Autoradiographic analysis of [(35)S]GTPgammaS binding was used to investigate functional activation of dopamine receptors in rat striatum. Dopamine-stimulated [(35)S]GTPgammaS binding was observed with a maximal increase of 38% over basal activity. A similar stimulatory response was obtained with the D(2) agonist quinpirole, but not SKF-238393, a D(1) agonist. The effect of dopamine was blocked...

G-protein coupled receptors interact to provide additional regulatory mechanisms for neurotransmitter signaling. Adenosine A(2A) receptors are expressed at a high density in striatal neurons, where they closely interact with dopamine D₂ receptors and modulate effects of dopamine and responses to psychostimulants. A(2A) receptors are expressed at much lower densities in other forebrain neurons b...

Aripiprazole is the first next-generation atypical antipsychotic with a mechanism of action that differs from currently marketed typical and atypical antipsychotics. Aripiprazole displays properties of an agonist and antagonist in animal models of dopaminergic hypoactivity and hyperactivity, respectively. This study examined the interactions of aripiprazole with a single population of human D2 ...

Research on Parkinson's disease has led to new hypotheses concerning the mechanisms of neurodegeneration and to the development of neuroprotective agents. Recent findings of impaired mitochondrial function, altered iron metabolism and increased lipid peroxidation in the substantia nigra of parkinsonian patients emphasize the significance of oxidative stress and free radical formation in the pat...

Dopaminergic neurotransmission has been highly implicated in the reinforcing properties of many substances of abuse, including marijuana. Cannabinoids activate ventral tegmental area dopaminergic neurons, the main ascending projections of the mesocorticolimbic dopamine system, and change their spiking pattern by increasing the number of impulses in a burst and elevating the frequency of bursts....

Dopaminergic axons in the prefrontal cortex synapse with interneurons as well as pyramidal cells. Electrophysiological data suggest that dopamine depolarizes certain gamma-aminobutyric acid (GABA)-containing interneurons in the cortex. We investigated the dopaminergic regulation of extracellular GABA levels in the prefrontal cortex using in vivo microdialysis. Systemic administration of the mix...

BACKGROUND Dopamine D2/3 receptor (D2/3R) agonist radiopharmaceuticals are considered superior to antagonists to detect dopamine release, e.g. induced by amphetamines. Agonists bind preferentially to the high-affinity state of the dopamine D2R, which has been proposed as the reason why agonists are more sensitive to detect dopamine release than antagonist radiopharmaceuticals, but this theory h...

BACKGROUND The atypical antipsychotic drug aripiprazole binds with high affinity to a number of G protein coupled receptors, including dopamine D₂ receptors, where its degree of efficacy as a partial agonist remains controversial. METHODS We examined the properties of aripiprazole at D₂-like autoreceptors by monitoring the changes of dopamine synthesis in adult rat brain striatal minces incub...

intramascular (im) administration of apomorphine (a mixed d1/d2 dopamine receptors agonist 0.2-1.6 mg/kg) induced pecking, a stereotype behavior in pigeons in a dose- dependent manner. in this study the effect of lithium (li+, 240 mg/kg, im) and ami-193 (a new 5-ht2 antagonist, 0.003 mg/pigeon) on apomorphine-induced peking (aip) were investigated. this study showed that li+ and ami-193 did not...

G protein coupled receptors (GPCRs) mediate a multitude of responses serving hormonal, neurotransmitter, and sensory functions. These receptors are important drug targets; in fact, about 27 % of prescribed drugs are GPCR ligands. The dopamine D2 receptor is prominently expressed within the CNS as two distinct isoforms; D2L (long isoform) and D2S (short isoform). The former is mainly expressed p...