Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. In the presence of atropine, mepyramine and ranitidine, electric field stimulation of the guinea-pig isolated ileum longitudinal muscle-myenteric plexus preparation resulted in a two component non-adrenergic non-cholinergic contraction. The initial contraction had a duration of approximately 1 s whereas the second contraction lasted approximately 10 s. The second contraction was completely inhibited by tetrodotoxin (0.2 x 10(-6) M) with minimal effect on the initial contraction. Phentolamine (3 x 10(-6) M), propranolol (3 x 10(-6) M) and hexamethonium (10(-4) M), did not significantly reduce either component of the contractile response. 2. The neurokinin NK1 receptor antagonists, GR82334 and GR71251, produced concentration-related (EC50 = 564 and 173 nM respectively) inhibitions of the second contraction with no effect on the initial contraction. The neurokinin NK2 receptor antagonists MEN 10207 and Ac-Leu-Asp-Gln-Trp-Phe-Gly-NH2 (R 396), 1 x 10(-9)-10(-5) M, were without effect on either component of the contractile response. 3. Concentration-related inhibitions of the second contraction, with no effect on the initial contraction, were observed after inclusion of the histamine H3 receptor agonists (R)-alpha-methylhistamine (pD2 = 7.6), N alpha-methylhistamine (pD2 = 7.7) and N alpha,N alpha-dimethylhistamine (pD2 = 6.3). Histamine also inhibited the second contraction (pD2 = 6.2) in a concentration-related manner but produced a lower maximum inhibitory effect than the other agonists tested. 4. Inclusion of the H3 receptor antagonists, thioperamide, burimamide, impromidine and phenylbutanoylhistamine, caused parallel concentration-related rightward shifts in the concentration-response curve to (R)-alpha-methylhistamine. In each case, Schild analysis of these data gave slopes not significantly different from unity. Antagonist affinity values for thioperamide (pA2 = 8.2), burimamide (pA2 = 7.0) and impromidine (pA2 = 7.0) were consistent with values obtained in other assays of the H3 receptor. However, phenylbutanoylhistamine (pA2 = 5.8) and betahistine (pKB < 4) had affinities more than ten fold lower than values obtained in other assays of the H3 receptor.5. Exposure of the tissues to N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (10-6 M) for 7-30min followed by extensive washing, had no effect on basal contractions, but produced a rightward shift in the concentration-response curves to (R-alpha-methylhistamine, Nalpha"-methylhistamine, Nalpha",Nalpha-dimethylhistamine and histamine. This treatment also resulted in a decrease in the maximum inhibitory response obtainable. Apparent agonist affinity (pKD) values of 7.01, 7.06, 6.09 and 6.13 were estimated for (R)-alpha-methylhistamine, Nalpha-methylhistamine, Nalpha',Nalpha"-dimethylhistamine and histamine respectively.6. In conclusion, pharmacological analysis has revealed that histamine H3 receptors in the guinea-pig ileum modulate the release of non-adrenergic non-cholinergic neurotransmitters, one of which is probably substance P. In addition we have identified N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline as an irreversible antagonist at H3 receptors and have used this compound to estimate apparent affinity values of agonists at H3 receptors in this preparation.
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PMID:Characterization of histamine-H3 receptors controlling non-adrenergic non-cholinergic contractions of the guinea-pig isolated ileum. 135 20

Recent immunohistochemical studies have shown the distribution of histaminergic neurons in the mammalian brain, which are concentrated in the tuberomammillary nucleus of the posterior hypothalamus and project efferent fibers to almost all parts of the brain from the olfactory bulb to the spinal cord. Histaminergic neurons co-express other neuroactive substances, such as gamma-aminobutyric acid, adenosine, substance P, galanin and Met-enkephalin-Arg-Phe. In addition, pharmacological studies have demonstrated the presence of presynaptic histamine H3-receptors (autoreceptor) in addition to H1- and H2-receptors. The specific agonist (alpha-methylhistamine) and antagonist (thioperamide) of H3-receptors were developed. Results from a number of studies indicate a variety of physiological roles of neuronal histamine such as thermoregulation, feeding behavior, sexual activity, sleep-wakefulness cycle, hormonal regulation and so on. Moreover, histaminergic drugs affect not only the emotional behavior, but also are effective to treat some patients of depression, Parkinson's disease, akathisia, motion sickness and so on. The central histaminergic neuron system is also affected by mental disorders and neuropsychopharmacological drugs. This review especially focused on these points and suggests that the central histaminergic neuron system may play an important role in the regulation of mental functions.
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PMID:[Recent advances in neuropsychopharmacology of the central histaminergic neuron system]. 192 57

