The effect of chronic sleep restriction and exercise in adolescence on anxiety behavior in adulthood: An experimental study

Background and Aim: It is known that anxiety disorders can develop in adolescence due to chronic sleep restriction. Furthermore, it is known from the literature that exercise can reduce anxiety-like behaviors. However, information on long-term outcomes is insufficient. The aim of our study was to determine the possible effect of aerobic exercise on anxiety-like behaviors that may develop due to chronic sleep restriction in adolescence and whether this effect will continue into adulthood. Material and Methods: In the present study, 40 adolescent male Wistar Albino rats were randomly assigned to one of four experimental groups: control, sleep restriction, exercise, and exercise+sleep restriction. The sleep restriction groups were subjected to sleep restriction for 20 hours per day, 4 days per week, for a period of 4 weeks, using a modified multi-platform method. The exercise groups participated in swimming exercises on four days of the week, starting with 30 minutes and then increasing to 60 minutes. At the conclusion of the four-week period, an evaluation of anxiety-like behaviors was contucted using the elevated plus maze and holeboard tests.Additionally, blood samples were collected for analysis. Subsequently, all groups were maintained in their respective cages, where they were permitted to engage in their normal sleep and movement patterns for a period of eight weeks, until they reached adulthood. The behavioral tests were repeated on two further occasions, at four-week intervals, and the animals were sacrificed at the conclusion of the eighth week. Tissues from the prefrontal cortex and hippocampus were removed, and blood samples were also collected. Adrenocorticotropic hormone and corticosterone were evaluated in the blood samples. Liquid chromatography tandem mass spectrometry was employed to evaluate the levels of various neurotransmitters, including adrenaline, noradrenaline, serotonin, and dopamine precursors and metabolites, in prefrontal cortex and hippocampus tissues. In addition, ELISA was utilized to assess the concentration of collybistin, while immunohistochemistry was employed to determine the expression of neuroligin-2. Additionally, histopathological examination was conducted using hematoxylin-eosin staining. Results: Sleep restriction did not increase anxiety-like behaviors. The frequency of open arm entries increased in the exercise group (E) compared to the control (C) and sleep restriction (SR) groups (E:45.6±6.9; C:20.3±4.1; SR:22.5±4.8; p=0.018 and p=0.042, respectively). In early adulthood, the frequency of open arm entries was significantly higher in the exercise group than in the control and sleep restriction groups (E:25.8±3.3; C:9.6±3.4; SR:6.8±2.1; p=0.040 and p=0.021, respectively). The relative weight of the hippocampus was lower in the sleep-restricted group compared to the control and exercise groups (C:130.5±10.6; ix E:134.8±7.6; SR: 96.6±4.8 (mg/kg)×1000; p=0.030 and p=0.011, respectively). Collybistin levels in prefrontal cortex were significantly decreased in the sleep restriction group and in the group whose sleep was restricted with exercise (E+SR) compared to the control group (C:3.05±0.22; SR:2.47±0.42; E+SR:2.50±0.42 ng/ml; p=0.017 and p=0.026, respectively). Neuroligin-2 immuno-histochemistry results did not differ between the groups. Histopathologic examination results showed the presence of neuronal dysregulation in both the sleep restriction and exercise with sleep restriction groups. Conclusion: In adolescence, sleep restriction did not increase anxiety-like behaviors, whereas swimming exercise decreased them. These effects of exercise partially persisted into early adulthood and then disappeared. Sleep restriction decreased hippocampus weight, while exercise partially prevented this effect. The decrease in prefrontal cortex tissue collybistin levels in adulthood indicated that sleep restriction may have a long-term effect on GABAergic neurotransmission. Keywords: REM sleep restriction, exercise, anxiety, collybistin, neuroligin-2