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PubMed1986

Monoamine oxidase activity in chick cerebral microvessels.

In chick brain microvessels, monoamine oxidase activity using catecholamines (dopamine and noradrenaline) and indoleamines (serotonin and tryptamine) as substrates was higher than that measured in synaptosomes and free mitochondria. In contrast, phenylalkyamines such as tyramine and 2-phenylethylamine were more deaminated in free mitochondria and synaptosomes than in microvessels. These results suggest that the activity of monoamine oxidase towards neurotransmitter amines in microvessels should be considered as a site of inactivation of these neurotransmitters in the chick brain parenchyma.

Animals↗
PubMed1987

Biotransformation of 1-methyl-1,2,3,4-tetrahydro-beta-carboline-1-carboxylic acid to harmalan, tetrahydroharman and harman in rats.

1-Methyl-1,2,3,4-tetrahydro-beta-carboline-1-carboxylic acid (1-carboxytetrahydroharman, 1-CTHH) has been detected in the brain of rats following intracerebroventricular injection of tryptamine and pyruvic acid. We now report the metabolism of this compound. Following intraperitoneal injection of 1-CTHH into rats, harmalan was found to be the major metabolite besides tetrahydroharman (THH) and harman. A high concentration of THH was measured in the lung while most of harman was found in the urine. Harmalan and THH could be detected in the brain in low concentrations. The products were separated following extraction from tissues by high-performance liquid chromatography (HPLC) on a reversed phase C18-DB column. The identity of the metabolites was confirmed by mass spectrometry (MS) analysis. The results demonstrate the role of 1-CTHH as a precursor of the biologically active compounds harmalan, THH and harman.

Animals↗
PubMed1975

Investigations on the venom of the South Indian scorpion Heterometrus scaber.

The enzymes from the venom of Heterometrus scaber, the indole compounds present and the toxic protein of the venom have been studied. The venom contains acid phosphatase, ribonuclease, 5'-nucleotidase, hyaluronidase, acetylcholine esterase and phospholipase. A. The indole compounds present in the venom have been identified as 5-hydroxytryptophan, tryptophan, serotonin and tryptamine, along with two unidentified indole compounds. The venom produces hyperglycaemia in sublethal doses and this has been found to be due to increased adrenaline secretion. The toxic protein of the venom has been obtained in a pure form by (NH4)2SO4 fractionation, followed by fractional precipitation with acetone and chromatography over DEAE-Sephadex. The toxic fraction has been found to be homogeneous on acrylamide gel electrophoresis. It is a glycoprotein (molecular weight 15 000) containing 1.74% glucosamine, 0.87% galactosamine, 0.313% sialic acid, 3.25% fucose and 0.45% of an unidentified neutral sugar. It did not show any enzyme activities, haemolytic activity or inhibition of succinate dehydrogenase activity but it produced hyperglycaemia in sublethal doses. The toxic level (intravenous administration in rats) was found to be 0.72 mg/kg body weight.

Acetylcholinesterase↗
PubMed1976

Monamine oxidase in outer membrane of skeletal muscle mitochondria.

(1) Monoamine oxidase (EC 1.4.3.4) is present in rat skeletal muscle mitochondria. (2) A radioassay procedure for the assay of monoamine oxidase in muscle mitochondria is described. It is based on teh procedure using side-chain [2-14C]-tryptamine as substate described by Wurtman, R.J. and Axelrod, J. (1963) Biochem. Pharmacol. 12, 1439--1441 and employs a pH of 8.0 and a substrate concentration of 0.25 mM. (3) The Km of the muscle mitochondrial enzyme at pH 8.0 is 1.34 - 10(-5) M and that of the liver enzyme under the same conditions is 2.5 - 10(-5) M. Muscle mitochondria contain only one quarter of the activity of enzyme present in liver mitochondria. (4) Monoamine oxidase is shown to be in the outer membrane of skeletal muscle mitochondria and thus to be a suitable marker enzyme for use in the fractionation of these mitochondria.

Animals↗
PubMed1976

The subcellular distribution and partial characterization of cholinesterase activities of canine platelets.

