167. The effect of des acyl ghrelin on cortical spreading depression
J. Yonekura, J. Hamada, E. Kitamura, K. Koizumi, R. Masuda, M. Fukuda, S. Maruyama and F. Sakai
Neurology, Kitasato University School of Medicine, Sagamihara, Japan
Objectives: Cortical spreading depression(CSD) is a short-lasting depolarization wave which moves across the cortex accompanied by changes in cellular activity and in cerebral blood flow (CBF). CSD has been discussed as a possible mechanism for the aura phase of migraine. We have recently shown that orexin-A inhibits CSD in rats (in preparation). It's generally known that des acyl ghrelin indirectly increases orexin concentration in the brain. In the present study, we investigated the influence of des acyl ghrelin on the CSD induced in the rats.
Methods: Fifteen male Splague-Dawley rats (350 to 450 g) (n = 9; intracerebroventricular injection, n = 6; intravenous injection) were anesthetized with α-chloralose and urethane, intubated, and ventilated mechanically. The right femoral artery was cannulated for measurement of blood pressure, and other physiological parameters were measured. CBF was continuously monitored by laser-Doppler flowmetry. The cortical DC-potential was measured by extracellular platinum electrode. The stainless tube with polyethylene resin was placed in the right lateral ventricle to administer des acyl ghrelin. Also, the right femoral vein was cannulated for intravenous administration of des acyl ghrelin. First, CSD was induced by dropping 3 μl of 1 M KCl on rat brain surface and DC-potential and CBF were measured continuously. Then, 2 μl of 100 pM of des acyl ghrelin in saline was injected in right lateral ventricle, and CSD was evaluated continuously. The mean value of CBF change was compared between pre and post injection. The average amplitude change of DC-potential was also evaluated in the same way. Also, the frequency of appearance of CSD was compared between pre and post injection. For statistical analysis, we used paired t-test.
Results: After the intracerebroventricular (i.c.v.) administration of des acyl ghrelin, the amplitude of DC potential was 26.5±4.9 m V (mean±s.e.m.) and there was no difference comparing with 28.4±4.1 mV of before injection. Also there was no significant difference in the mean change of CBF (before injection: 92.2%±9.1%, after injection of acyl ghrelin of i.c.v administration: 86.5%±11.5%). But there was a significant decrease in the frequency of CSD (before i.c.v. administration: 10±3.3, after the i.c.v. administration: 6.1±2.0) (P<0.001). After intravenous administration of des acyl ghrelin, the amplitude of DC potential was not changed (before: 16.7±0.9 mV, after: 14.7±1.4 mV). There was no difference between the mean change of CBF value (before: 80.3%±2.3%, after: 71.2±11.6%) by des acyl ghrelin intravenous administration (P<0.1). There was a significant decrease in the frequency of CSD (before i.v. administration: 8.2±1.1, after the administration: 6.5±0.7) (P<0.05). There was no difference in physiological parameters between pre and post administration of des acyl ghrelin.
Conclusions: Our study suggested that des acyl ghrelin inhibits frequency of CSD. CSD is known to occur during migraine aura. In the present study, it was suggested that des acyl ghrelin may give some influence on the pathogenetic mechanism of migraine aura. We have previously shown that orexin-A has some role in the regulation of CBF. It's suggested that des acyl ghrelin indirectly increase orexin concentrations in the central nervous system and inhibits the frequency of CSD. This is the first report that evaluated the influence of des acyl ghrelin on CSD.
540. Antimigraine effects of an L/N-type Ca2+ channel blocker cilnidipine in the rat
R. Masuda, J. Hamada, K. Koizumi, J. Yonekura, E. Kitamura and F. Sakai
Department of Neurology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
Objectives: Migraine is a recurrent neurovascular disorder characterized by throbbing headache associated with nausea, vomiting, photophobia and phonophobia. The pathogenesis of migraine is still unclear, but both of trigeminovascular system and cortical spreading depression (CSD) are thought to have some role on the pathogenesis of migraine. At present, some migraine preventive drugs such as valproate, topiramate, amitriptyline and propranol inhibit CSD in rat. On the other hand, cilnidipine is a Ca2+ channel blocker with suppressive effects on L- and N-type Ca2+ channels. It is known that N type Ca2+ channels are localized at the presynaptic terminals of the neurons and some L/N-type Ca2+ channel blocker have antinociceptive effect and neuroprotective effect. The aim of this study is to clarify the antimigraine effect of cilnidipine in two types of migraine model rat.
