Capsaicin

Lipidomics Gateway (23 June 2010) [doi:10.1038/lipidmaps.2010.20]

The pungent vanilloid compound capsaicin, or 8-methyl-N-vanillyl-6E-nonenamide, evokes the burning pain associated with eating chili peppers.

A chili pepper and the structure of capsaicin. Visit 8-methyl-N-vanillyl-6E-nonenamide in the LIPID MAPS structure database for more molecular information.

Capsaicin, an N-acyl amine, offers protection to plants due to the sensation of heat that it provokes on contact with skin. Studying the action of capsaicin has helped to delineate the mammalian pathways that respond to painful stimuli, both thermal and chemical. Even before the receptor for capsaicin was identified, the lipid was used an analgesic agent in several painful disorders. Furthermore, dietary capsaicin might attenuate obesity-related metabolic syndrome.

Nociceptors are a subgroup of neurons that are activated at peripheral terminals by painful stimuli. In 1997, Caterina et al. cloned the capsaicin receptor, transient receptor potential vanilloid 1 (TRPV1), which is expressed by nociceptors 1 . Activation of this channel is responsible for the sensation associated with eating chili peppers. This month we highlight in Pain sensation: Hot lipids, chili response the discovery that oxidized metabolites of linoleic acid are formed in cell membranes in response to noxious heat and that these activate TRPV1. Thus capsaicin taps into an endogenous mechanism of heat detection, although it probably binds to the receptor at a distinct site 2 .

Repeated exposure to capsaicin is thought to lead to depletion of the peptide neurotransmitter substance P in primary afferent neurons, and it is used to treat neuropathic and arthritic pain despite an initially unpleasant sensation 3 4 . It might be useful as a treatment for complications associated with obesity; in a recent study dietary capsaicin lowered fasting glucose and levels of leptin and insulin in obese mice, and reduced impairment of glucose tolerance 5 .

Emma Leah

References:

  1. Caterina, M. J. et al. The capsaicin receptor: a heat-activated ion channel in the pain pathway.

    Nature 389, 816-824 (1997). doi:10.1038/39807

  2. Patwardhan, A. M. et al. Heat generates oxidized linoleic acid metabolites that activate TRPV1 and produce pain in rodents.

    J. Clin. Invest. 120, 1617-1626 (2010). doi:10.1172/JCI41678

  3. De Felipe, C. et al. Altered nociception, analgesia and aggression in mice lacking the receptor for substance P.

    Nature 392, 394-397 (1998). doi:10.1038/32904

  4. Park, H. J. and Moon, D. E. Pharmacologic management of chronic pain.

    Korean J Pain 23, 99-108 (2010). doi:10.3344/kjp.2010.23.2.99

  5. Kang, J.-H. et al. Dietary capsaicin reduces obesity-induced insulin resistance and hepatic steatosis in obese mice fed a high-fat diet.

    Obesity 18, 780-787 (2010). doi:10.1038/oby.2009.301

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