The multiple cholinesterase activities in canine platelets have been investigated. Platelets were homogenized by rapid decompression under nitrogen, glass tube/Teflon pestle, and glycerol lysis techniques. Rapid decompression under nitrogen technique was found to be the most efficient and gentle method for cell disruption. Homogenates were subfractionated using sodium diatrizoate density gradients. Marker enzyme assays and pulse labeling experiments with 5-hydroxyl[14C] tryptamine and [125I] thrombin on prepared subcellular fractions confirmed that the soluble, plasma membrane and the granule-1 fractions were all in reasonably pure form. Furthermore, labeling of the plasma membrane with [125I] thrombin is cited as the first successful attempt at attaining significantly bound marker for this structure. Cholinesterase activity distributions measured in these fractions indicated that about 30% of the activity was present in the plasma membrane, 50% in granule-1 and 5% in soluble fractions. Kinetic data of cholinesterase activities obtained from intact platelets, plasma membrane preparations and platelet release supernatants indicated that they are strikingly similar.

Acetylglucosaminidase↗
PubMed1982

Purification of cytochromes P-448 from beta-naphthoflavone-treated rainbow trout.

Rainbow trout were treated with beta-naphthoflavone and the hepatic microsomal cytochrome P-450 solubilized with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. Chromatography on tryptamine-Sepharose 4B gave a single cytochrome P-450 peak which was further resolved into three components by elution from DEAE-Sepharose. The two main peaks were then chromatographed on hydroxyapatite and a total of four fractions obtained. Two of these fractions had similar properties and significantly metabolized [14C]benzo[a]pyrene in a reconstituted system containing rat cytochrome P-450 reductase. This activity was inhibited by alpha-naphthoflavone but not by metyrapone of SKF-525A. Purified cytochromes P-448 from 3-methylcholanthrene-treated rat had similar spectral properties and activity towards [14C]benzo[a]pyrene suggesting similarities between these forms.

Animals↗
PubMed1989

Semicarbazide-sensitive amine oxidase activity in catfish tissues.

1. Semicarbazide-sensitive amine oxidase activity was found in five tissues of the siluroid catfish, Parasilurus asotus, using benzylamine as substrate. It was highest in the intestine, followed by the liver and skin. 2. The apparent Km value and optimal pH for benzylamine in the intestine were 49.8 microns and 8.8, respectively. 3. Substrate specificity of the enzyme was tested in the intestine and the highest activity was found with beta-phenylethylamine, followed by tryptamine and benzylamine.

Amine Oxidase (Copper-Containing)↗
PubMed1982

Pharmacological comparison of the potential antidepressant UP 614-04 with viloxazine and imipramine; behavioral studies.

1. Several behavioral tests were used to compare the pharmacological activity of the potential antidepressant UP 614-04 with those of viloxazine and imipramine. 2. Orally-administered UP 614-04, like viloxazine, reduced locomotor activity in mice, and, like viloxazine and imipramine, it antagonized the hypothermia or ptosis induced by reserpine or tetrabenazine and the hypothermia induced by a high dose of apomorphine. 3. UP 614-04 antagonized oxotremorine-induced hypothermia, and to a lesser extent, oxotremorine-induced tremors, indicating that it possesses some CNS anticholinergic activity. 4. Both imipramine and viloxazine were more potent than UP 614-04 in potentiating yohimbine toxicity in mice. 5. Orally-administered UP 614-04 potentiated d-amphetamine-induced stereotypy to a greater extent than viloxazine, but to a lesser extent than imipramine. 6. Intraperitoneally-injected UP 614-04 was much more potent than viloxazine in increasing tryptamine convulsive potential in rats, indicating that it might exert an inhibitory action on monoamine oxidase. 7. These results indicate that UP 614-04 has a behavioral profile that is consistent with an antidepressant action, but that it differs from imipramine and viloxazine.

Animals↗
PubMed1995

Characterization of 5-hydroxytryptamine receptors in goat cerebral arteries.

1. In isolated goat middle cerebral artery segments, 5-hydroxytryptamine (5-HT, 10(-8)-3 x 10(-5) M) elicited concentration-dependent contractions with EC50 = 2.1 (1.9-2.5) x 10(-7) M and Emax = 64 +/- 2% of 50 mM KCl-induced contraction. 2. Several 5-HT receptor agonists were used: (a) the agonist of 5-HT2 receptors alpha-methyl-5-hydroxy-tryptamine (10(-7)-3 x 10(-4) M) induced strong contraction (51 +/- 6%); (b) the selective agonists of 5-HT1 receptors sumatriptan (10(-8)-10(-5) M) and 5-carboxamidotryptamine (10(-9)-10(-4) M) and the agonist of 5-HT1A receptors 8-hydroxy-2-(di-n-propylamino)tetralin (10(-7)-3 x 10(-5) M) induced weak contractions (8, 18 and 14%, respectively); and (c) the agonist of 5HT3 receptors 2-methyl-5-hydroxytryptamine (3 x 10(-6)-10(-4) M) induced almost negligible contraction. 3. Pretreatment with the antagonist of 5-HT1A and 5-HT1B receptors cyanopindolol (10(-8), 10(-6) M), the antagonist of 5-HT1/5-HT2 receptors methysergide (10(-11), 10(-9) M) and the antagonist of 5-HT2 receptors ketanserin (10(-11), 10(-9) M) induced non-competitive inhibition of the concentration-response curve to 5-HT. The antagonist of 5-HT3 receptors 3-trophanyl-3,5-dichlorobenzoate (10(-7), 10(-5) M) did not inhibit the contractile curve to 5-HT. 4. These results suggest that 5-HT contracts the goat middle cerebral artery by acting mainly on 5-HT2 receptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1984

