Correction of the profile of sex hormones in male rats under conditions of changing the light regime

Abstract

A study is aimed to determine the effect of enhancing the preventive and restorative effects of the drug melatonin on reproductive system of experimental animals, which have been exposed to prolonged light exposure, due to the introduction of adaptogen (natural origin — food supplement spirulina) into their diet. The aim of the study is to establish the destructive influence of the long-term prolongation of the lighting regime on the hormonal profile of sex hormones and justification of efficiency of combined melatonin and spirulina administration for preventing the process of dysregulation of reproductive function and its recovery in male rats. Materials and methods. The study has been performed on 140 adult male Wistar rats in summer and autumn periods, against the background of reducing the duration of been daylight (July-October). At the beginning of the experiment, 7 groups of 20 rats were formed according to the nature of light effect and intensity: control group K — the animals have been in a natural change of day and night; group 12/12 — rats have
been kept under artificial lighting for 12 hours a day; group 24/00 — animals have been kept in round-the-clock artificial lighting; groups 12/12+M and 24/00+M — rats, which, against the background of altered light regime, have received the drug «Vita-melatonin» (M) in the evening; groups 12/12+M+C and 24/00+M+C — rats, which, against the background of changed light regime, have been injected a bioadditive «Spirulina» (C) in the morning, and «Vita-melatonin» — in the evening. The modified photoperiod for rats was simulated for 3.5 months using electric lighting with 100-watt incandescent bulbs. The concentration of testosterone (T) and estradiol (E2) in the blood plasma of rats was determined by immunoenzyme method. Likelihood of differences was evaluated by using the Student’s t-test at p<0.05. Results. There has been a tendency to increase the testosterone level and decrease the estradiol content in the blood of rats from group 12/12 with administration of melatonin only one, which led to a significant increase in the T/E2 index by 25% (p<0.05). Under the conditions of co-administration of M+C a probable increase in testosterone level to control values and a proportional decrease in blood estradiol (by 23%,
p<0.05) were noted. In accordance with almost normal values, the ratio of T/E2 increased (to 342.7±29.7 versus 386.8±36.7 7 in the control, which was +54% of the indicators of group 12/12). In the group of rats 24/00 with the administration of melatonin, testosterone level increased by more than a third relative to the group of pathological control and had no significant differences from the values in the group of intact rats exposed to natural light. At the same time, estrogenemia in such animals decreased to a lesser extent — by 25% from group 24/00. In round-the-clock lighting, against the background of a complex course of M+C testosterone levels in group of rats 24/00+M+C increased by 47% from pathological control and practically did not differ from indicators of intact rats (31.8±0.9 nmol/l and 33.0±0.6 nmol/l, respectively). Although the level of E2 in the group of animals which were subjected to round-the-clock lighting, decreased by 31% from values of group 24/00, however, it was higher than the control values by 22%. Based on this, the T/E2 ratio, although it grew more than
twice, still not reached the values of the control group (289.8±21.1 and 386.8±36.7, respectively, p<0.05). Conclusions. 1. Profound changes in the profile of sex hormones, which progress and deepen with increasing light time were revealed in male rats against the background of light load. 2. Course administration of melatonin contributed to a significant increase in testosterone level in male rats, reduced the estradiol level, which led to a corresponding drop in the T/E2 ratio, but did not lead to complete normalization of the analyzed indicators. 3. The high efficiency of the used scheme of course compatible prophylactic use of melatonin in combination with spirulina for preventive decrease in the risk of reproductive disorders in male rats was shown.