Hindawi Neural Plasticity Volume 2017, Article ID 3710821, 11 pages https://doi.org/10.1155/2017/3710821 Research Article A Combined Water Extract of Frankincense and Myrrh Alleviates Neuropathic Pain in Mice via Modulation of TRPV1 1,2 1,2 3 4 1,2 1,2 Danyou Hu, Changming Wang, Fengxian Li, Shulan Su, Niuniu Yang, Yan Yang, 1,2 1,2 1,2 1,2 1,2 1,2 Chan Zhu, Hao Shi, Lei Yu, Xiao Geng, Leying Gu, Xiaolin Yuan, 1,2 1,2,4 1,2 Zhongli Wang, Guang Yu, and Zongxiang Tang 1Key Laboratory for Chinese Medicine of Prevention and Treatment in Neurological Diseases, Nanjing University of Chinese Medicine, 138 Xianlin Rd, Nanjing, 210023 Jiangsu, China 2School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, 138 Xianlin Rd, Nanjing, 210023 Jiangsu, China 3Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, 253 Gongye Rd, Guangzhou, 510282 Guangdong, China 4Jiangsu Key Laboratory for High Technology Research of TCM Formulae, Nanjing University of Chinese Medicine, 138 Xianlin Rd, Nanjing, 210023 Jiangsu, China Correspondence should be addressed to Guang Yu; [email protected] and Zongxiang Tang; [email protected] Received 28 October 2016; Revised 24 January 2017; Accepted 6 February 2017; Published 27 June 2017 Academic Editor: Fang Pan Copyright © 2017 Danyou Hu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Frankincense and myrrh are widely used in clinics as a pair of herbs to obtain a synergistic effect for relieving pain. To illuminate the analgesia mechanism of frankincense and myrrh, we assessed its effect in a neuropathic pain mouse model. Transient receptor potential vanilloid 1 (TRPV1) plays a crucial role in neuropathic pain and influences the plasticity of neuronal connectivity. We hypothesized that the water extraction of frankincense and myrrh (WFM) exerted its analgesia effect by modulating the neuronal function of TRPV1. In our study, WFM was verified by UHPLC-TQ/MS assay. In vivo study showed that nociceptive response in mouse by heat and capsaicin induced were relieved by WFM treatment. Furthermore, thermal hypersensitivity and mechanical allodynia were also alleviated by WFM treatment in a chronic constriction injury (CCI) mouse model. CCI resulted in increased TRPV1 expression at both the mRNA and protein levels in predominantly small-to-medium neurons. However, after WFM treatment, TRPV1 expression was reverted in real-time PCR, Western blot, and immunofluorescence experiments. Calcium response to capsaicin was also decreased in cultured DRG neurons from CCI model mouse after WFM treatment. In conclusion, WFM alleviated CCI-induced mechanical allodynia and thermal hypersensitivity via modulating TRPV1. 1. Introduction promising effects of multiple herbs including frankincense and myrrh in pain relief [6]. The main characteristics of neuropathic pain are allodynia, Frankincense is the dried gum resin of Boswellia carterii, hyperalgesia, and persistent pain [1, 2], which changes the one of 43 species in the genus Boswellia of the family Burser- quality of life for millions of people worldwide. Massive aceae. It has been commonly used to alleviate pain in differ- studies have been designed to disclose the precise mecha- ent diseases [7, 8]. In vitro studies have shown that boswellic nisms [3, 4]. However, the randomized clinical trial drugs acids, which are isolated from frankincense, have the poten- have shown that the analgesic effect is less than that of tial to regulate immune function [9]. Myrrh is an aromatic patients treated with conventional drugs [5]. This prompts gum resin, which is the plant stem resinous exudate of Com- us to find new strategies for the affliction. There is grow- miphora myrrha (Nees) Engl. (Burseraceae) and other differ- ing interest in herbal remedies. Clinical data have shown ent species of the Commiphora family. Myrrh is widely used 2 Neural Plasticity Table 1: The cone voltage and collision energy optimized for each analyte and selected values. Ionization MRM transitions (precursor- Cone voltage Collision energy Analytes mode product) (V) (eV) − β-Boswellic acid ES 455.415 → 377.356 44 30 3α-Acetoxy-tirucall-7,24- dien-21-oic ES+ 455.479 → 437.426 14 8 acid 3-Acetyl-11-keto-β-boswellic acid ES+ 513.479 → 95.06 40 42 3-Keto-tirucall-8,24-dien-21-oic acid ES+ 455.479 → 133.112 14 36 Abietic acid ES+ 303.287 → 93.109 16 30 in clinics in India, China, Rome, and Greece to treat painful extracted from boiling water (1600 ml) twice and filtered diseases such as ache and dysmenorrhea [10]. Pharmacolog- through gauze. Filtrates were then evaporated by rotary evap- ical studies have shown that myrrh has multiple activities oration under vacuum at 55°C. Finally, a semi dry mass of (effects), including anti-inflammatory and antimicrobial about 50 g