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Watanuki Y, Yajima S, Sashide Y, Takeda M. Effect of theanine on the hyperexcitability of trigeminal secondary nociceptive neurons following orofacial inflammation in rats. Eur J Oral Sci 2024; 132:e12961. [PMID: 37984410 DOI: 10.1111/eos.12961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 11/06/2023] [Indexed: 11/22/2023]
Abstract
The present in vivo study investigated whether systemic administration of theanine attenuates the inflammation-induced hyperexcitability of trigeminal spinal nucleus caudalis (SpVc) neurons associated with hyperalgesia. Complete Freund's adjuvant (CFA) was injected into the whisker pads of 24 rats to induce inflammation, and then mechanical stimulation was applied to the orofacial area to assess the threshold of escape. The mechanical threshold was statistically significantly lower in CFA-inflamed rats compared to uninjected naïve rats, and this lowered threshold returned to control levels after 2 days of theanine administration. The mean discharge frequency of SpVc wide-dynamic range (WDR) neurons to mechanical stimuli in anesthetized CFA-inflamed rats was statistically significantly lower after two days of theanine administration. In addition, the increased mean spontaneous discharge of SpVc WDR neurons in CFA-inflamed rats statistically significantly decreased after theanine administration. Similarly, theanine restored the expanded mean receptive field size in CFA-inflamed rats to control levels. Taken together, these results suggest that administration of theanine attenuates inflammatory hyperalgesia associated with hyperexcitability of nociceptive SpVc WDR neurons. These findings support the potential of theanine as a therapeutic agent in complementary alternative medicine strategies to prevent inflammatory hyperalgesia.
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Affiliation(s)
- Yui Watanuki
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Sagamihara, Kanagawa, Japan
| | - Sora Yajima
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Sagamihara, Kanagawa, Japan
| | - Yukito Sashide
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Sagamihara, Kanagawa, Japan
| | - Mamoru Takeda
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Sagamihara, Kanagawa, Japan
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Itou H, Toyota R, Takeda M. Phytochemical quercetin alleviates hyperexcitability of trigeminal nociceptive neurons associated with inflammatory hyperalgesia comparable to NSAIDs. Mol Pain 2022; 18:17448069221108971. [PMID: 35734996 PMCID: PMC9234920 DOI: 10.1177/17448069221108971] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Quercetin is a flavonoid that is widely found in fruits and vegetables. Quercetin inhibits cyclooxygenase-2 and modulates voltage-gated ion channels, however, its effect on nociceptive neuron-associated inflammatory hyperalgesia remains unknown. The present study investigated under in vivo conditions whether systemic administration of quercetin attenuates the inflammation-induced hyperexcitability of trigeminal spinal nucleus caudalis (SpVc) neurons associated with mechanical hyperalgesia and compared its effect to the non-steroidal anti-inflammatory drug, diclofenac. Complete Freund's adjuvant was injected into the whisker pads of rats to induce inflammation, and then mechanical stimulation was applied to the orofacial area to assess the threshold of escape. The mechanical threshold was significantly lower in inflamed rats compared to uninjected naïve rats, and this lowered threshold returned to control levels 2 days after administration of quercetin or diclofenac. The mean discharge frequency of SpVc wide-dynamic range (WDR) neurons to both non-noxious and noxious mechanical stimuli in inflamed rats was significantly decreased after quercetin or diclofenac administration under combination of three anesthetic agents (medetomidine, midazolam and butorphanol). In addition, the increased mean spontaneous discharge of SpVc WDR neurons in inflamed rats significantly decreased after quercetin or diclofenac administration. Similarly, quercetin or diclofenac restored the expanded mean receptive field size in inflamed rats to control levels. In this study, the combination of three anesthetic agents did not result in any obvious "noxious pinch-evoked after discharges" in CFA inflamed day 2 rat as described previously in pentobarbital-anesthetized rats. Together, these results suggest that administration of quercetin attenuates inflammatory hyperalgesia associated with hyperexcitability of nociceptive SpVc WDR neurons via inhibition of the peripheral cyclooxygenase-2 signaling cascade and voltage-gated ion channels. These findings support the proposed potential of quercetin as a therapeutic agent in complementary alternative medicine strategies for preventing trigeminal inflammatory mechanical hyperalgesia.
