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At least 955 records · Page 53Linked to original sources
PubMed1982

Dopamine-beta-hydroxylase activity in the axillary bodies, the heart and the splanchnic nerve in two elasmobranchs, Squalus acanthias and Etmopterus spinax.

1. The activity of dopamine-beta-hydroxylase (DBH) was examined in tissues from Squalus acanthias and Etmopterus spinax using tyramine as substrate. 2. The activity of DBH in axillary bodies in Squalus was 19040 +/- 240 nmol/g per hr and in Etmopterus 6120 +/- 245 nmol/g per hr. 3. DBH activity in nervous tissue, i.e. the splanchnic nerve (together with coeliac artery) was found to be 123 +/- 41 nmol/g per hr in Squalus and 384 +/- 62 nmol/g per hr in Etmopterus. 4. In Squalus heart DBH activity was undetectable, while Etmopterus heart had DBH activity both in atrium and ventricle, 40 +/- 13 and 18 +/- 8 nmol/g per hr respectively. 5. A small amount of DBH activity was found in Squalus blood plasma, 2 +/- 0.7 nmol/ml per hr. 6. The DBH activity gave high formation of octopamine in a wide temperature range from 24.5 to 32 degrees C.

Animals↗
PubMed1987

Pharmacological evidence that alpha 1-adrenoceptors mediate metamorphosis of the Pacific oyster, Crassostrea gigas.

Oyster larvae can be induced to metamorphose by exposure to the natural vertebrate adrenergic agonists, epinephrine and norepinephrine. The larval receptors mediating this induction were pharmacologically characterized by testing the ability of a variety of adrenergic agonists and selected structural analogs of epinephrine and norepinephrine to induce oyster metamorphosis, and by testing the ability of various adrenergic antagonists to block the induction of metamorphosis by epinephrine. Oyster metamorphosis can be induced by vertebrate adrenergic agonists with relative potencies: cirazoline greater than epinephrine greater than phenylephrine greater than or equal to norepinephrine greater than alpha-methylnorepinephrine greater than isoproterenol much greater than methoxamine = clonidine. Other structural analogs of epinephrine and norepinephrine, including dopamine and octopamine, were ineffective at inducing metamorphosis. Induction of metamorphosis by epinephrine can be blocked by vertebrate adrenergic antagonists with relative potencies: chlorpromazine greater than or equal to prazosin greater than phentolamine greater than WB4101 greater than propranolol greater than yohimbine greater than metoprolol. These data demonstrate that receptors similar to vertebrate-type alpha 1-adrenoceptors mediate oyster metamorphosis. This is the first evidence for alpha 1-adrenoceptors in molluscs, and provides an important clue to the control of the complex process of molluscan metamorphosis and to the evolution of vertebrate adrenergic receptors.

Adrenergic alpha-Agonists↗
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↗
PubMed1992

Preparation of an optimum mobile phase for the simultaneous determination of neurochemicals in mouse brain tissues by high-performance liquid chromatography with electrochemical detection.

A systematic method is described for the optimization of a mobile phase for the simultaneous determination of 24 neurochemicals consisting of catecholamine, serotonin, their precursors and metabolites and related materials. This mobile phase contained sodium acetate (0.04 M), citric acid (0.01 M), sodium chloride (0.0126 M), sodium octyl sulfate (91 mg/l), tetrasodium EDTA (50 mg/l) and 10% (v/v) methanol. When this optimum mobile phase was applied to the analysis of brain tissues of the Swiss male mouse, twelve neurochemicals were quantified in the free state: tyrosine, L-beta-3,4-dihydroxyphenylanine, dopamine, 3,4-dihydroxyphenylacetic acid, 4-hydroxy-3-methoxyphenylacetic acid, norepinephrine, 3-methoxy-4-hydroxyphenylglycol, DL-3,4-dihydroxymandelic acid, DL-4-hydroxy-3-methoxymandelic acid, serotonin, L-tryptophan, 5-hydroxyindole-3-acetic acid and DL-synephrine and normetanephrine, appearing as a fused peak. This fused peak was present on the chromatogram tracings of all the mouse brain tissues. The separable neurochemicals not found by this procedure in the Swiss male mouse tissues were DL-3,4-dihydroxyphenylglycol,5-hydroxytryptophan, epinephrine, DL-octopamine, metanephrine, deoxyepinephrine, homovanillyl alcohol, N-acetylserotonin, tyramine and 3-methyltyramine.

