-
Brain Research Bulletin Apr 2023Stress contributes to pain sensation by affecting several neural pathways, including mesolimbic-cortical dopamine neurons. Nucleus accumbens, an essential element of the...
Stress contributes to pain sensation by affecting several neural pathways, including mesolimbic-cortical dopamine neurons. Nucleus accumbens, an essential element of the mesolimbic dopaminergic pathway, plays a fundamental role in modulating pain and is differentially influenced by stressful events. Since we previously demonstrated the marked association of intra-NAc dopamine receptors with forced swim stress-evoked analgesia in acute pain state, this research was conducted to consider the contribution of intra-accumbal D1- and D2-like dopamine receptors to modulating effects of exposure to restraint stress in pain-related behaviors during the tail-flick test. Stereotaxic surgery was executed to implant a guide cannula within the NAc in male Wistar rats. On the test day, different concentrations of SCH23390 and Sulpiride as D1- and D2-like dopamine receptor antagonists, respectively, were unilaterally microinjected within the NAc. The vehicle animals received saline or 12 % DMSO (0.5 µl) instead of SCH23390 or Sulpiride into the NAc, respectively. Five minutes following receiving drug or vehicle, animals were restrained for 3 h and then their acute nociceptive threshold was measured for a 60-min period by the tail-flick test. Our data revealed that RS considerably enhanced antinociceptive reaction in acute pain states. The analgesia evoked by RS dramatically declined following blocking either D1- or D2-like dopamine receptors in the NAc, an effect was more noticeable by D1-like dopamine receptor antagonist. These findings indicated that intra-NAc dopamine receptors are considerably mediated in the RS-produced analgesia in acute pain states, suggesting their possible role in psychological stress and disease.
Topics: Rats; Animals; Male; Sulpiride; Rats, Wistar; Acute Pain; Receptors, Dopamine D2; Receptors, Dopamine D1; Dopamine Antagonists; Nucleus Accumbens; Analgesics
PubMed: 36889361
DOI: 10.1016/j.brainresbull.2023.03.003 -
Investigative Ophthalmology & Visual... Oct 2020Animal models have demonstrated a link between decreases in retinal dopamine levels and the development of form-deprivation myopia (FDM). However, the consistency of...
PURPOSE
Animal models have demonstrated a link between decreases in retinal dopamine levels and the development of form-deprivation myopia (FDM). However, the consistency of dopamine's role in the other major form of experimental myopia, that of lens-induced myopia (LIM), is less clear, raising the question as to what extent dopamine plays a role in human myopia. Therefore, to better define the role of dopamine in both forms of experimental myopia, we examined how consistent the protection afforded by dopamine and the dopamine agonist 6-amino-5,6,7,8-tetrahydronaphthalene-2,3-diol hydrobromide (ADTN) is between FDM and LIM.
METHODS
Intravitreal injections of dopamine (0.002, 0.015, 0.150, 1.500 µmol) or ADTN (0.001, 0.010, 0.100, 1.000 µmol) were administered daily to chicks developing FDM or LIM. Axial length and refraction were measured following 4 days of treatment. To determine the receptor subtype by which dopamine and ADTN inhibit FDM and LIM, both compounds were coadministered with either the dopamine D2-like antagonist spiperone (0.005 µmol) or the D1-like antagonist SCH-23390 (0.005 µmol).
RESULTS
Intravitreal administration of dopamine or ADTN inhibited the development of FDM (ED50 = 0.003 µmol and ED50 = 0.011 µmol, respectively) and LIM (ED50 = 0.002 µmol and ED50 = 0.010 µmol, respectively) in a dose-dependent manner, with a similar degree of protection observed in both paradigms (P = 0.471 and P = 0.969, respectively). Coadministration with spiperone, but not SCH-23390, inhibited the protective effects of dopamine and ADTN against the development of both FDM (P = 0.214 and P = 0.138, respectively) and LIM (P = 0.116 and P = 0.100, respectively).
CONCLUSIONS
pharmacological targeting of the retinal dopamine system inhibits FDM and LIM in a similar dose-dependent manner through a D2-like mechanism.
Topics: Animals; Axial Length, Eye; Chickens; Contact Lenses; Disease Models, Animal; Dopamine; Dopamine Agonists; Dopamine Antagonists; Dose-Response Relationship, Drug; Form Perception; Intravitreal Injections; Male; Myopia; Refraction, Ocular; Retina; Sensory Deprivation
PubMed: 33016984
DOI: 10.1167/iovs.61.12.4 -
Journal of Dairy Science Jun 2006The role of dopamine in regulating glucocorticoid and prolactin secretion was investigated in lactating Holstein cows by characterizing serum cortisol and prolactin...