Selective accumulation of hydroxytryptamines by frog tectal neurones.

By means of histofluorescence microscopy, 5,7-dihydroxytryptamine was shown to be taken up by selective populations of brain neurones of the frog, Rana pipiens, following both intracranial administration and in vitro incubation with isolated brain preparations. Presumptive non-aminergic cell bodies of the superficial aspect of tectal lamina 6 exhibited more avid uptake than did putative serotonin perikarya of the raphe complex. Within the tectum, 5,7-dihydroxytryptamine uptake appeared to be restricted to large piriform neurons; in the torus semicircularis, it occurred in a morphologically dissimilar group of scattered cells. The same tectal cell system accumulated 5-hydroxytryptamine and 6-hydroxytryptamine, but not N-acetylserotonin, melatonin, or noradrenaline. 5,7-Dihydroxytryptamine uptake was insensitive to cold or imipramine; however, it was blocked by ouabain at high but not low temperature. At concentrations greater than or equal to 100 microM, 5,7-dihydroxytryptamine-induced fluorescence was sufficiently intense to permit tracing of intratectal dendrites and tectofugal axonal processes projecting to a lateral diencephalic neuropil and an ipsilateral isthmic neuropil. While previous monoamine histofluorescence and immunohistologic studies have not revealed serotonin-containing perikarya in the ranid tectum, our findings demonstrate that lamina 6 piriform projection neurones, presumably lacking indolamine-synthesizing enzymes, possess a striking capability for accumulating hydroxylated tryptamines.

5,7-Dihydroxytryptamine↗
PubMed1987

Immunohistochemistry of tryptophan hydroxylase in the rat brain.

An antiserum raised against tryptophan tetrahydropterine oxygen oxidoreductase was used to examine in rat brain the immunohistochemical localization of this rate-limiting enzyme catalysing the biosynthesis of serotonin. Tryptophan tetrahydropterine oxygen oxidoreductase was detected in numerous nerve cell bodies, proximal dendrites and axon varicosities or terminals corresponding to those of serotonin neurons as judged by their anatomical distribution and concomitant immunoreactivity to an antiserum against serotonin. In hypothalamus, a serotonin-containing nerve cell group previously visualized in the pars ventralis of the nucleus dorsomedialis by radioautography after serotonin uptake, and by serotonin immunohistochemistry after tryptamine loading, remained tryptophan tetrahydropterine oxygen oxidoreductase-unreactive even in rats treated with colchicine. On the other hand, a small group of tryptophan tetrahydropterine oxygen oxidoreductase-positive cells was identified in the rostrolateral portion of nucleus dorsomedialis, which could play a part in the intrinsic serotonin innervation of hypothalamus. There was no overlap between tryptophan tetrahydropterine oxygen oxidoreductase immunostaining and the cellular distribution of N-acetyl serotonin as reported in earlier studies. It is therefore likely that the synthesis of N-acetyl serotonin from tryptophan does not take place in N-acetyl serotonin-containing neurons.

Animals↗
PubMed1992

Serotonin is a directly-acting hyperalgesic agent in the rat.