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Affiliation(s)
- Haruka Itou
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Kanagawa, Japan
| | - Ryou Toyota
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Kanagawa, Japan
| | - Mamoru Takeda
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Kanagawa, Japan
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Yamaguchi M, Kinouchi R, Morizumi S, Shimazu Y, Takeda M. Local administration of genistein as a local anesthetic agent inhibits the trigeminal nociceptive neuronal activity in rats. Brain Res Bull 2021; 172:120-128. [PMID: 33895269 DOI: 10.1016/j.brainresbull.2021.04.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/13/2021] [Accepted: 04/19/2021] [Indexed: 10/21/2022]
Abstract
A modulatory role has been reported for the isoflavone, genistein, on voltage-gated Na+ channels in the trigeminal ganglion in vitro. However, the acute effects of genistein in vivo, particularly on nociceptive transmission in the trigeminal system, remain to be determined. The aim of the present study was to examine whether acute local genistein administration to rats attenuates the excitability of wide-dynamic range (WDR) spinal trigeminal nucleus caudalis (SpVc) neurons in response to nociceptive and non-nociceptive mechanical stimulation in vivo. Extracellular single unit recordings were made from SpVc WDR neurons in response to orofacial non-noxious and noxious mechanical stimulation of pentobarbital-anesthetized rats. The effects of local administration of genistein, lidocaine, and lidocaine with genistein to the receptive field on the discharge frequency of SpVc neurons were evaluated. The mean firing frequency of SpVc WDR neurons in response to both non-noxious and noxious mechanical stimuli was significantly and dose-dependently (0.1-10 mM) inhibited by genistein, and maximum inhibition of the discharge frequency of both non-noxious and noxious mechanical stimuli was seen within 10 min. The inhibitory effect of genistein lasted for 20 min and was reversible. No significant difference was seen between the relative magnitude of inhibition by genistein on the SpVc WDR neuronal discharge frequency for noxious and non-noxious stimulation. The mean magnitude of inhibition by genistein (10 mM) on SpVc neuronal discharge frequency was almost equal to that of the local anesthetic, 1 % lidocaine (37 mM). Local injection of half-dose of lidocaine replaced the half-dose of genistein. These results suggest that local injection of genistein into the peripheral receptive field suppresses the excitability of SpVc neurons, possibly via inhibition of voltage-gated Na+ channels in the nociceptive nerve terminals of trigeminal ganglion. Therefore, administration of genistein as a local anesthetic may provide relief from trigeminal nociceptive pain without side effects, thus contributing to the area of complementary and alternative medicines.
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Affiliation(s)
- Manaka Yamaguchi
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan
| | - Rina Kinouchi
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan
| | - Shiori Morizumi
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan
| | - Yoshihito Shimazu
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan
| | - Mamoru Takeda
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan.
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Xie X, Cong L, Liu S, Xiang L, Fu X. Genistein alleviates chronic vascular inflammatory response via the miR‑21/NF‑κB p65 axis in lipopolysaccharide‑treated mice. Mol Med Rep 2021; 23:192. [PMID: 33495831 PMCID: PMC7809901 DOI: 10.3892/mmr.2021.11831] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 12/09/2020] [Indexed: 12/24/2022] Open
Abstract
Chronic vascular inflammatory response is an important pathological basis of cardiovascular disease. Genistein (GEN), a natural compound, exhibits anti‑inflammatory effects. The aim of the present study was to investigate the effects of GEN on lipopolysaccharide (LPS)‑induced chronic vascular inflammatory response in mice and explore the underlying anti‑inflammatory mechanisms. C57BL/6 mice were fed with a high‑fat diet combined with intraperitoneal injection of LPS to induce chronic vascular inflammation. The expression levels of TNF‑α, IL‑6 and microRNA (miR)‑21 in the vasculature were detected via reverse transcription‑quantitative (RT‑q)PCR. The protein levels of inducible nitric oxide synthase (iNOS) and NF‑κB p65 were detected via western blotting. NF‑κB p65 was also analyzed via immunohistochemistry and immunofluorescence (IF). In addition, after transfection with miR‑21 mimic or inhibitor for 24 h, vascular endothelial cells (VECs) were treated with GEN and LPS. RT‑qPCR and western blot analyses were performed to detect the expression of TNF‑α, IL‑6, miR‑21 and iNOS, and the protein levels of iNOS and NF‑κB p65, respectively. IF was used to measure NF‑κB p65 nuclear translocation. The results revealed that GEN significantly decreased the expression of inflammation‑associated vascular factors in LPS‑treated C57BL/6 mice, including TNF‑α, IL‑6, iNOS, NF‑κB p65 and miR‑21. Furthermore, miR‑21 antagomir enhanced the anti‑inflammatory effects of GEN. In LPS‑induced VECs, miR‑21 mimic increased inflammation‑associated factor expression and attenuated the anti‑inflammatory effects of GEN, whereas miR‑21 inhibitor induced opposing effects. Therefore, the results of the present study suggested that GEN inhibited chronic vascular inflammatory response in mice, which may be associated with the inhibition of VEC inflammatory injury via the miR‑21/NF‑κB p65 pathway.
