It has been revealed that dopamine (DA) modulates gastro-duodenal responses to stress. Several investigations have been made to identify the mechanisms and/or receptors by which DA or its promoters exert their gastroprotective function against stress, however there are many discrepancies in this respect. In order to clarify the relative contribution and/or interaction of two DA receptor subty...

Recently we have reported that rosiglitazone treatment of obese Zucker rats reduced plasma insulin and restored the ability of dopamine to inhibit Na,K-ATPase (NKA) in renal proximal tubules. The present study was performed to test the hypothesis that a chronic increase in levels of insulin causes a decrease in expression of the D1 receptor and its uncoupling from G proteins, which may account ...

The neurotransmitter, dopamine (DA), has been implicated in place conditioning but the role of D1 and D2 receptors has not been investigated. In Experiment 1, the effects of SKF 38393 (0, 0.01, 0.1, 1.0, 10.0 mg/kg) and quinpirole (0, 0.01, 0.1, 1.0, 2.0, 4.0 mg/kg), preferential D1 and D2 receptor agonists, respectively, were evaluated and compared to (+)-amphetamine (0, 0.01, 0.1, 1.0, 2.0, 4...

We have previously reported that age-associated oxidative stress via protein kinase C (PKC) increases D1 receptor (D1R) phosphorylation and causes D1R-G protein uncoupling in renal proximal tubules (RPTs) of old Fischer 344 rats. This results in reduced ability of D1R agonist SKF-38393 to inhibit Na+-K+-ATPase in RPTs of old rats. Here, we studied the effect of treadmill exercise on markers of ...

Hypertension related to insulin resistance results from increased sodium retention. Dopamine, by activating D1A receptors in renal proximal tubules, increases sodium excretion. Recently, dopamine has been shown to augment its own signaling by recruiting intracellular D1A receptors to cell surface in proximal tubules. In this study, we hypothesized that coupling of D1A receptors to G proteins an...

Impaired working memory is a common feature of neuropsychiatric disorders. It is dependent on control of the medial prefrontal cortex (mPFC) neurons by dopamine. The purpose of this study was to test the effects of a D1/5-type dopamine receptor agonist (SKF 38393, 10 microM) on the membrane potential and on voltage-dependent fast-inactivating Na+ currents in mPFC pyramidal neurons obtained from...

The role in spatial divided and sustained attention of D1 and D2-like dopamine (DA) receptors in the rat prelimbic medial prefrontal cortex (mPFC) was investigated in a five-choice serial reaction time task. Rats were trained to detect brief flashes of light (0.5-0.25 sec) presented randomly in a spatial array of five apertures. When performance stabilized, animals received bilateral microinfus...