The Role of Pain Receptors in the Main Symptoms of Covid-19 and How Diet Can Be a Therapy

Abstract

It is estimated that 80% of SARS-CoV-2 patients have olfactory disturbances and many also have dysgeusia or ageusia (an interruption or loss of taste, respectively) or changes in chemesthesis, the ability to perceive irritants by TRP receptors. Anosmia (loss of sense of smell) and dysgeusia been termed 'sentinel symptoms'. Anosmia and ageusia represent a real health risk and can also cause nutritional deficits'. Infection with SARS-CoV-2 in the oral cavity could cause changes in the production or quality of saliva, contributing to the symptoms of taste loss. Since the activation of TRPs by Reactive Oxygen Species (ROS) contributes to inflammation and pain, research is focusing on several biological mediators related to TRPs and oxidative radicals that could help the development of treatments for pain itself and some COVID related symptoms. Recent studies have found that Nuclear Factor Erythroid-Related Factor 2 (NRF2) is a transcription factor that regulates cellular defence against toxic and oxidative insults. Compounds that can activate or induce NRF2 include garlic H2S polysulphides, cinnaldehyde in cinnamon, polyphenols in green tea, curcumin, a polyphenolic compound found in curcuma, piperine, an alkaloid found in black pepper, and glucoraphanin found in broccoli. In addition, there is a substantial electrophilic interaction between NRF2, TRPA1 and TPV1 that results in their desensitisation. TRPV1 receptors enter a refractory state (commonly called desensitisation) that leads to inhibition of receptor function as repeated stimulation leads to a progressive reduction in their response. To counteract some of the effects induced by SARS-CoV-2, a rapid desensitisation of TRPs by certain foods is therefore proposed which could reduce the severity of symptoms (including cough, loss of taste and smell) and provide new therapeutic strategies.