Circadian variations of neurotransmitters in the brain – Its importance for neuroprotection
Francisco Estrada-Rojo, Carolina Escobar, Luz Navarro
Abstract
Circadian rhythms are expressed at the biochemical, physiological, and behavioral level; they help to maintain the internal temporal order of an organism and allow adaptation to a cyclical environment. Circadian rhythms have a substrate at the genetic level and are synchronized to geographical cycles, as well as to other external factors, of which the main one is the light-dark cycle. Cerebral functions present circadian rhythms, which influence the neuroprotective response to acquired brain damage, such as a traumatic brain injury (TBI). Knowing the moments of greatest vulnerability to such events will allow us to offer elements to develop better study models and therapeutic objectives. Here, we present a review on diurnal variation in the levels of noradrenaline, histamine, orexin, glutamate, gamma-aminobutyric acid, serotonin, acetylcholine (ACh), and dopamine, as well as in the expression of their receptors in the brain, neurotransmission systems that may be involved in neuroprotective responses to a TBI.