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G Rondouin

Publications and source records attributed to G Rondouin.

At least 55 records · Page 3Linked to original sources
PubMed1990

Catecholaminergic systems and amygdala kindling development. Effects of bilateral lesions of substantia nigra dopaminergic or locus coeruleus noradrenergic neurones.

The effects of the bilateral and selective destruction of substantia nigra (SN) dopaminergic or locus coeruleus (LC) noradrenergic neurones, consecutive to a local injection of 6-hydroxydopamine, were studied on the development of amygdala kindling. Immunohistochemical controls of lesions were performed using selective dopamine (DA) or norepinephrine (NE) antibodies. The results demonstrated that a massive destruction of SN pars compacta neurones did not modify the rate of kindling development. Conversely, the lesions of LC neurones (sparing lateral tegmental nuclei) markedly facilitated the development of amygdala kindling. This effect was related to the extent of NE denervation. Together, these results suggest that DA is not strongly involved in the development of kindling, and that the nigrostriatal output does not play a major role in the generalization of kindled seizures. In contrast, they confirm an inhibitory influence exerted by LC noradrenergic ascending pathways on the development of kindling.

Amygdala↗
PubMed1990

["Wet dog shakes" during olfactory bulb kindling].

Kindling phenomenon provides an experimental model of limbic secondarily generalized epilepsy. It can be easily obtained by stimulation of the olfactory bulb (OB) which is strongly connected to limbic structures. The after-discharge induced by subconvulsant electrical stimulations, is followed by a behavioral phenomenon, named Wet Dog Shakes (WDS). In the course of the Rat OB kindling, the development of WDS is biphasic: 1) an ascendant phase during the first three stages, and 2) a descendant phase in the stages 4 and 5, that may give evidence of the installation and the intensification of the kindling process. The significance of this behavior in seizure generalization is discussed.

Animals↗
PubMed1989

[Excitotoxic damage of the hippocampus in the rat: involvement of N-methyl-D-aspartate receptors].

The intrahippocampal injection of two agonists of excitatory aminoacid (EAA) receptors elicited neuronal damages localized in CA1 and dentate gyrus for N-methyl-D-aspartate (NMDA) (20 nmol) and extended to the various hippocampal areas, except dentate gyrus for kainic acid (KA) (2.5 nmol). The pretreatment of the animals with N-[1-(2-thienyl)cyclohexyl]piperidine (TCP) (20 mg/kg), a noncompetitive NMDA-receptor antagonist, prevented the neuronal injury induced by NMDA and KA in CA1. The distribution of neuronal damages and of TCP-protected areas closely correlated to that of EEA-receptors and of TCP binding sites in the hippocampus.

Animals↗
PubMed1988

Non-competitive antagonists of N-methyl-D-aspartate receptors protect cortical and hippocampal cell cultures against glutamate neurotoxicity.

Brief exposure of cortical or hippocampal cell cultures to glutamate (500 microM) resulted in a progressive neuronal necrosis which is maximal 18-24 h later. Pretreatment of the cultures by a phencyclidine derivative: thienylphencyclidine (TCP), or the TCP precursor: GK86, or MK801 protected against glutamate toxicity. Non-competitive antagonists of N-methyl-D-aspartate receptors appear as potent tools for the in vitro protection of neuronal cells against excitatory amino acid toxicity.

Animals↗
PubMed1987

Presynaptic alteration of [3H]GABA transport in hippocampus by amygdala kindling.

gamma-Amino[2,3-3H]butyric acid ([3H]GABA) transport was investigated in hippocampal synaptosomes prepared from amygdala kindled rats. Kindling enhanced [3H]GABA uptake by 10-20%, while the Km of uptake and the kinetics of the release were unchanged. The dose response curve of the inhibition of [3H]GABA uptake by veratridine was altered by kindling: the K0.5 of inhibition and the Hill number increased and the curve became biphasic after a long period of stimulations. This effect was interpreted in terms of a modification of the functioning of the presynaptic fast Na+ channels which initially become more resistant to depolarization. In the long term, it appears that new Na+ channels develop that are more sensitive to the action of veratridine.

