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Neuroscience May 2024Dopamine D receptor agonists improve spatial working memory, but their effects on temporal order memory, particularly prone to the effects of aging, have not been...
Dopamine D receptor agonists improve spatial working memory, but their effects on temporal order memory, particularly prone to the effects of aging, have not been studied. Two D agonists, PF6256142 (PF) and 2-methyldihydrexidine (2MDHX), were examined for their effects in a rodent temporal order recognition task. Our results are consistent with the hypothesis that there is an age-related decline in rodent temporal order memory. The data also show that either agonist rescues the poor memory performance with a large effective size. Interestingly, the optimal effective dose varied among individual rats of different age groups. PF showed greater potency for older rats, whereas 2MDHX showed better overall population effectiveness. Both PF and 2MDHX have high intrinsic activity at rodent D-mediated cAMP synthesis. Conversely, at D-mediated β-arrestin recruitment, PF has essentially no intrinsic activity, whereas 2MDHX is a super-agonist. These findings suggest that D agonists have potential to treat age-related cognitive decline, and the pattern of functional selectivity may be useful for developing drugs with an improved therapeutic index.
PubMed: 38823551
DOI: 10.1016/j.neuroscience.2024.05.033 -
European Journal of Pharmacology Aug 2024Dopaminergic neurons express a heteromer composed of the dopamine D3 receptor and the α4β2 nicotinic acetylcholine receptor, the D3R-nAChR heteromer, activated by both...
Dopaminergic neurons express a heteromer composed of the dopamine D3 receptor and the α4β2 nicotinic acetylcholine receptor, the D3R-nAChR heteromer, activated by both nicotine and dopamine D2 and D3 receptors agonists, such as quinpirole, and crucial for dopaminergic neuron homeostasis. We now report that D3R-nAChR heteromer activity is potentiated by 17-β-estradiol which acts as a positive allosteric modulator by binding a specific domain on the α4 subunit of the nicotinic receptor protomer. In mouse dopaminergic neurons, in fact, 17-β-estradiol significantly increased the ability of nicotine and quinpirole in promoting neuron dendritic remodeling and in protecting neurons against the accumulation of α-synuclein induced by deprivation of glucose, with a mechanism that does not involve the classical estrogen receptors. The potentiation induced by 17-β-estradiol required the D3R-nAChR heteromer since either nicotinic receptor or dopamine D3 receptor antagonists and interfering TAT-peptides, but not the estrogen receptor antagonist fulvestrant, specifically prevented 17-β-estradiol effects. Evidence of estrogens neuroprotection, mainly mediated by genomic mechanisms, have been provided, which is in line with epidemiological data reporting that females are less likely to develop Parkinson's Disease than males. Therefore, potentiation of D3R-nAChR heteromer activity may represent a further mechanism by which 17-β-estradiol reduces dopaminergic neuron vulnerability.
Topics: Receptors, Dopamine D3; Estradiol; Animals; Dopaminergic Neurons; Receptors, Nicotinic; Mice; Neuroprotective Agents; Female; Male
PubMed: 38821163
DOI: 10.1016/j.ejphar.2024.176678 -
Journal of Psychiatric Practice May 2024Prolactinomas-pituitary tumors that overproduce prolactin-can cause various troublesome symptoms. Dopamine agonists (DAs) reduce prolactin production in the prolactin...
OBJECTIVE
Prolactinomas-pituitary tumors that overproduce prolactin-can cause various troublesome symptoms. Dopamine agonists (DAs) reduce prolactin production in the prolactin pathway, making them the first-line treatment for prolactinomas. However, the main side effect of DA treatment, hyperdopaminergia, is an explicit etiology for psychiatric side effects. Psychiatric conditions are often treated with dopamine antagonists, which can induce hyperprolactinemia. This presents a challenge for patients with both a prolactinoma and a preexisting psychiatric condition, as treatment of one condition could worsen the other. This review seeks to identify an adequate therapeutic regimen for patients with coexisting prolactinomas and psychiatric symptoms.
METHODS
This review examined PubMed citations from 1960 to 2023 published in English and involving human subjects. Case reports, case series, and cohort studies involving patients with concomitant prolactinomas and psychiatric symptoms, as validated by brain imaging, serologic prolactin levels, and medical history or chart reports of psychiatric symptoms, were included.