The role of dopamine in regulating glucocorticoid and prolactin secretion was investigated in lactating Holstein cows by characterizing serum cortisol and prolactin responses to fluphenazine, a dopamine receptor antagonist. Twelve anovulatory cows received an intravenous bolus injection of either saline (n = 6) or 0.3 mg of fluphenazine/kg of body weight (n = 6) in wk 2 postpartum. Blood samples were collected every 30 min for 4 h before and 4 h after saline or fluphenazine injection. Serum progesterone concentration was 0.13 +/- 0.1 ng/mL and did not differ between groups. No difference in serum cortisol concentrations was detected between groups before treatments. Fluphenazine increased serum cortisol concentrations within 30 min after fluphenazine administration (>30 ng/mL) and concentrations remained elevated throughout the sampling period. Cortisol remained unchanged in saline-treated cows (<10 ng/mL). Prolactin concentrations also increased after fluphenazine administration (103.1 +/- 3.1 ng/mL), but were unaffected by saline (18 +/- 3.1 ng/mL). Prolactin concentrations remained elevated throughout the sampling period in fluphenazine-treated cows. Our results indicated that a dopamine antagonist increased cortisol, suggesting that endogenous dopamine, at least in part, regulates cortisol and prolactin secretion. These effects are regulated through dopamine receptors in anovulatory lactating dairy cows during the early postpartum period.
Topics: Animals; Cattle; Dopamine; Dopamine Antagonists; Female; Fluphenazine; Hydrocortisone; Lactation; Prolactin
PubMed: 16702268
DOI: 10.3168/jds.S0022-0302(06)72272-X -
The International Journal of... Mar 2004Clinician choice of an atypical antipsychotic may depend on a number of factors such as perceived efficacy, tolerability and cost. It is also important that the choice... (Review)
Review
Clinician choice of an atypical antipsychotic may depend on a number of factors such as perceived efficacy, tolerability and cost. It is also important that the choice of treatment takes into consideration the previous response to treatment, experience of side-effects and personal clinical characteristics. The receptor-affinity profiles of the atypical antipsychotics differ; with the exception of amisulpride, a selective D2/D3 antagonist, all the atypical antipsychotics exhibit a greater affinity for the serotonin-2A receptors than dopamine receptors. However, there is no evidence that the variation in receptor affinities is relevant to efficacy. Indeed, the crucial factor may be fast dissociation from low affinity for the D2 receptor. Tolerability also varies between the atypical antipsychotics and the side-effect profile may be related to the receptor-affinity profile of the individual drugs. Extrapyramidal side-effects are generally less of a problem with most atypical drugs than with conventional drugs, but weight gain, loss of glycaemic control, sedation and hyperprolactinaemia remain problematic in some patients. Amisulpride is effective for the treatment of both positive and negative symptoms, and is well tolerated with regard to weight gain, glucose tolerance and sedation. In two clinical trials, the AMIRIS and SOLIANOL studies, amisulpride demonstrated clear advantages over some other atypical antipsychotics with respect to negative symptoms, depressive symptoms and weight gain.
Topics: Adverse Drug Reaction Reporting Systems; Amisulpride; Antipsychotic Agents; Clinical Trials as Topic; Dopamine Antagonists; Humans; Psychiatric Status Rating Scales; Schizophrenia; Schizophrenic Psychology; Sulpiride; Treatment Outcome; Weight Gain
PubMed: 14972081
DOI: 10.1017/S1461145704004134 -
Cell Host & Microbe Oct 2022The gastrointestinal tract facilitates food digestion, with the gut microbiota playing pivotal roles in nutrient breakdown and absorption. However, the microbial...
The gastrointestinal tract facilitates food digestion, with the gut microbiota playing pivotal roles in nutrient breakdown and absorption. However, the microbial molecules and downstream signaling pathways that activate food digestion remain unexplored. Here, by establishing a food digestion system in C. elegans, we discover that food breakdown is regulated by the interaction between bacterial outer membrane proteins (OMPs) and a neural-immune pathway. E. coli OmpF/A activate digestion by increasing the neuropeptide NLP-12 that acts on the receptor CCKR. NLP-12 is homologous to mammalian cholecystokinin, known to stimulate dopamine, and we found that loss of dopamine receptors or addition of a dopamine antagonist inhibited OMP-mediated digestion. Dopamine and NLP-12-CKR-1 converge to inhibit PMK-1/p38 innate immune signaling. Moreover, directly inhibiting PMK-1/p38 boosts food digestion. This study uncovers a role of bacterial OMPs in regulating animal nutrient uptake and supports a key role for innate immunity in digestion.
