TAAR1 transforms thinking about a plant alkaloid that transformed the practice of medicine.

Abstract

In this issue of the Journal Sukhanov et al., report their experimental results in support of the hypothesis: trace amine-associated receptor 1 (TAAR1) mediates apomorphine's effects in mice – in particular, climbing activity. For many familiar with this alkaloid the conclusions reached by these authors come as a surprise. After all, apomorphine is one of the oldest and most studied drugs still used in human and veterinary medicine (Taba et al., 2013). Originally made by dehydrating morphine – itself an alkaloid produced by poppies of the somniferum species – in boiling sulfuric acid, a process first reported by Arppe in 1845, apomorphine was subsequently found to be native to two Nymphaea species of water lily: Nymphaea caerulea (the Egyptian blue lotus) and Nymphaea ampla . Interestingly, these same species of water lily are known to have been cultivated more than one thousand years ago on both sides of the Atlantic where they were consumed for their psychoactive effects during religious ceremonies (Bertol et al., 2004). Apomorphine's potential as a medication was first explored in 19th century Northern Europe where large animal veterinarians found it efficacious at controlling stereotypies (Feser, 1873) in addition to its usefulness as a forceful emetic (Siebert, 1871). However, it was in Harnack's (1874) publication of his extensive pharmacologic study of apomorphine's effects in various animal species that he made the significant observation that the drug probably acts on multiple brain areas given its pronounced effects on motivated behaviour, sensory perception, the gastrointestinal tract and cardiovascular and respiratory tone (Harnack, 1874). Ten years later Weil (1884) was the first to suggest that apomorphine might provide relief to sufferers of Parkinson's disease and other disorders of movement control; findings confirmed and expanded by Schwab et al. (1951) and Cotzias et al. (1970) transforming the treatment of …