Animals↗
PubMed1994

Modulation of cyclic AMP production by strial marginal cells from gerbil in culture.

To further investigate the role of marginal cells (MCs) in the secretion of endolymph and because of the limitations encountered in investigating these cells in vivo, we used primary cultures of MCs derived from explants of gerbil stria vascularis and investigated modulation of the adenylate cyclase-cyclic AMP system. After 10 days on type I collagen coated plastic dishes, a confluent monolayer of epithelial-like cells was obtained which exhibited the morphologic and immunohistochemical features of the native marginal cells. The cyclic AMP (cAMP) content was determined at 37 degrees C, after 5 min of incubation with various agents, in the presence of a specific inhibitor of type III cAMP-dependent phosphodiesterase, RO 20-1724. The adenylate cyclase-cAMP system was associated with beta 2-adrenergic receptors. The cAMP content was increased by isoproterenol (23-fold), a beta-agonist, but not by octopamine, an alpha-agonist, and the affinity for ICI 118.551, a specific beta 2-antagonist, was greater than for CGP 20712A, a specific beta 1-antagonist (Kd: 0.03 x 10(-6) M and 15 x 10(-6) M respectively). The cAMP content was maximally increased by prostaglandin E2 > beta 2-adrenergic agonist >> vasopressine type 2 receptor agonist (26-, 23-, and 3-fold the basal cAMP content, respectively). The present study demonstrates that cultured marginal cells retain some of their in vivo properties including a modulated enzymatic cAMP system. This culture model should allow further in-depth investigation of the function of marginal cells.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1990

Analysis of biogenic amines and their metabolites in biological tissues and fluids by gas chromatography-negative ion chemical ionization mass spectrometry (GC-NICIMS).

GC-NICIMS has been employed in the analysis of biogenic amines and their metabolites in human urine and human, bovine and porcine aqueous and vitreous humour. Several new chemical derivatization procedures have been developed in order to analyse these compounds. Concentrations of octopamines and synephrines were determined in urine from treated and untreated hypertensive subjects and normotensive individuals; there were no significant differences in concentrations of these metabolites between these groups. Human urine contained several dihydroxy-phenylethylamines which have not been reported as natural metabolites before and also 5- and 6-hydroxydopamine in relatively large amounts. Aqueous and vitreous humour contained very low quantities of noradrenaline, tyramine and dopamine but measurements were inconsistent because sometimes the levels were below the limits of detection. Metabolites of a number of biogenic amines were readily detected in aqueous and vitreous humour.

Animals↗
PubMed1983

Identification of three further giant neurons, r-APN, INN and FAN, in the caudal part on the dorsal surface of the suboesophageal ganglia of Achatina fulica Férussac.

In addition to the neurons of Achatina fulica Férussac examined previously, three more giant neurons, r-APN (right-anterior pallial neurons), INN (intestinal nerve neuron) and FAN (frequently autoactive neuron), were identified in the suboesophageal ganglia of the same animal. R-APN (200-250 microns in diameter), the somatic membrane of which was usually silent, was found near the exit of the right anterior pallial nerve in the right parietal ganglion. The most important feature in identifying the neuron is the one-by-one correspondence of somatic spikes to impulses in the right anterior pallial and the left anterior pallial nerves. R-APN was excited markedly by dopamine, 5-hydroxytryptamine, L-homocysteic acid, erythro-beta-hydroxy-L-glutamic acid and acetylcholine, and inhibited by GABA. INN (150-200 microns in diameter), which was also silent, was situated near the intestinal nerve in the visceral ganglion. INN somatic spikes corresponded to the impulses in the intestinal nerve. INN was excited by 5-hydroxytryptamine and histamine. Acetylcholine had biphasic effects (inhibitory followed by slight excitatory). FAN (100-150 microns in diameter), showing frequent spike discharges, about 60-120/min, was situated somewhat further from the exit of the left posterior pallial nerve in the visceral ganglion. No clear correspondence was observed between the FAN somatic spikes and impulses of any nerves. FAN was excited by 5-hydroxytryptamine, GABA and acetylcholine, and inhibited by octopamine and erythro-beta-hydroxy-L-glutamic acid.

