Dopamine Stabilizer Research Articles

Study of the stability of dopamine encapsulated in TiO2 and TiO2/15-crown-5 ether matrix

Dopamine (DA) is the most important catecholamide in the brain, as it is the most abundant and the precursor of other neurotransmitters; it is a highly reactive molecule, which is usually stored inside synaptic vesicles where it is stabilized by the existing low pH However, free cytosolic dopamine easily auto-oxidizes, generating reactive oxygen species. It is also known that the loss of dopaminergic neurons in the substantia nigra is the primary cause of Parkinson's Disease. The purpose of the present study was to prolong the stability of DA, delaying its oxidation by encapsulating it in a TiO2 matrix, giving rise to a TiO2/DA composite prepared by sol-gel. A second sample was obtained by adding 15-crown-5 ether (15C5) to the previous sample (TiO2/DA/15C5). The oxidation process was analyzed by monitoring the color of the solution, optical absorption, and infrared spectroscopy. The color change of the solution from bright orange to dark brown indicated that the oxidation process had begun. In the TiO2/DA sample, complete oxidation of the sample was delayed for 30 days. In the TiO2/DA/15C5 sample, complete oxidation was delayed for 47 days. Transmission electron microscopy showed that TiO2/DA/15C5 had partial crystallization, with anatase and rutile nanocrystals with sizes between 2 and 4.5 nm. Encapsulated DA/15C5 may be used as a longer alternative treatment for patients with depression or Parkinson's disease.

Motor impulsivity but not risk-related impulsive choice is associated to drug intake and drug-primed relapse.

Motor impulsivity and risk-related impulsive choice have been proposed as vulnerability factors for drug abuse, due to their high prevalence in drug abusers. However, how these two facets of impulsivity are associated to drug abuse remains unclear. Here, we investigated the predictive value of both motor impulsivity and risk-related impulsive choice on characteristics of drug abuse including initiation and maintenance of drug use, motivation for the drug, extinction of drug-seeking behavior following drug discontinuation and, finally, propensity to relapse. We used the Roman High- (RHA) and Low- Avoidance (RLA) rat lines, which display innate phenotypical differences in motor impulsivity, risk-related impulsive choice, and propensity to self-administer drugs. Individual levels of motor impulsivity and risk-related impulsive choice were measured using the rat Gambling task. Then, rats were allowed to self-administer cocaine (0.3 mg/kg/infusion; 14 days) to evaluate acquisition and maintenance of cocaine self-administration, after which motivation for cocaine was assessed using a progressive ratio schedule of reinforcement. Subsequently, rats were tested for their resistance to extinction, followed by cue-induced and drug-primed reinstatement sessions to evaluate relapse. Finally, we evaluated the effect of the dopamine stabilizer aripiprazole on reinstatement of drug-seeking behaviors. We found that motor impulsivity and risk-related impulsive choice were positively correlated at baseline. Furthermore, innate high levels of motor impulsivity were associated with higher drug use and increased vulnerability to cocaine-primed reinstatement of drug-seeking. However, no relationships were observed between motor impulsivity and the motivation for the drug, extinction or cue-induced reinstatement of drug-seeking. High levels of risk-related impulsive choice were not associated to any aspects of drug abuse measured in our study. Additionally, aripiprazole similarly blocked cocaine-primed reinstatement of drug-seeking in both high- and low-impulsive animals, suggesting that aripiprazole acts as a D2/3R antagonist to prevent relapse independently of the levels of impulsivity and propensity to self-administer drugs. Altogether, our study highlights motor impulsivity as an important predictive factor for drug abuse and drug-primed relapse. On the other hand, the involvement of risk-related impulsive choice as a risk factor for drug abuse appears to be limited.

