Evaluation of Local Chromotherapy on Carrageenaninduced Acute Inflammatory Pain in Rats

Abstract

Abstract Introduction: Pain is an unpleasant sensory and emotional experience, which follows a harmful stimulus. In conventional medicine pain is treated with non-steroidal anti-inflammatory drugs, opioid analgesics and local anesthetics. Chromotherapy is a noninvasive complementary therapy, which uses the colors of the visible light region of the electromagnetic spectrum for the treatment of pathologies such as inflammations, dermatological changes and respiratory tract disorders. The mechanism of treatment would be based on the fact that the body is able to absorb electromagnetic waves at different wavelengths, which interact with cells and substances producing a beneficial effect for the patient. This would happen due to the fact that electrons leave from a lower energy level to a higher one, the moment light reaches the tissues, and thus begins a cascade of biochemical reactions that lead to the improvement of the pathogenic picture, which remains until the electron returns to its normal energy level. That would be the theory of direct effect. The indirect effect theory proposes that tissues would not absorb light, but would react to chemical stimuli produced by photons, so that they would stimulate the release of hormones and anti-inflammatory mediators through photoreceptors that would be present in cells, which convert the electromagnetic wave into an electrical stimulus, passing through the terminations and being distributed throughout the body. These photoreceptors would be present especially in the retina. OBJECTIVE: evaluation of the antinociceptive action of chromotherapy, specifically evaluate seven colors of the visible light region of the electromagnetic spectrum using a pain model in rats. Methods: Wistar rats were used, divided into 8 groups, in which carrageenan was applied to the paw at a dose of 250 μg/animal to induce inflammatory pain. After 3 hours until the fourth hour, the rats were submitted to the nociceptive paw compression test every five minutes, and the pressure threshold for the occurrence of paw removal was measured in grams. Before starting the experiment, it was verified whether the effect of containment would influence the nociceptive response of the animal. All conditions of the chromotherapy experiment were reproduced, except for the fact that light was not applied. Results: There is no statistically significant difference between the responses of the animal with and without the containment in the pressure stimuli applied. The experiments show that the acute application, for 20 minutes, of the colors blue, red, green, orange, yellow, violet and white did not alter carrageenan-induced hyperalgesia in rats, and no significant difference was indicated between the values of the nociceptive threshold of the exposed groups and their respective controls. Conclusion: chromotherapy was not effective in the treatment of acute inflammatory pain, in the conditions described in this study. Keywords Chromotherapy; Antinociception; Inflammatory Pain