Sex features of the circadian rhythmicity of some biochemical parameters in wistar rats under constant lighting and chronic alcohol intoxication

BACKGROUND: Biological systems of all levels of organization are characterized by the rhythm of functioning processes, which are one of the fundamental properties of living matter. The complex of circadian rhythms of mammals, being genetically determined, is quite plastically modulated by the action of periodic factors of the external and internal environment. Significant factors in the disorganization of biorhythms in the modern world include a violation of the light-dark regime, so-called light pollution. Alcohol abuse remains one of the most important medical and social problems of modern society. One of the important effects of alcohol is its destructive effect on the circadian rhythms of many physiological processes.

AIM: The aim of the research was to study the influence of constant lighting, chronic alcohol intoxication and joint effect of these factors on the diurnal dynamics of several biochemical parameters in Wistar rats of both sexes.

MATERIALS AND METHODS: The study was conducted on 200 and 160 female outbred Wistar rats at the age of 6 months, weighing 350 ± 15 g. Rats were divided into 8 groups. 1^st group (control ♂) is kept at fixed light regime (light/dark 10:14 hours with lights on at 8:00 and off at 18:00). 2^nd group, males (n = 50) is kept under the same conditions as the control, but receives a 15 % aqueous solution of ethanol ad libitum as a drink instead of water, i.e. is subjected to chronic alcohol intoxication. Group 3, males (n = 50) are kept under constant light. The 4^th group, males (n = 50) are also kept under constant illumination and receive 15 % aqueous ethanol solution ad libitum as a drink. Group 5 (control ♀) females (n = 40), are kept at a fixed light regime (light/dark 10:14 am with lights on at 8:00 and off at 18:00). The 6^th group, females (n = 40) are kept under the same conditions as the control, but receive 15 % aqueous ethanol solution ad libitum instead of water as a drink, i.e. subjected to chronic alcohol intoxication. Group 7, females (n = 40) are kept under constant light. The 8^th group, females (n = 40) are also kept under constant light and receive 15 % aqueous ethanol solution ad libitum as a drink. In the blood samples taken at 9:00, 15:00, 21:00 and 3:00 hours the content of AST, ALT, glucose, total protein, albumin, total and direct bilirubin was measured. The reliability of circadian rhythmicity of studied parameters was assessed with use of cosinor analysis.

RESULTS: It is established that the chronic alcohol intoxication, constant illumination and joint action of this factors lead to similar changes in biochemical parameters in rats of both sexes, but in female rats the level of AST, total and direct bilirubin changes as a result of three weeks of intoxication, which is not observed in males. In turn, both individual and joint effects of chronic alcohol intoxication and dark deprivation lead to significant changes in rhythmostasis in rats, however, circadian rhythms of total protein, as well as both types of bilirubin, are more resistant to dark deprivation in females than in males.

CONCLUSIONS: The conducted study testifies that a three-week chronic alcohol intoxication causes more significant changes in the biochemical profile in female rats compared to males. At the same time, the studied circadian rhythms of the biochemical parameters of the organism of females turn out to be more resistant to dark deprivation than those of males, being destroyed only under the combined action of chronic alcohol intoxication and constant illumination.