At the moment you are looking forward to a glass of ice-cold cola for refreshment, then in the next moment you have a stabbing toothache. Many people complain about teeth that are sensitive to cold. So far, however, it has been largely unclear which biochemical process is underlying this hypersensitivity. Researchers have now discovered that a protein is responsible for the pain response of teeth when it is cold.
Cold pain as a protective mechanism
Toothache caused by cold can occur in various situations: A stronger reaction to cold food and drinks can be expected, especially if there is a hole in the tooth or age-related erosion of the gums. Cancer patients who are treated with platinum-based alkylating agents (drugs; prevent DNA replication) during chemotherapy are often confronted with extreme hypersensitivity to cold. However, it was never completely clear how this pain explicitly came about. It is now clear that the painful reaction of the teeth to cold is a way of the body to protect already damaged teeth from further injuries.
Experiments with mice
An international research group, in which representatives from the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and the Harvard Medical School participated, has now been able to find out which signal pathway triggers dental pain perception in cold weather. Her groundbreaking study results were published in the journal “Science Advances”. In studies with laboratory mice whose molars were drilled under anesthesia, toothache caused by the cold was to be simulated. Those animals with tooth injuries clearly showed their pain through specific behavior: They consumed up to 300 percent more sugar water. On the basis of this initial experiment, research was carried out on the protein TRPC5, which the researchers suspected to be a mediator of cold pain.
Protein causes toothache
The interaction of TRPC5 with the odontoblasts was specifically observed. Odontoblasts are cells that lie directly on the border between dentin (dentin) and pulp (tooth pulp). The TRPC5 protein is encoded by a gene of the same name. Genetically modified mice that did not have this gene behaved, despite tooth damage, like those experimental animals whose molars were not drilled. Laboratory mice without effective protein could not feel the toothache. Specifically, it can be said that the TRPC5 protein opens channels in the membrane (cell skin) of the odontoblasts when exposed to cold, which activates the signal transmission of the nerves. The neural signal reaches the brain via the tooth root, where in turn hypersensitivity and pain to cold are reported. This clearly proves that the TRPC5 acts as a temperature sensor.
TRPC5 blocker clove oil
What is particularly exciting is that the protein stimulates cell activity in the cold, while other cells and tissues usually shut down their metabolism in the presence of cold. Also of great importance is the discovery that odontoblasts sense cold only through the TRPC5 protein. This allows you to better intervene in the cold-sensitive function and alleviate any pain. Occasionally, it has been randomly identified that the active ingredient eugenol contained in clove oil can inhibit TRPC5. Clove oil has been used for toothache for centuries, and current research has now revealed its mode of action. In the future, for example, permanent treatment with eugenol for toothache during chemotherapy would be conceivable.