Models of modern-day circadian rhythm disruption and their diabetogenic potentials in adult male Wistar rats

Abstract

Background: Light at night (LAN) threatens metabolic health by delaying our sleep timing and allowing us to eat at odds with our circadian clocks. Circadian research interests are majorly focused on jet lags, shift work, and the non-24-h days. Since exposure to LAN, sleep loss, and late night eating are common scenarios of modern-day circadian rhythm disruption, developing an animal model that better mirrors these scenarios and investigation of their diabetogenic potentials is a research priority. Materials and Methods: Over the course of 6 weeks, we developed chronic LAN exposure (LAN), sleep restriction (SR), abnormal feeding (AF), rural social jetlag (RSJ), night shift work (NSW), and urban social jetlag (USJ) models, using male Wistar rats. Gentle handling was used to induce SR, while LAN was instituted using a customized light rack system. Circadian and blood glucose rhythms were, respectively, determined using 4 hourly temperature and blood glucose measurements. Statistical analysis was done using SPSS V20.0 and OCosinor SoftwareO. The data were summarized using mean ± standard deviation as well as MESoRs, amplitudes, and acrophases. Statistical significance was considered as P ≤ 0.05. Results: Our findings have revealed a significantly (P < 0.01) higher average nocturnal glucose (126 mg/dL) and temperature (36.53°C) rhythms compared to diurnal glucose (108 mg/dL) and temperature (35.50°C) rhythms in the controls rats. All the developed models are noted to have a distorted light: dark glucose and temperature rhythms with acrophases of the core body temperature in controls, RSJ and USJ models occurring at 08:16 pm, 2:43 pm, and 7:48 pm local time, respectively. The vector components of the phase changes revealed 5 h phase delay in the LAN model and 28 min, 1 h, and 4.5 h phase advancements among the USJ, AF, and SR models, respectively. These indicate circadian disruption and blood glucose dysrhythmia among the SR, AF, LAN, RSJ, USJ, and NSW models. Conclusion: Our findings have suggested the circadian disruptive and diabetogenic nature of our widespread modern-day social behaviors.