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Cancer Research Communications Jun 2024Glioblastoma (GBM) is the deadliest adult brain cancer. Under the current standard of care, almost all patients succumb to the disease and novel treatments are urgently...
UNLABELLED
Glioblastoma (GBM) is the deadliest adult brain cancer. Under the current standard of care, almost all patients succumb to the disease and novel treatments are urgently needed. Recognizing that GBMs are addicted to cholesterol, past clinical trials have repurposed statins against GBM but failed. The purpose of this study was to test whether treatments that upregulate the cholesterol biosynthesis pathway in GBM would generate a metabolic vulnerability that can be exploited using statins and to determine the underlying mechanisms.Effects of radiotherapy and temozolomide or dopamine receptor antagonists on the mevalonate pathway in GBM were assessed in vitro and in vivo. The impact of statins on self-renewal of glioma stem cells and median survival was studied. Branches of the mevalonate pathway were probed to identify relevant effector proteins.Cells surviving combination treatments that converge in activating the immediate early response, universally upregulated the mevalonate pathway and increased stemness of GBM cells through activation of the Rho-GTPase Rac-1. Activation of the mevalonate pathway and Rac-1 was inhibited by statins, which led to improved survival in mouse models of glioblastoma when combined with radiation and drugs that target the glioma stem cell pool and plasticity of glioma cells.We conclude that a combination of dopamine receptor antagonists and statins could potentially improve radiotherapy outcome and warrants further investigation.
SIGNIFICANCE
Combination therapies that activate the mevalonate pathway in GBM cells after sublethal treatment enhance self-renewal and migratory capacity through Rac-1 activation, which creates a metabolic vulnerability that can be further potentially exploited using statins.
Topics: Glioblastoma; Mevalonic Acid; Humans; Animals; rac1 GTP-Binding Protein; Mice; Brain Neoplasms; Cell Line, Tumor; Temozolomide; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Neoplasm Recurrence, Local; Xenograft Model Antitumor Assays; Neoplastic Stem Cells; Signal Transduction; Dopamine Antagonists
PubMed: 38837899
DOI: 10.1158/2767-9764.CRC-24-0049 -
Journal of Applied Toxicology : JAT Jun 2024Glyphosate (GLY) is a pesticide that severely alters nigrostriatal dopaminergic neurotransmission, inducing great increases in dopamine release from rat dorsal striatum....
Glyphosate (GLY) is a pesticide that severely alters nigrostriatal dopaminergic neurotransmission, inducing great increases in dopamine release from rat dorsal striatum. This GLY-induced striatal dopamine overflow occurs through mechanisms not yet fully understood, hence the interest in evaluating the role of other neurotransmitter systems in such effects. So, the main objective of this mechanistic study was to evaluate the possible mediation of the glutamatergic, cholinergic, and nitrergic systems in the GLY-induced in vivo dopamine release from rat dorsal striatum. The extracellular dopamine levels were measured by cerebral microdialysis and HPLC with electrochemical detection. Intrastriatal administration of GLY (5 mmol/L) significantly increased the dopamine release (1102%). Pretreatment with MK-801 (50 or 400 μmol/L), a non-competitive antagonist of NMDA receptors, significantly decreased the effect of GLY (by 70% and 74%, respectively), whereas AP-5 (400 μmol/L), a competitive antagonist of NMDA receptors, or CNQX (500 μmol/L), an AMPA/kainate receptor antagonist, had no significant effect. Administration of the nitric oxide synthase inhibitors, L-nitroarginine (L-NAME, 100 μmol/L) or 7-nitroindazole (7-NI, 100 μmol/L), also did not alter the effect of GLY on dopamine release. Finally, pretreatment of the animals with mecamylamine, an antagonist of nicotinic receptors, decreased the effect of GLY on dopamine release by 49%, whereas atropine, a muscarinic antagonist, had no significant effect. These results indicate that GLY-induced dopamine release largely depends on the activation of NMDA and nicotinic receptors in rat dorsal striatum. Future research is needed to determine the effects of this pesticide at environmentally relevant concentrations.
PubMed: 38828527
DOI: 10.1002/jat.4651 -
The Canadian Veterinary Journal = La... Jun 2024As a major animal control service provider in the city of Guelph and Wellington County in Ontario, the Guelph Humane Society transports and presents injured or ill...
BACKGROUND
As a major animal control service provider in the city of Guelph and Wellington County in Ontario, the Guelph Humane Society transports and presents injured or ill raccoons requiring humane euthanasia to the Ontario Veterinary College Health Sciences Centre (OVC-HSC). Issues around handling, transportation, and delays before euthanasia have recently raised some concerns for welfare and the need for means of improving this process.
OBJECTIVE
Investigation of a noncontrolled sedation and analgesia protocol for injured or ill raccoons intended to improve animal welfare by allowing humane handling, transport, and euthanasia following administration by an animal protection officer (APO).
ANIMALS AND PROCEDURE
Twenty-seven injured or ill raccoons requiring transport and euthanasia, as determined by the Guelph Humane Society APOs, were included in the study. Each raccoon was administered acepromazine (0.05 mg/kg), alfaxalone (4 mg/kg), and medetomidine (0.15 mg/kg), intramuscularly, before being transported to the OVC-HSC for humane euthanasia.
RESULTS
The combination of acepromazine, alfaxalone, and medetomidine was suitable for administration by APOs and provided the desired sedation depth to allow transport and humane euthanasia. Transit time was the only predictor of sedation depth upon arrival at the OVC-HSC. Two raccoons showed mild physical response to intracardiac injection for euthanasia. Numerical cutoff points of an in-hospital visual analog score of sedation of ≥ 70/100 and duration of sedation of < 62 min showed zero probability of response to euthanasia.
