1.Activation of Peripheral μ-opioid Receptors by Dermorphin [D-Arg2, Lys4] (1-4) Amide Leads to Modality-preferred Inhibition of Neuropathic Pain.
Tiwari V1, Yang F, He SQ, Shechter R, Zhang C, Shu B, Zhang T, Tiwari V, Wang Y, Dong X, Guan Y, Raja SN. Anesthesiology. 2016 Mar;124(3):706-20. doi: 10.1097/ALN.0000000000000993.
BACKGROUND: Opioids have long been regarded as the most effective drugs for the treatment of severe acute and chronic pain. Unfortunately, their therapeutic efficacy and clinical utility have been limited because of central and peripheral side effects.
2.Comparison of in vitro metabolism and cytotoxicity of capsaicin and dihydrocapsaicin.
Halme M1, Pesonen M2, Salo H3, Söderström M4, Pasanen M3, Vähäkangas K3, Vanninen P4. J Chromatogr B Analyt Technol Biomed Life Sci. 2016 Jan 15;1009-1010:17-24. doi: 10.1016/j.jchromb.2015.11.042. Epub 2015 Nov 25.
Capsaicin and dihydrocapsaicin are the major active components in pepper spray products, which are widely used for law enforcement and self-protection. The use of pepper sprays, due to their irreversible and other health effects has been under a strong debate. In this study, we compared metabolism and cytotoxicity of capsaicin and dihydrocapsaicin using human and pig liver cell fractions and human lung carcinoma cell line (A549) in vitro. Metabolites were screened and identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Using liver cell fractions, a novel aliphatic hydroxylated metabolite (m/z 322) was detected to dihydrocapsaicin but no structure was found corresponding to capsaicin. Instead, a novel phase I metabolite of capsaicin, corresponding to the structure of aliphatic demethylation and dehydrogenation (m/z 294) was identified. In addition, two novel conjugates, glycine conjugates (m/z 363 and m/z 365) and bi-glutathione (GSH) conjugates (m/z 902 and m/z 904), were identified for both capsaicin and dihydrocapsaicin.
3.Esophageal Submucosal Injection of Capsaicin not Acid Induces Symptoms in Normal Subjects.
Lee RH1, Korsapati H2,3, Bhalla V2,3, Varki N4, Mittal RK2,3. J Neurogastroenterol Motil. 2016 Feb 27. doi: 10.5056/jnm15166. [Epub ahead of print]
Background/Aims: Transient receptor potential Vanilloid-1 (TRPV1) is a candidate for mediating acid-induced symptoms in the esophagus. We conducted studies to determine if the presence of acid in the mucosa/submucosa and direct activation of TRPV1 by capsaicin elicited symptoms in normal healthy subjects. We also studied the presence of TRPV1 receptors in the esophagus.
4.Presence of hyperalgesia predicts analgesic efficacy of topically applied capsaicin 8% in patients with peripheral neuropathic pain.
Mainka T1,2, Malewicz NM1, Baron R3, Enax-Krumova EK4, Treede RD5, Maier C1. Eur J Pain. 2016 Jan;20(1):116-29. doi: 10.1002/ejp.703. Epub 2015 Apr 8.
BACKGROUND: Topical high-dose capsaicin acting on TRPV1 receptors and inducing an intraepidermal decrease in the small nerve fibre count is effective in treating neuropathic pain (NP). Sensory changes after capsaicin application, their correlation with pain relief and their role as possible predictors of response have been insufficiently analysed. We hypothesized a positive correlation between pain relief and increase in the warmth detection threshold (WDT), indicating loss of C-fibre function, and higher response rates in patients with preserved C-fibre function or heat hyperalgesia before application.