Methods: (For nasociliary nerve (NCN) stimulation model) 5 male Sprague-Dawley rats, weighing 350 to 500 g, were anesthetized with isoflurane, and ventilated mechanically with 30% O2. Parietal cortical blood flow (CoBF) was continuously monitored with the Laser-Doppler flowmeter. The NCN—a cerebrovascular branch of the trigeminal nerve in the rat—was approached from the orbit. NCN was stimulated electrically near its entrance to ethmoidal foramen through a bipolar platinum electrode with an electrical stimulator (2.3 V, 0.5 ms duration, 10 Hz, 30 sec stimulation). CoBF were measured during and after electrical stimulation of NCN under intraperitoneal injection of 2.0 ml saline (control) followed by cilnidipine, (100 μg/kg in 2.0 ml saline).
(For CSD model) A hydrogen electrode was placed in the open parietal cranial window to measure Direct current potential (DCP) after placement of Laser-Doppler flowmeter CSDs were triggered with an application of 1 M KCL solution with the volume of 3 μl through another open cranial window. DCP and CoBF were measured after application of KCL for 60 min under intraperitoneal injection of 2.0 ml saline followed by cilnidipine.
The CoBF data were analyzed by one-way ANOVA and Dunnett′s multiple comparisons and CSD data were analyzed by paired-t test.
Results: In NCS stimulation model, CoBF was maximally increased upon electrical NCN stimulation in control. This increase was significantly suppressed after the administration of cilnidipine (P<0.05). In CSD model, cilnidipine significantly attenuated the number of CSD from 6.2 to 5.0 (P<0.05).
Conclusions: Cilnidipine attenuated the blood flow increase upon NCS stimulation and number of CSD after KCl application. It is suggested that L/N-type Ca2+ channel blocker might have a potential of antimigraine prophylactic drug.
619. Orexin a attenuates vasodilatation by trigeminal stimulation
K. Koizumi1, R. Masuda1, M. Fukuda2, S. Tsukahara3, J. Yonekura1, S. Maruyama4, N. Kanazawa1, J. Hamada1 and F. Sakai1
1Neurology; 2Allied Health Sciences, Kitasato University, Sagamihara; 3Neurology, Sagamidai Hospital, Zama; 4Laboratory Animal Science, Kitasato University, Sagamihara, Japan
Introduction: The orexin has been studied for recent 10 years and reported that it has several physiological functions, sleep, feeding, nociception, autonomic system. And orexinergic fiber is known to project from neurons of lateral hypothalamus area (LH) to central nerves system, including PAG, dorsal raphe, locus coeruleus, spinal cord, which involve in the trigeminal pain transmission and pain control system in migraine attack. Clinically, migraine patients often experience that migraine could be induced either by lack of sleep or too much sleep, yet sleep may relieve headache. In migraine with aura patients, plasma orexin A level was decreased (1). Another in vivo study reported that orexin 1 receptor stimulation by orexin A inhibits neurogenic dural vasodilatation (2). Accordingly orexin system is likely to be involved in migraine pathogenesis. In order to elucidate the exact involvement of orexin system in the pathophysiology of migraine, we investigated the effect of orexin A administration on the activation of trigeminovascular system in rats.
Methods: Five male Sprague-Dawley rats, weighing 350 to 400 gram, were anesthetized with isoflurane, and ventilated mechanically with room air. Parietal cortical blood flow (CoBF) on the right side was continuously monitored with the Laser-Doppler flow meter system. The nasociliary nerve (NCN)—a cerebrovascular branch of the trigeminal nerve in the rat—was carefully approached from the orbit in the right side. The post-ganglionic nerves from the pterygopalatine ganglion were gently eliminated from the ethmoidal foramen (EF). NCN was stimulated electrically near its entrance to EF through a bipolar platinum electrode with an electrical stimulator (6 to 28 μA, 0.5 ms duration, 10 Hz, 30 secs stimulation). CoBF were measured during and after electrical stimulation of NCN under intravenous injection of 1.0 ml saline followed by orexin A (30 μg/kg in 1.0 ml saline).
Results: CoBF was significantly increased upon electrical NCN stimulation during 60 seconds from the initiation of stimulation in control state. This increase was suppressed after orexin A administration in 60 seconds from the stimulation. The amount of blood flow increase when orexin A was given was significantly less than the control data.
Conclusion: Orexin A attenuated the blood flow increase upon trigeminal nerve stimulation. It is hypothesized that orexin system palys some role on modulation of cerebral blood flow and orexinergic dysfunction induces vasodilatation in migraine attack.
