International research team investigates why we get cold
The mornings have turned really cold again causing our bodies to react – numb fingers and toes, streaming eyes and red, running noses are par for the course. These localised responses are triggered by cold sensors. In collaboration with scientists from the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), an international research group headed up by Harvard professor David Clapham has discovered a new, previously unknown cold sensor in the human skin. The research scientists believe that this sensor contributes to localised adaptive responses to the cold. Their findings have been recently published in the renowned scientific journal PNAS (http://www.pnas.org/content/early/2011/10/18/1115387108.abstract).
“When it gets colder, we register the decrease in temperature on a conscious level and wrap up more warmly”, says Dr Katharina Zimmermann from the FAU Institute for Physiology and Pathophysiology; one of the scientists involved in the discovery and characterisation of the new sensors. “At the same time however, various localised adaptive responses take place in our bodies which help to maintain body temperature at approx. 37°C. For example, our vessels narrow.” The scientists conjecture that the recently discovered cold sensor could also trigger this kind of reaction.
The TRPC5 sensor’s sensitivity to temperature is being investigated via cells in culture dishes. The molecule reacts acutely at temperatures ranging from 25-37°C – in other words, temperatures which lie below the normal human body temperature of 37°C. “We have carried out numerous experiments at even lower and higher temperatures. The molecule was at its most active, however, within this range of temperatures”, commented Dr Alexander Hein from FAU.
The third FAU researcher, Dr Jochen Lennerz, who is currently carrying out research at Universität Ulm, finally succeeded in proving the presence of the molecule in the delicate dendrites in human nerves. “The small and highly sensitive fibres are situated in the lowest layers of the epidermis and are wafer thin. It would take more than 50 of them to make up the thickness of a human hair”, he explains.
And it was from these delicate fibres that electrophysiologist, Dr Katharina Zimmermann, was able to register electrical impulses using a single-fibre recording technique, which is her field of expertise. This technique makes it possible to investigate the function of the sensor in the tissue. “I compared normal mice with those that did not have the TRCP5 molecule”, explains Zimmermann. “The results were interesting – it was apparent that other previously identified cold sensors were able to compensate for the lack of the cold sensor discovered by our team. The mice demonstrated no change in their sensitivity to the cold.” It has therefore been concluded that a whole range of factors are responsible for physical reactions to the cold.
At present, the international research team is working on the closer analysis of the TRPC5 molecule; in particular they hope to gain a better understanding of how it works. Their findings could contribute, for example, to the development of new pain relief medication in the future. “But before we go any further, we intend to toast our research success with a warm mug of mulled wine”, says Zimmermann.
Further information for the media:
PD Dr. Katharina Zimmermann
uni | media service | research No. 55/2011 on 21.11.2011