was obtained and used in the experiment. [11, 12]. However, the mechanism is not fully understood The UHPLC-TQ/MS method was applied for determin- for frankincense and myrrh, which are used as a pair of herbs ing the components of WFM as follows: Chromatographic to relieve pain sensation. Although several elements are analysis was performed on a Waters Acquity UHPLC system thought to be the key mechanisms—including reactive oxygen (Waters, Corp., Milford, MA, USA), consisting of a binary species and inflammatory cytokines for their antinociceptive pump solvent management system, an online degasser, and ff ™ e ect, the precise molecular mechanisms are still obscure [13]. an autosampler. An Acquity UPLC BEH C18 column The transient receptor potential vanilloid 1 (TRPV1) is a (2.1 mm × 50 mm, 1.7 μm) was employed, and the column nonselective cation channel involved in the detection and temperature was maintained at 30°C. The mobile phase was transduction of nociceptive stimulus [14]. Upregulation of composed of A (acetonitrile) and B (0.1% formic acid) using TRPV1 transcription can be induced by inflammation and a gradient elution of 10% A at 0-1 min, 5% A at 1–9 min, and − nerve damage. Modulating of TRPV1 activity is considered 10% A at 9-10 min with a flow rate set at 0.4 ml·min 1. an effective strategy in treating inflammatory and neuro- The sample injection volume was 2 μl. The ESI source pathic pain conditions [15, 16]. Hence, TRPV1 has become was set in both positive and negative ionization mode. a promising target for screening analgesics via either blocking The scanning mode was set multiple reaction monitoring the function of the receptor or eliminating the nociceptor by (MRM) mode, and the range of selected monitor ion was utilizing a high dose of agonists [17–19]. m/z 100–m/z 1000. The TQ mass spectrometer was oper- In China, formula is commonly used in pain treatment. ated with a capillary voltage of 3.5 kV, a sampling cone volt- The main herb pair is recognized to be the most important age of 35 V, and a capillary temperature of 275°C. The part of the formula. Frankincense and myrrh as an herb pair Helium gas flow was at 35 arb, and the auxiliary gas flow rate has shown promising effects in pain relief. It is possible that was at 15 arb. All of the data acquisition and analyses of data they might have the potential of alleviating neuropathic pain were controlled by Waters MassLynx v4.1 software. The cone by modulating TRPV1. However, there is almost no litera- voltage and collision energy optimized for each analyte and ture report on this pair of herb to relieve neuropathic pain selected values are given in Table 1. by regulating TRPV1. Here, we obtained WFM from frankin- cense and myrrh in boiled water and verified some effective 2.2. Animals. All experiments were performed under proto- components by UHPLC-TQ/MS assay. A CCI mouse model cols approved by the Animal Care and Use Committee of was then conducted to elucidate the modulating effect of the Nanjing University of Chinese Medicine. All mice used WFM on TRPV1, which achieved the pain relief effect. Fur- in the behavioral tests were 8- to 10-week old males in a thermore, we checked the inhibition effect of WFM on the C57Bl/6 background (WT mice). Tested animals were expression, sensitivity of TRPV1. housed, and behavior experiments were performed in a con- trolled environment of 20–24°C, humidity of 45–65%, and 2. Materials and Methods with a 12-hour day/night cycle. 2.1. WFM Extraction and UHPLC-TQ/MS Assay. The 2.3. CCI Model and Treatment. Unilateral CCI surgery was frankincense and myrrh were purchased from the Jiangsu performed in mice under chloral hydrate anesthesia (50 mg/ Traditional Chinese Medical Hospital (Nanjing, China), kg, i.p.). Briefly, after skin preparation and iodine complex identified and authenticated by Dr. Shulan Su in the College disinfection, the skin was incised and muscles were bluntly of Pharmacy, Nanjing University of Chinese Medicine. separated. The right sciatic nerve was found at the mid- Chemical standards including β-boswellic acid, 3α-acetoxy- thigh level. Then two ligations with gut were performed tirucall-7,24-dien-21-oic acid, 3-aectyl-11-keto-β-boswellic loosely on the nerve, each spaced 1 mm apart. Mice in the acid, 3-keto-tirucall-8,24-dien-21-oic acid, and abietic acid sham group received the same procedure without sciatic were separated and identified in previous studies. The dry nerve hypodesmus. Seventy two male mice were randomly herb of frankincense (100 g) and myrrh (100 g) were divided into six groups (n = 12 per group) based on the Neural Plasticity 3 treatment, naïve + vehicle (distilled water), sham + vehicle, procedure in accordance with the manufacture’s protocols.