[Effect of afobazole on brain-ischemia-induced anxiety in rats].

The ability of afobazole, a selective anxiolytic to prevent the brain local ischemia-induced anxiety has been studied in experiments on rats. It is established that middle cerebral artery occlusion (MCAO) is accompanied by the development of anxiety, the degree of which increases with the duration of occlusion. Afobazole in a doze of 1 mg/kg administrated during 6 days after MCAO prevents the development of anxiety. The effect is manifested by positive changes in the parameters describing the behavior of animals in elevated plus maze test. No tolerance to the drug is developed during continuous afobazole injection within 12 days after MCAO. The experimental data indicate that the well-known anxiolytic action of afobazole is also well pronounced under the conditions of a local cerebrtal ischemia.

[Tropoxin and cerebrovascular effects of serotonin]. / Tropoxin i tserebrovaskuliarnye éffekty serotonina.

The effect of serotonin on the brain blood supply was studied in rats before and after ischemic damage. The ischemic damage, induced by ligation of the middle meningeal artery, markedly enhanced the constrictor effect of serotonin on the brain vessels. Tropoxin, a 5HT2 receptor blocker, completely eliminated these cerebrovascular effects of serotonin.

[The different vascular reactions of intact and ischemic brain to adrenergic exposures]. / Razlichnye reaktsii sosudov intaktnogo i ishemizirovannogo mozga na adrenergicheskie vozdeistviia.

Electrical stimulation of the cervical sympathetic ganglion and norepinephrine increase the tonus of the cerebral vessels in intact animals. This points to the significant role of adrenergic mechanisms in regulation of blood circulation in the brain. Local ischemic affection of the brain removes the vasoconstrictor effects of stimulation of the cervical sympathetic ganglion and norepinephrine. Analysis by means of dihydroergotamine suggests that ischemia of the brain disturbs the property of alpha-adrenoceptors of the cerebral vessels to increase the tonus of the latter in response to adrenergic effects.

[Dopamine enhancement of the cerebral microcirculation in a local ischemic lesion]. / Uvelichenie dofaminom mikrotsirkuliatsii mozga pri ego lokal'nom ishemicheskom porazhenii.

The effect of dopamine on the local cerebral blood flow in parietal brain cortex region of rats was studied in conditions of local ischemia induced by middle cerebral artery occlusion. Registration of the local cerebral blood flow was performed on a ALF-21 laser doppler flowmeter ("Transonic System Inc.", USA). Dopamine produces a pronounced effect on cerebral circulation in conditions of local brain ischemia thus causing a significant increase in blood flow both in ischemic and intact hemispheres. The effect is observed both in the acute stage of ischemic brain injury and in the remote period of brain ischemia.

[The effect of nimodipine on a local ischemic brain lesion]. / Vliianie nimodipina na lokal'noe ishemicheskoe porazhenie mozga.

A modified rat model of ischemic brain injury caused by ligation of the middle cerebral artery is proposed. The time course of morphological changes in brain tissues was studied and bilateral cerebral circulatory disorders, hypoxic cortical neurocytic damages followed by intracellular regeneration, as well as metabolic and structural changes not only in the cortical neurocytes, but in the conduction paths and synaptic terminals. Nimodipine had no effect on blood supply to the ischemic brain either early or late in ischemic brain injury after ligation of the middle cerebral artery.

[Local cerebral ischemia in rats induced by ligation of the middle cerebral artery]. / Lokal'naia ishemiia mozga krys, vyzvannaia pereviazkoi srednei mozgovoi arterii.

A model of local cerebral ischemia induced by ligation of the middle cerebral artery, which is a modification of the techniques proposed by A. Tamura and others, is suggested. It allows experiments to be conducted on conscious animals with appraisal of the morpho-functional state of the nervous system. Ligation of the middle cerebral artery caused a marked decrease (by 85 +/- 9%) in the blood flow in the temporal area of the cerebral cortex. The use of this method will promote a purposeful search for drugs for the treatment of patients with ischemic disorders of cerebral circulation.

[The cerebral blood circulation during hypokinesia under the influence of hypercapnia, hypotonia, GABA and neurosensory stimulation]. / Mozgovoe krovoobrashchenie v usloviiakh gipokinezii pod vliianiem giperkapnii, gipotonii, GAMK i neirosensornog razdrazheniia.