RESULTS
Thematic analysis included 23 reports involving 42 participants; 27 of the 42 patients experienced a significant reduction in prolactin levels and psychiatric symptoms (64%). Treatment of those 42 patients included discontinuing or altering antipsychotic/dopamine antagonist therapy or discontinuing DA therapy to reduce psychiatric symptoms, with surgery or radiation postpharmacotherapy as a last-line strategy. However, in some cases (reported in Tables 2 to 4), either psychiatric or prolactin-related symptoms recurred despite adjustment.
CONCLUSIONS
Clinicians may find it beneficial to prioritize specific antipsychotics (aripiprazole, olanzapine, ziprasidone, or clozapine) over others (risperidone, thioridazine, thiothixene, and remoxipride). Discontinuing DA medication at least periodically until the patient's condition improves may also be advisable. If these 2 initial approaches do not yield a significant improvement in symptom management, surgery or radiation therapy may be considered. As patients may respond differently to these therapies, our study still recommends a patient-centered approach.
Topics: Humans; Prolactinoma; Pituitary Neoplasms; Mental Disorders; Dopamine Agonists; Antipsychotic Agents; Dopamine Antagonists
PubMed: 38819244
DOI: 10.1097/PRA.0000000000000783 -
The Journal of Pharmacology and... Jun 2024Haloperidol decanoate (HD) has been implicated in cognitive impairment. Agomelatine (AGO) has been claimed to improve cognition. We aimed at investigating the effects of...
High-dose Agomelatine Combined with Haloperidol Decanoate Improves Cognition, Downregulates MT2, Upregulates D5, and Maintains Krüppel-like Factor 9 But Alters Cardiac Electrophysiology.
Haloperidol decanoate (HD) has been implicated in cognitive impairment. Agomelatine (AGO) has been claimed to improve cognition. We aimed at investigating the effects of HD + low- or high-dose AGO on cognition, verifying the melatonergic/dopaminergic to the cholinergic hypothesis of cognition and exploring relevant cardiovascular issues in adult male Wistar albino rats. HD + high-dose AGO prolonged the step-through latency by +61.47% ( < 0.0001), increased the time spent in bright light by +439.49% ( < 0.0001), reduced the time spent in dim light by -66.25% ( < 0.0001), and increased the percent of alternations by +71.25% ( < 0.0001), despite the reductions in brain acetylcholine level by -10.67% ( < 0.0001). Neurodegeneration was minimal, while the mean power frequency of the source wave was reduced by -23.39% ( 0.05). Concurrently, the relative expression of brain melatonin type 2 receptors was reduced by -18.75% ( < 0.05), against increased expressions of dopamine type 5 receptors by +22.22% ( < 0.0001) and angiopoietin-like 4 by +119.18% ( 0.0001). Meanwhile, electrocardiogram (ECG) demonstrated inverted P wave, reduced P wave duration by -36.15% ( < 0.0001) and PR interval by -19.91% ( < 0.0001), prolonged RR interval by +27.97% ( < 0.05), increased R wave amplitude by +523.15% ( < 0.0001), and a depressed ST segment and inverted T wave. In rats administered AGO, HD, or HD+ low-dose AGO, Alzheimer's disease (AD)-like neuropathologic features were more evident, accompanied by extensive ECG and neurochemical alterations. HD + high-dose AGO enhances cognition but alters cardiac electrophysiology. SIGNIFICANCE STATEMENT: Given the issue of cognitive impairment associated with HD and the claimed cognitive-enhancing activity of AGO, combined high-dose AGO with HD improved cognition of adult male rats, who exhibited minimal neurodegenerative changes. HD+ high-dose AGO was relatively safe regarding triggering epileptogenesis, while it altered cardiac electrophysiology. In the presence of low acetylcholine, the melatonergic/dopaminergic hypothesis, added to angiopoietin-like 4 and Krüppel-like factor 9, could offer some clue, thus offering novel targets for pharmacologic manipulation of cognition.
Topics: Animals; Male; Rats, Wistar; Haloperidol; Rats; Cognition; Acetamides; Receptor, Melatonin, MT2; Down-Regulation; Up-Regulation; Heart; Dose-Response Relationship, Drug; Naphthalenes
PubMed: 38816228
DOI: 10.1124/jpet.123.002087 -
Journal of Pharmaceutical Sciences May 2024Rotigotine (RTG) is a dopamine agonist used in the treatment of Parkinson's disease. As it is susceptible to oxidation, stability studies must be carefully designed for...