Action Potentials↗
PubMed1984

The effects of some putative transmitters and biogenic amines on uropod abductor muscle in the crayfish Procambarus clarkii and Cambaroides japonicus.

The effects of some putative transmitters and biogenic amines were examined on the uropod ventral abductor exopodite (AbdExV) muscle in two crayfish species Procambarus clarkii and Cambaroides japonicus. Bath application of L-glutamate to the AbdExV muscle caused sustained contract while gamma-aminobutyric acid (GABA) depressed the nerve-evoked contraction of the muscle. Acetylcholine (ACh) had no effect on both the resting tension and the nerve-evoked contraction. Iontophoresis of L-glutamate and GABA onto the surface of the muscle fiber further confirmed that glutamate and GABA are the possible excitatory and inhibitory transmitters respectively at the neuromuscular junction of AbdExV muscle. Bath application of 5-hydroxytryptamine (5-HT) and octopamine (Oct) caused enhancement of the nerve-evoked contraction but dopamine (DA) had no effect on both the resting tension and the nerve-evoked contraction.

Action Potentials↗
PubMed1984

Investigation of the mode of action of the anaesthetic agent, ketamine, in the heart of the bivalve mollusc Tapes watlingi.

In the isolated heart preparation from the bivalve mollusc Tapes watlingi the anaesthetic agent ketamine produced two distinct effects; a positive inotropic effect and bradycardia. The dose-dependent positive inotropic effect was considered to be a direct effect on the cardiac muscle since it was not blocked by antagonists specific for the excitatory actions of acetylcholine, dopamine, serotonin and octopamine. Verapamil, a calcium ion antagonist, did not affect the inotropic response. The bradycardia caused by ketamine was blocked by inhibitors specific for the acetylcholine receptor but not by specific antagonists to the inhibitory dopamine receptor.

Acetylcholine↗
PubMed1985

Pharmacological characteristics of three silent giant neurons, v-LPSN, v-1-VOrN and v-VLN, identified on the ventral surface in the left parietal and the visceral ganglia of the suboesophageal ganglia of an African giant snail (Achatina fulica Férussac).

Three giant neurons, named v-LPSN, v-1-VOrN and v-VLN, were identified on the ventral surface of the left parietal ganglion and the visceral ganglion in the suboesophageal ganglia of an African giant snail (Achatina fulica Férussac). They lacked the spontaneous spike discharges in the normal state. The pharmacological features of the three neurons, in relation to the principal common neurotransmitter substances and their derivatives were examined. The v-LPSN (ventral-left parietal silent neuron) (diameter: about 130 microns) is situated in the left parietal ganglion close to the visceral ganglion. The neuron was excited by histamine (the minimum effective concentration [MEC]: 3 X 10(-4) M) and inhibited slightly by acetylcholine (Ach) and its related substances. The v-1-VOrN (ventral-left-visceral oral neuron) (diameter: about 130 microns) is situated in the left and oral part of the visceral ganglion. The neuron was inhibited markedly by dopamine (DA) (MEC: 3 X 10(-4) M) and slightly by Ach and its related substances. No substance producing a marked excitation of the neuron has been found yet. The v-VLN (ventral-visceral large neuron) (diameter: about 300 microns) is found in the centre of the visceral ganglion. The neuron was excited by L-norepinephrine (MEC: 10(-4) M), DL-octopamine (MEC: 2 X 10(-4) M), 5-hydroxytryptamine (MEC: 10(-4) M) and beta-hydroxy-L-glutamic acid (MEC: 10(-4) M) and inhibited by DA (MEC: 10(-4) M), GABA (MEC: 3 X 10(-5) M) and Ach (MEC: 10(-4) M). L-Epinephrine showed varied effects (MEC: 10(-4) M), which were either excitatory or inhibitory.

Action Potentials↗
PubMed1986

Effects of substituted phenylethylamines on blowfly feeding behavior.

