Effects of Stimulation of the Inferior Colliculi in Krushinskii–Molodkina Rats

Abstract

The inferior colliculi in rats of the Genetically Epile psyprone Rats (GEPR) strain are known to be the site at which epileptiform audiogenic convulsive seizures are initiated [24][25][26][27][28]35]. The role of the inferior colliculi in the formation of audiogenic paroxysmal reactions has not been studied in Krushinskii-Molodkina rats, which were developed and have been used in physiological studies in Russia [12,16]. The only data obtained show that convulsive responses to sound stimuli in rats of this strain are followed by decreases in the numbers of cells in the central nucleus of the inferior colliculi [6], while targeted implantation of embryonic striatal or cerebellar tissue into this structure decreased the intensity of audiogenic convulsions [8]. Furthermore, because of the wide use of Krushinskii-Molo dkina rats for studies of the actions of anticonvulsant agents [1,9,11,[13][14][15]18], there is an urgent need for more concrete explanations of the functional role of the inferior colliculi in the mechanisms of the formation and development of epileptiform convulsive manifestations in animals of this strain, as the similarities in audiogenic seizures between Krushinskii-Molodkina and GEPR rats does not suggest identity in the structural-functional mechanisms of their realization. Attention should be focused on the fact that Krushinskii-Molodkina rats are signifi cantly different from GEPR rats in terms of a number of biochemical parameters. Thus, Krushinskii-Molodkina rats have thyroid hyperfunction [7], while GEPR rats are hypothyroid during the neonatal period [32]. Animals of both strains also differ in terms of baseline (outside of audiogenic seizures) levels of various neurotransmitters. KrushinskiiMolodkina rats show increased dopamine and noradrenaline The effects of chemical and electrical stimulation of the central nucleus of the inferior colliculus on the generation and formation of convulsive manifestations and on the organization of sleep were studied in Krushinskii-Molodkina rats with an inherited predisposition to audiogenic convulsions. Microinjection of quinolinic acid (10 μg in 1 μl of distilled water) or electrical stimulation at a frequency of 70 Hz generated paroxysmal manifestations in the form of intense rotatory movement acts, similar to "wild running" of animals in the initial convulsion-free stage of audiogenic seizures. This provides grounds for suggesting that in Krushinskii-Molodkina rats the inferior colliculi are part of the neural network responsible for the generation and execution of the running stage during the formation of convulsive responses to sound stimuli. Application of these stimuli was also followed by a decrease in the total duration of fast-wave sleep during the poststimulus period. Conversely, electrical stimulation of the inferior colliculi at a frequency of 7 Hz on the background of deep slow-wave sleep induced episodes of fast-wave sleep in the rats; after 3-4 sessions of this stimulation producing this effect, there was an almost two-fold increase in th...

The Electromagnetic Field Changes on Emotional-motivated Behavior in Genetically Epilepsy-prone Rats

“…Transcranially applied weak fields generated by DC and AC have a wide variety of effects that are potentially significant for using the therapy. Furthermore, repetitive transcranial magnetic stimulation (rTMS) is seen as a safe treatment method, without enduring side effects: no longterm neurological, cognitive or cardiovascular side effects are reported (18,19) . EMF appears to be biologically active, penetrating into the living tissue without any impediments (14) .…”