Department of Clinical and Community Pharmacy, Faculty of Pharmacy, Universitas Jember, Jember, 68121, Indonesia.
Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia.
J Ethnopharmacol. 2020 Mar 1;249:112396. doi: 10.1016/j.jep.2019.112396. Epub 2019 Nov 16.
In silico data revealed that the active compound of ginger (Zingiber officinale Roscoe), 6-shogaol, has strong affinity toward transient receptor potential vanilloid-1 (TRPV-1). TRPV-1 is expressed in nervous tissue and pancreatic β-cells. Prolonged induction of TRPV-1 is related to the expression of N-methyl-D-aspartate receptor subunit 2B (NMDAR2B). However, there are no data on TRPV-1 and NMDAR2B expressions in nervous tissue after 6-shogaol or ginger extract treatment nor pancreatic islet morphology and insulin expression in mice model of painful diabetic neuropathy (PDN).
This study aimed to investigate the mechanism of action of ginger extract and its compound, 6-shogaol, on pancreatic islets as well as on expressions of TRPV-1 and NMDAR2B in the spinal cord of streptozotocin (STZ)-induced mice model of PDN.
Sixty-four 5-6 weeks old male-Balb/C mice were induced with 110 mg/kgBW STZ i.p., while eight mice were used as control group. Mice with blood glucose level ≥200 mg/d, that suffered hyperalgesia and allodynia were classified as PDN mice. Hot plate and von Frey filament tests were performed once a week until termination. At day 28 after considered as PDN, ginger extracts, 6-shogaol or gabapentin as control treatment were given once daily for 21 days until day 49, except for the diabetic control group. Upon termination, mice' pancreas were fixed, processed as paraffin sections and stained with hematoxylin eosin. Total volume of pancreatic islets was estimated using Cavalieri methods. Immunohistochemistry on pancreatic sections were performed to observe insulin expression. mRNA was extracted from lumbar segments of the spinal cord, followed by cDNA preparation and quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) to measure the expressions of TRPV1 and NMDAR2B. The mean differences between groups were analyzed using one-way analysis of variance (ANOVA) with p < 0.05 considered statistically significant.
Ginger extracts and 6-shogaol alleviated hyperalgesia and allodynia. The groups that received ginger extract 400 mg/kgBW or 6-shogaol 15 mg/kgBW had significantly lower TRPV1 and NMDAR2B expressions in the spinal cord compared to the diabetic control group (p < 0.001; p < 0.05). However, no differences in volume of pancreatic islets (p > 0.05) nor insulin expression were observed in all PDN groups.
Ginger extracts and its compound, 6-shogaol, reduced pain symptoms in PDN via its effect on decreasing TRPV1 and NMDAR2B expressions in the spinal cord, with very limited effect on pancreatic islets.
计算机数据显示，生姜（Zingiber officinale Roscoe）的活性化合物 6-姜酚对瞬时受体电位香草酸 1（TRPV-1）具有很强的亲和力。TRPV-1 表达于神经组织和胰岛β细胞中。TRPV-1 的持续诱导与 N-甲基-D-天冬氨酸受体亚基 2B（NMDAR2B）的表达有关。然而，目前尚无关于 6-姜酚或生姜提取物处理后神经组织中 TRPV-1 和 NMDAR2B 表达以及糖尿病性周围神经痛（PDN）小鼠模型中胰岛形态和胰岛素表达的相关数据。
本研究旨在探讨生姜提取物及其化合物 6-姜酚对胰岛的作用机制，以及对链脲佐菌素（STZ）诱导的 PDN 小鼠模型脊髓中 TRPV-1 和 NMDAR2B 表达的影响。
64 只 5-6 周龄雄性 Balb/C 小鼠腹腔注射 110mg/kgBW 的 STZ 诱导 PDN，8 只小鼠作为对照组。血糖水平≥200mg/d、出现痛觉过敏和感觉异常的小鼠被归类为 PDN 小鼠。每周进行一次热板和 von Frey 细丝测试，直到实验结束。在被认为患有 PDN 的第 28 天，给予生姜提取物、6-姜酚或加巴喷丁作为对照治疗，每天一次，共 21 天，直到第 49 天，糖尿病对照组除外。实验结束时，将小鼠的胰腺固定，制成石蜡切片，用苏木精-伊红染色。使用 Cavalieri 方法估计胰岛的总体积。对胰腺切片进行免疫组织化学染色，观察胰岛素表达。从脊髓腰段提取 mRNA，制备 cDNA，并进行实时定量聚合酶链反应（qRT-PCR），以测量 TRPV1 和 NMDAR2B 的表达。采用单因素方差分析（ANOVA）分析组间差异，p<0.05 为统计学显著差异。
生姜提取物和 6-姜酚缓解了痛觉过敏和感觉异常。接受生姜提取物 400mg/kgBW 或 6-姜酚 15mg/kgBW 治疗的组与糖尿病对照组相比，脊髓中 TRPV1 和 NMDAR2B 的表达显著降低（p<0.001;p<0.05）。然而，所有 PDN 组的胰岛体积（p>0.05）或胰岛素表达均无差异。
生姜提取物及其化合物 6-姜酚通过降低脊髓中 TRPV1 和 NMDAR2B 的表达来减轻 PDN 中的疼痛症状，对胰岛的作用非常有限。
