Chimeric D1/D2 receptors were constructed to identify structural determinants of drug affinity and efficacy. We previously reported that chimeras that had D1 receptor transmembrane domain VII together with amino-terminal sequence from the D2 receptor were nonfunctional. D2/D1 chimeras were constructed that contained D2 receptor sequence at the amino- and carboxyl-terminal ends and D1 receptor s...

The prokinetic effect of metoclopramide is mediated through the blockade of enteric (neuronal and muscular) inhibitory dopamine D2 receptors, and metoclopramide has the ability to stimulate 5-HT3 and 5-HT4 receptors (2). Metoclopramide also exerts inhibitory effects on D2 receptors centrally (located outside the blood-brain barrier), and these contribute to its antiemetic effect. Metoclopramide...

The anatomical distributions and affinity states of dopamine D1 and D2 receptors were compared in the rat central nervous system using quantitative autoradiography. [3H]SCH23390 and [3H]spiperone (in the presence of 100 nM mianserin) were used to label the D1 and D2 receptors, respectively. The densities of D1 and D2 receptors displayed a positive correlation among 21 brain regions (Pearson cor...

Olfactory receptor neurons of the nasal epithelium project via the olfactory nerve (ON) to the glomeruli of the main olfactory bulb, where they form glutamatergic synapses with the apical dendrites of mitral and tufted cells, the output cells of the olfactory bulb, and with juxtaglomerular interneurons. The glomerular layer contains one of the largest population of dopamine (DA) neurons in the ...

Dopamine's role in inhibitory control is well recognized and its disruption may contribute to behavioral disorders of discontrol such as obesity. However, the mechanism by which impaired dopamine neurotransmission interferes with inhibitory control is poorly understood. We had previously documented a reduction in dopamine D2 receptors in morbidly obese subjects. To assess if the reductions in d...

introduction: the protective and antisecretory effects of dopamine agonists on the stomach have been already reported, but the effect of bromocriptine (d2 dopamine agonist) on histamine stimulated gastric acid secretion (gas) needs to be investigated. methods: for gastric sampling, animals were anesthetized and a polyethylen tube was introduced into the stomach through esophagus. a cannula was ...

In recent years, the distribution of dopamine receptor subtypes among the principal neurons of the neostriatum has been the subject of debate. Conventional anatomical and physiological approaches have yielded starkly different estimates of the extent to which D1 and D2 class dopamine receptors are colocalized. One plausible explanation for the discrepancy is that some dopamine receptors are pre...

We examined the reproducibility of using the constant infusion paradigm for equilibrium measurement of D2/3 receptors using [ C](+)-propyl-hexahydro-naphtho-oxazin (PHNO) positron emission tomography (PET). Six subjects were scanned with a bolus plus constant infusion (Kbol 5 80 minutes) of [ C]-(+)-PHNO. Binding potential (BPND) was computed using the equilibrium approach and compared to a sim...

G protein-coupled receptors (GPCRs), including dopamine receptors, represent a group of important pharmacological targets. An increased formation of dopamine receptor D2 homodimers has been suggested to be associated with the pathophysiology of schizophrenia. Selective labeling and ligand-induced modulation of dimerization may therefore allow the investigation of the pathophysiological role of ...

Overeating in obese individuals shares similarities with the loss of control and compulsive drug taking behavior observed in drug-addicted subjects. The mechanism of these behaviors is not well understood. Our prior studies with positron emission tomography (PET) in drug-addicted subjects documented reductions in striatal dopamine (DA) D2 receptors. In pathologically obese subjects, we found re...