The pharmacology of adult Phormia regina (Meigen) feeding behavior was explored by injecting candidate drugs into starved blowflies and then determining their responsiveness to aqueous sucrose, via the proboscis extension reflex. d-Amphetamine caused responsiveness to fall dramatically, while related drugs and biogenic amines had varying effects. When d-amphetamine-treated flies were fed 1 M sucrose, they consumed significantly more than control flies. Electrophysiological studies demonstrated that the responses of tarsal sugar receptor neurons to aqueous sucrose were not significantly altered by d-amphetamine. These observations are compatible with our hypothesis that octopamine positively modulates blowfly feeding behavior and suggest that other aromatic biogenic amines affect feeding behavior in this insect.

Animals↗
PubMed1987

Modulation of dopamine receptors in the Tapes clam by dextroamphetamine and phenylethanolamine.

The mechanism underlying the modulation, by dextroamphetamine and compounds related to phenylethanolamine, of responses to dopamine and serotonin has been studied in the isolated ventricle and aortic bulb of the clam Tapes watlingi. Dextroamphetamine and phenylethanolamine but not cocaine and benztropine have the ability to unmask inhibitory responses to both dopamine and serotonin in the ventricle. Chlordimeform but not clozapine attenuates the inhibitory response to both dextroamphetamine and phenylethanolamine in concentrations which have little or no effect on the inhibitory response to dopamine in the ventricle. Phenylethanolamine, dextroamphetamine, phenylpropylolamine and p-chloro-phenylethanolamine but not octopamine or noradrenaline attenuate the contractile responses to both dopamine and serotonin in preparations of the quiescent aortic bulb. These data show that there are specific receptors for phenylethanolamine in the Tapes heart capable of modulating responses to dopamine and serotonin, and suggests that this biogenic phenethylamine can act as an environmental and physiological factor which may determine how the mollusc heart responds to dopamine.

Adenosine Monophosphate↗
PubMed1987

Species differences in lung mitochondrial monoamine oxidase activities.

Pulmonary mitochondrial monoamine oxidase (MAO) activity was examined in preparations from rat, rabbit and guinea-pig with 12 different amines as substrates: serotonin, norepinephrine, and octopamine (type A specific); tryptamine, benzylamine, 5-methoxytryptamine, 5-methyltryptamine, p-methoxyphenylethylamine, and 3,4-dimethoxyphenethylamine (type B specific); and tyramine, dopamine and 3-methoxytyramine (type A + B specific). The oxidation of type A and type A + B substrates was greater in guinea-pig lung mitochondria than in rat or rabbit preparations. Except for benzylamine, the oxidation of type B substrates was similar in all three species. Benzylamine was not oxidized by guinea-pig lung mitochondria but was actively metabolized by rat and rabbit preparations.

Animals↗
PubMed1987

Biogenic amines and their metabolites in Trichostrongylus colubriformis, a nematode parasite of ruminants.

The following biogenic amines (BA) and BA metabolites were identified via HPLC in homogenates prepared from adults of Trichostrongylus colubriformis (Nematoda) recovered from the intestines of goats: N-acetyldopamine, DOPA, dopamine, epinephrine, epinine, 5-hydroxyindoleacetic acid, 4-hydroxy-3-methoxy-phenylglycol, 3-(p-hydroxyphenyl) proprionic acid, metanephrine, O-methyl-DOPA, 3-methoxytyramine, norepinephrine, normetanephrine, octopamine, p-hydroxymandelic acid, serotonin, synephrine, tyramine and vanillylmandelic acid. The mean concentrations of these compounds in groups of worms collected from different goats did not differ significantly with sex, but between the groups variance was high with probable components of both host and nematode origin.

Animals↗
PubMed1988

Studies on the crustacean cardiac ganglion.

1. An overview of studies on the decapod crustacean cardiac ganglion is given emphasizing contributions to questions of general interest in cellular neurophysiology. 2. John Welsh, in 1951, introduced this 9-celled, semi-autonomous ganglion as a preparation offering physiologists unique experimental possibilities. 3. It exhibits remarkable reliability and stability in rhythmic pattern generation. The neurons show endogenous burst-forming capability mediated by "driver potentials". 4. These regenerative, Ca-mediated potentials are restricted to the soma, while impulse-generating membrane is segregated to the distal axon. 5. Thus, voltage-clamp analysis of the ionic currents underlying the burst-forming potentials is possible by isolating the soma with a ligature. 6. The isolated ganglion is spontaneously active, but the normal mechanism of pacemaking remains to be clarified, including the possible contribution of stretch-sensitive dendrites. 7. The activity of the ganglion is subject to modulation by neurohumors. These include the transmitter at intraganglionic synapses, transmitters of the pair of inhibitory and the two pairs of acceleratory fibers, and neurohormones released from the pericardial organs. The transmitters are not established. 8. Effects on the ganglion of substances isolated from the pericardial organs have been described. 9. These include 5-hydroxytryptamine, dopamine, octopamine, and two peptides. 10. One of these, proctolin, produces a long-lasting sequence of effects. 11. The work continues to raise new questions for which the ganglion offers excellent research material.

