.…”

Possible Involvement of Serotonergic Mechanism(s) in the Antinociceptive Effects of kaempferol

“…Accordingly, some KM effects are mediated by such receptors. The effects of 5-HT1 receptors on the modulation of nociception have been widely studied [43,44]; however, it is required to obtain exact data on the antinociceptive activities of 5-HT2 areas [34]. Nonetheless, 5-HT2 receptors are possibly involved in the antinociceptive impacts of periaqueductal grey stimulation and stress [45].…”

Analgesia for Sheep in Commercial Production: Where to Next?

“…The electromagnetic spectrum includes light (reviewed above), radio-frequency, microwave, x-ray, ultra-violet, infrared or gamma waves. EMFs can affect a variety of biological systems, including pain perception and modulation pathways [509][510][511][512][513][514]. Interestingly, EMFs can either increase nociceptive sensitivity (induce hyperalgesia) or decrease nociceptive sensitivity (induce analgesia), and this translates to the impact on concurrent medication: EMF having been found in separate studies either to enhance or to suppress the analgesic effects of opioid drugs [510,511,515].…”