In this study, we have investigated serotonin hyperalgesia employing the mechanical paw withdrawal nociceptive threshold test in the rat. Intradermally injected serotonin was found to produce a dose-dependent hyperalgesia that was not attenuated by procedures which eliminate the known indirect mechanisms of hyperalgesia such as sympathectomy, polymorphonuclear leukocyte depletion or cyclooxygenase inhibition. In addition, the latency to onset of serotonin hyperalgesia is extremely short, with maximal hyperalgesia observed in less than 1 min, a similar temporal onset to direct-acting hyperalgesic agents such as prostaglandin E2. The results suggest, therefore, that the hyperalgesic effects of serotonin in our animal model are exerted by direct action on primary afferent neurons. Only the intradermal injection of selective serotonin (5-hydroxytryptamine; 5-HT) agonists for the 1A receptor subset (5-HT1A), (+/-)-2-dipropylamino-8-hydroxy-1,2,3,4-tetrahydronaphthaline hydrobromide and N,N-dipropyl-5-carboxamido-tryptamine maleate, produced dose-dependent hyperalgesia. No hyperalgesia was seen after 5-HT1B, CGS-12066B maleate and m-trifluoromethylphenyl-piperazine hydrochloride; 5-HT2+IC, alpha methyl 5HT and (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl; or 5-HT3, 2-methyl-5-hydroxytryptamine maleate and phenylbiguanide, agonists. Similarly, only the 5-HT1A antagonists, spiroxatrine and spiperone, attenuated the hyperalgesia induced by intradermally injected serotonin. 5-HT2+IC antagonists, mesulergine and ketanserin, and 5-HT3 antagonists, quipazine and 3-tropanyl-indole-3-carboxylate, did not significantly attenuate 5-HT hyperalgesia. We conclude that serotonin produces hyperalgesia by a direct action on the primary afferent neuron via the 5-HT1A subset of serotonin receptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1985

Selective drug-induced reduction of blood flow in tumor transplants.

The effect of a calcium antagonist and a physiologic amine on tumor and muscle perfusion was investigated with the aim of improving the preconditions for external hyperthermia treatment of cancer. Nisoldipine (0.04-4.0 mg/kg) and 5-hydroxy tryptamine (5-HT) (0.2-8.0 mg/kg) were administered i.p. in Sprague-Dawley rats bearing Walker 256 carcinoma, Yoshida sarcoma, or a homologous tumor transplant derived from a spontaneous leiomyosarcoma of the uterus. At the maximum dosage used, nisoldipine injection caused a decrease of the regional washout rate of Xenon-133 of 63 +/- 8% (SEM) in the Walker carcinoma and an increase of 80 +/- 41% in the muscle of the hind leg. 5-HT (8 mg/kg) caused a drop of 79 +/- 29% in the Walker carcinoma and only a slight fall of the washout rate in muscle of 14 +/- 4.8%. Tumor-to-muscle uptake ratios of 11C-butanol fell from 5.63 +/- 1.98 to 3.32 +/- 1.21, and from 5.3 +/- 0.56 to 2.98 +/- 0.30, after injection of 0.2 mg/kg nisoldipine and 4 mg/kg 5-HT, respectively. Similar reaction patterns and percentage changes were observed in different tumor lines at constant doses of 0.2 mg/kg nisoldipine and 4 mg/kg 5-HT. Both drugs representing two different rationales of vasomotor action were able to reduce blood flow specifically in transplanted tumors; nisoldipine increased muscle blood flow and decreased arterial blood pressure, whereas 5-HT acted without substantial systemic effects.

Animals↗
PubMedDate not supplied

Progress in microfluorometric identification of monoamine fluorophores.

Techniques for the microfluorometric identification of monoamine fluorophores have been put forward along two different lines: (1) extension of the excitation range into the far UV and (2) computer-assisted on-line scanning recordings in combination with an automatic microfluorometric identification of fluorophores. By an extension of the excitation range to 250 nm it is possible to distinguish fluorophores of DOPA from those of dopamine, fluorophores of noradrenaline from those of adrenaline, and fluorophores of 5-OH-tryptophan from those of 5-OH-tryptamine. In a computer-assisted on-line scanning procedure using a high-aperture inverted illuminating microscope equipped with UV transmitting optics the specific formaldehyde-induced catecholamine fluorescence is characterized microfluorometrically by corrected ratios of excitation maxima (370:320 nm and 320:275 nm). Excitation data are plotted out with corresponding coordinates in the x- and in the y-axis. Furthermore the digitized values of fluorescence intensities obtained with the scanning procedure are processed according to principles of automatic image-analysis procedures.

5-Methoxytryptamine↗
PubMed1979

Depression and monoamine oxidase.

