- Email: [email protected]
Hot news about chili peppers
Gastroenterology News John H. Walsh, Section Editor
Hot News About Chili Peppers n a finding that could provide new clues to conditions of chronic pain in the gastrointestinal tract, researchers at the University of California, San Francisco have cloned the receptor for capsaicin, the ingredient in ‘‘hot’’ chili peppers that produces a burning sensation by activating sensory neurons that alert the central nervous system of noxious stimuli. The article by Caterina et al. was published in the October 23 issue of Nature. The sensory neurons that are ‘‘turned on’’ by capsaicin, the active ingredient of many spicy foods, are called nociceptors. Nociceptors transmit information concerning tissue damage to pain-processing centers in the brain and spinal cord. ‘‘The cloning of the capsaicin receptor represents a major and exciting advance in our ability to address the process of sensory transduction, and in particular nociception,’’ says Helen Raybould of UCLA and CURE. Raybould notes that in the gastrointestinal tract, there is substantial evidence that capsaicin-sensitive afferent neurons are activated under both physiological and pathophysiological conditions. ‘‘Understanding the consequences of activation of this
I
Future VA Training Will Consider Patient Needs, New Definitions of Primary Care n realigning its residency training programs to meet targets that call for a higher percentage of generalist physicians, the Veterans Health Administration (VHA) will take into account that its uniquely older, sicker, and poorer patient population requires greater expertise than the U.S. population as a whole, David P. Stevens, VHA chief academic affiliations officer, told Gastroenterology News.
I
receptor will help in elucidating the pathway and processes involved in chronic pain syndromes such as irritable bowel syndrome, and in the regulation of normal GI tract function,’’ Raybould says. ‘‘Since acid potentiates its activation, the VR1 receptor may enhance
pain produced by acid back diffusion of the upper GI mucosa,’’ adds Stephen Collins of McMaster University. ‘‘This also opens the way for new therapeutic strategies to exploit this receptor for selective modulation of pain without interfering with normal defense mechanisms.’’
Figure 1. A subgroup of sensor y 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 [Ca21]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 457C. 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.
Stevens also noted the movement toward specialists providing care to certain VA patients with chronic illnesses, including gastrointestinal (GI) conditions such as inflammatory bowel disease and chronic liver disease. ‘‘We’re committed to making sure that every VA patient is in an identifiable primary care setting; however, every patient may not receive primary care from just one category of physician,’’ Stevens said. ‘‘Primary care should be viewed as a process by which care is delivered, not a set of disciplines.’’
‘‘We are developing a program where specialties can identify that subset of patients (who receive primary care from specialists), develop appropriate curricula for their residents, and then we will do the accounting that gives them the primary care credit.’’ The VA supports nearly 9,000 residencies, training approximately onethird of the nation’s residents each year. In 1995, an advisory committee recommended that the VA increase the percentage of generalists among its trainees from 38% to 49% by eliminating some 1,000 specialty slots GASTROENTEROLOGY 1998;114:3–4
Hot News About Chili Peppers n a finding that could provide new clues to conditions of chronic pain in the gastrointestinal tract, researchers at the University of California, San Francisco have cloned the receptor for capsaicin, the ingredient in ‘‘hot’’ chili peppers that produces a burning sensation by activating sensory neurons that alert the central nervous system of noxious stimuli. The article by Caterina et al. was published in the October 23 issue of Nature. The sensory neurons that are ‘‘turned on’’ by capsaicin, the active ingredient of many spicy foods, are called nociceptors. Nociceptors transmit information concerning tissue damage to pain-processing centers in the brain and spinal cord. ‘‘The cloning of the capsaicin receptor represents a major and exciting advance in our ability to address the process of sensory transduction, and in particular nociception,’’ says Helen Raybould of UCLA and CURE. Raybould notes that in the gastrointestinal tract, there is substantial evidence that capsaicin-sensitive afferent neurons are activated under both physiological and pathophysiological conditions. ‘‘Understanding the consequences of activation of this
I
Future VA Training Will Consider Patient Needs, New Definitions of Primary Care n realigning its residency training programs to meet targets that call for a higher percentage of generalist physicians, the Veterans Health Administration (VHA) will take into account that its uniquely older, sicker, and poorer patient population requires greater expertise than the U.S. population as a whole, David P. Stevens, VHA chief academic affiliations officer, told Gastroenterology News.
I
receptor will help in elucidating the pathway and processes involved in chronic pain syndromes such as irritable bowel syndrome, and in the regulation of normal GI tract function,’’ Raybould says. ‘‘Since acid potentiates its activation, the VR1 receptor may enhance
pain produced by acid back diffusion of the upper GI mucosa,’’ adds Stephen Collins of McMaster University. ‘‘This also opens the way for new therapeutic strategies to exploit this receptor for selective modulation of pain without interfering with normal defense mechanisms.’’
Figure 1. A subgroup of sensor y 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 [Ca21]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 457C. 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.
Stevens also noted the movement toward specialists providing care to certain VA patients with chronic illnesses, including gastrointestinal (GI) conditions such as inflammatory bowel disease and chronic liver disease. ‘‘We’re committed to making sure that every VA patient is in an identifiable primary care setting; however, every patient may not receive primary care from just one category of physician,’’ Stevens said. ‘‘Primary care should be viewed as a process by which care is delivered, not a set of disciplines.’’
‘‘We are developing a program where specialties can identify that subset of patients (who receive primary care from specialists), develop appropriate curricula for their residents, and then we will do the accounting that gives them the primary care credit.’’ The VA supports nearly 9,000 residencies, training approximately onethird of the nation’s residents each year. In 1995, an advisory committee recommended that the VA increase the percentage of generalists among its trainees from 38% to 49% by eliminating some 1,000 specialty slots GASTROENTEROLOGY 1998;114:3–4