Electrical activity dynamics of the hippocampus under caffeine influence
Authors: Turitskaya T. G. , Sidorenko A. G. 
Published: February 2018

Multiple studies have shown that the hippocampus is a major part of the limbic system of the brain. It has complex cyclic connections with other brain structures. The hippocampus is an area that stores the sensory information that is associated with effective programs of behavior. The projection of this region in the cortex creates a sense of emotional background, which is a factor of automatic extraction and evaluation of programs, in accordance with past experience, including programs got with a new consciousness. Neurons of hippocampus differ with a severe background activity. Up to 60% of neurons in the hippocampus are responding on the sensory stimulation. Electrical activity is a manifestation of complex shape analyzer processes in stimulating tissues. Changes in activity may indicate the occurrence of adaptive processes that are the result of stress- realizing and stress- limiting systems. One of the main roles in these systems plays hippocampus. The main neurotransmitters of synaptic stimulation in the hippocampus are glutamate. In the hippocampus under conditions of chronic stress are developing neurodegenerative processes in which primary importance belongs to prolonged changes in membrane potential of neurons that potentiate the action of glutamate on nerve cells. Balanced job of synaptic stimulation/inhibition and neurotransmitters systems is underlying the transmission, processing and storage of information in the hippocampus, as well as generating its rhythms, which is a kind of clock operating frequencies of the structure of the brain. Obviously, the various factors that affect the body from the outside can affect on recovery efficiency of electric shift of homeostasis. One of such factors are caffeinated substances, due to their inhibitory effect on phosphodiesterase and interaction with the purine receptors, which ultimately leads to the predominance of stimulating in the brain. In addition, for many decades consumption of caffeinated products with neuro-stimulating properties have greatly increased. Leaders in this list remain coffee and tea. Today the well-known biological effects of caffeinated substances are investigated their chemical composition and process of the transformation in the body. The wide range of research is due to the high consumption of these substances. The environmental factors indirectly or directly, in combination or single affect health, and the caffeinated substances can go to one of the best in strength and impact performance. In neurochemical mechanism of stimulating effect of caffeine plays an important role its ability to bind to specific ("purine" or adenosine) receptors in the brain, the endogenous ligand for which is purine nucleoside – adenosine. The structural similarity of molecules of caffeine and adenosine contributes to this. Since adenosine is seen as a factor that reduces the stimulating processes in the brain, replacing its caffeine results in stimulative effect. Prolonged use of caffeine promotes the formation of new adenosine receptors and the effect of caffeine gradually decreases. However, the sudden cessation of caffeine consumption, adenosine covers all receptors that may lead to increased inhibition with symptoms of fatigue, sleepiness, depression. The relevance of this work is determined by the following observations. Activating mechanism of action of these substances is launching adaptive responses that represent the interaction stress-activating and stress-limiting systems. Energy shortage of the last one under these conditions can appear the cause of many neurodegenerative patalohiy. What may occur in terms of the electroencephalogramm. Electrical activity of the hippocampus, in turn, is one of the indicators of the functional state, which plays an important role in adaptive-compensatory reactions. Therefore, we can assume that prolonged consumption of caffeinated substances can lead to neurodegenerative changes that will show itself in terms of power on hippocampogramm. Therefore, the present study has to identify the dynamics of the bioelectrical activity of the hippocampus of rats under prolonged consumption of caffeinated substances. Experiments were carried out on non-linear white male rats. At the beginning rats were with weight 125–140 g. The animals were divided into 2 groups. The first group consisted of control animals (n = 20). The second group (n = 15) was presented by the animals feeded with pure caffeine in an amount of 150 mg/kg/day. Registration of electrohippocampogramm was performed in acute experiments in the subgroup of 3–5 animals every 2 weeks throughout the study, which lasted for 8 weeks. Background electrical activity of the hippocampus were recorded using standard electrophysiological complex equipment. Recordings started when the electrical activity of the hippocampus disappeared drugs spindle. Each animal spent 10–12 records for 1–2 minutes and then these records are digitally stored on a personal computer and processed using the application package consisting of "MathCAD 2001". Analyzed spectral power (mkV2) and normalized power (%) waves of background electrical activity of the hippocampus within common frequency bands. In the group of animals that continued to receive caffeine in its pure form at the beginning of experiment was observed desynchronization of rhythms in hippocampogramm that after 8 weeks of the study varied synchronization. The results may indicate that the effect of coffeine substances on neurophysiological parameters of electrical activity of the hippocampus of rats reflects one of the many lines of action of some form of nutritional stress, which mechanisms relate to the agreed work and limiting and activating systems of the brain over time.