1. Hot news about chili peppers
Dan Gordon 
Gastroenterology 
Volume 114, Issue 1, (January 1998)
DOI: /S (98)
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2. Fig. 1
A subgroup of sensory neurons that transmit sensations of pain, known as nociceptors, are characterized by their sensitivity to capsaicin, the active ingredient in hot peppers. The capsaicin receptor (VR1) was identified by expression cloning, using cDNA from dorsal root ganglia and monitoring the ability of capsaicin to cause [Ca2+]i stimulation in HEK293 cells transiently transfected with fractions of the cDNA library. Compounds that activate this receptor contain a vanilloid moiety, so the receptor was named vanilloid receptor subtype 1 (VR1). This 838 amino acid protein structurally resembled a subgroup of calcium channels known as store-operated channels. Its responses to capsaicin and to heat indicate that it is likely to be an important receptor involved in pain perception. Hot pepper extracts stimulated the VR1 receptor in direct proportion to their “hotness.” VR1 also was stimulated by acutely increasing the temperature to 45°C. This receptor is a calcium-permeable nonselective cation channel that is activated by capsaicin, antagonized by its competitive antagonist, capsazepine, and has an especially high permeability to calcium ions. Low pH enhances the action of capsaicin on VR1 but acidity alone does not stimulate it. It is found almost exclusively in small diameter afferent fibers originating from the dorsal root ganglia. Treatment with capsaicin of cells that contain VR1 leads to nonapoptotic cell death that resembles neuronal death produced by capsaicin. Studies of the VR1 receptor may lead to further understanding of fundamental mechanisms of pain production, just as cloning of opioid receptors has led to understanding of mechanisms of analgesia.
Gastroenterology  , DOI: ( /S (98) )
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