-
1.
Mean Diffusivity in the Dopaminergic System and Neural Differences Related to Dopaminergic System.
Takeuchi, H, Kawashima, R
Current neuropharmacology. 2018;(4):460-474
-
-
Free full text
-
Abstract
BACKGROUND The mean diffusivity (MD) parameter obtained by diffusion tensor imaging provides a measure of how freely water molecules move in brain tissue. Greater tissue density conferred by closely arrayed cellular structures is assumed to lower MD by inhibiting the free diffusion of water molecules. METHODS In this paper, we review studies showing MD variation among regions of the brain dopaminergic system (MDDS), especially subcortical structures such as the putamen, caudate nucleus, and globus pallidus, in different conditions with known associations to dopaminergic system function or dysfunction. The methodologies and background related to MD and MDDS are also discussed. RESULTS Past studies indicate that MDDS is sensitive to pathological derangement of dopaminergic activity, neural changes caused by cognitive and pharmacological interventions that are known to affect the dopaminergic system, and individual character traits related to dopaminergic function. CONCLUSION These results suggest that MDDS can be one useful tool to tap the neural differences related to the dopaminergic system.
-
2.
THE RESTLESS LEGS SYNDROME (REVIEW).
Japaridze, G, Kasradze, S, Maisuradze, L, Popp, R, Wetter, T
Georgian medical news. 2018;(285):74-81
Abstract
The restless legs syndrome (RLS), also known as Willis-Ekbom disease, is a common sleep related neurological disorder with prevalence between 1 and 10%, increasing with age. Women are more frequently affected than men. RLS is characterized by an urge to move the legs accompanied by uncomfortable and unpleasant sensations in the legs, worsening of complaints during periods of rest, improvement by movement and an increase of symptoms in the evening or at night. In addition, affected patients may also suffer from severe sleep disorders and negative effects on daily activities. There is often a history of RLS among first-degree relatives, especially with the primary form. Among other, comorbidities or causal factors are iron deficiency, terminal renal insufficiency, pregnancy, polyneuropathy, or psychotropic drugs. The etiology of primary (idiopathic) RLS has not been clarified yet; however, genetic factors and dysfunctional dopaminergic neurotransmission as well as alterations of central iron metabolism play an important role. In addition to non-pharmacological treatment such as lifestyle modifications or behavioral strategies, levodopa, dopamine agonists, or anticonvulsants are effective. Opioids may be used in otherwise refractory forms. In the case of secondary or comorbid RLS, treatment of the underlying disease is necessary.
-
3.
Dopamine-Related Genotypes and Physical Activity Change During an Intervention: The Lifestyle Interventions and Independence for Elders Study.
Rosso, AL, Metti, AL, Glynn, NW, Boudreau, RM, Rejeski, WJ, Bohnen, N, Chen, H, Johannsen, NM, King, AC, Manini, TM, et al
Journal of the American Geriatrics Society. 2018;(6):1172-1179
-
-
Free full text
-
Abstract
OBJECTIVES To determine whether intervention-induced physical activity (PA) changes in sedentary older adults differed according to dopamine-related genotype. DESIGN Randomized clinical trial (Lifestyle Interventions and Independence for Elders Trial (2010-13)). SETTING Multicenter study, 8 U.S. PARTICIPANTS Volunteer sample of sedentary adults aged 70 to 89 at risk of disability (N=1635). INTERVENTIONS Structured PA versus health education (HE) for an average of 2.6 years. MEASUREMENTS Single-nucleotide polymorphisms of dopamine-related genes (dopamine receptor (DR) D1, DRD2, DRD3, and catechol-O-methyltransferase (COMT)) were assessed. Average moderate to vigorous PA (MVPA) was calculated using accelerometry (min/d) at baseline and 6, 12, and 24 months. Between-arm MVPA differences according to genotype and genotype with square root-transformed MVPA separately according to arm were tested, stratified according to race, and adjusted for multiple comparisons. RESULTS White participants in the PA arm (n=513) had higher average square root transformed MVPA (4.91±1.91)than those in the HE arm (n=538) (4.51±1.82) (p=.001). Between-arm differences were greater for DRD2 Met/Met (high dopamine; HE: 4.76±1.80, PA: 5.53±1.60, p=.03) than Val/Val (low dopamine; HE: 4.58±1.92, PA: 4.81±1.83, p=.16); results were similar for COMT. In the PA arm, DRD2 Met/Met was associated with higher average MVPA (5.39±2.00) than Met/Val (4.46±2.51) (p=.01) and Val/Val (4.65±2.71) (p=.01). There were no associations for other genes. Associations were not significant in blacks but followed similar trends. CONCLUSION Higher dopamine signaling may support changes in PA during an intervention. The role of dopamine-related pathways in promoting PA participation and enhancing response to interventions in sedentary older adults should be studied. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01072500.
