Dim Light at Night Induced Neurodegeneration and Ameliorative Effect of Curcumin.

Dhondup Namgyal,Fahad A Al-Misned,Armiya Sultan,Kumari Chandan,Hamed A El-Serehy,Maryam Sarwat,Sher Ali,Mehreen Aftab,Rachna Mehta

doi:10.3390/cells9092093

Abstract

It is a well-known fact that following a proper routine light/dark or diurnal rhythm controls almost all biological processes. With the introduction of modern lighting and artificial illumination systems, continuous exposure to light at night may lead to the disruption of diurnal rhythm. However, the effect of light during the night on brain anatomy, physiology, and human body functions is less explored and poorly understood. In this study, we have evaluated the effect of exposure to dim light (5 lux) at night (dLAN) on Swiss Albino mice over a duration of three consecutive weeks. Results have revealed that exposure to dLAN led to an impairment of cognitive and non-cognitive behaviour, oxidative stress–mediated elevation of lipid peroxidation, and reduction of superoxide dismutase and catalase activity. It also led to the downregulation of hippocampal proteins (BDNF, Synapsin II and DCX) at both protein and mRNA level. Additionally, there was downregulation of CREB and SIRT1 mRNAs and neurodegeneration-associated miRNA21a-5p and miRNA34a-5p. The pyramidal and cortical neurons started showing pyknotic and chromatolysis characteristics. However, a dose of curcumin administered to the mice positively modulated these parameters in our experimental animals. We proposed the modulatory role of curcumin in addressing the deleterious effects of dLAN.

Highlights

Modernization and advancement of technology has brought about tremendous benefits and improvement in the health care system and has primarily led to an elongated human lifespan
150 mg/kg body weight) of curcumin, results showed a significant increase in brain-derived neurotrophic factor (BDNF) (F3,8 = 588.40, p < 0.001), Synapsin II (F3,8 = 65.52, p < 0.001), DCX (F3,8 = 43.84, p < 0.001), cycliccyclic response-element binding proteinprotein (CREB) (F3,8 = 1672.00, p < 0.001) and SIRT1 (F3,8 = 609.10, p < 0.001) mRNA expression in dose-dependent manner and curcumin dose 150 mg/kg was found to be a prominent one (Figure 5b,d,f,h,j). These findings suggest that SIRT1 mediated CREB signalling pathway paves for the upregulation of BDNF, Synapsin II and DCX hippocampal proteins in the dLAN treated groups
The current study revealed that chronic exposure to dLAN has led to the degeneration of hippocampal neuronal cells through oxidative stress mediated by reduction of hippocampal neurogenesis associated genes (BDNF, Synapsin II, DCX, CREB, and SIRT1)

Summary

Introduction

Modernization and advancement of technology has brought about tremendous benefits and improvement in the health care system and has primarily led to an elongated human lifespan. The natural cycle of day (light) and night (dark) had accompanied the evolution of animal and plants since the beginning of life on earth. This cycle has led to the development of a diurnal rhythm in each living organism; based on this cycle, our physiological processes are adapting and changing continuously. It is a well-established fact that the daily light/dark cycle or diurnal rhythm. People are gradually realizing the ill effects of night-time light exposure and considering it as an environmental perturbation [5,6]

Methods

Discussion

Conclusion