“Dorsal raphe nucleus”的意思、由来-开放百科全书

The dorsal raphe nucleus is located on the midline of the brainstem and is one of the raphe nuclei. It has rostral and caudal subdivisions.

An increased number of cells in the lateral aspects of the dorsal raphe is characteristic of humans and other primates.

Serotonin

The dorsal raphe is the largest serotonergic nucleus and provides a substantial proportion of the serotonin innervation to the forebrain.

Serotonergic neurons are found throughout the dorsal raphe nucleus and tend to be larger than other cells. A substantial population of cells synthesizing substance P are found in the rostral aspects, many of these co-express serotonin and substance P. There is also a population of catecholamine synthesizing neurons in the rostral dorsal raphe, and these cells appear to be relatively large.^[2]

The dorsal raphe nucleus is rich in pre-synaptic serotonin 5-HT_1A autoreceptors, and it's believed that the action of the selective serotonin reuptake inhibitors (SSRIs) in this region is responsible for the latency of their antidepressant effect.^[3]

Projections

Ten percent of the axons from the nucleus raphe dorsalis of the rat have been shown to project to the amygdala,^[4] while only medium cells seem to project to the caudate and putamen and olfactory bulb.^[5]^[6]

Role in naloxone-induced morphine withdrawal

The nucleus raphes dorsalis has also been implicated in naloxone-induced morphine withdrawal. It is known that endogenous opioid receptors exist on the nucleus raphes dorsalis, and that it is a focal point as an ascending and descending regulator. Pourshanazari et al. showed in their 2000 paper that electrical stimulation of the nucleus raphes dorsalis can partially alleviate morphine withdrawal symptoms via electrical stimulation of the raphe nucleus in question.^[7]

These are fascinating results; however no control was provided for the spread of electrical charge to other parts of the brain stem. It is quite possible that the charge spread to the nucleus raphes magnus and induced analgesia upon the rats. Knowing that the spread of charge across such a short area is very plausible, as is an alternate connection to the raphe magnus, these results could be called into question.

Role in narcolepsy

Wu M.F. et al. studied the nucleus raphes dorsalis as it pertained to narcolepsy. This is logical, as the raphe nuclei have been known to play a role in the sleep/wake cycle. Cataplexy is the symptom of narcolepsy when full awareness of the environment is maintained, but all muscle tone is lost. This has thought to be a dissociation of what normally happens during REM sleep, when all muscle tone is lost except for the eyes. The nucleus raphes dorsalis have been known to project to the lateral hypothalamus, along with the locus coeruleus and the tuberomammillary nucleus. The neurotransmitters of these three aforementioned nuclei, which project to the lateral hypothalamus, are serotonin, norepinephrine and histamine respectively. These neurotransmitters are fully active during waking hours, partially active during non-REM sleep, and have almost ceased during REM sleep. In cats with pontine lesions, their normal atonia is not present, the raphe dorsalis is fully active, as opposed to the cessation of action under normal conditions. A muscle relaxant, known as Mephenesin, reduces to activity of the dorsal nucleus, as well as microinjections of carbachol (which induces atonia while awake).^[8]

Role in depression and suicide

The rostral raphe nuclei, both the median raphe nucleus and particularly the dorsal raphe nucleus have long been implicated in depression. Some studies have suggested that the dorsal raphe may be decreased in size in people with depression and, paradoxically, an increased cell density in those who commit suicide.^[9]^[10]^[11]