Improved functional and histochemical outcomes in l-DOPA plus tolcapone treated VMAT2-deficient mice

Parkinson disease is typically treated with L-3,4-dihydroxyphenylalanine (or levodopa) co-prescribed with concentration stabilizers to prevent undesired motor fluctuations. However, the beneficial role of the chronic combined therapy on disease progression has not been thoroughly explored. We hypothesized that tolcapone, a catechol-O-methyl-transferase inhibitor, co-administered with levodopa may offer beneficial long-term disease-modifying effects through its dopamine stabilization actions. Here, we followed vesicular monoamine transporter 2-deficient and wild-type mice treated twice daily per os with vehicle, levodopa (20 mg/kg), tolcapone (15 mg/kg) or levodopa (12.5 mg/kg) + tolcapone (15 mg/kg) for 17 weeks. We assessed open field, bar test and rotarod performances at baseline and every 4th week thereafter, corresponding to OFF-medication weeks. Finally, we collected coronal sections from the frontal caudate-putamen and determined the reactivity level of dopamine transporter. Vesicular monoamine transporter 2-deficient mice responded positively to chronic levodopa + tolcapone intervention in the bar test during OFF-periods. Neither levodopa nor tolcapone interventions offered significant improvements on their own. Similarly, chronic levodopa + tolcapone intervention was associated with partially rescued dopamine transporter levels, whereas animals treated solely with levodopa or tolcapone did not present this effect. Interestingly, 4-month progression of bar test scores correlated significantly with dopamine-transporter-label density. Overall, we observed a moderate functional and histopathological improvement effect by chronic dopamine replacement when combined with tolcapone in vesicular monoamine transporter 2-deficient mice. Altogether, chronic stabilization of dopamine levels by catechol-O-methyl-transferase inhibition, besides its intended immediate actions, arises as a potential long-term beneficial approach during the progression of Parkinson disease.

ORAL ARIPIPRAZOLE FOR THE TREATMENT OF TOURETTE’S SYNDROME IN CHILDREN

Background Among the pharmacotherapy recommendations for Tourette syndrome (TS), Aripiprazole is a potential treatment option for TS and a relatively safe alternative in the pediatric population. Case presentation We report the case of a pediatric patient with TS who was admitted to the hospital after demonstrating severe involuntary movements. The symptoms emerged early in childhood and remained subclinical. It became more noticeable at 3 months before admission when the frequency and the severity started to increase progressively reaching its peak at one month before hospitalization. From further assessment, we found speech delay and a notably high score of Strength and Difficulties Questionnaire (SDQ) At the time of hospitalization, the symptom relieved following the admission of Aripiprazole 1 x 2 mg. It significantly diminished to infrequent minor facial tics. There was no adverse effect reported upon hospital discharge. We also performed family psychoeducation and speech therapy as adjuvant therapy. Conclusions We selected Aripiprazole because of its unique mechanism of action resulted in a dopamine stabilizer feature with less side effect. The most common ones are nausea, sedation, and increased appetite where, generally, are lessen within 2 weeks. Moreover, in contrast with other antipsychotics, Aripiprazole would not provoke hyperprolactinemia. The more severe side effect such as extrapyramidal symptoms and weight gain are usually dose-dependent at around 10 mg/day. Aripiprazole is also favourable, especially for refractory cases.

Sigma-1 and dopamine D2/D3 receptor occupancy of pridopidine in healthy volunteers and patients with Huntington disease: a [18F] fluspidine and [18F] fallypride PET study

PurposePridopidine is an investigational drug for Huntington disease (HD). Pridopidine was originally thought to act as a dopamine stabilizer. However, pridopidine shows highest affinity to the sigma-1 receptor (S1R) and enhances neuroprotection via the S1R in preclinical studies. Using [18F] fluspidine and [18F] fallypride PET, the purpose of this study was to assess in vivo target engagement/receptor occupancy of pridopidine to the S1R and dopamine D2/D3 receptor (D2/D3R) at clinical relevant doses in healthy volunteers (HVs) and as proof-of-concept in a small number of patients with HD.MethodsUsing [18F] fluspidine PET (300 MBq, 0–90 min), 11 male HVs (pridopidine 0.5 to 90 mg; six dose groups) and three male patients with HD (pridopidine 90 mg) were investigated twice, without and 2 h after single dose of pridopidine. Using [18F] fallypride PET (200 MBq, 0–210 min), four male HVs were studied without and 2 h following pridopidine administration (90 mg). Receptor occupancy was analyzed by the Lassen plot.ResultsS1R occupancy as function of pridopidine dose (or plasma concentration) in HVs could be described by a three-parameter Hill equation with a Hill coefficient larger than one. A high degree of S1R occupancy (87% to 91%) was found throughout the brain at pridopidine doses ranging from 22.5 to 90 mg. S1R occupancy was 43% at 1 mg pridopidine. In contrast, at 90 mg pridopidine, the D2/D3R occupancy was only minimal (~ 3%).ConclusionsOur PET findings indicate that at clinically relevant single dose of 90 mg, pridopidine acts as a selective S1R ligand showing near to complete S1R occupancy with negligible occupancy of the D2/D3R. The dose S1R occupancy relationship suggests cooperative binding of pridopidine to the S1R. Our findings provide significant clarification about pridopidine’s mechanism of action and support further use of the 45-mg twice-daily dose to achieve full and selective targeting of the S1R in future clinical trials of neurodegenerative disorders.Clinical Trials.gov Identifier: NCT03019289 January 12, 2017; EUDRA-CT-Nr. 2016-001757-41.

