Masaya Katagiri1, Koji Iida2, Kumatoshi Ishihara3, Dileep Nair4, Kana Harada5, Kota Kagawa6, Go Seyama7, Akira Hashizume8, Takashi Kuramoto9, Ryosuke Hanaya10, Kazunori Arita11, Kaoru Kurisu12. 1. Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan; Epilepsy Center, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan; Epilepsy Center, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH, 44195, USA. Electronic address: katagim@hiroshima-u.ac.jp. 2. Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan; Epilepsy Center, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan. Electronic address: iidak@hiroshima-u.ac.jp. 3. Laboratory of Neuropharmacology, Faculty of Pharmaceutical Sciences, Hiroshima International University, 5-1-1, Hirokoshingai, Kure, 737-0112, Japan. Electronic address: ishihara@hirokoku-u.ac.jp. 4. Epilepsy Center, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH, 44195, USA. Electronic address: naird@ccf.org. 5. Laboratory of Neuropharmacology, Faculty of Pharmaceutical Sciences, Hiroshima International University, 5-1-1, Hirokoshingai, Kure, 737-0112, Japan. Electronic address: haradak@hiroshima-u.ac.jp. 6. Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan; Epilepsy Center, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan. Electronic address: kotak.0801@miracle.ocn.ne.jp. 7. Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan; Epilepsy Center, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan. Electronic address: goseyama@hiroshima-u.ac.jp. 8. Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan; Epilepsy Center, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan. Electronic address: hashizume@jinyoukai.or.jp. 9. Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshida-Konoe cho, 606-8501, Kyoto, Japan. Electronic address: tkuramot@anim.med.kyoto-u.ac.jp. 10. Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1, Sakuragaoka, Kagoshima, 890-8520, Japan. Electronic address: hanaya@m2.kufm.kagoshima-u.ac.jp. 11. Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1, Sakuragaoka, Kagoshima, 890-8520, Japan. Electronic address: karita@m2.kufm.kagoshima-u.ac.jp. 12. Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan. Electronic address: kuka422@hiroshima-u.ac.jp.
Abstract
BACKGROUND: VNS showed time-dependent anti-seizure effect. However, the precise mechanism of VNS in acute and chronic anti-seizure effect has not been fully elucidated. Noda epileptic rat (NER) is genetic epilepsy model rat which exhibits spontaneous generalized tonic-clonic seizure (GTC) approximately once per 30 h and frequent dialeptic seizure (DS). We performed acute and chronic VNS on NER to focus on the acute and chronic anti-epileptic effect and neuronal activity change by VNS. METHODS: We performed acute VNS (2 h) on 22 NERs (VNS, n = 11, control, n = 11), then subsequently administered chronic (4 weeks) VNS on 10 of 22 NERs (VNS n = 5, control n = 5). We evaluated the acute and chronic anti-seizure effects of VNS on GTC and DS by behavioral and electroencephalographical observation (2 h every week). We carried out double immunofluorescence for biomarkers of short-term (c-Fos) and long-term (ΔFosB) neuronal activation to map regions in the brain that were activated by acute (VNS n = 6, control n = 6) or chronic VNS (VNS n = 5, control n = 5). Furthermore, we performed chronic VNS (4 w) on 12 NERs (VNS n = 6, control n = 6) with long-term observation (8 h a day, 5d per week) to obtain an adequate number of GTCs to elucidate the time dependent anti-epileptic effect on GTC. RESULTS: Acute VNS treatment reduced GTC seizure frequency and total duration of the DS. Chronic VNS resulted in a time-dependent reduction of DS frequency and duration. However, chronic VNS did not show time-dependent reduction of GTC frequency. There were significant c-Fos expressions in the central medial nucleus (CM), mediodorsal thalamic nucleus (MDM), locus coeruleus (LC), and nucleus of solitary tract (NTS) after acute VNS. And there were significant ΔFosB expressions in the lateral septal nucleus (LSV), medial septal nucleus (MSV), MDM, and pontine reticular nucleus caudal (PnC) after chronic VNS. Any decrease in frequency of GTCs by chronic VNS could not be confirmed even with long-term observation. CONCLUSION: We confirmed acute VNS significantly reduced the frequency of GTC and duration of DS. Chronic VNS decreased the frequency and duration of DS in a time-dependent manner. The brainstem and midline thalamus were activated after acute and chronic VNS. The forebrain was activated only after chronic VNS.
BACKGROUND: VNS showed time-dependent anti-seizure effect. However, the precise mechanism of VNS in acute and chronic anti-seizure effect has not been fully elucidated. Noda epilepticrat (NER) is genetic epilepsy model rat which exhibits spontaneous generalized tonic-clonic seizure (GTC) approximately once per 30 h and frequent dialeptic seizure (DS). We performed acute and chronic VNS on NER to focus on the acute and chronic anti-epileptic effect and neuronal activity change by VNS. METHODS: We performed acute VNS (2 h) on 22 NERs (VNS, n = 11, control, n = 11), then subsequently administered chronic (4 weeks) VNS on 10 of 22 NERs (VNS n = 5, control n = 5). We evaluated the acute and chronic anti-seizure effects of VNS on GTC and DS by behavioral and electroencephalographical observation (2 h every week). We carried out double immunofluorescence for biomarkers of short-term (c-Fos) and long-term (ΔFosB) neuronal activation to map regions in the brain that were activated by acute (VNS n = 6, control n = 6) or chronic VNS (VNS n = 5, control n = 5). Furthermore, we performed chronic VNS (4 w) on 12 NERs (VNS n = 6, control n = 6) with long-term observation (8 h a day, 5d per week) to obtain an adequate number of GTCs to elucidate the time dependent anti-epileptic effect on GTC. RESULTS: Acute VNS treatment reduced GTC seizure frequency and total duration of the DS. Chronic VNS resulted in a time-dependent reduction of DS frequency and duration. However, chronic VNS did not show time-dependent reduction of GTC frequency. There were significant c-Fos expressions in the central medial nucleus (CM), mediodorsal thalamic nucleus (MDM), locus coeruleus (LC), and nucleus of solitary tract (NTS) after acute VNS. And there were significant ΔFosB expressions in the lateral septal nucleus (LSV), medial septal nucleus (MSV), MDM, and pontine reticular nucleus caudal (PnC) after chronic VNS. Any decrease in frequency of GTCs by chronic VNS could not be confirmed even with long-term observation. CONCLUSION: We confirmed acute VNS significantly reduced the frequency of GTC and duration of DS. Chronic VNS decreased the frequency and duration of DS in a time-dependent manner. The brainstem and midline thalamus were activated after acute and chronic VNS. The forebrain was activated only after chronic VNS.