1. The first part of the paper is devoted to a critical review on the possible relationships between depression and monoamine oxidase. 2. This study describes the results of an investigation of MAO-activity in depression, using new approaches and methodology. This methodology was developed because the literature data indicated that a) previous results are difficult to compare because of varying methods and diverse target populations used; b) previous methodological deficiencies do not allow to draw definite conclusions about the relationship between MAO-activity and depression. 3. The present investigation selected 35 psychiatric patients according to clearly defined diagnostic criteria (20 endogenous depressive, 10 neurotic depressive, and 5 manic patients) matched to 25 healthy control-subjects. 4. The Michaelis-constant (Km), the maximum reaction speed (Vmax), and the 50% enzyme inhibition by tranylcypromine (IC50) of platelet-MAO were determined during and after recovery from the depressive or manic episode using 3 substrates (tyramine, tryptamine, and phenylethylamine). 5. The present investigation, in contrast to conventional methodology, utilized three different substrates at different concentrations. Significant correlations were demonstrated for the Vmax-values of each of the three substrates, whereas the Km and the IC50 (tranylcypromine)-values varied for each substrate. 6. The results show that there were no differences between the characteristics of the platelet-MAO in depressive or manic patients and those of normal subjects. Furthermore, treatment with tricyclic antidepressants had no effect on MAO-activity. A previous investigation indicated that the MAO-properties in human brain tissue were similar to that in human platelets.

Adult↗
PubMed1978

The identification of LSD-like hallucinogens using the chronic spinal dog.

The effects of several indoleamines and phenethylamines were studied in the chronic spinal dog and compared with two standard drugs, LSD and amphetamine. In the nontolerant chronic spinal dog, their effects on a variety of physiologic and behavioral functions were measured in untreated dogs, as well as dogs treated with certain antagonists. The effects of the antagonists phenoxybenzamine and cyproheptadine on the various physiologic effects were studied for all drugs. For some idoleamines and phenethylamines, the effects of chlorpromazine and pimozide were also studied. Indoleamines and phenethylamines in the LSD-tolerant chronic spinal dog and their anorexigenic effects in the intact dog were also studied. The results of these studies indicate that psilocin, mescaline, dimethyltryptamine and tryptamine are LSD-like drugs. DOM, DOB, DMA, and TMA are predominantly LSD-like drugs but do have some amphetamine-like action. PMA and PEA are predominantly amphetamine-like drugs with some LSD-like activity. MMDA and MDA have a more complicated pharmacology showing proerties that resemble LSD and amphetamine, but they have other actions which are not shared by either LSD or amphetamine, which suggests they have yet other modes of action.

Animals↗
PubMed1984

Alterations in monoamine oxidase activity after single and repeated exposure of rats to chlorphentermine.

Monoamine oxidase (MAO) activity was determined in rat tissues following in vivo treatments with chlorphentermine (CP). Oxidation of seven amine substrates by liver, lung or brain mitochondrial MAO was investigated at 2 h after a single i.p. injection (60 mg/kg) or after repeated injection (once daily for 3 days, 20 mg/kg, i.p.). Deamination of the type A substrates, norepinephrine, serotonin and octopamine, was decreased significantly in liver, lung and brain after both single and repeated injections. Oxidative deamination of tyramine and dopamine (type A + B substrates) was also lowered in all organs after single and repeated exposure to CP, but to a lesser degree than the type A substrates. However, oxidation of the type B substrates, benzylamine and tryptamine, was unaffected by CP administration in comparison to control. These data indicate that CP is a specific inhibitor of mitochondrial MAO, form A.

Amines↗
PubMed1995

Increased oxidation of ethylene glycol to formaldehyde by microsomes after ethanol treatment: role of oxygen radicals and cytochrome P450.

The production of ferryl-type oxidants by microsomes from ethanol-fed rats and pair-fed controls was determined by assaying for the production of formaldehyde from ethylene glycol. Microsomes from the ethanol-fed rats were more reactive than controls in oxidizing ethylene glycol. Catalase was a powerful inhibitor for this reaction, superoxide dismutase was slightly inhibitory and hydroxyl radical scavengers had no effect. These results suggest an important role for H2O2, but not O2-. or .OH in the overall pathway for oxidizing ethylene glycol to formaldehyde. The production of H2O2 by microsomes was increased after ethanol treatment, the extent of increase corresponding to the increase in oxidation of ethylene glycol. A variety of inhibitors and ligands of cytochrome P450, including miconazole, diethyldithiocarbamate, tryptamine, and 4-methylpyrazole, inhibited formaldehyde production by both microsomal preparations. Anti-cytochrome P4502E1 IgG also inhibited the reaction with both microsomal preparations and prevented the increase caused by ethanol treatment. These results indicate that microsomes from ethanol-treated rats are more reactive than pair-fed controls in generating ferryl-type oxidants and that increased production of H2O2 by cytochrome P4502E1 plays a role in the elevated oxidation of ethylene glycol to formaldehyde.

Animals↗