Pridopidine in the treatment of Huntington's disease.

Huntington's disease (HD) is a highly common inherited monogenic neurodegenerative disease, and the gene responsible for its development is located in the 4p16.3 chromosome. The product of that gene mutation is an abnormal huntingtin (Htt) protein that disrupts the neural conduction, thus leading to motor and cognitive disorders. The disease progresses to irreversible changes in the central nervous system (CNS). Although only a few drugs are available to symptomatic treatment, 'dopamine stabilizers' (as represented by the pridopidine) may be the new treatment options. The underlying causes of HD are dopaminergic conduction disorders. Initially, the disease is hyperkinetic (chorea) until it eventually reaches the hypokinetic phase. Studies confirmed a correlation between the amount of dopamine in the CNS and the stage of the disease. Pridopidine has the capacity to be a dopamine buffer, which could increase or decrease the dopamine content depending on the disease phase. A research carried out on animal models demonstrated the protective effect of pridopidine on nerve cells thanks to its ability to alter the cortical glutamatergic signaling through the N-methyl-D-aspartate (NMDA) receptors. Studies on dopamine stabilizers also reported that pridopidine has a 100-fold greater affinity for the sigma-1 receptor than for the D2 receptor. Disturbances in the activity of sigma-1 receptors occur in neurodegenerative diseases, including HD. Their interaction with pridopidine results in the neuroprotective effect, which is manifested as an increase in the plasticity of synaptic neurons and prevention of their atrophy within the striatum. To determine the effectiveness of pridopidine in the treatment of HD, large multicenter randomized studies such as HART, MermaiHD, and PRIDE-HD were carried out.

Effect of the dopamine stabilizer (-)-OSU6162 on potentiated incubation of opioid craving after electric barrier-induced voluntary abstinence.

In the classical incubation of drug craving rat model, drug seeking is assessed after homecage forced abstinence. However, human abstinence is often voluntary because negative consequences of drug seeking outweigh the desire for the drug. Here, we developed a rat model of incubation of opioid craving after electric barrier-induced voluntary abstinence and determined whether the dopamine stabilizer (-)-OSU6162 would decrease this new form of incubation. We trained male and female rats to self-administer oxycodone (0.1 mg/kg/infusion, 6 h/day) for 14 days. We then exposed them to either homecage forced abstinence or voluntary abstinence induced by an electric barrier of increasing intensity near the drug-paired lever. On abstinence days 1, 15, or 30, we tested the rats for oxycodone seeking without shock and drug. We also examined the effect of (-)-OSU6162 (7.5 and 15 mg/kg) on oxycodone seeking on abstinence day 1 or after 15 days of either voluntary or forced abstinence. Independent of sex, the time-dependent increase in oxycodone seeking after cessation of opioid self-administration (incubation of opioid craving) was stronger after voluntary abstinence than after forced abstinence. In males, (-)-OSU6162 decreased incubated (day 15) but not non-incubated (day 1) oxycodone seeking after either voluntary or forced abstinence. In females, (-)-OSU6162 modestly decreased incubated oxycodone seeking after voluntary but not forced abstinence. Results suggest that voluntary abstinence induced by negative consequences of drug seeking can paradoxically potentiate opioid craving and relapse. We propose the dopamine stabilizer (-)-OSU6162 may serve as an adjunct pharmacological treatment to prevent relapse in male opioid users.

Early reduced dopaminergic tone mediated by D3 receptor and dopamine transporter in absence epileptogenesis.