We studied the role of histamine H3-receptors on neurogenic microvascular leakage in guinea pig airways by measuring extravasation of Evans blue dye. In guinea pig airways the major component of the neurogenic leakage is nonadrenergic noncholinergic (NANC) mediated, due to release of tachykinins. Anesthetized guinea pigs were pretreated with propranolol and atropine to block the beta-adrenergic and cholinergic responses and with mepyramine and cimetidine to block histamine H1- and H2-receptors, respectively. Vagal stimulation significantly increased leakage of dye in trachea (Tr), main bronchi (MB), and central (cIPA) and peripheral intrapulmonary airways (pIPA). The selective H3-receptor agonist (R)-alpha-methylhistamine (alpha-MeHA, 0.3-3 mg/kg iv) did not alter basal leakage but inhibited NANC-mediated leakage in a dose-dependent manner with a maximal inhibition of 56.9 (Tr, P less than 0.01), 66.7 (MB, P less than 0.01), 67.5 (cIPA, P less than 0.01), and 58.2% (pIPA, P less than 0.05) at 1 mg/kg. Pretreatment with phentolamine (2.5 mg/kg iv) had no effect on the inhibitory response produced by alpha-MeHA, but the H3-receptor antagonist thioperamide (5 mg/kg ip) blocked its effect. Exogenous substance P (1 microgram/kg iv) caused comparable plasma leakage to NANC-mediated response but was not inhibited by alpha-MeHA. We conclude that H3-agonists inhibit neurogenic leakage by prejunctional inhibition of neuropeptide release from airway sensory nerves.
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PMID:Histamine H3-receptors inhibit neurogenic microvascular leakage in airways. 215 1

We have investigated whether the histamine H3-receptors influence nonadrenergic noncholinergic (NANC) bronchoconstriction in guinea-pig in vivo. Atropine, propranolol, mepyramine and cimetidine were administered to block the effects of beta-adrenoceptor-, acetylcholine, H1- and H2-receptor-mediated responses, respectively. Vagal stimulation evoked a NANC bronchoconstrictor response. The selective H3-agonist, alpha-methylhistamine (alpha-MeHA, 1-10 mg/kg i.v.) did not alter basal respiratory insufflation pressure, but reduced the NANC bronchoconstrictor response to vagal stimulation in dose-dependent manner (with a maximal inhibition of 46.0 +/- 10.3%; mean +/- S.E. at 10 mg/kg) (P less than 0.02). Histamine itself also had a significant inhibitory effect on NANC responses with H1- and H2-blockade. The alpha-adrenoceptor antagonist phentolamine had no effect on the inhibitory response produced by alpha-MeHA, but the H3-receptor antagonist thioperamide blocked the inhibitory effect of alpha-MeHA. alpha-MeHA had no inhibitory effect on bronchoconstriction induced by exogenous substance P (5-25 micrograms/kg i.v.). We conclude that H3-receptors inhibit the release of transmitter from NANC nerves and that H3-receptors might play a role in regulation of neurogenic inflammatory responses in the airways.
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PMID:Histamine H3-receptors modulate nonadrenergic noncholinergic neural bronchoconstriction in guinea-pig in vivo. 248 90

The actions of histamine on myenteric neurones were investigated with intracellular recording methods in guinea-pig small intestine. The actions of histamine at the ganglion cell soma were: membrane depolarization, increased input resistance, suppression of post-spike hyperpolarizing potentials, augmented excitability and repetitive spike discharge. Excitability was enhanced also at spike initiation sites remote from the cell body. Both H1, and H2, receptors were involved in the response to histamine. Dimaprit mimicked the responses to histamine in 80% and 2-methylhistamine in 50% of the trials. Cimetidine was an antagonist for histamine in 82% and for dimaprit in all of the trials. Pyrilamine blocked the actions of histamine in 59% of the cells and always blocked the action of 2-methylhistamine. Histamine mimicked slow synaptic excitation in the neurones, but was ruled out as a neurotransmitter for the slow excitatory post-synaptic potential (e.p.s.p.). Histamine either did not affect the responses to 5-hydroxytryptamine, substance P and acetylcholine or it potentiated the responses to these putative neurotransmitters for slow synaptic excitation. The results support the possibility that histamine released from mast cells by circulating peptidergic messengers, by neurotransmitters or during anaphylaxis could influence enteric nervous function.
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PMID:Intracellular study of effects of histamine on electrical behaviour of myenteric neurones in guinea-pig small intestine. 614 13

The involvement of the histamine H3 receptor in the regulation of substance P release in neurogenic inflammation was studied by using rat hindpaw skin. R-(-)-alpha-Methylhistamine, a specific histamine H3 receptor agonist, significantly inhibited the increased vascular permeability induced by antidromic electrical stimulation of the sciatic nerve in a dose-dependent manner at doses of 0.5-3 mg/kg (i.v.), and thioperamide (2 mg/kg i.p.), a specific histamine H3 receptor antagonist, prevented the inhibitory effect of R-(-)-alpha-methylhistamine. The antidromic stimulation also caused a significant increase in immunoreactive substance P release in the subcutaneous (s.c.) perfusate in the rat hindpaw. R-(-)-alpha-Methylhistamine (0.25-2 mg/kg) dose dependently inhibited the increase in release of immunoreactive substance P, and thioperamide (2 mg/mg i.p.) antagonized it. Perfusion of histamine (10(-3) M) elicited a significant increase of immunoreactive substance P release in the perfusate, which was reduced by R-(-)-alpha-methylhistamine and the antagonism of thioperamide was also observed. Histamine (in the presence of histamine H1 and H2 receptor antagonists) had an inhibitory effect on the electrically evoked release of immunoreactive substance P. These results strongly support the hypothesis that histamine regulates substance P release via prejunctional histamine H3 receptors that are located on peripheral endings of sensory nerves.
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PMID:Regulation of substance P release mediated via prejunctional histamine H3 receptors. 753 82

