Release of histamine by tryptamine and 5-hydroxytryptamine

Formula diet driven microbiota shifts tryptophan metabolism from serotonin to tryptamine in neonatal porcine colon

BACKGROUND

The gut microbiota of breast-fed and formula-fed infants differ significantly, as do the risks for allergies, gut dysfunction, and upper respiratory tract infections. The connections between breast milk, various formulas, and the profiles of gut bacteria to these childhood illnesses, as well as the mechanisms underlying the effects, are not well understood.

METHODS

We investigated distal colon microbiota by 16S RNA amplicon sequencing, morphology by histomorphometry, immune response by cytokine expression, and tryptophan metabolism in a pig model in which piglets were sow-fed, or fed soy or dairy milk-based formula from postnatal day (PND) 2 to 21.

RESULTS

Formula feeding significantly (p < 0.05) altered the colon microbiota relative to the sow feeding. A significant reduction in microbial diversity was noted with formula groups in comparison to sow-fed. Streptococcus, Blautia, Citrobacter, Butrycimonas, Parabacteroides, Lactococcus genera were increased with formula feeding relative to sow feeding. In addition, relative to sow feeding, Anaerotruncus, Akkermansia, Enterococcus, Acinetobacter, Christensenella, and Holdemania were increased in milk-fed piglets, and Biliophila, Ruminococcus, Clostridium were increased in soy-fed piglets. No significant gut morphological changes were noted. However, higher cytokine mRNA expression (BMP4, CCL11, CCL21) was observed in the distal colon of formula groups. Formula feeding reduced enterochromaffin cell number and serotonin, but increased tryptamine levels relative to sow feeding.

CONCLUSION

Our data confirm that formula diet alters the colon microbiota and appears to shift tryptophan metabolism from serotonin to tryptamine, which may lead to greater histamine levels and risk of allergies in infants.

Physiology of chemotherapy-induced emesis and antiemetic therapy. Predictive models for evaluation of new compounds

The physiology of emesis has been studied for several hundred years, focusing on the different centres involved and the mechanics of expulsion. The vomiting centre receives inputs from various emetic detectors such as the gut, the vestibular labyrinths and the chemoreceptor trigger zone. Emesis is a common disabling effect in motion sickness, postoperative conditions and in radio- and chemotherapy. Our current understanding of the mechanisms has been provided mainly by the recent introduction of serotonin 5-HT3 receptor antagonists into therapeutic use. Nevertheless, despite the considerable advances made in the understanding of the different pathways involved in emesis, there are number of areas that still require experimental investigation. Different animal and human models are available to study the physiology of emesis and to evaluate the antiemetic activity of new compounds, but they need to be predictors of clinical situations.

Dual presynaptic effects of 5-hydroxytryptamine on peripheral noradrenergic synapses

The aim of the present experiments was to study the effects of 5-hydroxytryptamine (5-HT) on the responses to postganglionic stimulation of two models of the peripheral sympathetic nervous system: the isolated nictitating membrane of the cat and the guinea-pig isolated atria. In the nictitating membrane of the cat, 5-HT (0.1 microM) shifted to the left the frequency-response curve to nerve stimulation. This potentiating effect was prevented by 5-HT receptor antagonists (0.1 microM methysergide, 0.1 microM pizotifen and 0.1 microM morphine) and also by the beta-adrenoreceptor blocker propranolol (0.1 microM). The alpha 2-adrenoreceptor antagonist yohimbine (0.1 microM) had no effect on the 5-HT-induced potentiation. In the guinea-pig isolated atria the responses to cardioaccelerans nerve stimulation were diminished by 5-HT (0.1 to 1.0 microM). The shift to the right in the frequency-response curve induced by 5-HT (1.0 microM) was additive to the antagonism caused in the atria by propranolol (0.1 microM). The inhibitory effect of 5-HT on the pacemaker responses to nerve stimulation was prevented by the 5-HT receptor antagonists methysergide (1.0 microM) and pizotifen (1.0 microM) and also by the alpha-adrenoreceptor antagonist phentolamine (0.1 microM). The selective alpha 2-adrenoreceptor agonist clonidine (0.01 microM) reduced to the same extent as 5-HT (1.0 microM) the responses to the guinea-pig atria to nerve stimulation. The inhibitory effect of clonidine was prevented by the alpha-adrenoreceptor blocker phentolamine (0.1 microM) but not by the 5-HT receptor blocker pizotifen (1.0 microM). With the exception of propranolol, which in the atria shifted to the right the concentration-response curve to exogenous noradrenaline (NA), neither 5-HT nor the different antagonists employed modified the sensitivity to NA in the tissues studied. The present observations show that 5-HT can produce a dual effect on the sympathetic neurotransmission. It is proposed that a modification in the overflow of NA in response to nerve stimulation is caused by 5-HT and results from the interaction of 5-HT with specific receptors located on the sympathetic fibres. These presynaptic 5-HT receptors behave as excitatory (cat nictitating membrane) or inhibitory (guinea-pig atria) depending on the tissue studied.

