Ascorbic acid and Mg-ATP were found to regulate norepinephrine biosynthesis in intact secretory vesicles synergistically and specifically, using the model system of isolated bovine chromaffin granules. Dopamine uptake into chromaffin granules was shown to be unrelated to the presence of Mg-ATP and ascorbic acid at external dopamine concentrations of 7.5 and 10 mM. Under these conditions of dopa...

By using the Coons indirect immunofluorescence technique, enkephalin-like immunoreactivity with a granular localization was observed in human adrenal medullary gland cells and pheochromocytomas. In two of the tumors and in a few adrenal gland cells, a somatostatin-like peptide could also be identified. Catecholamine cell types were visualized on adjacent sections with antisera to the synthesizi...

New methods for the synthesis of 3 beta-(4'-alkyl-, 4'-alkenyl-, and 4'-alkynylphenyl)nortropane-2 beta-carboxylic acid methyl esters 2-4, respectively, were developed. These methods involved coupling of the appropriate organometallic reagents to 3 beta-(4'-iodophenyl)tropane-2 beta-carboxylic acid methyl ester (6a, RTI-55) or to an N-protected derivative of 6a followed by N-demethylation or re...

Parkinson's disease (PD) is a progressive debilitating neurodegenerative disorder clinically manifest by motor, posture and gait abnormalities. Human neurophysiological studies recording local field potentials within the subthalamic nucleus and scalp-based electroencephalography have shown pathological beta synchrony throughout the basal ganglia-thalamic-cortical motor network in PD. Notably, s...

Neural activity in the brain of parkinsonian patients is characterized by the intermittently synchronized oscillatory dynamics. This imperfect synchronization, observed in the beta frequency band, is believed to be related to the hypokinetic motor symptoms of the disorder. Our study explores potential mechanisms behind this intermittent synchrony. We study the response of a bursting pallidal ne...

Rat embryonic mesencephalic cultures were employed to evaluate the consequences of adding GM1 ganglioside to cultures lesioned with the selective neurotoxin 1-methyl-4-phenylpyridinium (MPP+). MPP+ reduced dopamine and DOPAC content, dopamine uptake, aromatic L-amino acid decarboxylase activity, and the number of tyrosine hydroxylase-immunopositive neurons. The immunopositive neurons that remai...

OBJECTIVE The authors examined whether striatal dopamine transporters were altered in acutely (96 hours or less) abstinent cocaine-abusing subjects, as suggested by postmortem studies. METHOD [123I] beta-CIT and single photon emission computed tomography were used to assess striatal dopamine transporter levels in 28 cocaine-abusing subjects and 24 comparison subjects matched as a group for ag...

Much of the motor impairment associated with Parkinson's disease is thought to arise from pathological activity in the networks formed by the basal ganglia (BG) and motor cortex. To evaluate several hypotheses proposed to explain the emergence of pathological oscillations in Parkinsonism, we investigated changes to the directed connectivity in BG networks following dopamine depletion. We record...

Drugs that act on dopamine neurotransmission are important tools for the management of multiple neuropsychiatric disorders. Classically, dopamine receptors have been shown to regulate cAMP-PKA (protein kinase A) and Ca(2+) pathways through G-protein-mediated signaling. However, it has become apparent that, in addition to this canonical action, D(2)-class dopamine receptors can function through ...

Stimulus-evoked dopamine overflow in rat neostriatal slices was determined using fast cyclic voltammetry. The dopamine efflux induced by intrastriatal stimulation increased with stimulus intensity and was found to be enhanced by more than 100% upon application of the dopamine uptake inhibitor nomifensine. The acetylcholine esterase inhibitor eserine concentration-dependently and reversibly depr...