The present study compared interactions among dopamine D1-like agonists and partial agonists with cocaine on the locomotor stimulant effects of cocaine, as well as the discriminative-stimulus effects of cocaine, and effects of cocaine on rates of responding. Cocaine alone produced a dose-related stimulation of locomotor activity in Swiss-Webster mice and a dose-related increase in the proportio...

Gamma-aminobutyric acid (GABA)-containing medium spiny neurons constitute approximately 90% of the neuronal population in the neostriatum (caudate and putamen) and play an important role in motor programming. Cortical glutamatergic afferents provide the main excitatory drive for these neurons, whereas nigral dopaminergic neurons play a crucial role in regulating their activity. To further inves...

The objective of the present study was to examine the effects of perfusion of dopamine (DA) D1- and D2-like receptor agonists in the nucleus accumbens (ACB) on the long-loop negative feedback regulation of mesolimbic somatodendritic DA release in the ventral tegmental area (VTA) of Wistar rats employing ipsilateral dual probe in vivo microdialysis. Perfusion of the ACB for 60 min with the D1-li...

The roles of rod and cone input and of dopamine in the generation of oscillatory potentials were studied in tiger salamander retina. Under scotopic conditions, oscillations were elicited with a green, but not a red stimulus. With mesopic background illumination, both stimuli caused oscillations. Addition of quinpirole to a mesopic retina eliminated oscillations while SKF-38393 had no effect. Si...

The objectives of this study were to examine the involvement of D1 and D2 receptors within the nucleus accumbens (ACB) in mediating reinforcement. The intracranial self-administration (ICSA) of D1 and D2 agonists was used to determine whether activating D1 and/or D2 receptors within the ACB of Wistar rats is reinforcing. At concentrations of 0.25, 0.50, and 1.0 mM (25, 50, and 100 pmol/100 nl o...

Genetic factors influence behavioral responses to cocaine as seen in comparisons of Lewis and Fischer 344 inbred rats. Lewis rats have lower D2-like receptor and Gi(alpha) levels in nucleus accumbens, an important area in behavioral responses to cocaine. This study assessed the effects of manipulating D2- and D1 levels pharmacologically in these strains. Experiment 1 investigated how the D2-lik...

Aging is associated with an increase in oxidative stress and blood pressure (BP). Renal dopamine D1 (D1R) and angiotensin II AT1 (AT1R) receptors maintain sodium homeostasis and BP. We hypothesized that age-associated increase in oxidative stress causes altered D1R and AT1R functions and high BP in aging. To test this, adult (3 mo) and old (21 mo) Fischer 344 × Brown Norway F1 rats were supplem...