Spontaneous EEG Paroxysms in the Rat: Effects of Psychotropic and Alpha-Adrenergic Agents

Abstract

Approximately 20% of Charles River rats which were chronically implanted with brain electrodes for EEG recordings exhibited within half a year of the implantation spontaneous, paroxysmally occurring, steep EEG potentials of high amplitude (spikes and waves) whilst falling asleep. These EEG paroxysms were dose dependently antagonized by the ‘petit mal drugs dipropylacetate, ethosuximide and trimethadione as well as by the anticonvulsant drugs diazepam and nitrazepam. The neuroleptics chlorpromazine, haloperidol and thioridazine prolonged the EEG paroxysms. The α₁-adrenoceptor antagonist prazosin and the α₂-adrenoceptor agonists guanfacine and clonidine prolonged, whereas the α₂-adrenoceptor antagonist yohimbine shortened, the EEG paroxysms. The effect of guanfacine was antagonized by yohimbine. The convulsant drugs bicuculhne, 3-mercaptopropionic acid and pentetrazol had only a slight influence on the EEG paroxysms. The results are discussed with respect to the anti- and proconvulsant and convulsant activity of psychotropic drugs and their underlying mechanisms of action, particularly with regard to their interaction with central α-adrenergic mechanisms.

Dexamethasone and Hormones Related to the Hypothalamic-Pituitary-Adrenal Axis Modulate Inherited Neocortical Spindling in DBA/2J Mice

“…observations]. We note that clonidine can enhance S&W also in Sprague-Dawley rats [36], and in general, several investigations are consistent with the con cept that the presynaptic noradrenergic deficit present in Sprague-Dawley GEPR9 and GEPR3 rat brains is un compensated by postsynaptic receptor increments [37][38][39]. In the EEG of the C57B1/6 'tottering' mouse as well, S&W bursts may be observed that are very similar to those of DBA/2J mice and GEPR rats, and in this former mouse strain an elevation in norepinephrine levels within most locus coeruleus projection fields was shown [40] .…”

Impairment of intracortical GABAergic inhibition in a rat model of absence epilepsy

“…Also spike-wave discharges can be noticed in random bred Wistar rats, but the prevalence and incidence of these discharges is much lower compared to age-matched WAG/Rij rats [14]. In two studies it was shown that at an age of six months only 10 or 20% of random bred rats including Wistars show spike-wave discharges [15,31]. It is therefore safe to conclude that Wistar rats quantitatively, differ in the amount of spontaneously occurring spike-wave discharges from WAG/Rij rats.…”

Analysis of the Vigilance Stages in the Rat by Fast Fourier Transformation

“…Indeed, spindles arc generated by the caudate nucleus underlying the frontal cortex [5], The dominant frequency of the spin dles seems to be stage-dependent. During DoTr and Tran the power peaks were measured between 10 and 12 Hz, during PAROX between 6 and 9 Hz (spikes and waves; [9]) and between 12 and 18 Hz.…”

“…Delta-activity was low. Some rats suffer from spontaneously occurring parox ysmal spike and wave activity in the EEG without mo toric seizures (petit mal [9]). In this study 8 rats with EEG paroxysms were evaluated.…”