Scientists investigating the cough reflex have discovered a new group of molecules on the surface of nerve cells that make us cough when irritated.
The findings, to be presented at the British Pharmacological Society's Summer Meeting in Edinburgh this week, could lead to new drugs to treat cough, which when chronic affects about 10% of the UK population.
"Cough is the commonest symptom for which medical advice is sought and accounts for over half of new patient consultations to a GP," said Professor Alyn Morice, a Clinical Pharmacologist at the University of Hull, who is leading the research.
"Chronic cough can be socially isolating and disabling and people come from all over Europe to my cough clinic because the cough is ruining their lives, yet current treatment options are limited with remedies little better than honey and lemon."
Professor Morice and his team at Castle Hill Hospital in Hull have identified a group of protein molecules called receptors that sit on the surface of nerve cells and allow signals to be passed inside nerve cells.
The team have shown that the 'very cold' receptor (TRPA1) on nerve cells is stimulated by a cinnamon extract in normal volunteers, leading them to cough. Furthermore, the researchers have successfully cloned the TRPA1 receptor to allow them to investigate the pharmacology of these nerve endings.
"The receptor which has had the most drug development focused on it is the hot receptor TRPV1 , which is stimulated by capsaicin, the extract of chilli peppers, where a number of companies have produced potential drugs to block the receptor and have taken them as far as the clinic," said Professor Morice.
"Unfortunately, in this particular receptor's case it seems that blocking the receptor led to patients developing a higher body temperature and they were also less capable of feeling heat, which of course could be dangerous, so much of the development has stopped.