-
4.
Striatal dopamine in Parkinson disease: A meta-analysis of imaging studies.
Kaasinen, V, Vahlberg, T
Annals of neurology. 2017;(6):873-882
-
-
Free full text
-
Abstract
A meta-analysis of 142 positron emission tomography and single photon emission computed tomography studies that have investigated striatal presynaptic dopamine function in Parkinson disease (PD) was performed. Subregional estimates of striatal dopamine metabolism are presented. The aromatic L-amino-acid decarboxylase (AADC) defect appears to be consistently smaller than the dopamine transporter and vesicular monoamine transporter 2 defects, suggesting upregulation of AADC function in PD. The correlation between disease severity and dopamine loss appears linear, but the majority of longitudinal studies point to a negative exponential progression pattern of dopamine loss in PD. Ann Neurol 2017;82:873-882.
-
5.
Dopamine and light: effects on facial emotion recognition.
Cawley, E, Tippler, M, Coupland, NJ, Benkelfat, C, Boivin, DB, Aan Het Rot, M, Leyton, M
Journal of psychopharmacology (Oxford, England). 2017;(9):1225-1233
Abstract
Bright light can affect mood states and social behaviours. Here, we tested potential interacting effects of light and dopamine on facial emotion recognition. Participants were 32 women with subsyndromal seasonal affective disorder tested in either a bright (3000 lux) or dim light (10 lux) environment. Each participant completed two test days, one following the ingestion of a phenylalanine/tyrosine-deficient mixture and one with a nutritionally balanced control mixture, both administered double blind in a randomised order. Approximately four hours post-ingestion participants completed a self-report measure of mood followed by a facial emotion recognition task. All testing took place between November and March when seasonal symptoms would be present. Following acute phenylalanine/tyrosine depletion (APTD), compared to the nutritionally balanced control mixture, participants in the dim light condition were more accurate at recognising sad faces, less likely to misclassify them, and faster at responding to them, effects that were independent of changes in mood. Effects of APTD on responses to sad faces in the bright light group were less consistent. There were no APTD effects on responses to other emotions, with one exception: a significant light × mixture interaction was seen for the reaction time to fear, but the pattern of effect was not predicted a priori or seen on other measures. Together, the results suggest that the processing of sad emotional stimuli might be greater when dopamine transmission is low. Bright light exposure, used for the treatment of both seasonal and non-seasonal mood disorders, might produce some of its benefits by preventing this effect.
-
6.
Dopamine dysregulation syndrome in Parkinson's disease: a systematic review of published cases.
Warren, N, O'Gorman, C, Lehn, A, Siskind, D
Journal of neurology, neurosurgery, and psychiatry. 2017;(12):1060-1064
Abstract
OBJECTIVES Dopamine dysregulation syndrome (DDS) is an uncommon complication of the treatment of Parkinson's disease, characterised by addictive behaviour and excessive use of dopaminergic medication. DDS may frequently go unrecognised or misdiagnosed. We aimed to clarify current understanding of presentation, risk factors, comorbidities and management of DDS. METHODS Case reports were identified through a systematic search of databases (PubMed, Embase) with the following terms: dopaminergic dysregulation syndrome, hedonistic homeostatic dysregulation, dopamine/levodopa addiction. RESULTS We reviewed 390 articles, identifying 98 cases of DDS. Early-onset Parkinson's disease (67%) and male gender (83%) were common. DDS presented with significant physical and social impairment, actions to enable or prevent detection of overuse, as well as mood, anxiety and motor fluctuations. All DDS cases met DSM-V (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) substance use disorder criteria. Past substance and psychiatric history was present in 15.3% and 10.2% of cases. Comorbid impulse control disorders (61%), psychosis (32%) and panic attacks (14%) were common. A large variety of management strategies were used; only 56% of cases resolving. Sodium valproate was successful in 5/5 cases. The response to deep brain stimulation varied. CONCLUSIONS Given the functional impairment, medical and psychiatric consequences and the difficulties of treatment, early identification of DDS should be a priority.
