On the occurrence of 5-methoxytryptamine in brain

Bosin, Talmage R.; Jonsson, Gösta; Beck, Olof

doi:10.1016/0006-8993(79)91097-7

Cited by 17 publications

(11 citation statements)

References 19 publications

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“…The occurrence of 5-methoxytryptamine in the brain (Bosin, Jonsson & Beck, 1979) or pineal gland (Pévet, 1983) is still an open question. Trace amounts have been reported in the pineal gland of the cow, pig and sheep, and possibly in the rat (Beck, Jonsson & Lundman, 1981), as well as in the human pineal gland .…”

Section: Introductionmentioning

confidence: 99%

Day–night rhythm of 5-methoxytryptamine biosynthesis in the pineal gland of the golden hamster (Mesocricetus auratus)

Galzin

Eon²,

Esnaud³

et al. 1988

Journal of Endocrinology

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5-Methoxytryptamine is a potent agonist of presynaptic 5-hydroxytryptamine autoreceptors modulating serotonin release in the central nervous system. This methoxyindole can be synthesized in the pineal gland, but its presence in vivo is still controversial, probably because of rapid catabolism by monoamine oxidase. An improved high-pressure liquid chromatography method, with coulometric detection, has been developed for the simultaneous measurement of melatonin, 5-methoxytryptamine, 5-methoxytryptophol and 5-methoxyindolacetic acid. We have demonstrated a day-night rhythmicity in the amount of 5-methoxytryptamine in the pineal gland of golden hamsters (Mesocricetus auratus) maintained under a long photoperiod (14 h light: 10 h darkness) and pretreated with the monoamine oxidase inhibitor pargyline. Levels of 5-methoxytryptamine were highest at 16.30 h and lowest at 00.30 h. The rhythm for 5-methoxytryptamine appears to be the same as for serotonin (opposite in phase to that of melatonin). The identification of 5-methoxytryptamine has been confirmed by analysis with gas chromatography-mass spectrometry.

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Section: Introductionmentioning

confidence: 99%

Day–night rhythm of 5-methoxytryptamine biosynthesis in the pineal gland of the golden hamster (Mesocricetus auratus)

Galzin

Eon²,

Esnaud³

et al. 1988

Journal of Endocrinology

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“…Melatonin, pargyline hydrochloride and 5-MT hydrochloride were obtained from Sigma Chemical Co. (St. Louis, Missouri), and pentafluoropropionic anhydride (PFPA) from Massanalys AB (Bromma, Sweden). 5-Meth~xy-[a,a,P,P-~H,]tryptamine hydrochloride (5-MT-'H,) was synthesized in the laboratory, by a procedure reported previously (Beck and Bosin, 1979). All other chemicals were of analytical grade.…”

Section: Chemicals and Animalsmentioning

confidence: 99%

“…The CHC13 layers were transferred to another set of tubes and evaporated to dryness under a stream of nitrogen. The residues were treated with a mixture of 50 pl of PFPA and 50 p1 of 1% triethylamine in benzene at 60°C for 15 min, to form the dipentafluoropropionyl derivatives of 5-MT (Beck and Bosin, 1979). After cooling, the excess reagent was evaporated under a stream of nitrogen.…”

Section: Preparation Of Samplesmentioning

confidence: 99%

“…5-MT has furthermore been found to share some properties with indoleamine hallucinogens and has therefore been considered as a potential endogenous psychogenic compound (De Montigny and Aghajanian, 1977). The published data regarding the endogenous presence of 5-MT in animal tissues are, however, conflicting (Green et al, 1973;1975;Meek and Neckers, 1977;Prozialeck et al, 1978;Bosin et al, 1979;Dewhurst and McKim, 1979). There seems to be convincing evidence that 5-MT is present endogenously in mammalian tissues, while there is disagreement as to the quantitative levels which may be ascribed at least in part to the different analytical techniques used.…”

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confidence: 99%

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In Vivo Formation of 5‐Methoxytryptamine from Melatonin in Rat

