title: A BOLD-fMRI study of cerebral activation induced by injection of algesic chemical substances into the anesthetized rat forepaw.
abstract: This study was performed to examine whether the brain activities induced by noxious algesic chemical substances in anesthetized animals could be detected by blood oxygen-level-dependent functional magnetic resonance imaging (BOLD-fMRI). Multislice gradient echo images of the primary somatosensory cortex were obtained using a 7.05 T superconducting system and a one-turned surface coil centered over the primary somatosensory cortex of the 1.0%-isoflurane-anesthetized rat. The Z-score t-map of BOLD signals and its time-course analysis revealed that subcutaneous injection of formalin into the left forepaw immediately induced an early response in the contralateral primary sensory cortex lasting for a few minutes, followed by a late response until 20 min after stimulation. In contrast, injection of capsaicin into the left forepaw evoked only the early response. Furthermore, pretreatment with morphine completely abolished these responses induced by the chemical algesic substances. Thus BOLD-fMRI is a useful method to analyze the brain activities of painful stimulation in anesthetized animals.
authors.affiliation: Laboratory of Radiation Biology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan. asanuma@vetmed.hokudai.ac.jp
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Asanuma
authors.forename: Hironobu
authors.initials: H
authors.lastname: Yasui
authors.forename: Masayasu
authors.initials: M
authors.lastname: Sato
authors.forename: Osamu
authors.initials: O
authors.lastname: Inanami
authors.forename: Mikinori
authors.initials: M
authors.lastname: Kuwabara
mesh_terms: D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005552:Forelimb; D005557:Formaldehyde / Q000494:pharmacology; D007530:Isoflurane / Q000494:pharmacology; D008279:Magnetic Resonance Imaging; D010146:Pain / Q000139:chemically induced* / Q000378:metabolism*; D010147:Pain Measurement / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D013003:Somatosensory Cortex / Q000502:physiology*; D013047:Specific Pathogen-Free Organisms; D013268:Stimulation, Chemical
chemical_list: D005557:Formaldehyde; D007530:Isoflurane; D002211:Capsaicin