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Affiliation(s)
- Xiaolin Xie
- Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, Hunan Normal University, Changsha, Hunan 410013, P.R. China
- Department of Basic Medicine, School of Medicine, Hunan Normal University, Changsha, Hunan 410013, P.R. China
| | - Li Cong
- Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, Hunan Normal University, Changsha, Hunan 410013, P.R. China
| | - Sujuan Liu
- Department of Basic Medicine, School of Medicine, Hunan Normal University, Changsha, Hunan 410013, P.R. China
| | - Liping Xiang
- Department of Pathology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Xiaohua Fu
- Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, Hunan Normal University, Changsha, Hunan 410013, P.R. China
- Department of Basic Medicine, School of Medicine, Hunan Normal University, Changsha, Hunan 410013, P.R. China
- Correspondence to: Professor Xiaohua Fu, Department of Basic Medicine, School of Medicine, Hunan Normal University, 371 Tongzipo Road, Changsha, Hunan 410013, P.R. China, E-mail:
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Okubo N, Ishikawa H, Sano R, Shimazu Y, Takeda M. Effect of resveratrol on the hyperexcitability of nociceptive neurons associated with ectopic hyperalgesia induced by experimental tooth movement. Eur J Oral Sci 2020; 128:275-283. [PMID: 33856731 DOI: 10.1111/eos.12722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2020] [Indexed: 11/28/2022]
Abstract
The present study investigated whether, under in vivo conditions, systemic administration of resveratrol attenuates the experimental tooth movement-induced ectopic hyperalgesia associated with hyperexcitability of nociceptive trigeminal spinal nucleus caudalis (SpVc) neurons. The threshold of escape from mechanical stimulation applied to the ipsilateral whisker pad in rats exposed to experimental tooth movement was significantly lower than seen in control rats from day 1 to 3 following movement of the right maxillary first molar tooth. The lowered mechanical threshold in the rats exposed to experimental tooth movement had almost returned to the level of sham-treated naïve rats at day 3 following administration of resveratrol. The mean mechanical threshold of nociceptive SpVc neurons was significantly lower after experimental tooth movement but the lower threshold could be reversed by administration of resveratrol. The higher discharge frequency of nociceptive SpVc neurons for noxious mechanical stimuli observed in rats exposed to experimental tooth movement was statistically significantly lower following resveratrol administration. These results suggest that resveratrol attenuates experimental tooth movement-induced mechanical ectopic hyperalgesia via suppression of peripheral and/or central sensitization. These findings support the idea that resveratrol, a complementary alternative medicine, is a potential therapeutic agent for the prevention of experimental tooth movement-induced ectopic hyperalgesia.
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Affiliation(s)
- Nao Okubo
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Sagamihara, Japan
| | - Haruna Ishikawa
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Sagamihara, Japan
| | - Rena Sano
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Sagamihara, Japan
| | - Yoshihito Shimazu
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Sagamihara, Japan
| | - Mamoru Takeda
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Sagamihara, Japan
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