See also

References

1. ^{{cite journal |doi=10.1016/0361-9230(84)90232-6 |vauthors=O'Hearn E, Molliver ME |title=Organization of raphe-cortical projections in rat: a quantitative retrograde study |journal=Brain Res. Bull. |volume=13 |issue=6 |pages=709–26 |date=December 1984 |pmid=6099744 }}
2. ^{{cite journal |doi=10.1016/0306-4522(91)90043-N |vauthors=Baker KG, Halliday GM, Hornung JP, Geffen LB, Cotton RG, Törk I |title=Distribution, morphology and number of monoamine-synthesizing and substance P-containing neurons in the human dorsal raphe nucleus |journal=Neuroscience |volume=42 |issue=3 |pages=757–75 |year=1991 |pmid=1720227 |url=http://linkinghub.elsevier.com/retrieve/pii/0306-4522(91)90043-N}}
3. ^{{cite journal |doi=10.1097/00002826-199310000-00002 |vauthors=Briley M, Moret C |title=Neurobiological mechanisms involved in antidepressant therapies |journal=Clin Neuropharmacol |volume=16 |issue=5 |pages=387–400 |date=October 1993 |pmid=8221701 }}
4. ^{{cite journal |doi=10.1016/0304-3940(91)90499-J |vauthors=Ma QP, Yin GF, Ai MK, Han JS |title=Serotonergic projections from the nucleus raphe dorsalis to the amygdala in the rat |journal=Neurosci. Lett. |volume=134 |issue=1 |pages=21–4 |date=December 1991 |pmid=1815148 |url=http://linkinghub.elsevier.com/retrieve/pii/0304-3940(91)90499-J}}
5. ^{{cite journal |vauthors=Steinbusch HW, Nieuwenhuys R, Verhofstad AA, Van der Kooy D |title=The nucleus raphe dorsalis of the rat and its projection upon the caudatoputamen. A combined cytoarchitectonic, immunohistochemical and retrograde transport study |journal=J. Physiol. (Paris) |volume=77 |issue=2–3 |pages=157–74 |year=1981 |pmid=6169825 }}
6. ^{{cite journal |vauthors=Petzold GC, Hagiwara A, Murthy VN |title=Serotonergic modulation of odor input to the mammalian olfactory bulb |journal=Nat. Neurosci. |volume=12 |issue=6 |pages=784–91 |date=June 2009 |pmid=19430472 |doi=10.1038/nn.2335}}
7. ^{{cite journal |author=Pourshanazari, A.A. |author2=Alaei |author3=Rafati |title=Effects of Electrical Stimulation of Nucleus Raphe Dorsalis on initiation of morphine self-administration in rats |journal=Medical Journal of Islamic Academy of Sciences |volume=13 |issue=2 |pages=63–7 |year=2000}}
8. ^{{cite journal |vauthors=Wu MF, John J, Boehmer LN, Yau D, Nguyen GB, Siegel JM |title=Activity of dorsal raphe cells across the sleep–waking cycle and during cataplexy in narcoleptic dogs |journal=J. Physiol. |volume=554 |issue=Pt 1 |pages=202–15 |date=January 2004 |pmid=14678502 |pmc=1664742 |doi=10.1113/jphysiol.2003.052134 |url=http://www.jphysiol.org/cgi/content/full/554/1/202}}
9. ^{{cite journal |vauthors=Underwood MD, Khaibulina AA, Ellis SP, Moran A, Rice PM, Mann JJ, Arango V| title = Morphometry of the dorsal raphe nucleus serotonergic neurons in suicide victims | journal=Biol Psychiatry |volume=46 |issue=4 |pages=473–83 |date=August 1999 |pmid=10459396 |doi=10.1016/S0006-3223(99)00043-8}}
10. ^{{cite journal |vauthors=Arango V, Underwood MD, Boldrini M, Tamir H, Kassir SA, Hsiung S, Chen JJ, Mann JJ |title= Serotonin 1A receptors, serotonin transporter binding and serotonin transporter mRNA expression in the brainstem of depressed suicide victims | journal=Neuropsychopharmacology |volume=25 |issue=6 |pages=892–903 |date=December 2001 |pmid=11750182 |doi=10.1016/S0893-133X(01)00310-4}}
11. ^{{cite journal |vauthors=Matthews PR, Harrison PJ |title=A morphometric, immunohistochemical, and in situ hybridization study of the dorsal raphe nucleus in major depression, bipolar disorder, schizophrenia, and suicide |journal=J Affect Disord |volume=137 |issue=1-3 |pages=125–134 |date=March 2012 |pmid=22129767 |pmc=3314923 |doi=10.1016/j.jad.2011.10.043}}