Functional MRI-based identification of brain regions activated by mechanical noxious stimulation and modulatory effect of remifentanil in cats. (October 2017)

• Record Type: Journal Article
• Authors: Nagakubo, Dai; Hamamoto, Yuji; Hasegawa, Daisuke; Kamata, Masatoshi; Iizuka, Tomoya; Muta, Kanako; Fujita, Naoki; Nakagawa, Takayuki; Nishimura, Ryohei
• Is Part Of: Research in veterinary science. Volume 114(2017)
• Page Start: 444
• Page End: 449
• Publication Date: 2017-10
• Subjects: Analgesia -- Brain -- Cat -- fMRI -- Remifentanil; Veterinary medicine -- Periodicals; Veterinary Medicine -- Periodicals; Médecine vétérinaire -- Périodiques; Médecine vétérinaire -- Recherche -- Périodiques; Diergeneeskunde; 636.089
• DOI: 10.1016/j.rvsc.2017.07.024
• Languages: English
• ISSNs: 0034-5288

Abstract

Abstract: This study was conducted to identify the brain regions corresponding to mechanical noxious stimulation in cats using functional magnetic resonance imaging (fMRI) and to investigate the modulatory effect of remifentanil on the activation of these regions. Six healthy cats were anesthetized using a constant-rate infusion of alfaxalone. Cats were allocated to one of three treatment groups: remifentanil 0 (saline), 0.25, and 0.5 μg/kg/min. A 3.0-T MRI unit was used to collect fMRI data. During the fMRI scanning, mechanical noxious stimulation was applied by tail clamping. The brain regions activated by the stimulation were identified based on blood oxygenation level-dependent (BOLD) responses. The modulatory effects of remifentanil were evaluated using a region of interest (ROI) analysis comparing signal changes in each brain region. Increased activity from noxious stimulation was observed in the somatosensory area (the postcruciatus gyrus, the anterior part of the marginalis gyrus, and the anterior part of the ectomarginalis gyrus), the parietal association area (the middle part of the marginalis gyrus and the middle part of the ectomarginalis gyrus), the cingulate cortex, the hippocampus, and the cerebellum. The results of the ROI analysis indicated that activations in the somatosensory area, the cingulate cortex, the hippocampus, and the cerebellum were significantly modulated ( P < 0.05) by remifentanil. In cats, activation patterns evoked by mechanical noxious stimulation were observed in several brain regions thought to be involved in various aspects of pain processing, including sensory discrimination and integration, affect, and motor response. These brain responses were modulated by remifentanil. Highlights: The brain regions corresponding to mechanical noxious stimulation were identified using functional MRI (fMRI) in cats. Increased brain activity from mechanical noxious stimulation was observed in some areas such as the somatosensory area. Pain-related activation in the somatosensory area was significantly modulated by remifentanil.