Role of Neurotransmitter and Behavioral Changes in Mice due to Light- Dark Stress

Abdul Rahman K Al Asmari,Anvarbatcha Riyasdeen

doi:10.4172/2469-9780.1000103

Abstract

Light-dark cycle has an evident role in maintaining the circadian rhythm of complex living organisms. Disturbance of light-dark cycle has an effective role in distressing the normal functions of living organisms. In this study we have analyzed the behavioral changes and role of neurotransmitter in mice due to light-dark cycle disturbances. Batches of animals were exposed to continuous light and dark conditions for 1, 2, 3, 4 and 5 days. The physiological behavior analyses such as vertical, horizontal, ambulatory and response to light-dark exposures were recorded in the disturbed and control animals. Also the role of neurotransmitter such as Dopamine, 5-HT, 5-HIAA and Homovanillic acid were estimated in the disturbed and control animal nervous tissues such as cerebrum, cerebellum and brain stem. Based on the behavioral analysis it was found that continuous light exposures have increased the horizontal and ambulatory movement of mice more significantly than the continuous dark exposed animal upon comparison with normal 12-12 dark-light exposed animals. Also the continuous light exposed animals showed an aversion to light and liking to dark upon light-dark visit but the vice versa was not found with the dark exposed animals. Dopamines and 5-HT were found down regulated in both the light and dark exposed animals significantly when compared to the normally housed animals. The identified changes in behavioral and neurotransmitter level in mice due to light-dark disturbances are impacting the fact of association of stress, sleep and circadian rhythm in mice.

Highlights

The behavior and physiology of most of the animals existing on the earth are reliant on the 24-hour cyclic clock called light-dark cycle (LD)
Disturbance of LD cycle affects the normal functions of living organisms by disturbing their circadian rhythm
Mice exposed to continuous light and dark conditions showed discrete changes in their behavior upon analysis

Summary

Introduction

The behavior and physiology of most of the animals existing on the earth are reliant on the 24-hour cyclic clock called light-dark cycle (LD). Disturbance of LD cycle affects the normal functions of living organisms by disturbing their circadian rhythm. The inbuilt endogenous oscillators command the circadian rhythm such as blood pressure, heart rate, sleep-wake cycle, hormonal secretion and metabolism [1]. Mammals have the most complex and well-formulated circadian rhythm centered with light-dark cycle and sleep. The behavioral rhythms of rats were found deregulated with arrhythmic behavior when their circadian rhythms were disturbed by short light-dark and continuous light-dark exposures [5]. From our earlier study it has been shown that disturbances to LD cycle by exposing to continuous light or dark conditions causes adverse effect on zebra fish by deregulating large number of genes and proteins [6]

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