Rotigotine (RTG) is a dopamine agonist used in the treatment of Parkinson's disease. As it is susceptible to oxidation, stability studies must be carefully designed for the identification and characterization of all possible degradation products. Here, RTG degradation was evaluated according to the International Conference on Harmonization guidelines under various stress conditions, including acidic and basic hydrolysis, oxidative, metallic, photolytic, and thermal conditions. Additionally, more severe stress conditions were applied to induce RTG degradation. Significant degradation was only observed under oxidative and photolytic conditions. The samples were analyzed by high performance liquid chromatography coupled to photodiode array detectors, charged aerosol, and high-resolution mass spectrometry. Chromatographic analyses revealed the presence of eight substances related to RTG, four of which were already described and were qualified impurities (impurities B, C, K and E) and four new degradation products (DP-1 - DP-4), whose structures were characterized by high-resolution mass spectrometry through Q-Orbitrap and electrospray ionization. In the stress testing of the active pharmaceutical ingredient in solid form, significant RTG degradation was observed in the presence of the oxidative matrix. The results corroborate the literature that confirm the high susceptibility of RTG to oxidation and the importance of using different detectors to detect degradation products in forced degradation studies.
PubMed: 38815860
DOI: 10.1016/j.xphs.2024.05.028 -
Frontiers in Bioscience (Landmark... May 2024Colorectal cancer (CRC) is a major cause of mortality and morbidity. A study proved that brexpiprazole, as a novel dopamine receptor partial agonist, can also prevent...
BACKGROUND
Colorectal cancer (CRC) is a major cause of mortality and morbidity. A study proved that brexpiprazole, as a novel dopamine receptor partial agonist, can also prevent CRC cell proliferation. Therefore, clarifying the molecular mechanism of brexpiprazole is vital to developing a novel therapeutic strategy for CRC.
METHODS
The effect of brexpiprazole on human colorectal cancer cell proliferation was measured with Cell Counting Kit-8 (CCK-8) kits. Cell migration capability was measured using wound healing and transwell. Cell apoptosis was evaluated with a flow cytometer. Western blots and immunohistochemical staining were used to evaluate protein expression. The effects observed were also confirmed in xenograft models.
RESULTS
Brexpiprazole remarkably inhibited the proliferation, suppressed the migration ability, and induced apoptosis of colorectal cancer cells. Mechanism study showed that brexpiprazole exerted these effects by inhibiting the EGFR pathway. Brexpiprazole enhanced HCT116 cells' sensitivity to cetuximab, and a combination of brexpiprazole and cetuximab inhibited xenograft tumor growth .
CONCLUSIONS
Our finding suggested that brexpiprazole inhibits proliferation, promotes apoptosis, and enhances CRC cells' sensitivity to cetuximab by regulating the EGFR pathway and it might be an efficacious treatment strategy for CRC.
Topics: Humans; Colorectal Neoplasms; Thiophenes; ErbB Receptors; Animals; Cell Proliferation; Apoptosis; Cetuximab; Mice, Nude; Xenograft Model Antitumor Assays; Quinolones; Cell Movement; Cell Line, Tumor; Mice; HCT116 Cells; Mice, Inbred BALB C; Disease Progression
PubMed: 38812296
DOI: 10.31083/j.fbl2905174 -
Scientific Reports May 2024The relation of antipsychotics with severe Coronavirus Disease 19 (COVID-19) outcomes is a matter of debate since the beginning of the pandemic. To date, controversial...
The relation of antipsychotics with severe Coronavirus Disease 19 (COVID-19) outcomes is a matter of debate since the beginning of the pandemic. To date, controversial results have been published on this issue. We aimed to prove whether antipsychotics might exert adverse or protective effects against fatal outcomes derived from COVID-19. A population-based retrospective cohort study (January 2020 to November 2020) comprising inpatients (15,968 patients) who were at least 18 years old and had a laboratory-confirmed COVID-19 infection. Two sub-cohorts were delineated, comprising a total of 2536 inpatients: individuals who either had no prescription medication or were prescribed an antipsychotic within the 15 days preceding hospitalization. We conducted survival and odds ratio analyses to assess the association between antipsychotic use and mortality, reporting both unadjusted and covariate-adjusted results. We computed the average treatment effects, using the untreated group as the reference, and the average treatment effect on the treated, focusing solely on the antipsychotic-treated population. Among the eight antipsychotics found to be in use, only aripiprazole showed a significant decrease in the risk of death from COVID-19 [adjusted odds ratio (OR) = 0.86; 95% CI, 0.79-0.93, multiple-testing adjusted p-value < 0.05]. Importantly, these findings were consistent for both covariate-adjusted and unadjusted analyses. Aripiprazole has been shown to have a differentiated beneficial effect in protecting against fatal clinical outcome in COVID-19 infected individuals. We speculate that the differential effect of aripiprazole on controlling immunological pathways and inducible inflammatory enzymes, that are critical in COVID19 illness, may be associated with our findings herein.