Topics: Animals; Bacterial Outer Membrane Proteins; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Cholecystokinin; Dopamine; Dopamine Antagonists; Escherichia coli; Escherichia coli Proteins; Immunity, Innate; Mammals; Receptors, Dopamine
PubMed: 36057258
DOI: 10.1016/j.chom.2022.08.004 -
Psychopharmacology Jun 2024Evidence on the effect of dopamine D1-like and D2-like receptor antagonists on licking microstructure and the forced swimming response led us to suggest that (i)... (Review)
Review
RATIONALE
Evidence on the effect of dopamine D1-like and D2-like receptor antagonists on licking microstructure and the forced swimming response led us to suggest that (i) dopamine on D1-like receptors plays a role in activating reward-directed responses and (ii) the level of response activation is reboosted based on a process of evaluation of response efficacy requiring dopamine on D2-like receptors. A main piece of evidence in support of this hypothesis is the observation that the dopamine D2-like receptor antagonist raclopride induces a within-session decrement of burst number occurring after the contact with the reward. The few published studies with a detailed analysis of the time-course of this measure were conducted in our laboratory.
OBJECTIVES
The aim of this review is to recapitulate and discuss the evidence in support of the analysis of the within-session burst number as a behavioural substrate for the study of the mechanisms governing ingestion, behavioural activation and the related evaluation processes, and its relevance in the analysis of drug effects on ingestion.
CONCLUSIONS
The evidence gathered so far suggests that the analysis of the within-session time-course of burst number provides an important behavioural substrate for the study of the mechanisms governing ingestion, behavioural activation and the related evaluation processes, and might provide decisive evidence in the analysis of the effects of drugs on ingestion. However, further evidence from independent sources is necessary to validate the use and the proposed interpretation of this measure.
Topics: Dopamine; Animals; Humans; Receptors, Dopamine D1; Receptors, Dopamine D2; Time Factors; Dopamine Antagonists; Reward; Eating; Drinking Behavior; Dopamine D2 Receptor Antagonists
PubMed: 38702473
DOI: 10.1007/s00213-024-06600-1 -
Neuropsychopharmacology : Official... Aug 2015In Pavlovian conditioning, sign- and goal-tracking behaviors represent different approaches towards the conditioned stimulus. These behavioral patterns have been...
In Pavlovian conditioning, sign- and goal-tracking behaviors represent different approaches towards the conditioned stimulus. These behavioral patterns have been associated with predictive or incentive properties of the conditioned stimulus, with a crucial involvement of the mesolimbic dopamine system. As it is possible that sign tracking behavior is more sensitive to dopamine modulation, we evaluated the dopamine-dependence of sign- and goal-tracking behavior. We assessed responses to both a D2 agonist and an antagonist, and tested performance in a behavioral paradigm known to activate dopamine projections and in an animal model that affects mesolimbic and mesocortical function. Sign trackers displayed a greater sensitivity to a D2 agonist and smaller prepulse inhibition of the acoustic startle response than goal trackers, suggesting a reduced inhibitory ability. In addition, a neonatal ventral hippocampal lesion resulted in the loss of incentive salience of cues in sign trackers. Overall, these data indicate that sign-tracking behavior is more heavily controlled by dopamine than goal tracking.
Topics: Analysis of Variance; Animals; Animals, Newborn; Conditioning, Classical; Conditioning, Operant; Cues; Dopamine Antagonists; Goals; Male; Motivation; Prepulse Inhibition; Rats; Rats, Long-Evans; Receptors, Dopamine D2; Reflex, Startle; Salicylamides
PubMed: 25759299
DOI: 10.1038/npp.2015.68 -
Nutrients Apr 2019Inadequate breast milk supply is a frequently reported reason for early discontinuation of breastfeeding and represents a critical opportunity for intervening to improve... (Review)
Review
Inadequate breast milk supply is a frequently reported reason for early discontinuation of breastfeeding and represents a critical opportunity for intervening to improve breastfeeding outcomes. For women who continue to experience insufficient milk supply despite the utilisation of non-pharmacological lactation support strategies, pharmacological intervention with medications used to augment lactation, commonly referred to as galactagogues, is common. Galactagogues exert their pharmacological effects through altering the complex hormonal milieu regulating lactation, particularly prolactin and oxytocin. This narrative review provides an appraisal of the existing evidence regarding the efficacy and safety of pharmaceutical treatments for lactation insufficiency to guide their use in clinical practice. The greatest body of evidence surrounds the use of domperidone, with studies demonstrating moderate short-term improvements in breast milk supply. Evidence regarding the efficacy and safety of metoclopramide is less robust, but given that it shares the same mechanism of action as domperidone it may represent a potential treatment alternative where domperidone is unsuitable. Data on remaining interventions such as oxytocin, prolactin and metformin is too limited to support their use in clinical practice. The review provides an overview of key evidence gaps and areas of future research, including the impacts of pharmaceutical galactagogues on breast milk composition and understanding factors contributing to individual treatment response to pharmaceutical galactagogues.