Amygdala↗
PubMed1987

Wet dog shakes in limbic versus generalized seizures.

Wet dog shake behavior was studied in different models of epilepsy in the rat. Numerous wet dog shakes were associated with limbic seizures in the course of focal epilepsy induced by kindling stimulations or local injections of kainic or quisqualic acid and progressively disappeared during generalization. On the contrary, they were never observed in models of generalized epilepsy. This study suggests that the number of wet dog shakes may be an index of the progression of limbic seizures toward generalization.

Amygdala↗
PubMed1986

Facilitation of olfactory bulb kindling after specific destruction of serotoninergic terminals in the olfactory bulb of the rat.

The role of serotonin (5-HT) in the kindling model of epilepsy was investigated by performing specific lesions of the 5-HT innervation at the level of the primary epileptogenic focus. We injected bilaterally 5,6-dihydroxytryptamine in the olfactory bulb (OB) of adult rats which were submitted to electrical stimulations of the OB until the occurrence of stage-5 seizures. Immunohistochemical controls of lesions were realized with a specific anti-5-HT antibody. Results revealed that the lesions facilitated the initial development of kindling (increase of afterdischarge duration and of kindling rate), suggesting that 5-HT terminals exert a modulatory effect on the propagation of the epileptic activity.

Animals↗
PubMed1986

Plasma ACTH and corticosterone responses to limbic kindling in the rat.

Changes in plasma ACTH and corticosterone concentrations were measured in individual cannulated rats at stages 1 and 5 of limbic kindling induced by electrical stimulation of the basolateral amygdala or the dorsal hippocampus. At both stages, a stimulation of either structure produced swift surges, first of ACTH and then of corticosterone. At stage 5 of hippocampal stimulation, ACTH baseline concentrations were four times higher than in the controls. The results are discussed in relation to the central control of the adrenocorticotropic system and to the neuroendocrine correlates of the kindling process.

Adrenocorticotropic Hormone↗
PubMed1986

Clinical and neuropsychological rating scales for differential diagnosis of dementias.

Clinical and neuropsychological rating scales were used in two studies of patients. The first one included 20 patients with progressive dementia and was divided into two groups according to their ischemic score evaluation and ancillary examinations (EEG, cerebral evoked potentials, CT scan, Doppler, xenon-133 clearance). The first group consisted of 10 patients with primary degenerative dementia of the Alzheimer type (SDAT) (n = 10). The second group included 10 patients with dementia caused by multi-infarction (MID). The second study included 18 patients with a confusional state, examined repeatedly for 1-6 months afterwards. The clinical and neuropsychological procedure consisted of a multi-dimensional assessment including 8 rating scales. A significant difference was found in the overall clinical and neuropsychological profile of patients with SDAT and MID. Cognitive functions were homogeneously impaired in the group of SDAT patients and heterogeneously in the group of MID patients. In chronic confusional states the overall profile was similar to that of the group of MID patients. Further reassessment showed a normalization in 9 patients, a vascular MID profile in 6 cases, an SDAT profile in 3 cases, and an undifferentiated one in 2 cases. Reversibility of the confusional state might be predicted at the onset of the cognitive disorder by history-taking and evaluation of the ischemic score.

Aged↗
PubMed1986

[Specific lesions of serotoninergic cells in the raphe. Effect on kindling of the olfactory bulb in rats].

Limbic kindling obtained by electrical stimulation of the olfactory bulb in the rat has been studied after specific lesion of serotonergic cells in mesencephalic and pontic raphe nuclei with local microinjection of 5,7-dihydroxytryptamine. The extent of the raphe lesions was verified by immunocytochemical technics with antiserotonin antibody. Lesioned rats showed an increase of kindling rate, which confirms the inhibitory function of serotonin in the development of this phenomenon.