In Genetic Absence Epilepsy Rats From Strasbourg (GAERSs), epileptogenesis takes place during brain maturation and correlates with increased mRNA expression of D3 dopamine receptors (D3R). Whether these alterations are the consequence of seizure repetition or contribute to the development of epilepsy remains to be clarified. Here, we addressed the involvement of the dopaminergic system in epilepsy onset in GAERSs. Experiments were performed using rats at different stages of brain maturation from three strains according to their increasing propensity to develop absence seizures: nonepileptic control rats (NECs), Wistar Hannover rats, and GAERSs. Changes in dopaminergic neurotransmission were investigated using different behavioral and neurochemical approaches: autoradiography of D3R and dopamine transporter, single photon emission computed tomographic imaging, acute and chronic drug effects on seizure recordings (dopaminergic agonists and antagonists), quinpirole-induced yawns and dopamine synaptosomal uptake, microdialysis, brain tissue monoamines, and brain-derived neurotrophic factor quantification. Autoradiography revealed an increased expression of D3R in 14-day-old GAERSs, before absence seizure onset, that persists in adulthood, as compared to age-matched NECs. This was confirmed by increased yawns, a marker of D3R activity, and increased seizures when animals were injected with quinpirole at low doses to activate D3R. We also observed a concomitant increase in the expression and activity of the dopamine transporter in GAERSs before seizure onset, consistent with both lowered dopamine basal level and increased phasic responses. Our data show that the dopaminergic system is persistently altered in GAERSs, which may contribute not only to behavioral comorbidities but also as an etiopathogenic factor in the development of epilepsy. The data suggest that an imbalanced dopaminergic tone may contribute to absence epilepsy development and seizure onset, as its reversion by a chronic treatment with a dopamine stabilizer significantly suppressed epileptogenesis. Our data suggest a potential new target for antiepileptic therapies and/or improvement of quality of life of epileptic patients.

Effects of Cariprazine, Aripiprazole, and Olanzapine on Mouse Fibroblast Culture: Changes in Adiponectin Contents in Supernatants, Triglyceride Accumulation, and Peroxisome Proliferator-Activated Receptor-γ Expression.

Background and Objectives: The use of the dopamine-partial agonist subclass (also termed dopamine stabilizers) of atypical antipsychotics for the treatment of negative schizophrenia symptoms and some mood disorders has increased recently. Similar to other second-generation antipsychotics (SGAs), aripiprazole (ARI) and cariprazine (CAR) also influence food intake, but the peripheral effects of these drugs on adipose–tissue homeostasis, including adipokine secretion as well as lipo- and adipogenesis, are not fully elucidated. In this study, we explored the adipocyte-related mechanisms induced by second-generation antipsychotics (SGAs), leading to changes in peripheral signals involved in energy homeostasis. Materials and Methods: CAR, a new SGA, was compared with ARI and olanzapine (OLA), using cell cultures to study adipogenesis, and the expression levels of peroxisome proliferator-activated receptor-γ (PPAR-γ) was measured in adipocytes derived from mouse fibroblasts, by western blotting on days 7, 14, and 21 postinduction. The triglyceride (TG) content of the cells was also evaluated on day 15 using Oil Red O staining, and the adiponectin (AN) content in the cell culture supernatants was quantified on days 7 and 15 by enzyme-linked immunosorbent assay. Cells were treated with two concentrations of ARI (0.5 and 20 µg/mL), OLA (1 and 20 µg/mL), and CAR (0.1 and 2 µg/mL). Results: Both concentrations of ARI and OLA, as well as the lower concentration of CAR, significantly increased the TG contents. The AN levels in the supernatants were significantly increased by the higher concentration of ARI on days 7 and 15 (p < 0.05). Although PPAR-γ levels were not significantly affected by ARI and OLA, the lower concentration of CAR induced a significant time-dependent decrease in PPAR-γ expression (p < 0.05). Conclusions: The in vitro adipogenesis considered from TG accumulation, AN secretion, and PPAR-γ expression was differently influenced by ARI, CAR, and OLA. Understanding the adipocyte-related mechanisms of antipsychotics could contribute to understanding their weight-influencing effect.

Dopamine Autoxidation Is Controlled by Acidic pH.