[The effect of ethanol and antabus-antabus-alcohol-reaction on histamin and mast cell. Contents of the lung (author's transl)]

Alcohol--orally given in concentrations from 1 to 4 g/kg body-weight--leads to a reduction of mast cells in the guinea pig lung. At the same time a minor decrease of histamine concentration was observed. The incompatibility reaction with alcohol after disulfiram intake (DAR) shows an additional degranulation oft mast cells of the lungs and decrease of histamine-content. So far, there seems little difference between the influence of disulfiram alone and the DAR. Besides thrombocytes and basophile leucocytes, the mast cells of the lung are responsible for the release of histamine and serotonine during higher alcohol concentrations and alcohol-disulfiram-reactions. We think that the intolerance phenomena of humans after alcohol--f.e. in form of flush-reaction--is at least partly related to the concomitant influence oft mast cell-substances.

Release of smooth muscle-contracting substances from isolated perfused lungs

Infusion of tryptamine (1-4 mug/ml) through the pulmonary circulation of rat isolated lung perfused with Krebs solution caused release of a mixture of spasmogens contracting isolated smooth muscle preparations. One component of this mixture had biological activity comparable to E-type prostaglandins. Other components included a slow reacting substance comparable to SRS-A and a rabbit aorta-contracting substance comparable to RCS. Infusions of 5-hydroxytryptamine, acetylcholine and histamine (0.5-2 mug/ml) also caused release. Release induced by the tryptamines but not that by acetylcholine and histamine was prevented by methysergide whereas acetylcholine-induced release was prevented by hyoscine which did not affect tryptamine-induced release. The tryptamines and histamine released spasmogens from dog isolated lungs but only histamine was effective in guinea-pig lungs. We conclude that amine-induced release from isolated lungs is a fairly general phenomenon and that it may represent an endocrine function of lung.

Airways obstruction in the carcinoid syndrome. A study of the effect of drugs and other factors. II. Investigation of reversible airways obstruction

A patient with the carcinoid syndrome had reversible airways obstruction as his predominant complaint. Standard provocation by intravenous adrenaline in conjunction with serial recordings of FEV1 provided a simple and reproducible method for testing the patient's response to a variety of pharmacological agents and food factors. The degree of the airways obstruction was increased by food with a high protein content, and lessened by alcohol. No protection against adrenaline-induced airways obstruction was afforded by a specific 5-HT antagonist (methysergide), a kallikrein inhibitor (aprotinin), adrenergic blocking agents or corticosteroids. Other pharmacological studies suggested that the airways obstruction was mediated by the secretion of histamine by the carcinoid tumour. Despite the deleterious effect of intravenous catecholamines, the patient derived considerable benefit from adrenaline or isoprenaline given by inhalation. The timing of administration in relationship to meals was important for maximal effect.

Airways obstruction in the carcinoid syndrome. A study of the effect of drugs and other factors. I. Clinical and laboratory findings

A case of carcinoid syndrome is reported in which wheeze was the predominant complaint. Studies indicate the presence of abnormalities of both the kinin-forming system and the patient's indole metabolism. Nevertheless, provocation of airways obstruction by intravenous adrenaline did not produce any elevation of circulating levels of kinin, 5-HT or prostaglandin-like activity. The formation of kinin and its disposal was examined. A significant rise in urinary free histamine was obtained.

