Seventh International scientific and practical conference «Syringa L.: Collections, Cultivation, Use»

<p>Areview is given of the work of the Seventh International Scientific and Practical Conference «Syringa L.: Collections, Cultivation, Use», hosted on 20 to 22 February, 2023 by the Peter the Great Botanical Garden of the Komarov Botanical Institute of the RAS in St. Petersburg and visited by more than 100 participants from 11 countries. Information about the main directions of the conference work and the most interesting reports are given.</p&gt

Long-term disease-modifying effect of the endocannabinoid agonist WIN55,212-2 in a rat model of audiogenic epilepsy

Item does not contain fulltextBACKGROUND: Modulation of the endocannabinoid (eCB) transmission is a promising approach to treating epilepsy. Animal models can be used to investigate this approach. Krushinsky-Molodkina (KM) rats have, genetically, audiogenic epilepsy. Moreover, in these animals, repeated induction of audiogenic seizures results in a progressive prolongation of the seizures, known as audiogenic kindling. METHODS: The present study evaluated, in these KM rats, acute and long-term effects of a single dose of 4 mg/kg of the cannabinoid-receptor agonist WIN55,212-2. RESULTS: Administration of the single dose of WIN55,212-2 one hour before the 4th seizure delayed the kindling process by two weeks, without any acute effect on the audiogenic seizures. CONCLUSIONS: This result suggests that short-term potentiation of the eCB system might modify the epileptogenic disease process in patients with a progressive course of epilepsy.3 p

Unilateral cortical spreading depression induced by sound in rats

Item does not contain fulltextCortical spreading depression (SD) is thought to underlie the migraine aura but the mechanisms of triggering SD in the human cortex remain unknown. Because growing evidence points to a key role of brainstem circuits in initiating migraine attacks, the present study examined whether recurrent episodes of brainstem activation in rats could induce cortical SD. Explosive running elicited by sounds in rodents with inherited hypersensitivity to acoustic stimuli (reflex audiogenic epilepsy), is known to reflect a transient aberrant activation of the brainstem. Repeated induction of such audiogenic responses enhances the excitability of the cortex, culminating in its epileptic activation (audiogenic kindling). In Wistar rats with inherited hypersensitivity to sounds, 15 brief episodes of running were induced by sound stimulation, and slow potential shifts as well as the EEG were recorded in the cortex. Single unilateral SD began to occur in the cortex following a running episode after the 5th to 15th test (mean 9.4 +/- 1.2). Once appeared, SD was regularly recorded in subsequent tests. The side of the SD initiation closely correlated with the direction of running. Triggering SD was not associated with epileptic activation of the cortex in most rats. The present findings suggest that the sensory-induced brainstem excitation could be a potent trigger of SD in the hyperexcitable cortex, providing an experimental evidence of a possible causative role of the brainstem activation in initiating the migraine aura

Cortical spreading depression as a consequence of recurrent convulsive seizures

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Audiogenic seizures associated with a cortical spreading depression wave suppress spike-wave discharges in rats

Contains fulltext : 55688.pdf (publisher's version ) (Closed access)To study the role of the cortex and sub-cortical structures in the generation of epileptic spike-wave discharges in more detail, cortical and striatal activity was eliminated by the induction of spreading depression in a non-invasive way. EEG and DC potentials were recorded from the cortex and striatum of WAG/Rij rats. Several of these rats show two forms of generalised epilepsy: spontaneously occurring non-convulsive absence seizures, together with convulsive audiogenic seizures. The latter can be evoked by a brief sound stimulation, provoking a fit of wild running, which is regarded as the first phase of an audiogenic seizure. In a majority of fits the cortical DC potential does not show main changes, while the spontaneously occurring spike-wave discharges are briefly suppressed for some minutes. In a minority of fits, however, audiogenic seizures are associated with a spreading depression wave, clearly expressed in the cortical DC potential. This wave is bilaterally initiated in the cortex and propagates to the caudate nucleus of the striatum. In these cases spontaneously occurring spike-wave discharges are fully suppressed for about 1 h. It is suggested that cortical spreading depression, triggered by a short audiogenic seizure, induces a long-lasting suppression of spike-wave discharges. These results are in line with the concept that spike-wave discharges are originally initiated in the cortex, as proposed by the ‘cortical focus’ theory. The precise role of the striatum remains less clear, although this structure seems not to play a pivotal role in spike-wave generation