We studied the reaction mechanism of dopamine autoxidation using quantum chemical methods. Unlike other biogenic amines important in the central nervous system, dopamine and noradrenaline are capable of undergoing a non-enzymatic autoxidative reaction giving rise to a superoxide anion that further decomposes to reactive oxygen species. The reaction in question, which takes place in an aqueous solution, is as such not limited to the mitochondrial membrane where scavenging enzymes such as catalase and superoxide dismutase are located. With the experimental rate constant of 0.147 s−1, the dopamine autoxidation reaction is comparably as fast as the monoamine oxidase B catalyzed dopamine decomposition with a rate constant of 1 s−1. By using quantum chemical calculations, we demonstrated that the rate-limiting step is the formation of a hydroxide ion from a water molecule, which attacks the amino group that enters intramolecular Michael addition, giving rise to a pharmacologically inert aminochrome. We have shown that for dopamine stability on a time scale of days, it is essential that the pH value of the synaptic vesicle interior is acidic. The pathophysiologic correlates of the results are discussed in the context of Parkinson's disease as well as the pathology caused by long-term amphetamine and cocaine administration.

Effects of the Dopamine Stabilizer, Pridopidine, on Basal and Phencyclidine-Induced Locomotion: Role of Dopamine D2 and Sigma-1 Receptors.

Pridopidine, a compound in clinical trials for Huntington's disease treatment, was originally synthesized as a dopamine D2 receptor (D2R) ligand, but later found to possess higher affinity for the sigma-1 receptor (S1R). However, the putative contributions of D2R and S1R to the behavioral profile of acutely administered pridopidine have not been investigated. The present study sought to compare the effects of acute pridopidine on wild-type vs. D2R and S1R knockout mice, at high (60 mg/kg) and low (6 mg/kg) doses. Pridopidine effects on basal and phencyclidine-induced locomotor activity was measured in the open field test. Additionally, the actions of pridopidine on prepulse inhibition was measured in animals treated with saline or phencyclidine. Whereas inhibition of spontaneous and phencyclidine-induced locomotion was readily observed at 60 mg/kg pridopidine, neither locomotor stimulation in habituated mice, nor any effects on prepulse inhibition were detected upon pridopidine treatment. Surprisingly, inhibition of spontaneous locomotion was unaffected by both D2R and S1R deletion. The present results suggest the involvement of additional targets, besides D2R and S1R, in mediating locomotor inhibition by pridopidine.

Effects of the monoamine stabilizer (-)-OSU6162 on locomotor and sensorimotor responses predictive of antipsychotic activity.

The monoamine stabilizer (3S)-3-[3-(methenesulfonyl)phenyl]-1-propylpiperidine hidrochloride [(-)-OSU6162] is a promising compound for the treatment of neurological and psychiatric disorders, such as schizophrenia. Here, we tested the hypothesis that (-)-OSU6162 prevents hyperlocomotion and sensorimotor deficits in prepulse inhibition of the startle response (PPI) induced by psychomimetic drugs. Male Swiss mice received injections of (-)-OSU6162 (1, 3, 10, or 30mg/kg), and their motor responses were investigated in the open field and in the catalepsy tests, which predicts liability to induce sedation and extrapyramidal side effects, respectively. Next, in independent experiments, this compound was evaluated for its efficacy to prevent hyperlocomotion induced by cocaine (10mg/kg; dopamine transporter inhibitor) or ketamine (60mg/kg; glutamate NMDA channel blocker) in the open field. Finally, we tested if (-)-OSU6162 prevents PPI disruption induced by MK-801 (0.5mg/kg; glutamate NMDA channel blocker). (-)-OSU6162 induced neither locomotion impairment nor catalepsy. This compound prevented cocaine-induced hyperlocomotion at the doses of 10 and 30mg/kg and ketamine-induced hyperlocomotion at the doses of 1 and 3mg/kg. In the sensorimotor test, (-)-OSU6162 failed to reverse MK-801-induced PPI deficits. The dopamine stabilizer (-)-OSU6162 prevents the hyperactivity induced by dopaminergic and anti-glutamatergic drugs at doses that preserve motor functions, although it failed in the PPI test. Its therapeutic potential for specific symptoms of schizophrenia warrants further investigation in both preclinical and clinical studies.

Understanding the Stability of Dopamine and Dobutamine Over 24h in Simulated Neonatal Ward Conditions.

