System Normalized Gamma Oscillations of Brain Structures: Pharmacological Analysis of Neurochemical and Metabolic Processes

Abstract

A systematic study of γ-oscillations was carried out using rats with chronically implanted electrodes in the proreal gyrus, somatosensory cortex, dorsal hippocampus, and hypothalamus. Brain electrograms (BE) were recorded and investigated using an original software and hardware module. Linear diagrams were constructed using a QMS17 device in a frequency range of 60–250 Hz or greater. A mathematical analysis, normalization, and rationing of the series of γ-rhythms under the action of gamma-aminobutyric acid (GABA), acetylcholine (ACC), and insulin relative to similar background series were performed by double discrete-time Fourier transform and double angle arctangent function, which allowed us to extract relevant information from extremely small (1–2 μV) values of γ-oscillations. The accumulation of the substances under study was achieved by introducing the Aminalon (GABA), Galantamine (ACC), and liposomal Insulin pharmaceuticals. The plasma concentrations of the studied drugs were verified by HPLC and mathematical modeling. The normalized BE (NBE) reflected the intracentral mechanisms of action of the tested drugs, which were characterized by a stable picture in the resting state of the animals and under the action of Aminalon, Galantamine, and Insulin at the peak of their plasma concentrations (according to pharmacokinetic parameters). The γ-activity of the brain is maintained at the systemic level. Blockade of γ-oscillations in the frontal pole leads to their activation in the associated brain structures: the hypo-thalamus, reticular formation, caudate nucleus, etc. Under the influence of Aminalon, the total depressive effects were observed over the entire analyzed range in the posterior nucleus of the hypothalamus and proreal gyrus, as well as activating effects in the frequency range 60–75 Hz in the anterior suprasylvian gyrus. Under the action of Galantamine, partial depressive effects in the hippocampus and hypothalamus were observed at   frequencies of about 60–65, 95–105, and 150 Hz. Under the action of liposomal Insulin, partial activating effects were noted in the anterior suprasylvian gyrus and in the dorsal hippocampus in the frequency range of 60–85 Hz.