Search PubMed⌕ Search

Biomedical subjects

J Axelrod

Publications and source records attributed to J Axelrod.

At least 217 records · Page 12Linked to original sources
PubMed1973

Chronobiology.

Explore the source record for details and available documents.

Circadian Rhythm↗
PubMed1972

Catecholamines.

Explore the source record for details and available documents.

Adrenal Medulla↗
PubMed1972

Psychotomimetic N-methylated tryptamines: formation in brain in vivo and in vitro.

The use of a sensitive enzymatic assay demonstrates that tryptamine occurs normally in rat brain. Intracisternal administration of [(14)C]tryptamine results in the formation of N-methyl-and dimethyltryptamine(a psychotomimetic compound)in the rat brain. An enzyme that converts tryptamine and N-methyl-tryptamine to N-methyl-and dimethyltryptamine was found to be present in rat and human brain. The N-methylation of tryptamine was inhibited by normally occurring compounds present in rat brain.

Animals↗
PubMed1972

Inhibition of release of dopamine- -hydroxylase and norepinephrine from sympathetic nerves by colchicine, vinblastine, or cytochalasin-B (hypogastric nerve stimulation-exocytosis-microtubules-microfilaments-guinea pig).

Stimulation of the hypogastric nerve to the guinea pig vas deferens in the presence of phenoxybenzamine produced an enhanced release of both dopamine-beta-hydroxylase (EC 1.14.2.1) and norepinephrine. Addition of colchicine, vinblastine, or cytochalasin-B to the incubation medium caused an almost complete inhibition of release of both the amine and the enzyme. Colchicine and cytochalasin-B produced a blocking effect but did not, however, modify the ratio of dopamine-beta-hydroxylase to norepinephrine recovered in the bath fluid. The findings indicate that norepinephrine and dopamine-beta-hydroxylase are released from sympathetic nerve terminals by exocytosis and that this process is dependent upon the integrity of both microtubules and microfilaments.

Animals↗
PubMed1972

Induction and superinduction of serotonin N-acetyltransferase by adrenergic drugs and denervation in rat pineal organ.

Activity of serotonin N-acetyltransferase (EC 2.3.1.5) in rat pineal organ is rapidly and markedly elevated in vivo after administration of beta-(3,4-dihydroxyphenyl)-L-alanine (L-DOPA), norepinephrine, epinephrine, isoproterenol, monoamine oxidase inhibitors, or theophylline. Serotonin or 5-hydroxytryptophan has no effect on the increase in activity of this enzyme. Inhibitors of protein synthesis or propranolol, a beta-adrenergic blocking agent completely inhibit(s) the increase in activity of serotonin N-acetyltransferase induced by drugs, indicating that new enzyme molecules are formed via stimulation of beta-receptors of pineal cells and adenosine 3':5'-cyclic monophosphate. When rat pineal organ is denervated by ganglionectomy, beta-(3,4-dihydroxyphenyl)-L-alanine induces much more serotonin N-acetyltransferase than in the innervated gland. This superinduction by denervation appears to be due to changes of the postsynaptic site, probably the beta-adrenergic receptor on the pineal cell.

5-Hydroxytryptophan↗
PubMed1972

Control of circadian change of serotonin N-acetyltransferase activity in the pineal organ by the beta--adrenergic receptor.

Serotonin N-acetyltransferase (EC 2.3.1.5) activity in the rat pineal organ is enhanced 50-fold at night. Rats exposed to light at night or kept in darkness during the daytime do not show any elevation of enzyme activity. Treatment with reserpine, a compound that depletes norepinephrine from nerves, 1-propranolol, a beta-adrenergic blocking agent, or cycloheximide, an inhibitor of protein synthesis, abolishes the nocturnal increase in serotonin N-acetyltransferase activity, indicating that the enzyme activity is modulated by neural release of norepinephrine from sympathetic nerves via beta-adrenergic receptors, and that the increase in enzyme activity is due to synthesis of new enzyme molecules. When rats are exposed to light at night or injected with 1-propranolol, there is a precipitous fall in serotonin N-acetyltransferase activity (half-life 5 min). Cycloheximide administered at night results in a slow fall in enzyme activity (half-life 60 min). When rats are kept in darkness and then exposed to light for 10 min, L-isoproterenol rapidly initiates the elevation of serotonin N-acetyltransferase activity to the initial level in 60 min. On the other hand, when the rats are kept in continuous light, L-isoproterenol initiates an increase in serotonin N-acetyltransferase activity after a lag phase of 60 min. The results indicate that there are two types of changes in serotonin N-acetyltransferase activity; a rapid increase and decrease mediated by the beta-adrenergic receptor, and a slow increase and decrease in enzyme activity that appears to represent the turnover of the enzyme.

Acyltransferases↗