Changes in the Odor Quality of Androstadienone During

Androstadienone is a steroid found in human sweat and other secretions. It has beenwidely proposed as a candidate for a human pheromone. As an odorant it possesses some unique properties. Here we demonstrate that, firstly, there is a very wide range of thresholds in the human population, and they are not normally distributed. Secondly, repetitive exposure causes a decrease in detection threshold ofmore than four orders ofmagnitude, and thirdly, accompanying this sensitization process is a change in the perceived odor quality. Thosewith low to intermediate sensitivities ascribe to it awide range of odor descriptors across the hedonic scale, but as these individuals become sensitized, their description changes to predominantly putrid.We propose that this change in odor quality reflects the presence of at least two receptor populations for androstadienone; a low-affinity receptor conveying pleasant odor qualities and a high-affinity receptor mediating unpleasant odor qualities. We further propose that repetitive ex-posure results in the increased expression of the high-affinity receptor thereby shifting the balance of perception to the negative end of the hedonic scale. Key words: odor, olfaction, olfactory, pheromone, smel