-
7.
N-acetylcysteine versus Dopamine to Prevent Acute Kidney Injury after Cardiac Surgery in Patients with Preexisting Moderate Renal Insufficiency.
Savluk, OF, Guzelmeric, F, Yavuz, Y, Cevirme, D, Gurcu, E, Ogus, H, Orki, T, Kocak, T
Brazilian journal of cardiovascular surgery. 2017;(1):8-14
Abstract
OBJECTIVE Acute kidney injury after cardiac surgery is associated with mortality and morbidity. Therefore, strategies to prevent acute kidney injury are very important. The aim of this placebo-controlled randomized double-blind study was to compare the prophylactic efficacy of N-Acetylcysteine and dopamine administration in patients with pre-existing moderate renal insufficiency who were undergoing cardiopulmonary bypass. METHODS This study included 135 patients with pre-existing moderate renal insufficiency who were scheduled for coronary artery bypass grafting surgery. Serum creatinine and GFR were recorded preoperatively and on the first and second postoperative days. RESULTS On the first and second postoperative days, the drugs used showed statistically significant differences among the creatinine groups (P<0.001). According to Tukey's HSD, on the first and second PO, the creatinine of Group N, D and P were significantly different (P<0.001). On the first and second PO, the used drugs showed statistically significant differences among the effects of eGFR (P<0.001). According to Tukey's HSD on the first postoperative day, the average eGFR score of Group N compared to D and P were significantly difference (P<0.001). On the second postoperative day, the eGFR of Group N and D showed no difference (P=0.37), but P showed a difference (P<0.001). CONCLUSION We found that the prophylactic use of intravenous N-Acetylcysteine had a protective effect on renal function, whereas the application of renal dose dopamine did not have a protective effect in patients with pre-existing moderate renal failure.
-
8.
Human Laboratory Studies on Cannabinoids and Psychosis.
Sherif, M, Radhakrishnan, R, D'Souza, DC, Ranganathan, M
Biological psychiatry. 2016;(7):526-38
Abstract
Some of the most compelling evidence supporting an association between cannabinoid agonists and psychosis comes from controlled laboratory studies in humans. Randomized, double-blind, placebo-controlled, crossover laboratory studies demonstrate that cannabinoid agonists, including phytocannabinoids and synthetic cannabinoids, produce a wide range of positive, negative, and cognitive symptoms and psychophysiologic deficits in healthy human subjects that resemble the phenomenology of schizophrenia. These effects are time locked to drug administration, are dose related, and are transient and rarely necessitate intervention. The magnitude of effects is similar to the effects of ketamine but qualitatively distinct from other psychotomimetic drugs, including ketamine, amphetamine, and salvinorin A. Cannabinoid agonists have also been shown to transiently exacerbate symptoms in individuals with schizophrenia in laboratory studies. Patients with schizophrenia are more vulnerable than healthy control subjects to the acute behavioral and cognitive effects of cannabinoid agonists and experience transient exacerbation of symptoms despite treatment with antipsychotic medications. Furthermore, laboratory studies have failed to demonstrate any "beneficial" effects of cannabinoid agonists in individuals with schizophrenia-challenging the cannabis self-medication hypothesis. Emerging evidence suggests that polymorphisms of several genes related to dopamine metabolism (e.g., COMT, DAT1, and AKT1) may moderate the effects of cannabinoid agonists in laboratory studies. Cannabinoid agonists induce dopamine release, although the magnitude of release does not appear to be commensurate to the magnitude and spectrum of their acute psychotomimetic effects. Interactions between the endocannabinoid, gamma-aminobutyric acid, and glutamate systems and their individual and interactive effects on neural oscillations provide a plausible mechanism underlying the psychotomimetic effects of cannabinoids.
-
9.
Complicated function of dopamine in Aβ-related neurotoxicity: Dual interactions with Tyr10 and SNK(26-28) of Aβ.
