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At least 1,369 records · Page 76Linked to original sources
PubMed2000

Electrophysiological responses of crayfish oocytes to biogenic amines.

Intracellular recordings were made from immature, growing oocytes of the crayfish Pacifastacus leniusciulus. Oocytes had a relatively negative resting potential of -74.7+/-2.2 mV (n=26; range -53 to -90) and a mean input resistance of 0.86+/-0.19 MOmega (n=22; range 0.17-3.3). Octopamine induced a long-lasting response involving biphasic changes in input resistance, together with bi- or multiphasic changes in membrane potential. The resistance-decreasing phase involved (in different oocytes) membrane hyperpolarization, depolarization or both. The resistance-increasing phase was usually a depolarization. The hyperpolarizing form of the resistance-decreasing response, and the depolarizing resistance-increasing response reversed in polarity at membrane potentials of (respectively) -90 and -92 mV, suggesting increases and decreases in K(+) conductance underly the biphasic changes in input resistance. The threshold concentration for the response was remarkably low (>10(-12) M) and showed little or no dose-dependence over the concentration range 10(-12)-10(-6) M. Similar responses were evoked by dopamine and serotonin (at 10(-9) M), although a higher proportion of oocytes responded to octopamine and/or dopamine than to serotonin.

Animals↗
PubMedDate not supplied

Ion conductors derived from biogenic amines, bile acids, and amino acids.

A family of conjugates has been synthesized from spermine, putrescine, lysine, gamma-aminobutyric acid, sarcosine, cholic acid, glycocholic acid, 3alpha,7alpha-dihydroxycholic acid, and 3alpha,12alpha-dihydroxycholic acid, based on a design principle previously reported (Bandyopadhyay, P., Janout, V., Zhang, L., Regen, S. L. (2001) J. Am. Chem. Soc. 123, 7691). Each of these conjugates was found to exhibit significant activity in promoting the transport of Na(+) across liposomal membranes derived from 1,2-dimyristoleoyl-sn-glycero-3-phosphocholine, and also from 1,2-dipalmitoleoyl-sn-glycero-3-phosphocholine. In all cases, plots of pseudo first-order rate constants, k(obsd) vs (mol % of ion conductor)(2) were found to be linear, indicating that transport-active dimers are involved and that only a small fraction of the conjugates are in an aggregated form. An operational comparison that has been made within this series of conjugates indicates that Na(+) transport activity and membrane selectivity have a moderate dependency on the composition and the structure of the ion conductor.

Amino Acids↗
PubMed1995

Fluorine for hydroxy substitution in biogenic amines: asymmetric synthesis and biological evaluation of fluorine-18-labeled beta-fluorophenylalkylamines as model systems.

This work explores the biomimetic potential of [18F]fluorine for hydroxy substitution in beta-phenethanolamines as a possible strategy for developing radiotracers for in vivo imaging. Stereospecific syntheses of the two model compounds (1R,2S)-1-[18F]fluoro-1-deoxyephedrine ([18F]FDE) and (1S,2S)-1-[18F]fluoro-1-deoxypseudoephedrine ([18F]FDP) were achieved in high radiochemical yield (62%, decay corrected) and high specific activity (> 2500 Ci/mmol) by reaction of [18F]fluoride ion with the appropriate chiral cyclic sulfamidate precursor. Both tracers exhibited good stability toward metabolic defluorination in vivo. High, homogeneous brain uptake (approximately 8% of injected dose) was observed after intravenous injection in mice similar to that reported for the structurally related analog [11C]methamphetamine. The 1R,2S isomer (FDE) showed a 3-fold higher concentration of radioactivity in whole brain as compared to the 1S,2S isomer (FDP). These results suggest possible employment of this strategy for chiral radiolabeling of biologically important phenethanolamines and catecholamines.

Animals↗
PubMed2001

Metabolism of biogenic amines in rat brain during pilocarpine-induced aggression.

Quantitative distribution of bioactive substances in the brain of aggressive rats was studied. The norepinephrine/serotonin ratio increased in the temporal and parietal lobes, hypothalamus, and hippocampus of killer rats. The open filed behavior of aggressive rats is characterized by a long latency period, low locomotor activity, and slow movements. Exposure to constant darkness aggravated abnormal behavioral characteristics of aggressive rats. Serotonin content in the hypothalamus and visual cortex of these rats decreased by 75 and 76%, respectively.

Aggression↗
PubMed1998

Effects of electromagnetic fields on the levels of biogenic amine metabolites, quinolinic acid, and beta-endorphin in the cerebrospinal fluid of dairy cows.

Eight multiparous non-lactating pregnant Holstein cows at 198 +/- 35 d of gestation, weighing 608 +/- 24 kg, were confined to wooden metabolic cages in an electric and magnetic field chamber with a 12:12 h light:dark cycle. Subarachnoidal catheters were installed 5 d before the activation of the electric and magnetic fields. The cows were exposed to electric and magnetic fields (60 Hz, 10 kV/m and 30 microT) continuously except for the feeding and cleaning time for an average of 21.44 +/- 1.4 h per day for a period of 30 d. Cerebrospinal fluid samples were collected on three consecutive days before an exposure period of 30 d, on the last 3 d of the exposure period, and for 3 d starting 5 d after the exposure period. The concentrations of beta-endorphin, tryptophan, 5-hydroxyindoleacetic acid, homovanillic acid, 3-methoxy-4-hydroxyphenylethyleneglycol and quinolinic acid in cerebrospinal fluid were determined. There was a significant increase in quinolinic acid, and a trend towards an increase in tryptophan, findings consistent with a weakening of the blood-brain barrier due to exposure to the electric and magnetic fields.

Animals↗
PubMed2003

Effects of potentiated antibodies against brain-specific S100 protein on biogenic amine content and lipid peroxidation in rats under conditions of alcoholization.

Antibodies against S100 protein in ultralow doses specifically affected catecholamine metabolism in rats withdrawn from chronic ethanol exposure. The contents of tryptophan, tyrosine, and norepinephrine in brain structures returned to normal. The concentrations of dopamine, epinephrine, and norepinephrine in the peripheral blood decreased. Modulation of monoamine content in the peripheral blood suggests that antibodies against S100 protein possess stress-protective activity during ethanol withdrawal.

Animals↗