Audiogenic seizures accompanied by a cortico-striatal spreading depression wave are associated with a long-term suppression of spike-wave discharges

Item does not contain fulltextDC potential recordings were made in the cortex and the caudate nucleus of WAG/Rij rats. A selection of these rats shows two forms of generalised epilepsy: spontaneously occurring non-convulsive absence seizures together with convulsive audiogenic seizures, evoked by brief sound stimulation. Sound stimulation evokes in these rats wild running lasting for about 8 seconds, which is the expression of the first phase of an audiogenic fit. In 29% of cases this fit is associated with a spreading depression wave, which is bilaterally initiated in the cortex and propagates to the caudate nucleus. In these cases spontaneously occurring spike-wave discharges are fully suppressed for about one hour. In the remaining 71% of fits the cortical spreading depression wave is not evoked. In these cases the suppression of spike-wave activity lasts only shortly, about 3 till 6 minutes. It is suggested that the long-lasting suppression of spike-wave discharges is induced by the bilateral cortico-striatal spreading depression wave. This might be related to the inhibition of the cortico-thalamic pacemaker generating the spike-wave activity

Pro-epileptic effects of the cannabinoid receptor antagonist SR141716 in a model of audiogenic epilepsy

Item does not contain fulltextEndocannabinoid system and its CB1 receptors are suggested to provide endogeneous protection against seizures. The present study examines whether CB1 receptors contribute to resistance to seizures and kindling epileptogenesis in a model of audiogenic epilepsy. Three groups of Wistar rats were used: rats unsusceptible to audiogenic seizures, rats with acquired resistance to audiogenic seizures and rats with reproducible audiogenic running seizures. Chronic treatment with the CB1 receptor antagonist SR141716 (5 daily dosing of 30 mg/kg) did not change innate resistance to audiogenic seizures in non-epileptic rats but reverted acquired seizure resistance in rats which lost their epileptic sensitivity with repeated testing. In the latter rats, audiogenic running seizures reappeared for at least two weeks after the end of treatment. In rats with reproducible seizure response, acutely, SR lengthened audiogenic seizures due to prolongation or appearance, de novo, of post-running limbic clonus without any effect on running seizure per se. This limbic component mimicked audiogenic kindling and indicated propagation of sound-induced brainstem seizure to the limbic forebrain. After chronic SR administration the incidence of the limbic clonus remained to be increased for at least two weeks. The present study supports the hypothesis about a role of CB1 receptors in endogeneous anticonvulsive mechanisms of the brain

Intracortical microinjections may cause spreading depression and suppress absence seizures

Item does not contain fulltextIntracerebral microinjection is a commonly used technique for local delivery of biologically active agents. However, it is known that mechanical injury of the cortex can induce spreading depression (SD), a wave of transient cellular depolarization. We examined the effects of intracortical microinjections of a new selective I-h channel antagonist ORG 34167 and of different control treatments (saline and sham microinjections) on spontaneously occurring spike-wave discharges (SWDs) in WAG/Rij rats, a valid genetic model of absence epilepsy. Electroencephalographic (EEG) recording in awake rats has shown that both the drug and control microinjections are followed by long-term (for more than an hour) suppression of SWDs. dc-EEG recording in WAG/Rij rats has revealed that sham microinjections induce SD in 65% (31/48) cases. Number of SWDs decreased substantially for at least 90 min after the sham injections which induced cortical SD but remained unchanged if SD was not triggered by microinjection. These findings suggest that SD induced by intracortical microinjection may contribute to long-term suppression of non-convulsive epileptic activity after this experimental procedure

Endocannabinoid system protects against cryptogenic seizures

Contains fulltext : 99304.pdf (publisher's version ) (Closed access)Effects of the cannabinoid antagonist rimonabant on the EEG were investigated in healthy, non-epileptic rats. The drug was administered orally at 30 mg/kg/day for 3 weeks. The EEG was recorded continuously. In 3 out of 13 rats, limbic convulsive seizures, which were not related to the time of drug administration, were observed after 5-8 days. We hypothesize that an accumulation of micro-injuries in the brain is responsible for these "spontaneous" seizures.4 p