Cocaine (25 mg/kg i.p.) produces analgesia in the rat within 5 min and for a duration of 90 min as determined by the formalin test or for 30 min as determined by the hot plate test. Cocaine analgesia is unaffected by doses of naloxone that are sufficient to attenuate morphine analgesia in both tests. Chlorpromazine (3 mg/kg i.p.), SCH 23390 (100 micrograms/kg i.p.; a D1 dopamine receptor antago...

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 ...

The acute administration of dopamine D(1) receptor agonists induces the expression of the immediate early gene c-fos. In wild type mice, this induction is completely abolished by pretreatment with the D(1)-selective antagonist SCH23390, and pretreatment with the D(2)-like receptor antagonist eticlopride reduces the levels of c-fos expressed in response to D(1) receptor stimulation. Mice deficie...

Excessive physical activity is commonly described as symptom of Anorexia Nervosa (AN). Activity-based anorexia (ABA) is considered an animal model for AN. The ABA model mimics severe body weight loss and increased physical activity. Suppression of hyperactivity by olanzapine in anorectic patients as well as in ABA rats suggested a role of dopamine and/or serotonin in this trait. Here, we invest...

Dopamine modulates movement, cognition, and emotion through activation of dopamine G protein-coupled receptors in the brain. The crystal structure of the human dopamine D3 receptor (D3R) in complex with the small molecule D2R/D3R-specific antagonist eticlopride reveals important features of the ligand binding pocket and extracellular loops. On the intracellular side of the receptor, a locked co...

Microinjections of the dopamine agonist apomorphine into the nucleus basalis prosencephali of pigeons elicit stereotyped pecking behaviour. Injections of 6-hydroxydopamine, a toxic dopamine antagonist, into the same nucleus impair stereotyped pecking induced by systemic apomorphine administration, but do not interfere with pecking in the normal feeding context.

We identified subsets of neurons in the brain that coexpress the dopamine receptor subtype-2 (DRD2) and the ghrelin receptor (GHSR1a). Combination of FRET confocal microscopy and Tr-FRET established the presence of GHSR1a:DRD2 heteromers in hypothalamic neurons. To interrogate function, mice were treated with the selective DRD2 agonist cabergoline, which produced anorexia in wild-type and ghrel...

effective symptomatic relief in patients with dysmotility-like functional dyspepsia, and is widely used in the treatment of gastritis. Gastric motility may be regulated by multiple neural systems. Studies on the mechanisms involving the neuronal systems suggest the involvement of cholinergic and noradrenergic systems. Additionally, various studies have suggested the existence of dopamine neuron...

This study was designed to assess the involvement of D1 dopamine actions in the ventral tegmental area (VTA) on intravenous cocaine self-administration. Rats were trained to self-administer intravenous injections of cocaine (1.0 mg/kg per injection) on a fixed-ratio 1 (FR-1) schedule or a progressive ratio (PR) schedule of reinforcement and then were tested under the influence of bilateral VTA ...

Frog monocular optokinetic nystagmus (OKN) displays a directional asymmetry, reacting only to stimulations in the temporal-nasal (T-N) direction. The nasal-temporal (N-T) component is almost absent. The systemic or intrapretectal injection of Piribedil, a D2 dopamine agonist, provokes the appearance of a N-T component suppressing the monocular OKN asymmetry. Conversely, dopamine or haloperidol ...