Serotonin raphe nuclei

Enterochromaffin cells are interspersed with mucosal cells mainly in the stomach and small intestine. In the blood, serotonin is present at high concentrations in platelets, which take up serotonin from the plasma by an active transport process. Serotonin is released on platelet activation. In the central nervous system, serotonin serves as a transmitter. The main serotonin-containing neurons are those clustered in form of the Raphe nuclei. Serotonin exerts its biological effects through the activation of specific receptors. Most of them are G-protein coupled receptors (GPCRs) and belong to the 5-HTr, 5-HT2-, 5-HT4-, 5-HTs-, 5-HT6-, 5-HT7-receptor subfamilies. The 5-HT3-receptor is a ligand-operated ion channel. 

Dorsal raphe nucleus (serotonin) highest lower lowest increased during W... 

Monti JM, Monti D (2000) Role of the dorsal raphe nucleus serotonin 5-HT1A receptor in the regulation of sleep. Life Sci 21 1999-2012... 

Maier SF, Watkins LR (2005) Sdessor condollability and learned helplessness The roles of the dorsal raphe nucleus, serotonin, and cordcodophin-releasing factor. Neurosci Biobehav Rev 29 829-841. 

Portas, C. M., Thakkar, M., Rainnie, D. McCarley, R. W. (1996). Microdialysis perfusion of 8-hydroxy-2-(di-n-propylamino)tetrahn (8-OH-DPAT) in the dorsal raphe nucleus decreases serotonin release and increases rapid eye movement sleep in the freely moving cat. J. Neurosci. 16, 2820-8. 

Figure 4.2 Model of the network responsible for paradoxical sleep onset and maintenance Abbreviations DRN, dorsal raphe nucleus 5-HT, serotonin LC, locus coeruleus NA, noradrenaline LDT, laterodorsal tegmental nucleus Ach, acetylcholine Me, magnocellular reticular nucleus Gly glycine DPMe, deep mesencephalic reticular nucleus PAG, periaqueductal gray DPGi, dorsal paragigantocellular reticular nucleus PPT, pedunculopontine nucleus PRN, pontine reticular nucleus SLD, sublaterodorsal nucleus Glu, glutamate Pef/HLA perifornical/lateral hypothalamic area Hcrt, hypocretin (i.e. orexin).

Liu, R., Jolas, T. Aghajanian, G. (2000). Serotonin 5-HT(2) receptors activate local GABA inhibitory inputs to serotonergic neurons of the dorsal raphe nucleus. Brain Res. 873, 34-45. 

The neural structures involved in the promotion of the waking (W) state are located in the (1) brainstem [dorsal raphe nucleus (DRN), median raphe nucleus (MRN), locus coeruleus (LC), laterodorsal and pedunculopontine tegmental nuclei (LDT/PPT), and medial-pontine reticular formation (mPRF)] (2) hypothalamus [tuberomammillary nucleus (TMN) and lateral hypothalamus (LH)[ (3) basal forebrain (BFB) (medial septal area, nucleus basalis of Meynert) and (4) midbrain ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) (Pace-Schott Hobson, 2002 Jones, 2003). The following neurotransmitters function to promote W (1) acetylcholine (ACh LDT/PPT, BFB) (2) noradrenaline (NA LC) (3) serotonin (5-HT DRN, MRN) (4) histamine (HA TMN) (5) glutamate (GLU mPRF, BFB, thalamus) (6) orexin (OX LH) and (7) dopamine (DA VTA, SNc) (Zoltoski et al, 1999 Monti, 2004). 

Hensler, J. G., Ferry, R. C., Labow, D. M., Kovachich, G. B. 8r Frazer, A. (1994). Quantitative autoradiography of the serotonin transporter to assess the distribution of serotonergic projections from the dorsal raphe nucleus. Synapse 17, 115. 

Janowski, M. P. Sesack, S. R. (2004). Prefrontal cortical projections to the rat dorsal raphe nucleus ultrastructural features and association with serotonin and gamma-aminobutyric acid neurons. J. Comp. Neurol. 468, 518-29. 

Van Bockstaele, E. J., Biswas, A. Pickel, V. M. (1993). Topography of serotonin neurons in the dorsal raphe nucleus that send axon collaterals to the rat prefrontal cortex and nucleus accumbens. Brain Res. 624, 188-98. 

Sleep is reduced when there is decreased serotonin activity or destruction of the dorsal raphe nucleus. 

Pernar L, Curtis AL, Vale WW, Rivier JE, Valentino RJ (2004) Selective activation of corticotropin-releasing factor-2 receptors on neurochemicaUy identified neurons in the rat dorsal raphe nucleus reveals dual actions. J Neimosci 24 1305-1311 Petty F, Kramer G, Wilson L, Jordan S (1994) In vivo serotonin release and learned helplessness. Psychiatry Res 52 285-293... 

Fibiger HC, Lepiane FG, Phillips AG Disruption of memory produced by stimulation of the dorsal raphe nucleus mediation by serotonin. Brain Res 155 380-386, 1978... 

Parsons, Loren H., and Joseph B. Justice Jr. 1993. "Serotonin and Dopamine Sensitization in the Nucleus Accumbens, Ventral Tegmental Area, and Dorsal Raphe Nucleus Following Repeated Cocaine Administration." Journal of Neurochemistry 61 1611-19. 

Hess s model is all the more prescient because, at the time of its articulation, the cellular and molecular neurobiology of the central instantiation of the two branches of the autonomic nervous system were completely unknown. He had to infer their existence from his knowledge of the peripheral system and from the effects of his manipulation of the brain upon their outflow. The breakthrough came only in the early 1960s, when Anica Dahlstrom, K]ell Euxe, and others identified the norepinephrine containing cells of the locus coeruleus and the serotonin containing cells of the midline raphe nucleus. And it was even later when Marcel Mesulam and others mapped the central cholinergic neuronal system. 

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