Our objectives were to investigate the possible effects of temperature and light on the stability of dopamine and dobutamine continuous infusions over 24h when prepared in a variety of dilution vehicles. Syringe-driver infusion apparatuses were set up for dopamine and dobutamine diluted with either 0.9% sodium chloride (NaCl) or 5% glucose delivering 3 and 5μg/kg/min, respectively, via 206-cm extension sets. All infusions were prepared for a neonate weight of 1kg. Infusions were run over 24h with approximately half the tubing within an incubator set at 35°C. Cyclic voltammetry was used to monitor the concentration of the inotrope within the syringe and at the end of the extension set, both initially and after 24h. The variation in the concentration of dopamine and dobutamine in the vials (n=6) was 3.58 and 1.22%, respectively. This variation increased to 10.88% for dopamine and 5.76% for dobutamine in the syringe. After 24h, a significant reduction in the concentration of dopamine was observed at the end of the extension set when prepared in 0.9% NaCl versus 5% glucose (p<0.001; n=6-7) and in dobutamine when prepared in 0.9% NaCl (p<0.001; n=6-7). No differences in the concentration of dopamine prepared in 0.9% NaCl were observed after 24h in light-exposed and light-protected extension sets (n=6-7). Dobutamine is more stable in dilution vehicles than dopamine, and inotropes are more stable in the 5% glucose dilution vehicle than in 0.9% NaCl. Such findings will provide guidance on the choice of inotropes.

Antipsychotic adjuvant treatment in OCD

Antidepressant drugs selective inhibitors of serotonin reuptake (IRS) are the drugs effective in obsessive compulsive disorder. It has not been proven more effective none of them except clomipramine. Around 40–60% of the Patients with obsessive-compulsive disorder (OCD) remain unimproved by serotonin reuptake inhibitors (SRIs).Two cases are presented in relation to this disorder and its treatment.Twenty-three year old woman begins to present anhedonia, apathy, isolation and low mood. Treatment was initiated with escitalopram with partial improvement.Obsessive component traitsThirty year old man with obsessive clinic of years of evolution, with worsening in recent months treatment with 200 mg sertraline.In both cases treatment with oral aripiprazole it was associated with a dose of 5 mg daily with improvement in obsessive symptoms.ResultsThe efficacy of aripiprazole as adjunctive drug treatment and obsessive anxiety is observed. However, we must take into account the potential risks posed as neuroleptic malignant syndrome and QTc prolongation.ConclusionAripiprazole is an antipsychotic which has a novel mechanism of action to be a partial agonist of dopamine D2 receptors. This fact has led to its inclusion in the group of antipsychotics called third generation, also called partial dopamine agonists, dopamine stabilizers or “dopamine-serotonin modulators system.” Its most common side effects such as nausea, headaches, agitation and akathisia were observed in studies on schizophrenia, schizoaffective disorder and bipolar disorder. Unlike other atypical antipsychotics, is considered a relatively neutral drug to weight gain, hyperprolactinemia, changes in metabolic parameters and sedation.Disclosure of interestThe authors have not supplied their declaration of competing interest.

The sigma-1 receptor mediates the beneficial effects of pridopidine in a mouse model of Huntington disease

The tri-nucleotide repeat expansion underlying Huntington disease (HD) results in corticostriatal synaptic dysfunction and subsequent neurodegeneration of striatal medium spiny neurons (MSNs). HD is a devastating autosomal dominant disease with no disease-modifying treatments. Pridopidine, a postulated “dopamine stabilizer”, has been shown to improve motor symptoms in clinical trials of HD. However, the target(s) and mechanism of action of pridopidine remain to be fully elucidated. As binding studies identified sigma-1 receptor (S1R) as a high-affinity receptor for pridopidine, we evaluated the relevance of S1R as a therapeutic target of pridopidine in HD. S1R is an endoplasmic reticulum - (ER) resident transmembrane protein and is regulated by ER calcium homeostasis, which is perturbed in HD. Consistent with ER calcium dysregulation, we observed striatal upregulation of S1R in aged YAC128 transgenic HD mice and HD patients. We previously demonstrated that dendritic MSN spines are lost in aged corticostriatal co-cultures from YAC128 mice. We report here that pridopidine and the chemically similar S1R agonist 3-PPP prevent MSN spine loss in aging YAC128 co-cultures. Spine protection was blocked by neuronal deletion of S1R. Pridopidine treatment suppressed supranormal ER Ca2+ release, restored ER calcium levels and reduced excessive store-operated calcium (SOC) entry in spines, which may account for its synaptoprotective effects. Normalization of ER Ca2+ levels by pridopidine was prevented by S1R deletion. To evaluate long-term effects of pridopidine, we analyzed expression profiles of calcium signaling genes. Pridopidine elevated striatal expression of calbindin and homer1a, whereas their striatal expression was reduced in aged Q175KI and YAC128 HD mouse models compared to WT. Pridopidine and 3-PPP are proposed to prevent calcium dysregulation and synaptic loss in a YAC128 corticostriatal co-culture model of HD. The actions of pridopidine were mediated by S1R and led to normalization of ER Ca2+ release, ER Ca2+ levels and spine SOC entry in YAC128 MSNs. This is a new potential mechanism of action for pridopidine, highlighting S1R as a potential target for HD therapy. Upregulation of striatal proteins that regulate calcium, including calbindin and homer1a, upon chronic therapy with pridopidine, may further contribute to long-term beneficial effects of pridopidine in HD.

