Claudia Cervantes-Durán1, Guadalupe C Vidal-Cantú2, Beatriz Godínez-Chaparro3, Vinicio Granados-Soto4. 1. División de Estudios de Posgrado de la Facultad de Ciencias Médicas y Biológicas "Dr. Ignacio Chávez", Morelia Michoacán, Mexico. 2. Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados (Cinvestav), Sede Sur, México, D.F., Mexico. 3. Departamento de Sistemas Biológicos, División de Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana-Xochimilco, México, D.F., Mexico. 4. Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados (Cinvestav), Sede Sur, México, D.F., Mexico. Electronic address: vgranados@prodigy.net.mx.
Abstract
BACKGROUND: The purpose of this study was to determine the role of spinal 5-HT2A, 5-HT2B and 5-HT2C receptors in the development and maintenance of formalin-induced long-lasting secondary allodynia and hyperalgesia in rats, as well as their expression in the dorsal root ganglia (DRG) during this process. METHODS: 0.5-1% formalin was used to produce long-lasting secondary allodynia and hyperalgesia in rats. Western blot was used to determine 5-HT2 receptors expression in DRG. RESULTS: Formalin (0.5-1%) injection produced long-lasting (1-12 days) secondary allodynia and hyperalgesia in both ipsilateral and contralateral hind paws. Intrathecal pre-treatment or post-treatment with the 5-HT2 receptor agonist, DOI (1-10nmol), increased 0.5% formalin-induced secondary allodynia and hyperalgesia in both paws. In contrast, intrathecal pre-treatment with the selective 5-HT2A (ketanserin 1-100nmol), 5-HT2B (RS 127445 1-100nmol) or 5-HT2C (RS 102221 1-100nmol) receptor antagonists prevented and reversed, respectively, 1% formalin-induced secondary allodynia and hyperalgesia in both paws. Likewise, the pronociceptive effect of DOI (10nmol) was blocked by ketanserin, RS 127445 or RS 102221 (0.01nmol). 5-HT2A/2B/2C receptors were expressed in DRG of naïve rats. Formalin injection (1%) increased bilaterally 5-HT2A/2B receptors expression in DRG. In contrast, formalin injection decreased 5-HT2C receptors expression bilaterally in DRG. CONCLUSION: Data suggest that spinal 5-HT2A/2B/2C receptors have pronociceptive effects and participate in the development and maintenance of formalin-induced long-lasting hypersensitivity. These receptors are expressed in DRG and their expression is modulated by formalin.
BACKGROUND: The purpose of this study was to determine the role of spinal 5-HT2A, 5-HT2B and 5-HT2C receptors in the development and maintenance of formalin-induced long-lasting secondary allodynia and hyperalgesia in rats, as well as their expression in the dorsal root ganglia (DRG) during this process. METHODS: 0.5-1% formalin was used to produce long-lasting secondary allodynia and hyperalgesia in rats. Western blot was used to determine 5-HT2 receptors expression in DRG. RESULTS:Formalin (0.5-1%) injection produced long-lasting (1-12 days) secondary allodynia and hyperalgesia in both ipsilateral and contralateral hind paws. Intrathecal pre-treatment or post-treatment with the 5-HT2 receptor agonist, DOI (1-10nmol), increased 0.5% formalin-induced secondary allodynia and hyperalgesia in both paws. In contrast, intrathecal pre-treatment with the selective 5-HT2A (ketanserin 1-100nmol), 5-HT2B (RS 127445 1-100nmol) or 5-HT2C (RS 102221 1-100nmol) receptor antagonists prevented and reversed, respectively, 1% formalin-induced secondary allodynia and hyperalgesia in both paws. Likewise, the pronociceptive effect of DOI (10nmol) was blocked by ketanserin, RS 127445 or RS 102221 (0.01nmol). 5-HT2A/2B/2C receptors were expressed in DRG of naïve rats. Formalin injection (1%) increased bilaterally 5-HT2A/2B receptors expression in DRG. In contrast, formalin injection decreased 5-HT2C receptors expression bilaterally in DRG. CONCLUSION: Data suggest that spinal 5-HT2A/2B/2C receptors have pronociceptive effects and participate in the development and maintenance of formalin-induced long-lasting hypersensitivity. These receptors are expressed in DRG and their expression is modulated by formalin.
Authors: Carmen De Caro; Roberto Russo; Carmen Avagliano; Claudia Cristiano; Antonio Calignano; Andrea Aramini; Gianluca Bianchini; Marcello Allegretti; Laura Brandolini Journal: Br J Pharmacol Date: 2018-04-14 Impact factor: 8.739
Authors: Mariama Salihu; Gaber El-Saber Batiha; Keneth Iceland Kasozi; George D Zouganelis; Souty M Z Sharkawi; Eman Ibrahim Ahmed; Ibe Michael Usman; Halima Nalugo; Juma J Ochieng; Ibrahim Ssengendo; Olatayo Segun Okeniran; Theophilus Pius; Kyobe Ronald Kimanje; Eric Simidi Kegoye; Ritah Kenganzi; Fred Ssempijja Journal: Toxicol Rep Date: 2022-03-29