5,7-Dihydroxytryptamine↗
PubMed1986

[Transplantation of serotonin neurons in the olfactory bulb of the adult rat].

Serotonergic neurons have their perikaraya concentrated in the raphe nuclei. In the present experiment, pieces of raphe nuclei containing serotonergic neuroblasts were dissected from 14 days rat embryos, mechanically dissociated, and 1 microliter of a cell suspension containing 30,000 cells was injected slowly under stereotaxic control in the olfactory bulb of adult rats. Three weeks after transplantation, the brain of the rats were processed for immunocytochemical detection of 5-HT. In all of the grafted animals, 5-HT neurons were found in the olfactory bulb. They exhibited the morphology of adult neurons, with well developed axon and dendrites, extending far from the injection site. Ultrastructural immunocytochemistry disclosed afferent and efferent synapses to the grafted neurons. Three preliminary results indicates that the transplanted neurons have been integrated in the host's neuronal circuitry. Ongoing electrophysiological studies are now directed at investigating the functional status of these grafted neurons.

Animals↗
PubMed1985

Absence of modifications in gamma-aminobutyric acid metabolism after repeated generalized seizures in amygdala-kindled rats.

Alterations in gamma-aminobutyric acid (GABA) metabolism have been investigated in the kindling model of epilepsy. Numerous generalized seizures were induced by amygdala-kindling stimulations in rats. One week after the last stimulation, there were no changes in GABA levels nor in the activity of enzymes responsible for the synthesis (glutamic acid decarboxylase) and catabolism (GABA transaminase and succinyl semialdehyde dehydrogenase). These results do not exclude other changes in GABA function as modifications of transport or receptors.

4-Aminobutyrate Transaminase↗
PubMed1984

Hippocampal kindling in the rat: intrastructural differences.

Kindling patterns were compared in different regions of the hippocampus of the rat. The duration, morphology, and frequency of the electrical responses were different after stimulation of the dorsal and the ventral hippocampus, but these parameters showed the same evolution as kindling progressed. Comparison of the threshold intensity and of the kindling rate revealed some differences not only between dorsal and ventral hippocampus, but also within the dorsal hippocampus: The central layers had higher thresholds and longer kindling periods than the outer layers and the fimbria hippocampi. We suggest that stimulation of hippocampal efferents is responsible for the greater ease of kindling in the outer layers than in the central regions of this structure. The degree of connection of the different parts of the hippocampus with the amygdala and the influence of the intrinsic inhibitory GABAergic circuitry are discussed.

Action Potentials↗
PubMed1984

Evolution of wet dog shakes during kindling in rats: comparison between hippocampal and amygdala kindling.

The occurrence of wet dog shakes (WDS) was studied during hippocampal kindling and amygdala kindling. Many WDS were observed after the first stimulation of the dorsal and ventral hippocampus. Their number rapidly increased to a maximal value (after five to six stimulations) and then progressively decreased during the development of hippocampal kindling. Their distribution during the afterdischarge (AD) was impaired by kindling. During amygdala kindling, WDS were observed only when the ADs attained a total duration of at least 50 s. In this case too, the repetition of stimulations was concomitant with a progressive decrease in the number of WDS. We suggest that the regression of the number of WDS may be considered as an additional criterion of the fully kindled state.

Amygdala↗
PubMed1984

[Brain stem auditory evoked potentials in "alcoholic epilepsy"].

BAEPs were studied in a group of subjects suffering from 'alcoholic epilepsy.' Results were then compared with data from normal subjects and chronic alcoholics without epilepsy. The latency for peak V and the inter-peak latencies (I-III, III-V, I-V) were significantly longer in the 'alcoholic epilepsy' group than in the control group. This increase of neural transmission time in the brain-stem auditory pathways was less important in the 'chronic alcoholics without epilepsy' group than in the alcoholic epilepsy group.

Adult↗