Pridopidine activates neuroprotective pathways impaired in Huntington Disease.

Pridopidine has demonstrated improvement in Huntington Disease (HD) motor symptoms as measured by secondary endpoints in clinical trials. Originally described as a dopamine stabilizer, this mechanism is insufficient to explain the clinical and preclinical effects of pridopidine. This study therefore explored pridopidine’s potential mechanisms of action. The effect of pridopidine versus sham treatment on genome-wide expression profiling in the rat striatum was analysed and compared to the pathological expression profile in Q175 knock-in (Q175 KI) vs Q25 WT mouse models. A broad, unbiased pathway analysis was conducted, followed by testing the enrichment of relevant pathways. Pridopidine upregulated the BDNF pathway (P = 1.73E-10), and its effect on BDNF secretion was sigma 1 receptor (S1R) dependent. Many of the same genes were independently found to be downregulated in Q175 KI mice compared to WT (5.2e-7 < P < 0.04). In addition, pridopidine treatment upregulated the glucocorticoid receptor (GR) response, D1R-associated genes and the AKT/PI3K pathway (P = 1E-10, P = 0.001, P = 0.004, respectively). Pridopidine upregulates expression of BDNF, D1R, GR and AKT/PI3K pathways, known to promote neuronal plasticity and survival, as well as reported to demonstrate therapeutic benefit in HD animal models. Activation of S1R, necessary for its effect on the BDNF pathway, represents a core component of the mode of action of pridopidine. Since the newly identified pathways are downregulated in neurodegenerative diseases, including HD, these findings suggest that pridopidine may exert neuroprotective effects beyond its role in alleviating some symptoms of HD.

Low-dose aripiprazole for refractory burning mouth syndrome

We report a case of refractory burning mouth syndrome (BMS) ameliorated with low dose of aripiprazole. The patient was a 66-year-old female who had suffered from chronic burning pain in her tongue for 13 months. No abnormality associated with the burning sensation was detected in the laboratory tests and the oral findings. Considering the clinical feature and the history together, we diagnosed the burning sensation as BMS. The BMS pain was decreased by aripiprazole (powder) 1.0 mg/d, though no other antidepressants had satisfying pain relief. It could be supposed that the efficacy of aripiprazole is caused by dopamine stabilization in this case, and BMS might have a subtype that is reactive to aripiprazole. Further studies are needed to confirm the efficacy of aripiprazole for BMS.

The effects of the dopamine stabilizer (-)-OSU6162 on aggressive and sexual behavior in rodents.

The dopamine stabilizer (−)-OSU61612 dampens locomotion in rodents rendered hyperactive by exposure to a novel environment or treatment with amphetamine, but stimulates locomotion in habituated animals displaying low motor activity, tentatively exerting this profile by selectively blocking extrasynaptic D2 receptors. The major aim of the present study was to explore the possible usefulness of (−)-OSU61612 as an anti-aggressive drug. To this end, the effect of (−)-OSU61612 on isolation-induced aggression in male mice and estrous cycle-dependent aggression in female rats were studied using the resident intruder test; in addition, the possible influence of (−)-OSU61612 on sexual behavior in male mice and on elevated plus maze (EPM) performance in male rats were assessed. (−)-OSU61612 at doses influencing neither locomotion nor sexual activity reduced aggression in male mice. The effect was observed also in serotonin-depleted animals and is hence probably not caused by the antagonism of serotonin receptors displayed by the drug; refuting the possibility that it is due to 5-HT1B activation, it was also not counteracted by isamoltane. (−)-OSU61612 did not display the profile of an anxiogenic or anxiolytic drug in the EPM but caused a general reduction in activity that is well in line with the previous finding that it reduces exploratory behavior of non-habituated animals. In line with the observations in males, (−)-OSU61612 reduced estrus cycle-related aggression in female Wistar rats, a tentative animal model of premenstrual dysphoria. By stabilizing dopaminergic transmission, (−)-OSU61612 may prove useful as a well-tolerated treatment of various forms of aggression and irritability.

