Sleep apnea pathophysiology

Abstract

Objective The purpose of this study is to examine the pathophysiology underlying sleep apnea (SA). Background We consider several critical features of SA including the roles played by the ascending reticular activating system (ARAS) that controls vegetative functions and electroencephalographic findings associated with both SA and normal sleep. We evaluate this knowledge together with our current understanding of the anatomy, histology, and physiology of the mesencephalic trigeminal nucleus (MTN) and mechanisms that contribute directly to normal and disordered sleep. MTN neurons express γ-aminobutyric acid (GABA) receptors which activate them (make chlorine come out of the cells) and that can be activated by GABA released from the hypothalamic preoptic area. Method We reviewed the published literature focused on sleep apnea (SA) reported in Google Scholar, Scopus, and PubMed databases. Results The MTN neurons respond to the hypothalamic GABA release by releasing glutamate that activates neurons in the ARAS. Based on these findings, we conclude that a dysfunctional MTN may be incapable of activating neurons in the ARAS, notably those in the parabrachial nucleus, and that this will ultimately lead to SA. Despite its name, obstructive sleep apnea (OSA) is not caused by an airway obstruction that prevents breathing. Conclusions While obstruction may contribute to the overall pathology, the primary factor involved in this scenario is the lack of neurotransmitters.

Astrocyte-induced firing in primary afferent axons

“…However, there is accumulating evidence that their functions go beyond the relaying of jaw proprioceptive inputs for oro-sensory-motor control. Indeed, those cells are involved in numerous other brain functions, such as whisker pad proprioception (Mameli et al, 2010;Mameli et al, 2017), food intake regulation (Fortin et al, 2021), stress-induced masseter hyperactivity (Zhao et al, 2022) and sleep physiology (Andrisani & Andrisani, 2023), to name a few. This implies that understanding the factors that regulate their excitability is paramount, and more studies are required to reach this objective.…”