Search PubMed⌕ Search

Biomedical subjects

C Gottesmann

Publications and source records attributed to C Gottesmann.

At least 37 records · Page 2Linked to original sources
PubMed1994

Benzodiazepines promote the intermediate stage at the expense of paradoxical sleep in the rat.

The effects of diazepam, a long half-life benzodiazepine, midazolam and triazolam, two with short half-life, on the transitional stage between deep slow wave sleep and paradoxical sleep were studied in Wistar and WAG/Rij rats. This intermediate stage is characterized by the unusual association of cortical spindles and low frequency hippocampal theta rhythm. The main result was extension of the intermediate stage at the expense of paradoxical sleep by diazepam and triazolam by influencing only the duration of the intermediate stage and both the onset and maintenance of paradoxical sleep. Midazolam increased both intermediate stage and paradoxical sleep. Several differences in the qualitative modulation of the stage characteristics and between rat strains were found. In regard to the possible peculiar physiological significance of the intermediate stage, we conclude that benzodiazepines promote a transient pharmacological cerveau isolé-like stage during sleep in rats.

Animals↗
PubMed1994

Event-related potentials in humans as indices of access to stored information during sleep.

The even-related potentials are good indices of brain functions during sleep stages. The contingent negative variation (CNV), occurring in the interval between a conditional and a target stimulus, reflects information processing. The emitted potential which occurs when an expected stimulus is omitted reflects the access to a specific memory. During waking, deep slow wave sleep (stage 4) and paradoxical sleep seven subjects were submitted to a CNV paradigm, the target stimulus of which was occasionally omitted. The endogenous components of the evoked potentials induced at Fz, Cz and Pz locations by the auditory stimuli were analysed during the three behavioral stages. During stage 4 they were of largest amplitude and longest latency. These results are discussed in terms of neural excitability. CNV and emitted potentials were observed during waking and paradoxical sleep, but not during stage 4. These results suggest that information processing occurs during paradoxical sleep with access to waking memories during this stage of sleep, whereas information processing is absent during stage 4.

Adult↗
PubMed1993

Waking electroencephalograms in the blood-lymph and encephalitic stages of gambian trypanosomiasis.

Waking electroencephalograms (EEG) were recorded from 48 patients infected with Trypanosoma gambiense. The EEG of the 10 patients with blood-lymph involvement were indistinguishable from those of healthy controls but recordings from the 38 patients with the encephalitic phase of the disease showed three unusual profiles. One profile type, apparently indicative of early cerebral impairment, had a sustained low-voltage background similar to that seen during light sleep. A second profile type, seen in cases with acute cerebral involvement but without focal seizures, showed paroxystic waves. The third unusual EEG pattern was of various types of delta wave (similar to those seen in demyelinating encephalitis) and rapid, intermittent high-voltage delta bursts between periods of lower-voltage delta activity (as often seen in meningo-encephalitis); all types of delta wave were of higher voltage than the spike and wave complexes. Although no definite correlation has been established between the severity of the disease, the results of clinical tests, and waking EEG patterns, it appears that the three types of EEG profile are indicative of the degree of cerebral involvement.

Electroencephalography↗
PubMed1992

Study of the 5-HT2 antagonist ritanserin on sleep-walking cycle in the rat.

Ritanserin, a 5-HT2 receptor antagonist, was injected intraperitoneally to rats at light onset. It was found that 0.63 mg/kg decreased waking, increased the slow waves characteristic of the first stage of sleep, and decreased paradoxical sleep (PS) during the first four hours. Active waking was further decreased and slow wave stage increased during the following four hours. The number of synchronized and paradoxical sleep phases decreased whereas their duration increased during the first four hours. Ritanserin at 2.5 mg/kg decreased active waking and PS, whereas quite waking and slow wave stage were increased during the first four hours. Quiet waking was increased during the following four hours. It is concluded that serotonin acting on 5 HT2 receptors is actively involved in sleep-waking regulation.

Animals↗
PubMed1992

Theta rhythm: the brain stem involvement.