Topics: Humans; Aripiprazole; COVID-19; Male; Female; Antipsychotic Agents; Middle Aged; Retrospective Studies; Aged; SARS-CoV-2; COVID-19 Drug Treatment; Adult; Aged, 80 and over
PubMed: 38811612
DOI: 10.1038/s41598-024-60297-y -
ENeuro Jun 2024Amylin, a pancreatic hormone that is cosecreted with insulin, has been highlighted as a potential treatment target for obesity. Amylin receptors are distributed widely...
Amylin, a pancreatic hormone that is cosecreted with insulin, has been highlighted as a potential treatment target for obesity. Amylin receptors are distributed widely throughout the brain and are coexpressed on mesolimbic dopamine neurons. Activation of amylin receptors is known to reduce food intake, but the neurochemical mechanisms behind this remain to be elucidated. Amylin receptor activation in the ventral tegmental area (VTA), a key dopaminergic nucleus in the mesolimbic reward system, has a potent ability to suppress intake of palatable fat and sugar solutions. Although previous work has demonstrated that VTA amylin receptor activation can dampen mesolimbic dopamine signaling elicited by random delivery of sucrose, whether this is also the case for fat remains unknown. Herein we tested the hypothesis that amylin receptor activation in the VTA of male rats would attenuate dopamine signaling in the nucleus accumbens core in response to random intraoral delivery of either fat or sugar solutions. Results show that fat solution produces a greater potentiation of accumbens dopamine than an isocaloric sucrose solution. Moreover, activation of VTA amylin receptors elicits a more robust suppression of accumbens dopamine signaling in response to fat solution than to sucrose. Taken together these results shed new light on the amylin system as a therapeutic target for obesity and emphasize the reinforcing nature of high-fat/high-sugar diets.
Topics: Animals; Ventral Tegmental Area; Male; Dopamine; Nucleus Accumbens; Receptors, Islet Amyloid Polypeptide; Rats, Sprague-Dawley; Dietary Fats; Signal Transduction; Amylin Receptor Agonists; Rats; Sucrose
PubMed: 38806231
DOI: 10.1523/ENEURO.0133-24.2024 -
Journal of Medicinal Chemistry Jun 2024Development of more efficacious medications with improved safety profiles to manage and treat multiple forms of pain is a critical element of healthcare. To this end, we...
Development of more efficacious medications with improved safety profiles to manage and treat multiple forms of pain is a critical element of healthcare. To this end, we have designed and synthesized a novel class of tetracyclic pyridopyrroloquinoxalinone derivatives with analgesic properties. The receptor binding profiles and analgesic properties of these tetracyclic compounds were studied. Systematic optimizations of this novel scaffold culminated in the discovery of the clinical candidate, (6,10)-8-[3-(4-fluorophenoxy)propyl]-6,7,8,9,10,10-hexahydro-1-pyrido[3',4':4,5]pyrrolo[1,2,3-]quinoxalin-2(3)-one (compound , ITI-333), which exhibited potent binding affinity to serotonin 5-HT ( = 8.3 nM) and μ-opioid receptors (MOR, = 11 nM) and moderate affinity to adrenergic α ( = 28 nM) and dopamine D ( = 50 nM) receptors. ITI-333 acts as a 5-HT receptor antagonist, a MOR partial agonist, and an adrenergic α receptor antagonist. ITI-333 exhibited dose-dependent analgesic effects in rodent models of acute pain. Currently, this investigational new drug is in phase I clinical development.
Topics: Animals; Humans; Analgesics; Structure-Activity Relationship; Administration, Oral; Pain; Mice; Male; Rats; Drug Discovery; Rats, Sprague-Dawley; Biological Availability; Receptors, Opioid, mu; Pyridines; Pyrroles
PubMed: 38805667
DOI: 10.1021/acs.jmedchem.4c00480