Undoubtedly caffeine is widespread in modern society. Coffee, tea, cocoa, energy drinks, chocolate are just few highly popular examples of the caffeine-containing products that have become an integral part of most people’s lives. Therefore, the impact of caffeine on the organism’ autonomous functioning in a particular age period is extremely important. Assessment of heart rate variability indicates the absence or presence of possible changes, which also describes the excitation or inhibition of a particular part of the autonomic nervous system, as well as possible cardiac regulation mechanisms that are involved in this process. The ratio between the parasympathetic and sympathetic nervous system supports both the metabolic balance and all physiological body systems’ functioning. The obtained results can serve the basis for creating prognostic models of the caffeine effect on human body, and obtaining new data towards the nervous system of pubertal rats autonomous functioning under the influence of the particular substance. The experiments were carried out on non-linear mongrel white pubertal male and female rats. Rats of the corresponding age were divided into 4 groups. The control animals were kept in regular conditions of detention and had a normal diet. Male and female rats of experimental groups were kept in regular detention conditions for laboratory animals and daily consumed caffeine at a dosage of 150 mg/kg for one month. An electrocardiogram (ECG) was recorded using needle electrodes (II standard lead). The paper assesses the changes in heart rate variability (HR, Mo, AMo, VAR, AEI, SI) of non-linear pubertal male and female rats after one month of daily caffeine intake. Taking into consideration that the analysis of heart rate variability (HRV) is one of the most informative and neoteric methods of research of the nervous system’ autonomous functioning, the indices of typical correlation rhythmograms and variation pulsograms of animals of the control and experimental groups were analyzed. The monthly caffeine usage by rats of both sexes indicated that the changes in the indices on correlation rhythmograms and variationalpulsograms were noticeable even visually. Such differences were discovered: firstly in the image and location of the cloud, secondly in the range of the R-R intervals location that were the most common. We recorded similar changes in heart rate variability indices, which reflect the features of its regulation, under the influence of caffeine on both male and female young rats. Daily caffeine consumption during one month resulted in significant changes in all indicators of cardiac rhythm variability of male rats, namely, an increase in heart rate, Mo and AMo by 1.1, SI by 1.8, AEI by 2 and VAR decrease by 1.9. Significant changes for female rats were increase of SI by 1.7 and AEI by 1.9. Consumption of caffeine, at a dosage of 150 mg / kg, for one month by young rats of both sexes had a stronger effect on male compared to female rats of the corresponding age. The results obtained after monthly caffeine exposure to young rats indicated a predominance of activity of the heart rate regulation mechanisms, both for males and females. The study clarified that under the influence of caffeine on young rats there was observed a predominance of sympathetic over parasympathetic autonomous nervous system, an increase in the heart rate, a decrease in VAR and an increase in other indicators of heart rate variability. Thus, the adaptation-compensatory reactions were activated and the excitation processes predominated in the pubertal female and male rats due to the activation of the sympathetic autonomous nervous system.
Keywords: caffeine, autonomous nervous system, heart rate variability, young rats
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