Tryptophan (Trp), serotonin (5-HT), monoamino oxidase (MAO) and 5-hydroxyindole acetic acid (5-HIAA) in brain and subesophagic ganglions of earthworms. Effects of Parathion

Summary Tryptophan, 5-HT, MAO and 5-HIAA were determined in the first 5 segments of earthworms (Oligochaetae) where the brain and subesophagic ganglions are located. Tranylcypromine (IMAO) decreased MAO activity increasing 5-HT and decreasing 5-HIAA. Motility and survival of worms were disturbed. InAllolobophora species (young worms), parathion fumigation decreased acetylcholinesterase (AChE) activity and increased Trp, 5-HT and 5-HIAA. Motility was diminished after 24 h: it worsened after 72, but returned to normal levels 40/50 days later.Publication of the National Institute of Agrarian Technology (INTA), Argentina.Acknowledgments. We are most grateful to Prof. Zlatko Tomsic (from the Lillo Institute, Tucumán) and to Leticia Alvarado (from INTA) and to Prof. Mirta P. de Matosian for earthworm classification.     

The involvement of serotonin in induced ovulation in the immature rat.

In pregnant mare's serum gonadotropin (PMS) treated immature rats the cortex, cerebellum, caudate nucleus and hypothalamus were isolated and analyzed for their serotonin (5-HT) content at 6-h intervals for 72 h. Results showed a general trend of significant variation occurring in days 1 and 3 after PMS injection with no major variations observed on the second day. The results obtained suggest a possible involvement of 5-HT in the control of ovulation.     

The involvement of serotonin in induced ovulation in the immature rat

Summary In pregnant mare's serum gonadotropin (PMS) treated immature rats the cortex, cerebellum, caudate nucleus and hypothalamus were isolated and analyzed for their serotonin (5-HT) content at 6-h intervals for 72 h. Results showed a general trend of significant variation occurring in days 1 and 3 after PMS injection with no major variations observed on the second day. The results obtained suggest a possible involvement of 5-HT in the control of ovulation.     

The occurrence of 5-hydroxytryptamine in the holothurian,Pentacter crassa

Summary 5-Hydroxytryptamine (5-HT) and hypoxanthine were isolated chromatographically from the holothurianPentacter crassa. This study was initiated as a result of the observed hypotensive activity of aP. crassa extract. This activity was also encountered in extracts of the holothuriansThelenota ananus andStichopus chloronatus and can be attributed to 5-HT.     

Observations on the metabolism of endogenous 5-hydroxytryptamine (enteramine) in the rat

Zusammenfassung Der Rattenurin enthält 1,34µg 5-Hydroxyindolyl-essigsäure je Kubikzentimeter (=81,4µg/kg/24 h). Daraus ist zu berechnen, dass in der Ratte täglich 216–236µg/kg 5-Hydroxytryptamin metabolisiert werden. Dies bedeutet, dass das Blutplättchen-5-HT alle 3–4 h und das Gesamt-5-HT des Organismus alle 12–14 h erneuert werden wird.Die erhaltenen quantitativen Daten sind hauptsächlich im Hinblick auf die fragliche Bildungsstelle des 5-HT und die biologische Bedeutung der Substanz selber wichtig.     

Cardioactive peptides of the CNS of the pulmonate snailLymnaea stagnalis

Summary In the pulmonate snailLymnaea stagnalis the cardioactive effects (tested on isolated auricles) of acetylcholine (ACh), 5-hydroxytryptamine (5-HT), the bivalve tetrapeptide FMRFamide, and of chromatographically separated snail brain substances have been established. Besides ACh and 5-HT, in brain extracts, small FMRFamide-like and large cardioexcitatory peptides were found.     

Diurnal variations in cholinesterase activities in the slug,Laevicaulis alte

Summary Cyclical variations in acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) levels in foot muscle (FM) and AChE activity in central nervous system (CNS) ofLaevicaulis, during 24-h-day, were maximal at 04.00 h and minimal at 12.00 h. But BuChE activity was 180°C out of phase with AChE in CNS. The rhythmic trend of AChE in CNS might be due to true cholinesterase activity.Acknowledgements. The Senior Fellowship (CSIR) awarded to TPK is thankfully acknowledged.     

Studies on a compound antagonistic to 5-hydroxytryptamine

Riassunto La 1-metil-8-carbobenzilossi-aminometil-10-ergoline (MCE) impedisce la morte dei feti in ratte gravide trattate con enteramina (5-HT). L'effetto massimo è ottenuto quando l'MCE è somministrato 3 h prima della 5-HT, ma si manifesta anche 14 giorni dopo una iniezione del composto.     

