In cultured embryonic chick motoneurons, glutamate-activated currents rise quickly and then decay rapidly to relatively small steady-state current levels. Dopaminergic modulation of these receptors was studied using patch-clamp recording techniques. At concentrations > or = 10 nM, dopamine enhanced glutamate-activated currents by about 200%. This enhancement was diminished by the nonspecific do...

The modulation of pro-opiomelanocortin (POMC) synthesis in Xenopus laevis pituitary intermediate lobe (IL) during background adaptation and the role of dopamine and cAMP in mediating this effect were examined. Neurointermediate lobes (NILs) were pulselabeled in vitro with [3H]arginine and analyzed for POMC synthesis by acid-urea gel electrophoresis. After black background adaptation of the anim...

Appropriate termination of regenerative processes is critical for producing the correct number of cells in tissues. Here we provide evidence for an end-product inhibition of dopamine neuron regeneration that is mediated by dopamine. Ablation of midbrain dopamine neurons leads to complete regeneration in salamanders. Regeneration involves extensive neurogenesis and requires activation of quiesce...

Cortical neurons respond in a variety of ways to locally applied dopamine, perhaps because of the activation of different receptors within or among subpopulations of cells. This study was conducted to assess the effects of dopamine and the receptor subtypes that mediate the responses of a specific population of neurons, the pyramidal tract neurons (PTNs) in the rodent motor cortex. The specific...

Although both dopamine and dobutamine are potent positive inotropic agents, multiple studies indicate that dopamine may produce a rise in left ventricular (LV) filling pressure, while dobutamine often has the opposite effect. To ascertain the pharmacological and hemodynamic mechanisms responsible for the elevation in LV filling pressure observed with dopamine, we administered incremental infusi...

Destruction of the substantia nigra produces striatal D1 dopamine receptor supersensitivity without increasing receptor number or affinity, thus implicating postreceptor mechanisms. The nature of these mechanisms is unknown. Increased striatal c-fos expression ipsilateral to a unilateral lesion of the substantia nigra in rats treated with appropriate dopamine agonists provides a cellular marker...

Studies conducted with nonhuman laboratory animals have consistently shown that atypical antipsychotics that are mixed dopamine and serotonin antagonists attenuate the discriminative-stimulus effects of amphetamine. In the present experiment, eight healthy humans learned to discriminate 15 mg of oral d-amphetamine. After acquiring the discrimination (i.e., > or = 80% correct responding on four ...

Methamphetamine (METH) is an addictive psychostimulant whose societal impact is on the rise. Emerging evidence suggests that psychostimulants alter synaptic plasticity in the brain--which may partly account for their adverse effects. While it is known that METH increases the extracellular concentration of monoamines dopamine, serotonin, and norepinephrine, it is not clear how METH alters glutam...

The effects of dopamine (DA) and its antagonists on the transcallosal activity of pyramidal tract neurons (PTNs) and non-PTNs in the anesthetized cat motor cortex were studied with iontophoretic applications; dopamine, SCH 23390 (D1 antagonist), sulpiride (D2 antagonist) and haloperidol. Neuronal activity was recorded with a multi-barreled glass microelectrode. Transcallosal neuronal activity w...

Protein-protein interactions between G protein-coupled receptors (GPCRs) can augment their functionality and increase the repertoire of signaling pathways they regulate. New therapeutics designed to modulate such may allow for targeting a specific GPCR activity, thus reducing potential side effects. Dopamine receptor (DR) heteromers are promising candidates targeted therapy neurological conditi...