So recently, I managed to cut myself on the palm of my hand with a pair of scissors while trying to open a package. Yes, I'm aware... But hear me out, when I went to wash my hands, it stung badly, and it was painful to clean the cut with soap and water. I'm sure the majority of you have had or known someone who has experienced this. So it got me thinking what the heck causes that? Why do I feel as if someone just pressed a heated rod against my palm when all I did was try to clean the area around my open wound? It turns out it's in the soap. The two most common key ingredients in antiseptics are ethanol and hydrogen peroxide. They both activate a receptor in the body, causing it to burn. Ethanol specifically activates the vanilloid receptor-1 (VR1), which is responsible for the burning sensation you experience when you come into contact with something hot or certain chemicals. The transient receptor potential vanilloid-1 is the most diverse multifunctional vanilloid receptor found in the body (TRPV-1). This group of receptors is also linked to the warmth sensation you get when drinking alcohol in the form of a shot; it is located in your esophagus, which is why you feel a temporary change in temperature. Other alcohol-infused beverages do not produce this effect because the concentration is thought to be insufficient to activate that receptor. We know hydrogen peroxide acts in a similar manner, but we know less about its mechanism.
Since we'd been discussing the way proteins interact and how cell signaling occurs, I was curious about the mechanics of what was going on with my hand. As it turns out, these "thermo"-receptors are not the only ones involved in or capable of regulating temperature, they manage many sensory signals. Now, the majority of TRPV-1 research and interest has been focused on pain management; TRPV-1 acts as a therapeutic target; however, these receptors are frequently involved in and play a significant role in a variety of diseases, and they may be a critical component in treating these diseases. What I discovered is that we do not understand the processes as well as we would like to. Because TRPV-1 is involved in so many processes, researchers believe that this targeted treatment may have an adverse effect on healthy channels. TRPV-1 has, however, been proposed as a therapeutic target for diseases such as digestive, cardiovascular, and respiratory. When activated, the TPRV-1 channel causes inflammation and the transmission of pain signals. Capsaicin, an active component found in chili peppers, can activate it, causing a burning sensation in any tissue it comes into contact with. So, for example, if you have chronic gastric ulcers, it is usually advised that you avoid peppers; however, it has been reported that a moderate amount of capsaicin has a protective effect on the gastric mucosa. The key difference is which mucosa is being secreted. Maintaining a relatively normal level of capsaicin in the diet increases the production of alkaline mucus and increases blood flow to the gastric mucosa, thereby aiding in the prevention and treatment of ulcers. TRPV-1 also promotes prostaglandin secretion and cell growth via the epidermal growth factor (EGF) protein. When TRPV-1 interacts with capsaicin at therapeutic doses, the results last for a few months but are fully reversible, with the excited neurons remaining unresponsive, "silent." This is known as desensitization, which helps to relieve pain. TRP channels are found in free nerve endings and allow for a variety of functions in the cells, including nociception and the production and release of inflammatory mediators.
To summarize, they do a lot more than tell you when something is cold or hot and annoy you when you try to wash your hands after getting a paper cut or other superficial cuts.
Citations:
Du Q, Liao Q, Chen C, Yang X, Xie R and Xu J (2019) The Role of Transient Receptor Potential Vanilloid 1 in Common Diseases of the Digestive Tract and the Cardiovascular and Respiratory System. Front. Physiol. 10:1064. doi: 10.3389/fphys.2019.01064
Koivisto, AP., Belvisi, M.G., Gaudet, R. et al. Advances in TRP channel drug discovery: from target validation to clinical studies. Nat Rev Drug Discov 21, 41–59 (2022). https://doi.org/10.1038/s41573-021-00268-4
Upon reading this article I became intrigued into how hydrogen peroxide works as an antiseptic. I was able to learn that immediately following an injury such as a laceration the levels of hydrogen peroxide in the area of injury rises. (Zhu et al., 2017) This is coming directly from the cells, before individuals generally clean out a wound with a hydrogen peroxide solution. Do you think this plays a role in the burning sensation that lacerations gives rise to? As an antiseptic the way hydrogen peroxide helps keep a wound from getting infected is it's oxidative properties as well as its signaling abilities. (Zhu et al., 2017) I too had difficulty finding the mechanism and receptor that hydrogen peroxide binds to, that causes the burning sensation.
ReplyDeleteZhu, G., Wang, Q., Lu, S., & Niu, Y. (2017). Hydrogen peroxide: A potential wound therapeutic target? Medical principles and practice : international journal of the Kuwait University, Health Science Centre. Retrieved October 3, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5768111/