Effect of 5-hydroxytryptamine antibodies on pigment migration in the erythrophores of the fiddler crab,Uca pugilator: Further evidence for 5-hydroxytryptamine as a neurotransmitter that stimulates release of red pigment-dispersing hormone

Summary 5-Hydroxytryptamine (5-HT) antibodies inhibit red pigment dispersion in the fiddler crab,Uca pugilator. This observation supports the hypothesis that 5-HT stimulates release of red pigment-dispersing hormone.The 5-HT antibody preparation was a generous gift from Dr S. Spector, Roche Institute of Molecular Biology, Nutley, New Jersey.     

The effect of substance P on the amount of 5-Hydroxytryptamine in the gut

Résumé L'injection intrapéritonéale de la substanceP (60 à 120 U/kg) chez le rat provoque une augmentation marquée de 5-HT dans la paroi de l'estomac et dans l'iléon. Dans la rate de cet animal, on n'y observe pas d'augmentation de 5-HT.L'administration intraluminale de la substanceP (60–80 U) dans l'iléon isolé du cobaye, augmente aussi sensiblement la quantité de 5-HT.     

Evidence for serotonin (5-hydroxytryptamine) as transmitter in the penis retractor muscle ofHelix pomatia L.

Summary Microchromatography of dansylated substances was used to estimate the serotonin content of the penis retractor muscle (PRM) ofHelix pomatia. Pharmacological data in connection with the biochemical results suggest that 5-HT plays a role in the regulation of the mechanical activity of the PRM.     

The enteric neural receptor for 5-hydroxytryptamine

Summary An enteric neural receptor for serotonin (5-HT) has been characterized. This receptor was assayed, using³H-5-HT as a radiologand, by rapid filtration of isolated enteric membranes and by radioautography. In addition, intracellular recordings were made from ganglion cells of the myenteric plexus. High affinity, saturable, reversible, and specific binding of³H-5-HT was demonstrated both to membranes of the dissected longitudinal muscle with adherent myenteric plexus and the mucosa-submucosa. Radioautographs showed these³H-5-HT binding sites to be in myenteric ganglia and in a broad unresolved band at the mucosal-submucosal interface. Antagonists active at receptors for other neurotransmitters than 5-HT, at either of the two known types of CNS 5-HT receptor, and at 5-HT uptake sites on serotonergic neurons failed to inhibit binding of³H-5-HT. The structural requirements of analogues for binding to the enteric 5-HT receptor matched the known pharmacology of M or neural 5-HT receptors. A novel 5-HT antagonist was found. This compound, N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide (5-HTP-DP), antagonized the action of 5-HT on type II/AH cells of the myenteric plexus but did not affect the release or actions of acetylcholine (nicotinic or muscarinic) or substance P. 5-HTP-DP was also an equally potent displacer of³H-5-HT from its binding sites on enteric membranes. It is concluded that the sites responsible for specific binding of³H-5-HT are enteric M or neural 5-HT receptors. These receptors differ from those now known to be present in the CNS.     

Serotonin metabolism in the CNS in cerebellar ataxic mice

The metabolism of 5-hydroxytryptamine (5-HT) in the CNS was investigated in four kinds of morphologically different ataxic mice; reeler, staggerer, weaver and Purkinje cell degeneration mutants, and in hypocerebellar mice experimentally produced by injection of cytosine arabinoside. 5-HT and 5-hydroxyidoleacetic acid concentrations and tryptophan hydroxylase (TrpOH) activity were measured in the cerebrum, cerebellum and brain stem, respectively. TrpOH activity was significantly reduced only in the reeler mouse. The enhancements of the cerebellar 5-HT metabolism observed in the ataxic mice other than the reeler were supposed to be pseudo-enhancements subsequent to the cerebellar hypoplasia.     

Comparison of diurnal and nocturnal rates of 5-hydroxytryptamine turnover in the rat mediobasal hypothalamus

Rates of 5-hydroxytryptamine (5-HT) turnover in the mediobasal hypothalamus of male rats were estimated using pharmacological methods during the daytime and at night. Concentrations of 5-HT in this hypothalamic area were higher nocturnally than diurnally; this was apparently due to increased 5-HT synthesis and decreased 5-HT catabolism at night.     