Animals↗
PubMed1991

Neuromodulatory effects of acetylcholine and serotonin on the sensitivity of leech mechanoreceptors.

1. Each segmental ganglion of the leech Hirudo medicinalis contains 6 touch (T) cells, 4 pressure (P) cells and 4 nociceptive (N) cells. The receptive terminals of these cells innervate the skin in discrete areas. These cells are known to have extrasynaptic receptors. 2. We tested the effect of transmitter substances present in leech CNS on the sensitivity of T and P cells to mechanical stimuli. Substances tested included octopamine, FMRFamide, proctolin, substance P, glutamate, GABA, acetylcholine and serotonin. 3. Only acetylcholine and serotonin had consistent effects. Serotonin (1 x 10(-3) M) increased the number of action potentials of T cells elicited by a standard stimulus. Serotonin (1 x 10(-4) M) and acetylcholine (1 x 10(-3) M) increased the number and frequency of action potentials in P cells.

Acetylcholine↗
PubMed1993

Levels of biogenic amines and peptides in individual corn earworm moths, Helicoverpa zea, using high performance liquid chromatography with electrochemical detection.

Quantitative levels of octopamine, serotonin, and dopamine were measured from brain and corpus cardiacum in individual male and female Helicoverpa zea, using high performance liquid chromatography (HPLC) with electrochemical detection. By increasing the proportion of organic modifiers in the mobile phase we were also able to quantify two peptides, adipokinetic hormone and hypertrehalosemic hormone. Levels of amines in both tissues were similar in males and females, but with greater quantities in the brain than the corpus cardiacum. In contrast, the two hormones were found predominantly in the corpus cardiacum, with the level of adipokinetic hormone three times greater than that of the hypertrehalosemic hormone, a finding in agreement with other studies. The described methodology demonstrates the power of HPLC with electrochemical detection for analysis of amines and peptides found in small quantities within the nervous tissue of individual insects.

Amino Acid Sequence↗
PubMed1993

Purification and properties of the soluble midgut trehalase from the gypsy moth, Lymantria dispar.

The midgut trehalase (THA) from fifth instar Lymantria dispar (gypsy moth) larvae was purified to homogeneity by two separate methods: gel filtration followed by Rotofor preparative IEF, and affinity chromatography on trehalose coupled to Sepharose 6B followed by preparative polyacrylamide gel electrophoresis. Midgut THA from the last stadium L. dispar larvae existed mainly in soluble form and displayed a single band of activity in nondenaturing polyacrylamide gels when stained by a THA-specific staining procedure. Analytical IEF of purified midgut THA revealed a single protein band with an apparent pI of 4.6. SDS-PAGE and gel permeation studies indicated that the smallest active form of THA in the late fifth instar larval midgut was a monomeric protein with an approximate size of 60 kDa. A specific activity of 67 units/mg of protein at 30 degrees C and at pH 6.4 was determined for the enzyme purified by affinity chromatography and preparative gel electrophoresis. The midgut enzyme exhibited a very high substrate specificity with a Km of 0.4 mM for trehalose. The enzyme was maximally active at pH 5.4-6.0 and was thermally stable at temperatures up to 65 degrees C. The midgut THA was insensitive to inhibition by a high concentration of Tris, sucrose, p-nitrophenyl-beta-D-glucoside or phloridzin. Divalent cations metal ions, hypertrehalosaemic hormone and octopamine had no significant effect on the activity of the purified enzyme in vitro. The purified enzyme was inactivated by modification with DEP and was competitively inhibited by castanospermine with an apparent Ki of 0.8 x 10(-6)M at pH 6.4.

Amino Acid Sequence↗