This review considers the influence of brain stem transections on hippocampal theta rhythm appearance in the acute transected rat and cat. The pretrigeminal transection induces in both species continuous or almost continuous low-frequency theta rhythm while the cortex is desynchronized. The intercollicular transection induces in both species high amounts of low-frequency theta rhythm, whereas the cortex shows cortical spindle bursts of high amplitude. The precollicular transected rat generally shows high amounts of low-frequency theta rhythm while the cortex is synchronized. This theta rhythm is increased in frequency, or induced when absent, by median posterior hypothalamic stimulation. In contrast, in the cat there is no theta rhythm but the limbic rhythm is easily induced by the same hypothalamic stimulation. In the midhypothalamic transected rat there is not theta rhythm and the cortex is synchronized. These data suggest that the posterior hypothalamus could be a trigger zone for theta rhythm particularly involved during sleep.

Animals↗
PubMed1992

Detection of seven sleep-waking stages in the rat.

Seven meaningful sleep-waking stages can be dissociated in the rat. 1) Waking with theta activity in the dorsal hippocampus which corresponds to attentive and/or psychomotor active behavior. 2) Waking without theta activity during which the animal is mainly quiet. 3) The first sleep stage is characterized by cortical slow waves of progressive increasing amplitude. 4) As synchronized sleep deepens, anterior cortex spindles of progressively increasing number, amplitude and duration appear. 5) Just prior to paradoxical sleep occurs an intermediate stage characterized by cortical high amplitude spindles and low frequency theta rhythm. It corresponds to a functional cerveau isolé-like preparation since it is related to a massive decrease of thalamic sensory transmission processes, and acute intercollicular transections induce for hours the same unusual association of EEG patterns. This stage is massively extended at the expense of paradoxical sleep by several psychotropic drugs. 6) Paradoxical sleep without eye movements. 7) Eye movement periods of paradoxical sleep. The central responsiveness and neurophysiological correlations of these stages are discussed.

Animals↗
PubMed1991

Anticonvulsant and sleep-waking influences of riluzole in a rat model of absence epilepsy.

Six WAG/Rij rats, an animal model of human absence epilepsy, were injected intraperitoneally with riluzole. At 4 mg/kg, riluzole decreased the number, mean duration and spike-frequency of the spontaneously occurring discharges for 3 h. Riluzole also increased slow wave sleep at the expense of waking. As riluzole at 3 mg/kg decreased the number and spike-frequency of the discharges without inducing a sedative effect, this compound could be of therapeutic interest in human absence epilepsy.

Animals↗
PubMed1991

Riluzole prevents hyperexcitability produced by the mast cell degranulating peptide and dendrotoxin I in the rat.

Using electroencephalographic (EEG) recordings in freely moving rats and extracellular neuronal firing-rate recordings in hippocampal slices, we examined the effects of riluzole (RP 54274), a compound with anti-glutamate properties, against the convulsive seizures and the cellular hyperexcitability produced by the mast-cell degranulating peptide (MCD), dendrotoxin I (DTXi) and 4-aminopyridine (4-AP). I.c.v. administration of riluzole (10 nmol) prevented the seizures induced by MCD, and to a lesser extent those due to DIXi, whilst leaving 4-AP seizures unaffected. This effect was also present after oral administration of the compound (4 mg kg-1) and lasted for approximately 6 h. Electrophysiological recordings in vitro confirmed that riluzole dose dependently and reversibly abolished the sustained increase in firing rate induced by both MCD and DTXi in the hippocampus. These results indicate that the anti-epileptic spectrum of riluzole in this model has similarities with, but is not identical to, that of classical potassium channel openers, and differs from that of calcium channel blockers or other glutamate antagonists such as D(-)-2-amino-5-phosphono-valeric acid. However, since MCD releases glutamate, the preventive effect of riluzole in this model may involve direct or indirect interaction with glutamatergic processes.

4-Aminopyridine↗
PubMed1991

The intermediate stage of sleep in mice.

Seven mice of Balb/C strain were implanted with electrodes to perform sleep-waking recordings. In 100% of the cases, the mice showed, prior to paradoxical sleep, the intermediate stage of sleep characterized by high-amplitude cortical spindles interspersed with slow waves and low-frequency theta rhythm in the dorsal hippocampus. Consequently, the intermediate stage which seems to correspond to a transient functional isolated forebrain does exist in the rat, cat and mouse. in the rat, cat and mouse.

