Search results for "Tyramine"
showing 8 items of 38 documents
New phenolics, cytotoxicity and chemosystematic significance of Atriplex semibaccata
2019
Abstract The chemical characterization of the 70% hydromethanolic extract of Atriplex semibaccata (family: Chenopodiaceae) afforded a new methoxylated flavonol triglycoside, atrisemibaccatoside A (1), and a new lignanamide, (N-[(E)-m-hydroxycinnamoyl]tyramine (7), as well as, five known flavonols (2–6) and two lignanamides (8–9). The structures of the isolated compounds were established depending upon LR&HR-FAB-MS, 1D and 2D NMR spectroscopic analyses. The cytotoxic activity of the isolated compounds (1–4, and 7–9) was investigated. Compounds 7, 8 and 9 weakly inhibited the proliferation of leukemia CCRF-CEM cells with IC50 values of 78.5, 46.3, and 71.2 μg/ml, respectively, and exhibited n…
Tyramine action on motoneuron excitability and adaptable tyramine/octopamine ratios adjust Drosophila locomotion to nutritional state
2019
Adrenergic signaling profoundly modulates animal behavior. For example, the invertebrate counterpart of norepinephrine, octopamine, and its biological precursor and functional antagonist, tyramine, adjust motor behavior to different nutritional states. In Drosophila larvae, food deprivation increases locomotor speed via octopamine-mediated structural plasticity of neuromuscular synapses, whereas tyramine reduces locomotor speed, but the underlying cellular and molecular mechanisms remain unknown. We show that tyramine is released into the CNS to reduce motoneuron intrinsic excitability and responses to excitatory cholinergic input, both by tyraminehonoka receptor activation and by downstrea…
Tyramine Actions on
2017
The biogenic amines octopamine (OA) and tyramine (TA) modulate insect motor behavior in an antagonistic manner. OA generally enhances locomotor behaviors such as Drosophila larval crawling and flight, whereas TA decreases locomotor activity. However, the mechanisms and cellular targets of TA modulation of locomotor activity are incompletely understood. This study combines immunocytochemistry, genetics and flight behavioral assays in the Drosophila model system to test the role of a candidate enzyme for TA catabolism, named Nazgul (Naz), in flight motor behavioral control. We hypothesize that the dehydrogenase/reductase Naz represents a critical step in TA catabolism. Immunocytochemistry rev…
Tyramine Actions on Drosophila Flight Behavior Are Affected by a Glial Dehydrogenase/Reductase
2017
The biogenic amines octopamine (OA) and tyramine (TA) modulate insect motor behavior in an antagonistic manner. OA generally enhances locomotor behaviors such as Drosophila larval crawling and flight, whereas TA decreases locomotor activity. However, the mechanisms and cellular targets of TA modulation of locomotor activity are incompletely understood. This study combines immunocytochemistry, genetics and flight behavioral assays in the Drosophila model system to test the role of a candidate enzyme for TA catabolism, named Nazgul (Naz), in flight motor behavioral control. We hypothesize that the dehydrogenase/reductase Naz represents a critical step in TA catabolism. Immunocytochemistry rev…
Presence of muscarinic inhibitory and absence of nicotinic excitatory receptors at the terminal sympathetic nerves of chicken hearts.
1976
Nicotine (2 X 10(-4) M) or acetylcholine (5.5 X 10(-4) M) in the presence of 3 X 10(-6) M atropine did not increase the rate or amplitude of contraction in isolated atria or ventricular strips of the chicken heart; both drugs also did not cause an output of noradrenaline or adrenaline and did not evoke antidromic discharges in the right sympathetic nerves of isolated perfused chicken hearts. In contrast, "high K+-solutions" evoked an output of noradrenaline and adrenaline and caused a burst of antidromic discharges. Dimethylphenylpiperazine (DMPP; 3.1 X 10(-4) M), by a tyramine-like action, elicited a small output of noradrenaline and increased rate and amplitude of contraction" but did not…
Modulatory action of acetylcholine on cerebrovascular sympathetic neurotransmission
1991
1. Acetylcholine (10 micrograms/min) diminished the electrically-induced cerebral blood flow reductions. Atropine (1-2 mg) partially blocked this inhibitory effect. 2. Exogenously administered noradrenaline (1-10 micrograms) and tyramine (50-500 micrograms) reduced cerebral blood flow but this effect was unchanged by acetylcholine infusion. 3. Acetylcholine inhibited the nonadrenergic component of the electrically-induced contraction at a concentration greater than or equal to 10(-6) M and potentiated the adrenergic component at a concentration greater than or equal to 10(5) M. Atropine 10(-7) M) inhibited both of these effects. In addition, acetylcholine (10(-4) M) enhanced the electricall…
Kinetic properties of catecholoxidase activity of tarantula hemocyanin
2008
Phenoloxidases occur in almost all organisms, being essentially involved in various processes such as the immune response, wound healing, pigmentation and sclerotization in arthropods. Many hemocyanins are also capable of phenoloxidase activity after activation. Notably, in chelicerates, a phenoloxidase has not been identified in the hemolymph, and thus hemocyanin is assumed to be the physiological phenoloxidase in these animals. Although phenoloxidase activity has been shown for hemocyanin from several chelicerate species, a characterization of the enzymatic properties is still lacking. In this article, the enzymatic properties of activated hemocyanin from the tarantula Eurypelma californi…
Adsorption of methotrexate and calcium leucovorin onto cholestyramine in vitro.
2003
Abstract Methotrexate (MTX), an antimetabolite of folic acid, is a drug widely used in the treatment of different types of cancer. When high doses are administered, it is necessary to interrupt its action by administering calcium leucovorin (CaL). The main pathway of MTX and CaL elimination in humans occurs through the kidney, but about 10% is excreted in the faeces via the bile. Drugs, foods and sorbents in intestinal lumen modify MTX and CaL reabsorption. Individual and simultaneous studies on the adsorption of MTX and CaL from aqueous phosphate buffer by cholestyramine were carried out in order to calculate the adsorption process of MTX and CaL to cholestyramine, and to characterize the …