In vitro synthesis of noradrenaline in ganglia and salivary glands after in vivo preganglionic stimulation

The extent of synthesis of [14C]noradrenaline from [14C]tyrosine and from [14C]dopamine was assessed in slices of superior cervical ganglia, representing cell bodies, and in submaxillary salivary glands, representing terminals of noradrenergic neurons of the cat. Immediately and 6 h after preganglionic stimulation for 3 h the rate of synthesis of noradrenaline from tyrosine and dopamine was not altered in ganglia. In salivary glands, however, synthesis of noradrenaline from both tyrosine and dopamine was increased at both times. These results suggest that acute periods of increased neural activity results in the acceleration of noradrenaline synthesis in the terminals but not in the cell bodies of noradrenergic neurons.

Dopamine: release from the brain in vivo by amantadine

After dopamine stores in the caudate nucleus of cats were labeled with [(3)H]dopamine, the ventricular system was perfused with artificial cerebrospinal fluid. The addition of amantadine to the perfusing fluid caused a doserelated increase in the concentrations of [(3)H]dopamine appearing in the perfusion effluent. Subthreshold concentrations of amantadine also enhanced the efflux of [(3)H]dopamine induced by electrical stimulation of the caudate nucleus.

Norepinephrine: release from brain by d-amphetamine in vivo

After injection of H(3)-norepinephrine into the left lateral cerebral ventricle of cats, the lateral and third cerebral ventricles were perfused with an artificial cerebrospinal fluid. Addition of d-amphetamine to the perfusion fluid caused a significant increase in the concentration of H(3)-norepinephrine in the effluent.

Studies with chronically isolated rats: tissue levels and urinary excretion of catecholamines and plasma levels of corticosterone

Rats were maintained in individual cages (isolated) or were housed six per cage (community) for 15–17 weeks. There were no significant differences between the body or organ weights or in the tissue content of catecholamines in the two groups. Isolated animals exhibited an increased sensitivity to the toxicity of isoproterenol. The resting plasma levels of corticosterone and the urinary excretion of noradrenaline and adrenaline were the same for both groups. However, when subjected to a mild stress (a new cage and other animals) only isolated rats responded with increased plasma levels of corticosterone and increased urinary excretion of catecholamines.