Animals↗
PubMed1991

Hippocampal and cortical EEG activity in rats with transected hypothalamus.

The brain was transected in eight rats: the transection passed through the posterior pole of the superior colliculi and ended down at midhypothalamic level. The EEG activity in the dorsal hippocampus and cortex showed continuously slow, high amplitude waves. Thus the posterior hypothalamus is critical for the previously described hippocampal theta rhythm found in rats transected at the posthypothalamic level.

Animals↗
PubMed1990

Genetically epileptic rats show a pronounced intermediate stage of sleep.

Rats of the genetically epileptic WAG/Rij strain show a more long-lasting intermediate stage of sleep compared to rats of the Wistar strain. Therefore the WAG/Rij strain provides a privileged model for studying this stage of sleep. On the other hand, the percentage of paradoxical sleep in WAG/Rij rats is lower than in Wistar rats, for the reason that the intermediate stage in WAG/Rij rats is less frequently followed by paradoxical sleep and more frequently by slow wave sleep and especially by arousals. It is speculated that the epileptic rats encounter a greater difficulty in entering into paradoxical sleep.

Animals↗
PubMed1989

Analogies and differences in the mode of action and properties of binding sites (localization and mutual interactions) of two K+ channel toxins, MCD peptide and dendrotoxin I.

Both the bee venom toxin, mast cell degranulating (MCD) peptide, and the snake toxin, dendrotoxin 1 (DTX1) induce epileptiform activity and paroxystic seizures after intracerebroventricular (i.c.v.) injection to rats. Although many of the properties of the two toxins, which are blockers of the same K+ channel, appear to be very similar, a number of differences have been found. (1) Induced seizures have an hippocampal origin for MCD and two different origins, situated in the cortex and in the limbic system, for DTX1. (2) A first i.c.v. administration of DTXI desensitizes against a second ipsilateral injection of the same peptide as we had previously observed for MCD. However no cross-desensitization was observed between the two different toxins. (3) The number of high affinity (Kd = 41 pM) binding sites for 125I-DTXI in synaptic membranes is about 5 times higher than the number of high affinity (Kd = 158 pM) binding sites for 125I-MCD. (4) Autoradiographic analysis of the distribution of high affinity 125I-DTX1 binding sites has been compared to our previous analysis of high affinity 125I-MCD binding sites. High levels of high affinity binding sites for both toxins seem to be localized in synapse-rich areas. However high affinity binding sites for the two toxins are not always co-localized. Analysis of the mutual interactions between DTXI and MCD binding sites has revealed the presence of classes of low affinity binding sites for MCD. In most areas of the brain, a large proportion of high affinity binding sites for DTXI is allosterically related to low affinity binding for MCD.

Animals↗
PubMed1989

Subtypes of K+ channels differentiated by the effect of K+ channel openers upon K+ channel blocker-induced seizures.

Intracerebroventricular injection of mast-cell degranulating peptide (MCD), dendrotoxin I (DTXI) and 4-aminopyridine (4-AP), 3 blockers of a subclass of K+ channel, produces seizures and convulsions. Three different K+ channel openers are potent blockers of MCD-induced hyperexicitatory effects when they are administered preventively but they are unable to inhibit the epileptogenic effects induced by DTXI and 4-AP which were thought to block the same K+ channel which is blocked by MCD.

4-Aminopyridine↗
PubMed1989

Ca2+ channel blockers prevent seizures induced by a class of K+ channel inhibitors.

Intracerebroventricular injection into rats of mast-cell degranulating peptide (MCD), dendrotoxin I (DTXI) and 4-aminopyridine (4-AP), three blockers of a subclass of K+ channels, elicited epileptiform wave bursts and convulsions. Three different types of L-type Ca2+ channel inhibitors (+)PN 200-110, a 1,4-dihydropyridine, (-)D888, a phenylalkylamine, and fluspirilene, a diphenylbutylpiperidine, were potent blockers of the convulsant-induced hyperexcitatory effects when they were administered preventively. D-AP5, a N-methyl-D-aspartate antagonist, was active on the 4-AP-induced seizures but was without effect on the MCD- and dendrotoxin-induced seizures.

4-Aminopyridine↗