Volume 1 • Issue 1 • 1000103 Short Communication Open Access Neurochemistry & Neuropharmacology N e u r o c h e m i s t r y & N e u r o p h a r m a c o l o g y ISSN: 2469-9780 Al-Asmari et al., Neuropharm Open Access 2015, 1:1 Keywords: Light-dark cycle; Stress; Sleep; Neurotransmitter; Behaviour Introduction Te 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 afects the normal functions of living organisms by disturbing their circadian rhythm. Te inbuilt endogenous oscillators command the circadian rhythm such as blood pressure, heart rate, sleep-wake cycle, hormonal secretion and metabolism [1]. Te central circadian clock of mammals is maintained by the suprachiasmatic nucleus (SCN) of the anterior hypothalamus [2,3]. Mammals have the most complex and well-formulated circadian rhythm centered with light-dark cycle and sleep. Mice, the nocturnal animal does most of its active work during the dark phase, which is in contrary to the diurnal animals, which does majority of the activity in light phase. Sleep is regulated by homeostatic interaction of circadian processes, which controls the duration and optimal time for sleep [4]. Similarly 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 efect on zebra fsh by deregulating large number of genes and proteins [6]. It is well understood that neurotransmitter plays prominent role in maintenance of circadian cycle by exhibiting its function in SCN. Fluctuations in the level of neurotransmitter in rat were observed when they were exposed to disturbed light-dark cycles [7]. In this study we aimed to understand the efective role of disturbance of LD cycle in mice by exposing the animals to continuous light and dark conditions. Materials and Methods Light/dark experiments in mice Healthy Adult C57BL/6J mice of 3 months old maintained at the Animal house facility, Research Center, PSMMC, under standard 12-12 light-dark conditions were selected for the study. Te animals were fed with continuous water and food for the entire period of the experiment. Batches of animals (6 animals per batch) were exposed to continuous light, continuous dark and the 12-12 light/dark conditions for 1, 2, 3, 4 and 5 days. For continuous dark experiment the animals were housed in the standard laboratory conditions in dark environment and similarly for the light experiment the animals were exposed to continuous light of 600 luminous fux intensity. Behavioral analysis Te behavior of the animals housed at standard, continuous light and continuous dark conditions were monitored for its horizontal movement, vertical movement, ambulatory movement and grooming using Animal activity meter (Opto-Varimex, USA). Te animals were monitored for 2 minutes per activity afer acclimatizing the animal in the activity meter in their respective light-dark conditions. Te time and light-dark conditions for the measurement of activity were maintained same throughout the experiment. Te dark condition experiments were performed under a dim red light, whose illumination does not have any role in disturbing the dark conditions. Obtained readings were tabulated for statistical analysis. Biochemical analysis of neurotransmitter After behavioral analysis in their respective light-dark conditions the animals were sacrificed using cervical disc Role of Neurotransmitter and Behavioral Changes in Mice due to Light- Dark Stress Abdul Rahman K Al-Asmari*, Anvarbatcha Riyasdeen, Hamoud M Al-Shahrani and Mohammed M Idris Research Center, Prince Sultan Military Medical City (PSMMC), Riyadh, Saudi Arabia 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 signifcantly 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 signifcantly when compared to the normally housed animals. The identifed 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. *Corresponding author: Abdul Rahman K. Al-Asmari, Research Center, Prince Sultan Military Medical City, Riyadh, 11159, Saudi Arabia, Tel: 00966506417236; E-mail: abdulrahman.alasmari@gmail.com Received September 16, 2015; Accepted October 05, 2015; Published October 11, 2015 Citation: Al-Asmari ARK, Riyasdeen A, Al-Shahrani HM, Idris MM (2015) Role of Neurotransmitter and Behavioral Changes in Mice due to Light-Dark Stress. Neurochem Neuropharm Open Access 1: 103. Copyright: © 2015 Al-Asmari ARK, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Neurochem Neuropharm Open Access, an open access journal ISSN: 2469-9780