Quantified EEG, somatosensory evoked potentials and cerebral blood flow in monitoring experimental brain ischemia

Cerebral ischemic lesions were induced in rabbits through internal carotid artery embolization by means of microspheres. Different models of stroke ranging from single focal cortical lesion to massive bilateral brain edema were reproduced and monitored up to the 24th hour by electroencephalogram (EEG and QEEG), somatosensory evoked potentials (SEPs), cerebral blood flow (CBF), platelet aggregation. The site and extent of the lesions were verified by histological examinations. Results obtained and physiopathological implications are discussed.

Influence of L-5-hydroxytryptophan and DL-p-chlorophenylalanine on neurophysiological profiles of serotonin reuptake inhibitors in rabbits

In a previous study we noted that some drugs, which exert their action by inhibiting serotonin (5-HT) reuptake, caused different EEGraphic, behavioural and autonomic patterns. These drugs (Alaproclate, Citalopram, Fluoxetine, Fluvoxamine, Indalpine, Zimelidine) have now been studied in two groups of animals pretreated with L-5-hydroxytryptophan (L-5-HTP), the 5-HT precursor, and with DL-p-chlorophenylalanine (PCPA), a 5-HT depletor. The administration of 5-HT reuptake inhibitors, after pretreatment with L-5-HTP, caused homogeneous changes, i.e. EEG cortical desynchronization and behavioural serotonergic syndrome. No significant modifications of the parameters examined were observed in the animals of the second group (pretreated with PCPA). The possible mechanisms of action of these drugs and some aspects of the role of serotonin in the central nervous system are discussed.

Developmental expression of the Sturge-Weber syndrome-associated genetic mutation in Gnaq: a formal test of Happle's paradominant inheritance hypothesis

Sturge-Weber Syndrome (SWS) is a sporadic (non-inherited) syndrome characterized by capillary vascular malformations in the facial skin, leptomeninges, or the choroid. A hallmark feature is the mosaic nature of the phenotype. SWS is caused by a somatic mosaic mutation in the GNAQ gene (p.R183Q), leading to activation of the G protein, Gαq. Decades ago, Rudolf Happle hypothesized SWS as an example of "paradominant inheritance", that is, a "lethal gene (mutation) surviving by mosaicism". He predicted that the "presence of the mutation in the zygote will lead to death of the embryo at an early stage of development". We have created a mouse model for SWS using gene targeting to conditionally express the GNAQ p.R183Q mutation. We have employed two different Cre-drivers to examine the phenotypic effects of expression of this mutation at different levels and stages of development. As predicted by Happle, global, ubiquitous expression of this mutation in the blastocyst stage results in 100% embryonic death. The majority of these developing embryos show vascular defects consistent with the human vascular phenotype. By contrast, global but mosaic expression of the mutation enables a fraction of the embryos to survive, but those that survive to birth and beyond do not exhibit obvious vascular defects. These data validate Happle's paradominant inheritance hypothesis for SWS and suggest the requirement of a tight temporal and developmental window of mutation expression for the generation of the vascular phenotype. Furthermore, these engineered murine alleles provide the template for the development of a mouse model of SWS that acquires the somatic mutation during embryonic development, but permits the embryo to progress to live birth and beyond, so that postnatal phenotypes can also be investigated. These mice could then also be employed in pre-clinical studies of novel therapies.

Synchronizing EEG effect of mianserin

The AA. report on the eegraphic, behavioral and neurovegetative effects caused by the i.v. administration of mianserin, in the rabbit. This substances induces behavioral sedation and EEG synchronization. In addition, these changes are partially reinforced with L-5-hydroxytryptophan (L-5HTP) and inhibited by pretreatment with DL-p-chlorophenylalanine (PCPA). In the light of these data, the AA. discuss the possible interactions between mianserin and neurotransmitter systems, particularly the serotoninergic one.

Deciphering the functional impact of Alzheimer's Disease-associated variants in resting and proinflammatory immune cells

Genome-wide association studies have identified loci associated with Alzheimer's Disease (AD), but identifying the exact causal variants and genes at each locus is challenging due to linkage disequilibrium and their largely non-coding nature. To address this, we performed a massively parallel reporter assay of 3,576 AD-associated variants in THP-1 macrophages in both resting and proinflammatory states and identified 47 expression-modulating variants (emVars). To understand the endogenous chromatin context of emVars, we built an activity-by-contact model using epigenomic maps of macrophage inflammation and inferred condition-specific enhancer-promoter pairs. Intersection of emVars with enhancer-promoter pairs and microglia expression quantitative trait loci allowed us to connect 39 emVars to 76 putative AD risk genes enriched for AD-associated molecular signatures. Overall, systematic characterization of AD-associated variants enhances our understanding of the regulatory mechanisms underlying AD pathogenesis.

Behavioral and eegraphic changes induced by dopaminergic antidepressants in rabbits

Nomifensine, Bupropion and Amineptine, "second generation" antidepressants with dopaminergic effects, were studied in the rabbit with special regard to their action on somatic and autonomic behavior, and cerebral electrical activity. All three drugs induced an "alarm" reaction and typical dopaminergic behavioral responses including sniffing, jumping and chewing. Mydriasis was also observed especially at high dose levels. EEG showed an arousal pattern for each of these drugs. A marked increase in the hippocampal spiking resulted from the i.v. administration of 15 mg/kg of Bupropion.

Neuropharmacological profile of ketanserin

Eegraphic, behavioural, autonomic changes were studied in rabbits, after intravenous (i.v.) administration of L-5-hydroxytryptophan (L-5-HTP) and intracerebroventricular (i.c.v.) administration of ketanserin. The cerebral electrical activity on cortex and Cornu Ammonis dorsale (CAd) was evaluated by means of quantitative EEG analysis. The two drugs induced specific changes in all the parameters examined. L-5-HTP caused stereotyped movements typical of the serotoninergic syndrome and EEG "arousal" pattern. Ketanserin did not induce any behavioural change; quantitative EEG analysis showed an increase in those parameters typical of "slow sleep" pattern. The changes caused in guinea pigs by pretreatment with ketanserin, in the experimental model of myoclonus induced by L-5-HTP, were investigated. In the present study the possible mechanisms of action which subtend these results are discussed.

Neurophysiological changes induced by 5-HT reuptake inhibitors in rabbits

The EEGraphic, behavioural and autonomic changes induced by the administration of some inhibitors of serotonin (5-HT) reuptake were evaluated in the rabbit. The drugs examined were: Alaproclate (Ala), Citalopram (Cit), Fluoxetine (Fluo), Fluvoxamine (Fluvo), Indalpine (Ind), Zimelidine (Zim). It seems that all these drugs would act exclusively or prevalently on 5-HT uptake. The changes of the parameters studied were not homogeneous. Some of these drugs (Cit, Zim) induced an EEGraphic and behavioural "arousal" pattern, others (Fluo, Fluvo) a "slow wave sleep" one, others (Ala, Ind) a biphasic one (alteration of the two above-mentioned patterns). The possible hypotheses subtending these data are discussed.