Factors Affecting the Circadian Rhythm: Toxicological Perspective

Abstract

Since the beginning of animal evolution, adaptation to the environmental factors has been key to survival in order to maintain the continuity of the spe cies. Therefore, numerous physiological mechanisms developed over the years to overcome adversities to the point where living organisms learnt to anticipate them through an internal biological clock: the circadian rhythm. Its discovery opened a new dimensi on of study in the scientific field with more and more researchers gaining interest about this subject up to the present day. It has been found that this internal rhythm is entrained by both internal and external factors and is responsible for the synchron ization of all physiological processes through peripheral clocks, where the main pacemaker, the suprachiasmatic nucleus (SCN), is located in the hypothalamus. The SCN releases neurotransmitters that orchestrate the rest of the system acting in different ta rget tissues, but recent studies showed that a deeper level of control governed the protein synthesis: the genetic molecular level. This means that our genetic material contains clock genes that regulate the biological clock. The goal of this work is to de scribe the main factors that negatively affect in different ways the correct function of the circadian rhythm, leading to health issues due to the chronodisruption and the consequent metabolic disorder. These can act in a wide range of situations, being cl assified as environmental, behavioural, intrinsic and iatrogenic factors. Finally, taken the fact that in modern life we’re constantly exposed to many of these factors, some ideas are exposed about the application of this knowledge into people’s lifestyles and into vital aspects such as pharmacological therapy, technological and chemical industry, etc which seek to protect and even promote human beings’ health.