Raphe nuclei
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| Brain: Raphe nuclei | ||
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| Section of the medulla oblongata at about the middle of the olive. (Raphe nuclei not labeled, but 'raphe' labeled at left.) | ||
| Latin | nuclei raphes | |
| MeSH | Raphe+Nuclei | |
The raphe nuclei ("raffe", Greek: ραφή = seam) are a moderate-size cluster of nuclei found in the brain stem. Their main function is to release serotonin to the rest of the brain.[1] Selective serotonin reuptake inhibitor (SSRI) antidepressants are believed to act in these nuclei, as well as at their targets.[2]
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[edit] Anatomy
The raphe nuclei are traditionally considered to be the medial portion of the reticular formation, and they appear as a ridge of cells in the center and most medial portion of the brain stem.
In order from caudal to rostral, the raphe nuclei are known as the nucleus raphe obscurus, the raphe magnus, the raphe pontis, the raphe pallidus, the nucleus centralis superior, nucleus raphe dorsalis, nuclei linearis intermedius and linearis rostralis.[3] Some scientists chose to group the linearis nuclei into one nucleus, shrinking the number of raphe to seven, e.g., NeuroNames makes the following ordering:[4]
- Raphe nuclei of medulla
- Nucleus raphe obscurus (nucleus raphe obscurus)
- Nucleus raphe magnus (raphe magnus)
- Nucleus pallidus (raphe pallidus)
- Raphe nuclei of the pontine reticular formation
- Pontine raphe nucleus (raphe pontis)
- Inferior central nucleus
- Raphe nuclei of the midbrain reticular formation
- Superior central nucleus (nucleus centralis superior)
- Dorsal raphe nucleus (nucleus raphe dorsalis)
[edit] Projections
These nuclei interact with almost every pertinent portion of the brain, but only a few of them have specifically independent interaction. These select nuclei are discussed as follows.
Overall, the caudal raphe nuclei, including the raphe magnus, pallidus and raphe obscurus, all project towards the spinal cord and brain stem. The more-rostral nuclei, including the raphe pontis, centralis (also called median), dorsal, tend to project towards the brain areas of higher function.[5]
[edit] Function
The raphe nuclei have a vast impact upon the central nervous system. Many of the neurons in the nuclei (but not the majority) are serotonergic; i.e., contain serotonin, a type of monoamine neurotransmitter. It is important to note that pharmacology traditionally affects global serotonin levels, while the actions of the raphe nuclei are dependent on the complex interplay between nuclei.[citation needed]
Projections from the raphe nuclei also terminate in the dorsal horn of spinal gray matter where they regulate the release of enkephalins, which inhibit pain sensation.
[edit] Further reading
- Currie, David (2005). "A Lecture, Higher Brain Function: Activation of the Brain and Levels of Consciousness". East Tennessee State University. http://faculty.etsu.edu/currie/ras.htm. Retrieved 18 April 2006.
- Sari, Youssef (October 2004). "Serotonin1B receptors: from protein to physiological function and behavior". Neuroscience & Biobehavioral Reviews 28 (6): 565–582. doi:. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T0J-4DPCHW4-2&_coverDate=10%2F01%2F2004&_alid=299916628&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=4864&_sort=d&view=c&_acct=C000002898&_version=1&_urlVersion=0&_userid=27541&md5=ed404d8b8b83823517993851bd03c937. Retrieved 2006-04-18.
[edit] Additional images
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Dopamine and serotonin |
[edit] References
- ^ George J. Siegel, ed (1999). "Understanding the neuroanatomical organization of serotonergic cells in brain provides insight into the functions of this neurotransmitter". Basic Neurochemistry. Bernard W. Agranoff, Stephen K. Fisher, R. Wayne Albers, Michael D. Uhler (Sixth ed.). Lippincott Williams and Wilkins. ISBN 0-397-51820-X. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=raphe+AND+serotonin+release+AND+bnchm%5Bbook%5D+AND+160428%5Buid%5D&rid=bnchm.section.946#949. "In 1964, Dahlstrom and Fuxe (discussed in [2]), using the Falck-Hillarp technique of histofluorescence, observed that the majority of serotonergic soma are found in cell body groups, which previously had been designated as the raphe nuclei."
- ^ Briley, M (October 1993). "Neurobiological mechanisms involved in antidepressant therapies". Clin Neuropharmacol 16 (5): 387–400. doi:. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8221701&query_hl=14&itool=pubmed_docsum.
- ^ "Fig. 5. The midsagittal section of the brain stem indicating the position of the raphe nuclei" (GIF). 1998. http://www.hallym.ac.kr/~de1610/nana/5-5.gif. Retrieved 18 April 2006.
- ^ NeuroNames ancil-190
- ^ BilZ0r; Erowid (2005). "Figure 4. Diagram of the human brain showing the divergent serotonergic projections of the raphe nuclei to both cortical and subcortical locations throughout the brain." (PNG). The Neuropharmacology of Hallucinogens: a technical overview. Erowid Pharmacology Vaults. http://www.erowid.org/psychoactives/pharmacology/images/pharmacology_article2-4-med.png. Retrieved 18 April 2006.
[edit] See also
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