963. Familial hemiplegic migraine is associated with increased habituation of evoked responses: a contrast with the common forms of migraine
J.M. Hansen1, M. Bolla2,3, D. Magis2, L.L. Thomsen4, V. de Pasqua2, M. Ashina1, J. Olesen1 and J. Schoenen2
1Danish Headache Center, Department of Neurology, Glostrup Hospital, University of Copenhagen, Glostrup, Copenhagen, Denmark; 2Headache Research Unit, Department of Neurology and Neurobiology Research Center CNCM, Liège University, Liège, Belgium; 3IRRCS C. Mondino, University of Pavia, Pavia, Italy; 4Danish Headache Center, Department of Pediatrics, Glostrup Hospital, University of Copenhagen, Glostrup, Copenhagen, Denmark
Objectives: Familial hemiplegic migraine (FHM) is a dominantly inherited subtype of migraine with aura and transient hemiplegia associated with several mutations in genes coding for neuronal ion channels. These mutations lead to neuronal hyperexcitability and decreased threshold for cortical spreading depression in transgenic animal models. FHM and the common forms of migraine are thought to belong to a spectrum of migraine phenotypes with similar pathophysiology. The common forms of migraine are characterised interictally by a habituation deficit of cortical and subcortical evoked responses, which has been attributed to neuronal dysexcitability.
The FHM genotype has been linked to neuronal hyper excitability, and we therefore tested the hypothesis that a similar abnormal habituation pattern would be found in FHM patients.
Methods: We included 9 FHM patients with known gene mutations and 7 healthy controls. To optimize recruitment, we used portable devices to record most subjects with their agreement at their own homes.
We recorded: Habituation of visual evoked potentials (VEP), auditory evoked potentials including intensity dependence (IDAP) and the nociception-specific blink reflex (nsBR).
Results: FHM patients had a more pronounced habituation during VEP (P = 0.025) and nsBR recordings (P = 0.023) than HV. There was no significant difference for IDAP, but the slope tended to be steeper in FHM.
Conclusion: Contrary to the common forms of migraine, FHM patients are not characterized by a deficient, but rather by an increased habituation in cortical/brain stem evoked activities. These results suggest that there may be some striking pathophysiological differences between FHM and the common forms of migraine, as far as central neuronal processing is concerned.
1055. Novel optical imaging reveals changes in cerebral blood flow and deoxy-hemoglobin in response to abnormal trigeminal activation
N. Li, K. Murari, A. Rege, P. Miao, X. Jia and N. Thakor
Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
Objectives: A strong association between migraine headache and vascular malfunction has been shown in literature. Active cerebral vasodilation is believed to be a major factor in inducing migraine headaches. However the relation is unclear and a thorough study is required to understand the disturbance of cerebrovascular activity. Blood vessel size reflects the local response in vessels, blood flow reflects both local and global responses and oxy- and deoxy-hemoglobin concentration reflects the metabolism response. Using a revised laser speckle imaging system, we obtained the information on both deoxy-hemoglobin concentration and blood flow changes simultaneously using a single laser source. The responses in arterioles and venules were distinguished and analyzed separately.
Methods: In the experiment, peripheral trigeminal nerve fibers of adult female Wistar rats were electrically stimulated. A laser source at 632 nm was used to illuminate the region of interest through a thinned skull preparation. Without using any contrast agents, laser light reflectance images were acquired from the brain of a rat fixed in a stereotactic frame. Responses in deoxy-hemoglobin concentration were obtained by analyzing the reflectance images. Laser speckle contrast images of the same area were obtained by analyzing a stack of raw speckle images. Blood flow responses were also analyzed through the speckle contrast images Arterioles and venules were distinguished using a combination of speckle contrast and white light reflectance images.
Results: Eight animals were studied with similar ROIs in corresponding pairs of arterioles and venules being selected for comparison. The results showed that for each pair, hemodynamic changes were greater in the venules than in the arterioles. The venules showed a 71%±6% mean peak increase in the blood velocity, versus a 62%±3% mean peak increase in case of arterioles. The two main cortical venules close to the stimulation site showed a remarkable increase in deoxy-hemoglobin concentration, and the pattern of the increase is propagating from distal to proximal point of the venule branch. On the other hand arterioles did not show any such obvious deoxy-hemoglobin concentration increase as venules.
Conclusions: In this study we exploit the high temporal-spatial resolution revised laser speckle imaging. This is the first study to optically characterize responses of both deoxy-hemoglobin concentration and blood flow simultaneously. The instrumentation is very simple, no contrast agents are needed, and no post registration is needed for the two imaging modalities: reflectance image and contrast image. The study of both deoxy-hemoglobin concentration and blood flow simultaneously should provide a deeper understanding of migraine and other neurovascular studies.
