Suppressive effect of electromagnetic field on analgesic activity of tramadol in rats

Abstract

The electromagnetic fields (EMFs) have been shown to alter animal and human behavior, such as directional orientation, learning, pain perception (nociception or analgesia) and anxiety-related behaviors. The aim of this study was to evaluate the influence of electromagnetic fields of high-frequency microwaves on pain perception and anti-nociceptive activity of tramadol (TRAM) -analgetic effective in the treatment of moderate to severe acute and chronic pain states.Electromagnetic fields exposures of a)1500 MHz frequency and b) modulated, 1800 MHz (which is identical to that generated by mobile phones) were applied. Paw withdrawal latency (PWL) to thermal stimulus was measured in vehicle or tramadol (TRAM) treated animals before and after 30, 60 and 90 minutes from injections.The differences in the level of pain (PWL) between control group and rats exposed to EMF alone in three measurements, were not observed. Tramadol alone significantly increased PWLs to thermal stimulus in comparison to vehicle results at 30 (p < 0.001) and 60 minutes (p < 0.05) after drug injection. EMF exposure of both frequencies transiently suppressed analgesic effect of tramadol, significantly reducing paw withdrawal latency in animals treated with this drug at 30 minutes from the drug injection.

Effect of Radiofrequency Electromagnetic Fields on Thermal Sensitivity in the Rat

“…Previous studies using subjective scales or reflex responses in the hot plate paradigm suggested contradictory RF-EMF effects on thermal sensitivity [ 13 , 15 , 29 , 30 ]. Here, RF-EMF effects on thermal sensitivity were assessed for the first time in an operant paradigm in the rat.…”

“…In addition, one may hypothesize that local skin thermal sensitivity was modulated through the chemical mediators influencing the higher-order midbrain regions controlling pain perception. Indeed, some studies suggested that cortisol release, central catecholamine or opioid peptide (endorphin) were influenced by RF-EMF exposures [ 15 , 16 , 17 , 18 , 35 , 36 , 37 , 38 ].…”

“…In rodents, Mathur et al [ 14 ] showed that intermittent RF-EMF exposures (0.4 W/kg, 73.5 MHz, whole body) heightened the emotional component of phasic pain. Bodera et al [ 15 ] showed that RF-EMF exposures (1500 MHz and 1800 MHz) transiently suppressed the effect of tramadol, an analgesic acting through opioids and monoaminergic transmissions. On the contrary, in snails, Nittby et al [ 16 ] showed analgesia after exposure (Global System for Mobile Communications (GSM), 1900 MHz, 48 mW/kg).…”

Influence of electromagnetic field (1800 MHz) on lipid peroxidation in brain, blood, liver and kidney in rats

“…In our previous studies we concluded that: -High frequency electromagnetic fields of 1500 MHz and 1800 MHz, when applied alone, did not influence pain perception threshold to thermal stimuli. It did, however, account for an unwanted effect -the diminishing analgesic action of tramadol [10]. -Electromagnetic fields exposure of 1800 MHz frequency and 20 V/m intensity, which is similar to cell phones, did not markedly influence the nociceptive threshold to thermal stimuli, although it did transiently decrease analgesic efficacy of tramadol in rats with complete Freund's adjuvant-induced paw inflammation [11].…”

“…It did, however, account for an unwanted effect -the diminishing analgesic action of tramadol [10]. -Electromagnetic fields exposure of 1800 MHz frequency and 20 V/m intensity, which is similar to cell phones, did not markedly influence the nociceptive threshold to thermal stimuli, although it did transiently decrease analgesic efficacy of tramadol in rats with complete Freund's adjuvant-induced paw inflammation [11]. In the last study [12] we recorded interesting findings for the groups of rats receiving tramadol and, concurrently, being exposed to an electromagnetic field.…”