In vitro development ofXenopus skin glands producing 5-hydroxytryptamine and caerulein

The granular glands of amphibian skin synthesize and store a large amount of bioactive amines and peptides which are structurally similar to mammalian brain-gut peptides. To investigate the development of peptide- and amine-producing cells in the granular glands, pieces of dorsal skin taken at various stages fromXenopus laevis tadpoles were cultured, and the contents of caerulein and 5-hydroxytryptamine (5-HT) were measured. When pieces of skin from tadpoles at stages 57 to 60 (Nieuwkoop and Faber stages) were cultured in a medium containing 10% fetal calf serum (FCS medium) or one containing FCS treated with charcoal (chFCS medium), the caerulein and 5-HT levels were increased for the six days of the incubation period. The caerulein content was lower in the chFCS medium than in the FCS medium. Addition of thyroxine to the chFCS medium had no significant effect on the caerulein content. These results show that the caerulein-and 5-HT-producing cells of the granular glands can develop in a culture system with FCS- or chFCS-containing media, and suggest that FCS contains substances which are absorbed by charcoal and stimulate development of the amine- and peptideproducing cells of the glands. In a preliminary search for correlation between caerulein and 5-HT synthesis, addition of 5-hydroxytryptophan (5-HTP), a precursor to 5-HT, to the FCS medium increased 5-HT content and, conversely, caused significant decrease in caerulein content, suggesting that accumulation of caerulein in the granular glands is influenced by the amount of 5-HT synthesis. These studies indicate that this culture system is a useful model for investigating the development of peptide- and amine-producing cells.     

Comparison of diurnal and nocturnal rates of 5-hydroxytryptamine turnover in the rat mediobasal hypothalamus

Summary Rates of 5-hydroxytryptamine (5-HT) turnover in the mediobasal hypothalamus of male rats were estimated using pharmacological methods during the daytime and at night. Concentrations of 5-HT in this hypothalamic area were higher nocturnally than diurnally; this was apparently due to increased 5-HT synthesis and decreased 5-HT catabolism at night.Supported by NIH grant RR07187 (TSK) and NIH grant HD10202 (Neuroendocrine Core).     

Differential effects of the serotonin receptors on cultured rat cerebral cortical neurons

Effects of serotonin (5-HT) on cerebral cortical neurons were examined by patch clamp techniques. 5-HT produced a variety of responses such as outward (19/73 patches/neurons), slow inward (15/73 patches/neurons), fast inward (8/73 patches/neurons), and mixed currents (initially fast inward deflection followed by an outward response: 2/73 patches/neurons), with a latency of 12 sec, 15 sec, 0 sec, and 0 sec respectively, at a holding potential of −60 mV in whole-cell patches. The fast inward currents were again evoked by a selective 5-HT3 receptor agonist, 1-(m-chlorophenyl)-biguanide hydrochloride (CPBG). In the cell-attached patch clamp configuration, 5-HT inside the patch pipette elicited single channel currents with slope conductances of 42 pS and 132 pS (4/42 patches/neurons). CPBG inside the patch pipette evoked inward single channel currents with a lower slope conductance of 41 pS (3/23 patches/neurons). In contrast, application of 5-HT or a 5-HT₂ receptor agonist, α-methyl-5-hydroxytryptamine-maleate, outside the patch pipette induced outward single channel currents with a major slope conductance of 140 pS (8/30 patches/neurons) or 135 pS (6/20 patches/neurons), respectively. These results indicate that the outward and fast inward currents may be mediated respectively by the 5-HT₂ receptor, which is coupled to a G-protein, and by the 5-HT₃ receptor, which contains the non-selective cation channel, and that the mixed type may be caused by both the 5-HT₂ and 5-HT₃ receptors. Received 27 September 1996; received after revision 4 November 1996; accepted 7 November 1996     

Circadian rhythm in the subcommissural organ of the frog,Rana arvalis Nilsson,under natural conditions

Summary A circadian activity of SCO ependymal cells, judged by changes in the nuclear volume, has been found in juvenile frogs (Rana arvalis) under natural summer conditions. The nuclear volume reaches its maximum at 12.00 h and a minimum at 24.00 h. A significant increase in activity occurs between 06.00 and 09.00 h and a gradual decrease is observed from 12.00 to 24.00 h.     

Advantages ofn-heptanol in the extraction of 5-hydroxytryptamine (5-HT)

Zusammenfassung Mitn-Heptanol als Extraktionsmittel können kleine Mengen von 5-Hydroxytryptamin (5-HT) aus biologischem Material, das 5-Hydroxytryptaphan (5-HTP) in grossen Mengen enthält, extrahiert werden.     

5-Methoxy- and 5-hydroxy-indolealkylamines in the skin ofBufo alvarius

Riassunto Gli estratti di pelle diBufo alvarius, rospo delle regioni desertiche del Nord America, contengono, oltre alle consuete 5-idrossiindolalchilamine (5-HT, N-metil-5-HT, bufotenina) enormi quantitativi di derivati 5-metossiindolici, rappresentati soprattutto daO-metilbufotenina. Questa può giungere a costituire fino il 16% del peso delle ghiandole cutanee secche. Si insiste sulla probabile presenza di 5-idrossiindolo-O-metiltransferasi nella pelle diBufo alvarius.

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Supported by a grant from the Consiglio Nazionale delle Ricerche, Roma.