Beck

Jonsson

1981

Journal of Neurochemistry

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Deacetylation of melatonin to 5-methoxytryptamine (5-MT) in vitro and in vivo was investigated in rat liver and brain tissue, using a gas chromatographic--mass spectrometric 5-MT assay method. In vitro incubation of liver but not brain (hypothalamic, Mesencephalic) slices with melatonin led to a concentration-dependent formation of small amounts of 5-MT; the conversion being 0.3--0.8%. In vivo administration of melatonin resulted in a dose-dependent formation of 5-MT in small quantities in the liver. The time course showed a peak maximum within 0.5 h, with a rapid decline; the half-life being about 1 h. 5-MT could be detected in both the blood and the hypothalamus after in vivo injection of melatonin. The time course of 5-MT in the blood was similar to that in the liver, but 5-MT could only be detected in the hypothalamus after large doses shortly after the melatonin injection. MAO had to be inhibited both in the in vitro and in vivo experiments in order to recover 5-MT, indicating that formed 5-MT is normally rapidly metabolised by MAO. It is concluded that a small fraction of melatonin can be converted to 5-MT by deacetylation (by aryl acylamidase) in the liver in vivo, constituting a minor pathway. Such a pathway could not be demonstrated in the brain. Trace amounts of 5-MT previously reported to be present in various tissues could originate from deacetylation of melatonin in the liver and possibly some other peripheral organs known to contain the deacetylating enzyme. The present results indicate that peripherally formed 5-MT, a psychoactive compound, is unlikely to have any effect on brain function under normal circumstances.

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“…In conclusion, it appears that MEL is considerably more effective than 5-MT in inhibiting T4 levels when administered as a daily afternoon injection. On the other hand, when implanted s.c. as part of a beeswax pellet, 5-MT appears to be as effective as MEL in preventing suppression of T4 that otherwise occurs as a result of either repeated afternoon injections of MEL (experiment 1) or exposure to short photoperiod (experiment 5).5-Methoxytryptamine (5-MT), a methylated indole formed directly from its precursor serotonin by hydroxyindoie-O-methyltransferase, is found in the pineal gland of many mammalian species [ 1,2,5,6,10]. This compound has received attention lately as a potential pineal hormone since it, like another pineal indoleamine melatonin (MEL), causes testicular atrophy in Syrian hamsters when adminis tered as a single afternoon injection for several weeks [9,13].…”

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confidence: 99%

Effects of Injections and/or Chronic Implants of Melatonin and 5-Methoxytryptamine on Plasma Thyroid Hormones in Male and Female Syrian Hamsters

et al. 1984

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Plasma thyroid hormone concentrations in male and female Syrian hamsters were evaluated in five experiments after two pineal indoles, melatonin (MEL) and 5-methoxytryptamine (5-MT), were administered as chronic s.c. implants and/or daily afternoon injections. Circulating concentrations of thyroxine (T₄), ordinarily maintained by the long photoperiod (LD 14:10), were inhibited by daily afternoon injections of 25 µg MEL but not 5-MT in male (experiment 1) and female (experiment 2) Syrian hamsters. The suppressive effect of MEL injections on T₄ concentration in the long photoperiod was prevented in both sexes by a s.c. beeswax pellet containing either 1 mg MEL or 5-MT. In the third experiment, various doses of MEL or 5-MT were injected each afternoon for 12 weeks to compare the effectiveness of these two indoles in reducing T₄ concentrations in hamsters maintained in the long photoperiod. Only the highest dose (200 µg) of 5-MT effectively suppressed T₄ concentrations whereas all doses of MEL (≧ 5 µg) significantly reduced plasma T₄. MEL or 5-MT (1–1,000 µg) were implanted in beeswax pellets in male hamsters exposed to short photoperiod (LD 10:14) to determine if either indole could prevent the short photoperiod-induced suppression of T₄ (experiments 4 and 5). Regression and covariance analyses showed a significant log dose-related elevation of T₄ in these hamsters, indicating equal potency of MEL and 5-MT in preventing the short photoperiod-induced suppression of T₄. 5-MT given by either injection or implantation raised plasma triiodothyronine (T₃) in female (experiment 2) but not in male hamsters. Otherwise, photoperiod, MEL and 5-MT had no consistent effect on plasma T₃ concentrations. In conclusion, it appears that MEL is considerably more effective than 5-MT in inhibiting T₄ levels when administered as a daily afternoon injection. On the other hand, when implanted s.c. as part of a beeswax pellet, 5-MT appears to be as effective as MEL in preventing suppression of T₄ that otherwise occurs as a result of either repeated afternoon injections of MEL (experiment 1) or exposure to short photoperiod (experiment 5).

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On the occurrence of 5-methoxytryptamine in brain

Cited by 17 publications

References 19 publications

Day–night rhythm of 5-methoxytryptamine biosynthesis in the pineal gland of the golden hamster (Mesocricetus auratus)

Day–night rhythm of 5-methoxytryptamine biosynthesis in the pineal gland of the golden hamster (Mesocricetus auratus)

In Vivo Formation of 5‐Methoxytryptamine from Melatonin in Rat

Effects of Injections and/or Chronic Implants of Melatonin and 5-Methoxytryptamine on Plasma Thyroid Hormones in Male and Female Syrian Hamsters

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