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Neurotransmitters and pharmacology
Published in Mark J. Ashley, David A. Hovda, Traumatic Brain Injury, 2017
Ronald A. Browning, Richard W. Clough
ACh is also a neurotransmitter in the CNS, where specific pathways have been identified in the brains of primates and other species. Basically, there are two groups of ACh neurons (cell bodies) from which axonal pathways project:17 1) those pathways innervating the forebrain (cell bodies in the basal forebrain in and around the medial septum and nucleus basalis of Meynert) as well as the interneurons in the striatum (basal ganglia) and 2) those innervating the brain stem and diencephalon (cell bodies in the laterodorsal tegmental nucleus and the pedunculopontine tegmental nucleus). Some of the proposed functions of ACh in these CNS pathways are given in Table 16.2, but clearly, there is much to learn about the intricate details of how ACh regulates such things as learning and memory, sleep, seizures, and emotional states, each of which are or may be changed following TBI (see below). First, however, it is essential to review the physiology and pharmacology of ACh.1
Correlations with REM sleep behavior disorder severity in isolated rapid eye movement sleep behavior disorders patients
Published in International Journal of Neuroscience, 2023
Sang Jin Kim, Eun Ju Chung, Ki-Hwan Ji, Mi-Ri Kang, Jin Yong Hong, Sunseong Lee, Ji Sun Park, Jungsu S. Oh, Jae Seung Kim, Suk Yun Kang
The correlation between pain and visuospatial dysfunction with RBD severity may be associated with RBD pathophysiology. This pathophysiology is currently poorly understood, but RBD is thought to be associated with several nuclei in the pontomedullary brainstem that include the locus coeruleus, subcoeruleus/sublateral dorsal nucleus, laterodorsal tegmental nuclei, the PPN, and medullary magnocellular reticular formation [8]. These nuclei play a role in pain modulation, visuospatial attention, and cognition including visuospatial function and memory [24–26]. The locus coeruleus is a norepinephrine-producing nucleus in the dorsal pons, and projects to the brain widely and is involved in homeostasis, sensory processing, and cognitive and motor function [24,26]. The raphe nuclei are serotonin-producing nuclei in the midline from the medulla to the midbrain and are also involved in sensory processing that includes pain, heat, touch [27], and visual orientation [28]. One recent study reported increased thermal detection threshold in iRBD patients, and they assumed that peripheral small nerve fibers might be associated because they did not find a difference in laser evoked potentials and conditioned pain modulation between iRBD patients and controls. However, more studies are needed, because they did not perform skin biopsies to check nerve pathology and did not assess the presence and severity of pain in iRBD patients [29]. Besides, there was no PSG data to determine RBD severity in that study.
EEG coherence and power spectra during REM sleep related to melatonin intake in mild-to-moderate Alzheimer’s disease: a pilot study
Published in International Journal of Neuroscience, 2023
Manuel Alejandro Cruz-Aguilar, Ignacio Ramírez-Salado, Marisela Hernández-González, Miguel Angel Guevara, Ana Paula Rivera-García
Regarding the neurophysiological mechanisms of REM sleep, currently there is evidence that the cholinergic neurons of the pedunculopontine (PPT) and laterodorsal tegmental nuclei (LDT) promote REM sleep and the fast EEG activity typical of this stage. Likewise, glutamatergic neurons of the sublaterodorsal nucleus (SLD) produce muscle paralysis during REM sleep by exciting GABAergic/glycinergic neurons in the ventromedial medulla and spinal cord that hyperpolarize motor neurons. During REM sleep, the ventrolateral periaqueductal gray is likely inhibited by GABAergic neurons in the SLD and medulla [23, 24]. In addition, studies describe that a group of neurons of the ventrolateral pre-optic area (VLPO) is capable of inducing REM sleep through projections that inhibit the expression of monoamines of the dorsal raphe and locus coeruleus [25–27].
Advances in pharmaceutical treatment options for narcolepsy
Published in Expert Opinion on Orphan Drugs, 2018
Tatsunori Takahashi, Sakai Noriaki, Mari Matsumura, Chenyu Li, Kayo Takahashi, Seiji Nishino
Hypocretin neurons have widespread projections to the brainstem areas linked to sleep/wake controls and motor inhibitions including the dopaminergic (DA) ventral tegmental area, noradrenergic (NA) locus coeruleus, serotonergic (5HT) raphe nuclei, and cholinergic laterodorsal tegmental nuclei [41]. Hypocretin −1 and hypocretin-2, which are also called orexin A and orexin B are synthesized in the lateral hypothalamus and cleaved from a single precursor preprohypocretin (preproorexin) peptide (Figure 1(a)) [42]. Both are medium-sized peptides. Hypocretin-1 consists of 33 amino acids with four cysteine residues forming two disulfide bonds (Figure 1(b)). On the other hand, hypocretin-2 is a linear peptide that consists of 28 amino acids and doesn’t have any disulfide bond (Figure 1 (b)).