The autoregulation of the histamine release via the histamine H3 receptor in the periphery was studied in vivo and in vitro. Antidromic electrical stimulation of the sciatic nerve caused a significant increase in histamine release in the subcutaneous perfusate in the rat hindpaw. (R)alpha-methylhistamine, a specific H3 receptor agonist, significantly and dose-dependently inhibited the increase in release of histamine by antidromic stimulation at intravenous doses of 0.25-2 mg/kg. Thioperamide (2 mg/kg, intraperitoneally), a specific H3 antagonist, prevented the inhibitory effect of (R)alpha-methylhistamine. Substance P perfusion (5-50 microM) also elicited a significant increase in histamine, and a significant inhibition by (R)alpha-methylhistamine and the antagonism of thioperamide were observed. (R)alpha-methylhistamine inhibited the histamine release by substance P from rat peritoneal mast cells in vitro, and thioperamide reduced the response to (R)alpha-methylhistamine. These data suggest that mast cells may have histamine H3 receptors, and that histamine probably modulates its own release through the H3 receptor in neurogenic inflammation.
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PMID:Autoregulation of histamine release via the histamine H3 receptor on mast cells in the rat skin. 754 64

Perfusion of histamine (10(-3) M) elicited a significant increase of immunoreactive substance P release in the subcutaneous perfusate in the rat hindpaw. The active L-enantiomer of cromakalim, lemakalim (50 micrograms/kg, i.v.), a selective K+ channel activator, significantly inhibited the immunoreactive substance P release. Glibenclamide (10 mg/kg, i.v.), an ATP-sensitive K+ channel blocker, abolished the response to lemakalim on the release of immunoreactive substance P. R(-)-alpha-methylhistamine (1 mg/kg, i.v.), a specific histamine H3 receptor agonist, significantly inhibited the release of immunoreactive substance P. Glibenclamide (10 mg/kg, i.v.) antagonized the inhibitory effect of R(-)-alpha-methylhistamine. Tetraethylammonium (10 mg/kg, i.p.), a K+ channel blocker, also reduced the inhibitory effect significantly. These results suggest that the inhibition of substance P release from sensory nerve endings via prejunctional histamine H3 receptors may be achieved by activating the ATP-sensitive K+ channel coupled to the histamine H3 receptor in the rat skin.
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PMID:ATP-sensitive K+ channels mediate regulation of substance P release via the prejunctional histamine H3 receptor. 754 12

Many patients with interstitial cystitis (IC) also have irritable bowel syndrome (IBS), both of which occur overwhelmingly in women, are characterized by pain, and worsen under stress. Bladder and colon biopsies of a female patient with both IC and IBS were evaluated immunohistochemically. There were 40 +/- 10 mast cells (MC)/mm2 (normal, less than 10) in the bladder, which were degranulated. The colon contained 148 +/- 11 MC/mm2 (normal, less than 50), mostly close to numerous substance P (SP)-positive nerves. Histamine, methylhistamine, and the unique MC enzyme tryptase were evaluated in 24-hour urine during two flare-ups. These results may help explain the concurrent presentation and the painful nature of these syndromes.
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PMID:Mast cell and substance P-positive nerve involvement in a patient with both irritable bowel syndrome and interstitial cystitis. 863 18

Effects of histamine and related compounds on the bovine iris dilator were investigated. Histamine caused a concentration-related contraction of the bovine iris dilator and IC50 was 1.57 x 10(-7) M. The potency of histamine on the bovine iris dilator was almost the same as that observed in guinea pig ileum. Histamine-induced contraction of the bovine iris dilator was antagonized by the H1 antagonists pyrilamine, diphenhydramine and chlorpheniramine, whereas pretreatment with the H2 antagonists cimetidine and ranitidine was most effective. In addition, histamine and the H1 agonist 2-methylhistamine caused a contraction of bovine iris dilator, but the H2 agonist 4-methylhistamine was not effective. An H3 antagonist, thioperamide, also had no contractive effects on the bovine iris dilator. The bovine iris dilator contained a considerable amount of histamine, which was not released by compound 48/80, substance P or by increasing K+ concentration in the medium. In conclusion, histamine caused a potent contraction of the bovine iris dilator via H1 receptor, and this muscle showed a high sensitivity to histamine similar to guinea pig ileum.
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PMID:EFFECTS OF HISTAMINE AND RELATED COMPOUNDS ON THE BOVINE IRIS DILATOR. 880 59


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