Antinociceptive Effect of Lodenafil Carbonate in Rodent Models of Inflammatory Pain and Spinal Nerve Ligation-Induced Neuropathic Pain
Received 11 December 2020
Accepted for publication 16 February 2021
Published 30 March 2021 Volume 2021:14 Pages 857—866
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 3
Editor who approved publication: Professor E. Alfonso Romero-Sandoval
Marcio Carneiro Vieira,1,2 Fernanda Bezerra de Mello Monte,3 Bruno Eduardo Dematte,3 Tadeu Lima Montagnoli,3 Guilherme Carneiro Montes,3 Jaqueline Soares da Silva,3 Rosalia Mendez-Otero,4 Margarete Manhães Trachez,3 Roberto Takashi Sudo,1,3 Gisele Zapata-Sudo1,3
1Programa de Pós-graduação em Ciências Cirúrgicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-902, Brazil; 2Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-902, Brazil; 3Programa de Pesquisa em Desenvolvimento de Fármacos, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-902, Brazil; 4Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio De Janeiro, 21941-902, Brazil
Correspondence: Gisele Zapata-Sudo
Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-902, Brazil
Tel +55 21 3938 6505
Email [email protected]
Introduction: New therapeutic alternatives for pain relief include the use of phosphodiesterase-5 (PDE5) inhibitors, which could prevent the transmission of painful stimuli by neuron hyperpolarization via nitric oxide (NO)/cyclic 3ʹ,5ʹ-guanosine monophosphate (cGMP) pathway. The present work investigated the antinociceptive activity of a new PDE5 inhibitor, lodenafil carbonate, in inflammatory and neuropathic pain models.
Methods and Results: Although no effect was detected on neurogenic phase of formalin test in mice, oral administration of lodenafil carbonate dose-dependently reduced reactivity in the inflammatory phase (200.6 ± 39.1 to 81.9 ± 18.8 s at 10 μmol/kg, p= 0.0172) and this effect was totally blocked by NO synthase inhibitor, L-Nω-nitroarginine methyl ester (L-NAME). Lodenafil carbonate (10 μmol/kg p.o.) significantly reduced nociceptive response as demonstrated by increased paw withdrawal latency to thermal stimulus (from 6.8 ± 0.7 to 10.6 ± 1.3 s, p= 0.0006) and paw withdrawal threshold to compressive force (from 188.0 ± 14.0 to 252.5 ± 5.3 g, p< 0.0001) in carrageenan-induced paw inflammation model. In a spinal nerve ligation-induced neuropathic pain, oral lodenafil carbonate (10 μmol/kg) also reversed thermal hyperalgesia and mechanical allodynia by increasing paw withdrawal latency from 17.9 ± 1.5 to 22.8 ± 1.9 s (p= 0.0062) and paw withdrawal threshold from 26.0 ± 2.8 to 41.4 ± 2.9 g (p= 0.0196). These effects were reinforced by the reduced GFAP (3.4 ± 0.5 to 1.4 ± 0.3%, p= 0.0253) and TNF-alpha (1.1 ± 0.1 to 0.4 ± 0.1%, p= 0.0111) stained area densities as detected by immunofluorescence in ipsilateral dorsal horns.
Conclusion: Lodenafil carbonate demonstrates important analgesic activity by promoting presynaptic hyperpolarization and preventing neuroplastic changes, which may perpetuate chronic pain, thus representing a potential treatment for neuropathic pain.
Keywords: neuropathic pain, inflammatory pain, phosphodiesterase 5 inhibitor, lodenafil carbonate, spinal cord, GFAP
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