Fig 1.
Effects of constant light exposure on body weight and food intake in rats.
(A) Experimental timeline. Rats were randomly assigned to either the control group (12:12 h light/dark cycle, L/D) or the constant light group (24-hour light exposure, L/L) for 30 days. (B) Body weight and food intake were monitored regularly throughout the experiment. On Day 30, motor coordination was evaluated using the Rota Rod test, followed by euthanasia and sample collection for biochemical analyses. (C) Food intake was measured every two days per cage (n:5). Total food consumption was significantly lower in the CL group compared to the control group (**p:0.0102; n:15). (D) Initial body weights were similar between groups. By the end of the study, control animals exhibited a significant increase in body weight, whereas the CL group showed no significant change. At week 4, body weight in the control group was significantly higher compared to the CL group (*p = 0.0302; n:15). All data are presented as mean ± SEM.
Fig 2.
Biochemical effects of constant light exposure on Otolin-1, melatonin, and 25(OH)D levels in rats.
(A) Serum Otolin-1 levels were significantly higher in the constant light (CL) group compared to controls, indicating a potential biomarker of otoconial disturbance (**p:0.0075; n:12-14). (B) Similarly, cochlear Otolin-1 concentrations were elevated in the CL group, supporting the possibility of inner ear structural changes under circadian disruption (*p:0.0129; n:9). (C) Melatonin levels, measured at the onset of the passive period, were significantly reduced in the CL group, confirming suppression of pineal activity and disruption of the circadian rhythm (*p:0.0113; n:12-14). (D) Serum vitamin D concentrations were markedly lower in CL-exposed rats, suggesting impaired synthesis or altered metabolism due to lack of dark-phase signaling (**p:0.0094; n:7). All data are expressed as mean ± SEM.
Fig 3.
Assessment of serum electrolyte levels following constant light exposure.
Serum levels of chloride (A), calcium (B), sodium (C), and potassium (D) were measured to evaluate the impact of circadian rhythm disruption on electrolyte homeostasis. No statistically significant differences were observed between the CL and control groups (p > 0.05; n:8), and all values remained within normal physiological limits. These findings suggest that constant light does not markedly affect systemic electrolyte balance in young rats. Data are expressed as mean ± SEM.
Fig 4.
Rota Rod performance indicating impaired motor coordination in the CL group.
The CL group showed a significantly reduced latency to fall compared to controls (p = 0.0014), suggesting vestibular dysfunction associated with circadian rhythm disruption. Data are expressed as mean ± SEM.