Chronic carotid occlusion and sleep:

experimental model of ischemic stroke

 

Rutskova E.M.¹, Fesenko G.N.², Loginov V.V.³, Dorokhov V.B.³, Kovalzon V.M.²

¹Department of Higher Nervous Activity, Biological Faculty, Moscow State University; ²Severtsov Institute Ecology/Evolution and ³Institute Higher Nervous Activity/Neurophysiology, Academy of Sciences, Moscow, Russia

 

E-mail: Elizaveta Rutskova, li-za-za@yandex.ru

 

Classical morphological studies of the cerebral ischemia and hypoxia revealed not only degenerative but also restorative processes in the brain tissue, including proliferation of stem cells. On the other hand, early studies of Ian Oswald in 1960ties clearly demonstrated an important role of paradoxical sleep (PS) in brain tissue restoration. This shows that objective quantitative changes in natural sleep structure should be expected in those animals which undergo an experimental cerebral ischemia. The anticipated changes should probably due to activation of regenerative functions of the brain. To check the hypothesis, two series of experiments have been carried out: in adult male rats (i), and "aged" male rabbits (age 2-2,5 years) (ii). Animals preliminary implanted (under local or light chloral-hydrate anesthesia) with conventional electrodes for the EEG and EMG, were subjected (under deep chloral-hydrate anesthesia) to full permanent occlusion of either one (rabbits and the 1^st group of rats) or both (the 2^nd rat group) common carotid arteries. After this procedure, 30% of rats and  rabbits survived irrespective of whether it was a uni- or bilateral occlusion. (i) Polygraphic recording were undertaken in free-moving rats survived through these procedures, either during 3 hrs per day (9-12 a.m.) or during 24 hrs continuously, from the 1^st till 40^th day since occlusion. Comparing to the control groups, polygram analysis revealed a great increase in PS percentage on the 1^st and 2^nd day since occlusion, up to 20% from total recording time; subsequently, PS percentage gradually decreased and reached initial level of 2.5% by the 40^th day. Uni- and bilateral occlusion induced the same effects. Slow wave sleep (SWS) underwent less appreciable changes though the 1^st day since occlusion showed similar increase. (ii) Rabbits were exposed to continuous 24 hr polygraphic recording just before the occlusion (0 day, the control), and then on the 5^th, 9^th, 18^th and 24^th days after it. The gradual increase in PS and SWS percentage after occlusion has been seen: from 1.6% of PS and 31.5% of SWS at zero day to 4,5%  and 48% at the 18^th day, consequently. On the 24^th day both parameters began to decrease. The time-course of this increase in both SWS and PS was different for the dark and light periods of a day. The results strongly support a hypothesis of the paramount role of PS in cerebral tissue restoration. Supported by RHSF grant (N04-06-00242a) and Biological Department of the Russian Academy of Sciences Programme “Fundamental sciences contribution to Medicine”.

 

Хроническая каротидная окклюзия и сон: экспериментальная модель ишемического инсульта

 

Руцкова Е.М., Фесенко Г.Н., Логинов В.В., Дорохов В.Б., Ковальзон В.М.

 

Кафедра физиологии высшей нервной деятельности биологического факультета МГУ, Институт проблем экологии и эволюции им. А.Н.Северцова РАН,

Институт высшей нервной деятельности и нейрофизиологии РАН, Москва