We studied the formation of vasomotor reflexes in hypokinesia and responses of the brain vessels to the action of GABA, hypotension, and hypercapnia. We found that the response of the brain vessels to GABA is delayed and the mechanisms which supported an adequate cerebral vasculation are distorted in hypotension. At the same time the disturbance of the reflectory reaction of the brain vessels in the course of forming the vasomotor reflexes and the absence of significant changes in response to GABA were noticed. The capability of GABA of inhibiting cerebral blood circulation arising in hypokinesia is shown.

[The central vascular and metabolic effects of pyroglutamic acid]. / Tsentral'nye sosudistye i metabolicheskie éffekty piroglutaminovoi kisloty.

The ability of pyroglutamic acid, a cyclic glutamic acid derivative, to increase cerebral blood flow, to decrease the resistance of brain vessels, and to relax the isolated grafts of cerebral arteries has been demonstrated. Pyroglutamic acid markedly stimulated brain metabolism: increased glucose uptake and utilization by cerebral tissues and decreased brain lactate dehydrogenase activity.

[The antihypoxic activity of endogenous cyclic derivatives of gamma-aminobutyric acid]. / Antigipoksicheskaia aktivnost' éndogennykh tsiklicheskikh proizvodnykh gamma-aminomaslianoi kisloty.

Pirrolidone-2, gamma-butyrolacton, succinic anhydride were found to possess pronounced antihypoxic activity that manifested itself in their ability to decrease the level of lactic acid accumulated during hypoxia. Pirrolidone-2 and succinic anhydride increase succinic dehydrogenase activity in vitro. At intraperitoneal administration the above mentioned compounds lead to lactate dehydrogenase activity inhibition under normal conditions while during circulatory hypoxia they stimulate lactate dehydrogenase reaction promoting the maintenance of energy balance of the cerebral tissue at the appropriate level.

[Effect of 2-pyrrolidone and gamma-butyrolactone on the rate of 14C-leucine incorporation into the proteins of different brain structures and of their arterial tissues]. / Vliianie pirrolidona-2 i gamma-butirolaktona na skorost' vkliucheniia 14C-leitsina v belki razlichnykh struktur golovnogo mozga i tkanei ego arterii.

The ability of cyclic GABA and GHBA derivatives--2-pyrrolidone and gamma-butyrolactone--to increase markedly the inclusion of 14C-leucine in the proteins of hypothalamus and cerebral arteries both normally and in condition of cerebral blood supply disturbances produced by unilateral 20 min ligation of a common carotid artery has been demonstrated.

[Contractile capacity of isolated flaps from the aorta of rats with stable arterial hypertension caused by the prolonged administration of cerebrosides]. / Sokratitel'naia sposobnost' izolirovannykh loskutov iz aorty krys so stoikoi arterial'noi gipertenziei, vyzvannoi dlitel'nym vvedeniem tserebrozidov.

A study was made of the contractility of smooth muscle cells of abdominal aorta strips of noninbred white rats with stable arterial hypertension induced by protracted intraperitoneal injection of cerebrosides isolated from cattle brain. It was demonstrated that as compared with normotensive animals, smooth muscle cells of the animals' arteries are characterized by the increased influx of extracellular calcium via slow potential-dependent calcium channels and hypersensitivity to noradrenaline and serotonin.

[Role of GABA and its derivatives in regulating cerebral circulation]. / O roli GAMK i ee prevrashchenii v reguliatsii mozgovogo krovotoka.

GABA, its derivative -- gamma-hydroxybuturic acid and metabolite --succinic acid have a pronounced dilatatory activity on cerebral circulation in various brain parts. GABA increases cerebral circulation by 25.3%, gamma-hydroxybutyric acid by 35.9% and sucinic acid by 20.4%. In ischaemia of the brain a relationship has been established between cerebral circulation, changes in the GABA system in brain and in the walls of cerebral arteries. The content of GABA increases following enhancement of GAD activity and inhibition of GABA-T. The increase of endogenous GABA level in brain during hypoxia of the brain brings to an improvement of blood circulation through increasing collateral vessels. Experiments with GABA-T inhibition by aminooxyacetic acid give direct evidence about the role of the GABA system in cerebral blood circulation. This mechanism is evaluated by us as an example of an autoregulatory system that is realized by a feed-back mechanism providing the adaptability and compensatory function of cerebral haemodynamics to changing conditions.