The comparison of effects of the endogenous enantiomer, (R)- with the racemate (R,S)- 1-methyl-1,2,3,4-tetrahydroisoquinoline on dopamine metabolism in the brain structures and its in vivo release in rat striatum

We describe here an autoradiographic method to measure the in vivo rate of serotonin synthesis in rat brain. The method is based on the use of the l-tryptophan analogue a-methyl-l-tryptophan ( a-MTrp), which is converted in vivo into a-methylserotonin ( a-M5HT). Since a-M5HT is not a substrate for monoamine oxidase, it is accumulated in the brain tissue. Data are presented to confirm time-dependent conversion of a-MTrp into a-M5HT in the dorsal raphe nucleus and also in the pineal body, an organ outside the blood–brain barrier. It has also been shown that washing brain slices in 10% trichloroacetic acid results in <3% incorporation of a-MTrp into brain proteins. The rates of synthesis are calculated in several grossly dissected brain structures by using tracer kinetics and a three-compartment biological model. The half-life of the precursor pool is estimated to be ∼20 min. The rate of serotonin synthesis is highest in the pineal body.

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Measurement of the in vivo release of 3H-serotonin using a push-pull cannula implanted in selected brain structures of the cat.

Journal of Histochemistry & Cytochemistry ◽

10.1177/30.8.7119424 ◽

1982 ◽

Vol 30 (8) ◽

pp. 817-820 ◽

Cited By ~ 4

Author(s):

P P Soubrie

Keyword(s):

Brain Structures ◽

In Vivo Release

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An M3-like muscarinic autoreceptor regulates the in vivo release of acetylcholine in rat striatum

European Journal of Pharmacology ◽

10.1016/0014-2999(90)90414-2 ◽

1990 ◽

Vol 179 (1-2) ◽

pp. 167-172 ◽

Cited By ~ 33

Author(s):

Peter De Boer ◽

Ben H.C. Westerink ◽

Hans Rollema ◽

Johan Zaagsma ◽

Alan S. Horn

Keyword(s):

Rat Striatum ◽

In Vivo Release ◽

Release Of Acetylcholine

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Effects of CGP 28014 on the in vivo release and metabolism of dopamine in the rat striatum assessed by brain microdialysis

Neurochemical Research ◽

10.1007/bf00978363 ◽

1993 ◽

Vol 18 (11) ◽

pp. 1131-1136 ◽

Cited By ~ 5

Author(s):

Anne-Fran�oise Steulet ◽

Kurt St�cklin ◽

Peter Wicki ◽

Peter Waldmeier

Keyword(s):

Rat Striatum ◽

Brain Microdialysis ◽

In Vivo Release

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Endogenous Serotonin Acts on 5-HT2C-Like Receptors in Key Vocal Areas of the Brain Stem to Initiate Vocalizations in Xenopus laevis

Journal of Neurophysiology ◽

10.1152/jn.00827.2009 ◽

2010 ◽

Vol 103 (2) ◽

pp. 648-658 ◽

Cited By ~ 12

Author(s):

Heather J. Yu ◽

Ayako Yamaguchi

Keyword(s):

Xenopus Laevis ◽

Brain Stem ◽

Motor Nucleus ◽

African Clawed Frog ◽

In Vivo Release ◽

Rhythmic Behaviors ◽

Clawed Frog ◽

The Brain

Serotonin initiates various rhythmic behaviors in vertebrates. Previously we have shown that serotonergic neurons innervate the central vocal pathway in the African clawed frog ( Xenopus laevis ). We also discovered that exogenous serotonin applied to isolated brains in vitro activates fictive vocalizations by activating 5-HT2C-like receptors. In this study, we examined the location of 5-HT2C-like receptors and determined whether endogenously released serotonin also initiates vocalizations by activating 5-HT2C-like receptors in male Xenopus brains. To this end, we first identified the specific location of 5-HT2C-like receptors using immunohistochemistry. We next examined which of the populations of neurons that express 5-HT2C-like receptors are functionally relevant for initiating fictive vocalizations by applying a 5-HT2C receptor agonist to brains transected at various levels. Of four populations of immunopositive neurons, we showed that 5-HT2C-like receptors located in two areas of the brain stem vocal circuit, the raphe nucleus and motor nucleus IX-X, initiate fictive vocalizations. We next showed that endogenous serotonin can also activate fictive vocalizations by increasing the extracellular concentration of endogenous serotonin using a selective serotonin reuptake inhibitor (SSRI). The SSRI-induced vocal initiation is also mediated by activation of 5-HT2C-like receptors because blockade of these receptors prevents fictive vocalization. The results suggest that in vivo release of serotonin initiates male vocalizations by activating 5-HT2C-like receptors in the brain stem vocal nuclei.

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