KB220Z™ a Pro-Dopamine Regulator Associated with the Protracted, Alleviation of Terrifying Lucid Dreams. Can We Infer Neuroplasticity-induced Changes in the Reward Circuit?

BackgroundRecent reports by our laboratory have indicated that lucid dreams may be linked to psychiatric conditions, including Attention Deficit Hyperactivity Disorder (ADHD) and other Reward Deficiency Syndrome-related diagnoses. In the latter case, it has been our observation that such lucid dreams can be unpleasant and frequently terrifying.Case presentationsWe present four cases of a dramatic and persistent alleviation of terrifying, lucid dreams in patients diagnosed with ADHD/PTSD and/or opiate/opioid addiction. The amelioration of such dreams could well be permanent, since the patients had stopped taking the nutraceutical for between 10 to 12 months, without their recollection or recurrence. In the first case, the patient is a 47-year-old, married male who required continued Buprenorphine/ Naloxone (Suboxone) treatment. The second case involved a 32-year-old female with the sole diagnosis of ADHD. The third case involves a 38-year-old male who carried the diagnoses of Substance Use Dependence and ADHD. The fourth case involved a 50-year-old female with the diagnoses of Alcohol Abuse, ADHD and Posttraumatic Stress Disorder.ResultsIn order to attempt to understand the possibility of neuroplasticity, we evaluated the effect of KB220Z in non-opioid-addicted rats utilizing functional Magnetic Resonance Imaging methodology. While we cannot make a definitive claim because rat brain functional connectivity may not be exactly the same as humans, it does provide some interesting clues. We did find following seeding of the dorsal hippocampus, enhanced connectivity volume across several Regions of Interest (ROI), with the exception of the pre- frontal cortex. Interestingly, the latter region is only infrequently activated in lucid human dreaming, when the dreamer reports that he/she had the thought that they were dreaming during the lucid dream.ConclusionsThe four patients initially reported a gradual but, then, complete amelioration of their long-term, terrifying, lucid dreams, while taking KB220Z. The persistent amelioration of these dreams continued for up to 12 months, after a self-initiated, cessation of use of KB220Z. These particular cases raise the scientific possibility that KB200Z increases both dopamine stability as well as functional connectivity between networks of brain reward circuitry in both rodents and humans. The increase in connectivity volume in rodents suggest the induction of neuroplasticity changes, which may be analogous to those involved in human lucid dreaming as well as Rapid Eye Movement sleep. The possibility that the complex induces long-term, neuroplasticity changes must await more intensive investigations, involving large-population, double-blinded studies.

Hypothesizing Balancing Endorphinergic and Glutaminergic Systems to Treat and Prevent Relapse to Reward Deficiency Behaviors: Coupling D-Phenylalanine and N-Acetyl-L-Cysteine (NAC) as a Novel Therapeutic Modality.

In this hypothesis, we are proposing that the combination of D-Phenylalanine and N-acetyl-L-cysteine (NAC) - two substances that have never been utilized together - is an important advancement to treat Reward Deficiency Syndrome (RDS) [1]. The key motivation for this notion is that the combination will have synergistic attributes to induce dopamine release as well as dopamine stabilization at the brain reward circuitry via different mechanisms. We hypothesize that preferential release of Dopamine, for example, at the Nucleus Accumbens (NAc) along with glutaminergic homeostasis induces not only the release, but also the appropriate regulation of dopamine function that could lead to required “Dopamine Homeostasis.” One way to explain this premise is to review the Brain Reward Cascade (BRC) developed by the one of us (KB) along with Gerald Kozlowski (Blum & Kozlowski 1989) [Figure 1] [1]. The BRC highlights the mechanism in which the proposed D-Phenylalanine and NAC combination works. Open in a separate window Figure 1 Brain Reward Cascade (BRC)