Protection against burn, tourniquet and endotoxin shock by histamine, 5-hydroxytryptamine and 5-hydroxytryptamine derivatives

1. 5-Hydroxytryptamine (5-HT), tryptamine, 5-methyltryptamine, 5-methoxytryptamine, N-methyltryptamine, 5-hydroxy-N,N-dimethyltryptamine, and histamine markedly protect mice subjected to burn, tourniquet and endotoxin shock. All of these compounds protect when given 30 min before the production of shock, but not when administered afterwards.2. The above compounds, as well as purines and purine derivatives have a similar chemical structure. Protection requires the compounds to contain a 5-membered ring with one unsubstituted N atom and a side chain with a basic N atom three atoms from the ring.3. All other biological amines tested without this chemical structure did not protect.4. Since the simplest compounds containing all the prerequisites for protection is histamine, this compound may play the key role in protection, for both 5-HT and purines release histamine from tissues.5. Protective doses of 5-HT and histamine prevent swelling of the injured area after tourniquet trauma and produce an increased bleeding volume and lower haematocrit value after burning. These actions of the drugs on the circulation may account for the increased survival after thermal trauma.

Circulating factors in the etiology of pulmonary insufficiency and right heart failure accompanying severe sepsis (peritonitis)

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Responses of skin blood vessels to bradykinin, histamine and 5-hydroxytryptamine

1. The responses of human cutaneous blood vessels to intradermal injection of bradykinin, histamine and 5-hydroxytryptamine (serotonin) are studied in order to evaluate the ability of these agents to mediate the vascular changes of sustained acute inflammation in the skin.2. Bradykinin produces erythema, owing to a direct effect on blood vessels, and wealing. Dose-response studies indicate that bradykinin is more potent than serotonin or histamine in respect of wealing.3. The response to serotonin differs qualitatively as well as quantitatively according to dose. High doses cause wealing and erythema with the characteristics of an axon reflex flare, but low doses produce erythema by a local effect without wealing.4. Using the technique of arterial occlusion, the occurrence of tachyphylaxis in respect of wealing was demonstrated with histamine and serotonin, but not with bradykinin. This evidence suggests that of the three agents, only bradykinin can mediate increased vascular permeability in sustained acute inflammation.5. The specificity of tachyphylaxis and the failure of anti-histamine to antagonize bradykinin wealing suggest that bradykinin and histamine act on separate blood vessel receptors.6. Corticosteroids do not inhibit wealing due to a wide range of doses of bradykinin. The anti-inflammatory activity of corticosteroids may therefore be due to reduced formation of kinins.

Experimental pulmonary embolism by platelet agglutinates in dogs

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The role of humoral factors in the dumping syndrome: experimentally induced dumping before and after portal systemic shunt

Although most patients have a satisfactory permanent result following partial gastrectomy for peptic ulcer, some have severe and occasionally disabling postprandial distress, due mainly to the postgastrectomy dumping syndrome. Despite 50 years of extensive research the etiology of this syndrome is not fully understood, although recent evidence suggests that this is, at least in part, a chemically mediated phenomenon due to release of humoral factor(s) from the intestinal mucosa during stimulation by hyperosmotic material.Animal experiments which have yielded evidence in support of the humoral theory have been reported by several workers, but this communication is the first in which experimentally induced dumping has been reported in man before and after portal systemic shunt. The symptoms elicited add further support to the hypothesis that a humoral factor is responsible for initiation of the dumping syndrome.

Release of 5-hydroxytryptamine and histamine from tissues of the rat

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5-Hydroxytryptamine and histamine as mediators of the vascular injury produced by agents which damage mast cells in rats

Each of the four agents, ovomucoid, dextran, 48/80, and testis extract, when injected beneath the skin of the dorsa of the paws of rats produces a local vascular injury characterized by a protein-rich edema. Each agent also produces damage to mast cells. Either 5-hydroxytryptamine or histamine produces a response similar in the gross to that elicited by the agents which damage mast cells; however, neither of these two agents produces mast cell damage. On a weight basis 5-hydroxytryptamine is a much more potent edema-producing agent than histamine. The edema-producing action of 5-hydroxytryptamine can be differentiated from the similar action of histamine by the use of specific antagonists; dibenamine is a 5-hydroxytryptamine antagonist and pyrilamine a histamine antagonist. The edema produced by the mast cell-damaging agents is partially inhibited by dibenamine but is not diminished by pyrilamine. It is completely inhibited by treatment of rats with both drugs. The drugs which inhibit edema do not prevent mast cell damage by ovomucoid, dextran, 48/80, or testis extract. The observations are consistent with the hypothesis that agents which damage mast cells, "release" both 5-hydroxytryptamine and histamine and that in the rat the edema associated with mast cell damage is mediated largely by 5-hydroxytryptamine.