Liu, M, Kou, L, Bin, Y, Wan, L, Xiang, J
Journal of inorganic biochemistry. 2016;:119-128
Abstract
With the capability to inhibit the formation of amyloid β peptides (Aβ) fibril, dopamine (DA) and other catechol derivatives have been considered for the potential treatment of Alzheimer's disease (AD). Such treatment, however, remains debatable because of the diverse functions of Aβ and DA in AD pathology. Moreover, the complicated oxidation accompanying DA has caused the majority of the previous research to focus on the binding of DA oxides onto Aβ. The molecular mechanism by which Aβ interacts with the reduction state of DA, which is correlative with the brain function, should be urgently explored. By controlling rigorous anaerobic experimental conditions, this work investigated the molecular mechanism of the Aβ/DA interaction, and two binding sites were revealed. For the binding of DA, Tyrosine (Tyr10) was identified as the strong binding site, and serine-asparagine-lysing (SNK(26-28)) segment was the weak binding segment. Furthermore, the Thioflavin T (THT) fluorescence confirmed DA's positive function of inhibiting Aβ aggregation through its weakly binding with SNK(26-28) segment. Meanwhile, 7-OHCCA fluorescence exhibited DA's negative function of enhancing OH generation through inhibiting the Aβ/Cu2+ coordination. The viability tests of the neuroblastoma SH-SY5Y cells displayed that the coexistence of DA, Cu2+, and Aβ induced lower cell viability than free Cu2+, indicating the significant negative effect of excessive DA on AD progression. This research revealed the potential DA-induced damage in AD brain, which is significant for understanding the function of DA in AD neuropathology and for designing a DA-related therapeutic strategy for AD.
-
10.
Dopamine Activation Preserves Visual Motion Perception Despite Noise Interference of Human V5/MT.
Yousif, N, Fu, RZ, Abou-El-Ela Bourquin, B, Bhrugubanda, V, Schultz, SR, Seemungal, BM
The Journal of neuroscience : the official journal of the Society for Neuroscience. 2016;(36):9303-12
Abstract
UNLABELLED When processing sensory signals, the brain must account for noise, both noise in the stimulus and that arising from within its own neuronal circuitry. Dopamine receptor activation is known to enhance both visual cortical signal-to-noise-ratio (SNR) and visual perceptual performance; however, it is unknown whether these two dopamine-mediated phenomena are linked. To assess this, we used single-pulse transcranial magnetic stimulation (TMS) applied to visual cortical area V5/MT to reduce the SNR focally and thus disrupt visual motion discrimination performance to visual targets located in the same retinotopic space. The hypothesis that dopamine receptor activation enhances perceptual performance by improving cortical SNR predicts that dopamine activation should antagonize TMS disruption of visual perception. We assessed this hypothesis via a double-blinded, placebo-controlled study with the dopamine receptor agonists cabergoline (a D2 agonist) and pergolide (a D1/D2 agonist) administered in separate sessions (separated by 2 weeks) in 12 healthy volunteers in a William's balance-order design. TMS degraded visual motion perception when the evoked phosphene and the visual stimulus overlapped in time and space in the placebo and cabergoline conditions, but not in the pergolide condition. This suggests that dopamine D1 or combined D1 and D2 receptor activation enhances cortical SNR to boost perceptual performance. That local visual cortical excitability was unchanged across drug conditions suggests the involvement of long-range intracortical interactions in this D1 effect. Because increased internal noise (and thus lower SNR) can impair visual perceptual learning, improving visual cortical SNR via D1/D2 agonist therapy may be useful in boosting rehabilitation programs involving visual perceptual training. SIGNIFICANCE STATEMENT In this study, we address the issue of whether dopamine activation improves visual perception despite increasing sensory noise in the visual cortex. We show specifically that dopamine D1 (or combined D1/D2) receptor activation enhances the cortical signal-to-noise-ratio to boost perceptual performance. Together with the previously reported effects of dopamine upon brain plasticity and learning (Wolf et al., 2003; Hansen and Manahan-Vaughan, 2014), our results suggest that combining rehabilitation with dopamine agonists could enhance both the saliency of the training signal and the long-term effects on brain plasticity to boost rehabilitation regimens for brain injury.