Topics: Domperidone; Dopamine Antagonists; Female; Galactogogues; Humans; Lactation
PubMed: 31035376
DOI: 10.3390/nu11050974 -
Psychopharmacology Jul 2019Methamphetamine (MA) is an abused psychostimulant that causes cognitive deficits after chronic use. Neostriatal dopamine receptors play a role in MA monoamine...
RATIONALE
Methamphetamine (MA) is an abused psychostimulant that causes cognitive deficits after chronic use. Neostriatal dopamine receptors play a role in MA monoamine neurotoxicity. Blocking dopamine receptors prior to MA exposure in adult rats attenuates monoamine reductions and reactive gliosis.
OBJECTIVES
We tested whether blocking dopamine receptors protects against cognitive deficits.
METHODS
First, we determined the effects of MA alone versus MA in combination with the dopamine receptor D1 antagonist SCH-23390 or the dopamine receptor D2 antagonist sulpiride on cFos expression and monoamines at the age when rats in the cognitive experiment were to begin testing and monoamines in rats after cognitive testing.
RESULTS
SCH-23390 infused into the neostriatum prior to systemic administration of MA attenuated MA-induced cFos activation while sulpiride induced cFos activation. Two weeks after MA, rats had dopamine and serotonin reductions that were attenuated by each antagonist. Other rats treated the same way, were tested for egocentric learning and memory in the Cincinnati water maze, for navigational strategy in a star water maze, and spatial learning and memory in a Morris water maze. Pre-treatment with SCH-23390 or sulpiride attenuated the effects of MA on egocentric and spatial learning and memory. MA-treated rats showed a shift from an egocentric to a disorganized strategy in the star maze that was less disorganized in groups receiving MA and an antagonist. Post-behavior monoamine reductions remained but were attenuated by the antagonists but not identically to what was seen in rats not behaviorally tested.
CONCLUSIONS
The results show for the first time that dopamine receptors are mediators of MA-induced cognitive deficits.
Topics: Animals; Central Nervous System Stimulants; Dopamine; Dopamine Antagonists; Dopamine D2 Receptor Antagonists; Egocentrism; Injections, Intraventricular; Male; Maze Learning; Memory Disorders; Methamphetamine; Neostriatum; Rats; Rats, Sprague-Dawley; Receptors, Dopamine D1; Receptors, Dopamine D2
PubMed: 30919007
DOI: 10.1007/s00213-019-05221-3 -
Journal of Physiology and Pharmacology... Dec 2020Chronic epigastric pain syndrome (CEPS) is an important diagnostic problem, especially in patients without macroscopic and microscopic changes in gastric mucosa. The... (Comparative Study)
Comparative Study Randomized Controlled Trial
Chronic epigastric pain syndrome (CEPS) is an important diagnostic problem, especially in patients without macroscopic and microscopic changes in gastric mucosa. The cause of this ailment is unclear. The aim of this study was the assessment of coexistence between symptoms of this syndrome and secretion level of dopamine (DA), as well as the efficacy of peripheral and central D2 receptors antagonist. Sixty depressive patients with CEPS occurring independently of the diet and with no Helicobacter pylori infection and 30 healthy subjects were enrolled in this study. Plasma DA and urinary homovanilic acid (HVA) concentration were measured by ELISA, and the mRNA expression of dopa decarboxylase (DDC) in gastric mucosa was evaluated by RT-PCR in 30 patients with CEPS and 30 controls. Severity of epigastric pain before and after 12 weeks 2 x 50 mg itopride or sulpiride treatment was evaluated using the modified 10-point Visual Analogue Scale. Higher average levels of plasma DA and urinary HVA levels in CEPS patients than controls 129.5 ± 22.0 versus 109.1 ± 18.4 pg/ml (p < 0.001) and 6.82 ± 1.55 versus 5.39 ± 1.04 mg/24 h, respectively were obtained. Moreover, the expression of DDC in gastric mucosa of CEPS patients was higher than in healthy subjects (p < 0.01). Sulpiride subsided epigastric pain in 73.3%, but itopride reduced it only in 6.6% of CEPS patients. We concluded that altered dopamine signalling may affect locally-and-centrally mediated chronic epigastric pain.
Topics: Abdominal Pain; Adult; Benzamides; Benzyl Compounds; Case-Control Studies; Chronic Pain; Depression; Dopamine; Dopamine Antagonists; Female; Gastric Mucosa; Homovanillic Acid; Humans; Male; Middle Aged; Pain Measurement; Signal Transduction; Sulpiride
PubMed: 33727428
DOI: 10.26402/jpp.2020.6.05