CONCLUSION AND CLINICAL RELEVANCE
Administration of acepromazine, alfaxalone, and medetomidine at the stated doses provided acceptable sedation and analgesia to improve animal welfare during transport and eventual euthanasia of raccoons.
Topics: Animals; Medetomidine; Pregnanediones; Hypnotics and Sedatives; Acepromazine; Male; Raccoons; Female; Euthanasia, Animal; Injections, Intramuscular; Animal Welfare
PubMed: 38827599
DOI: No ID Found -
Experimental & Molecular Medicine Jun 2024The effects of ultraviolet (UV) radiation on brain function have previously been investigated; however, the specific neurotransmitter-mediated mechanisms responsible for...
The effects of ultraviolet (UV) radiation on brain function have previously been investigated; however, the specific neurotransmitter-mediated mechanisms responsible for UV radiation-induced neurobehavioral changes remain elusive. In this study, we aimed to explore the mechanisms underlying UV radiation-induced neurobehavioral changes. In a mouse model, we observed that UV irradiation of the skin induces deficits in hippocampal memory, synaptic plasticity, and adult neurogenesis, as well as increased dopamine levels in the skin, adrenal glands, and brain. Chronic UV exposure altered the expression of genes involved in dopaminergic neuron differentiation. Furthermore, chronic peripheral dopamine treatments resulted in memory deficits. Systemic administration of a dopamine D1/D5 receptor antagonist reversed changes in memory, synaptic plasticity, adult neurogenesis, and gene expression in UV-irradiated mice. Our findings provide converging evidence that chronic UV exposure alters dopamine levels in the central nervous system and peripheral organs, including the skin, which may underlie the observed neurobehavioral shifts, such as hippocampal memory deficits and impaired neurogenesis. This study underscores the importance of protection from UV exposure and introduces the potential of pharmacological approaches targeting dopamine receptors to counteract the adverse neurological impacts of UV exposure.
PubMed: 38825641
DOI: 10.1038/s12276-024-01242-x -
International Heart Journal 2024The impact of tolvaptan and low-dose dopamine on heart failure (HF) patients with acute kidney injury (AKI) remains uncertain from a clinical standpoint.HF patients with... (Randomized Controlled Trial)
Randomized Controlled Trial
The impact of tolvaptan and low-dose dopamine on heart failure (HF) patients with acute kidney injury (AKI) remains uncertain from a clinical standpoint.HF patients with AKI were selected and divided in a 1:1 fashion into the dopamine combined with the tolvaptan group (DTG), the tolvaptan group (TG), and the control group (CG). According to the standard of care, TG received tolvaptan 15 mg orally daily for a week. DTG received combination treatment, including 7 consecutive days of dopamine infusion (2 μg/kg・minutes) and oral tolvaptan 15 mg. Venous blood and urine samples were taken before and after therapy. The primary endpoint was the cardiorenal serological index after 7 days of treatment.Sixty-five patients were chosen randomly for the DTG (22 patients), TG (20 patients), and CG (23 patients), which were similar before the treatment. The serum indexes related to cardiac function (N-terminal probrain natriuretic peptide and cardiac troponin I) in DTG were decreased, compared with TG and CG (P < 0.05). Furthermore, the serological markers of renal function (serum cystatin C, serum creatinine, and neutrophil gelatinase-associated lipocalin) in DTG were lower than those in TG and CG (P < 0.05). There was no significant difference in the incidence of adverse reactions among groups.Low-dose dopamine combined with tolvaptan can markedly improve patients' cardiac and renal function. This may be considered a new therapeutic method for HF patients with AKI.
Topics: Humans; Tolvaptan; Heart Failure; Male; Female; Dopamine; Acute Kidney Injury; Aged; Middle Aged; Antidiuretic Hormone Receptor Antagonists; Drug Therapy, Combination; Natriuretic Peptide, Brain; Treatment Outcome; Benzazepines; Peptide Fragments
PubMed: 38825491
DOI: 10.1536/ihj.23-442 -
Psychiatry Research Aug 2024The aim of the study was to evaluate interaction effect of various augmentation strategies with clozapine in patients with Treatment-resistant schizophrenia.
Evaluation of the pharmacodynamic interaction effect of augmentation agents with clozapine in patients with treatment-resistant schizophrenia: A simulation study of clinical data.
INTRODUCTION
The aim of the study was to evaluate interaction effect of various augmentation strategies with clozapine in patients with Treatment-resistant schizophrenia.
METHODS
Data was extracted for change in positive and negative syndrome scale (PANSS) or brief psychiatric rating scale (BPRS) scores for monotherapy with various antipsychotic agents alone and their combination with clozapine. Individual patient data was generated using simulation of data (factorial trial framework) from published clinical trials for sample sizes from eight to 400 to evaluate interaction effect through linear modeling. Dose equivalents were calculated, and best fit models were determined for simulated data.
RESULTS
The polynomial model was found to be the best fit for the simulated data to determine interaction effect of combination. The clozapine augmentation with risperidone and ziprasidone was found to be antagonistic, whereas it was additive for haloperidol, aripiprazole, and quetiapine. A synergistic effect was observed for ECT combined with clozapine (Interaction effect: -7.62; p <0.001). A sample size of 250-300 may be sufficient to demonstrate a clinically significant interaction in future trials.
CONCLUSION
Clozapine may be augmented with electroconvulsive therapy, leading to the enhancement of antipsychotic effect. Though some antipsychotics like aripiprazole demonstrate additive effects, they may also add to the adverse effects.
Topics: Humans; Clozapine; Antipsychotic Agents; Drug Therapy, Combination; Schizophrenia, Treatment-Resistant; Adult; Male; Female; Computer Simulation; Drug Interactions; Drug Synergism; Middle Aged; Schizophrenia; Risperidone; Piperazines; Thiazoles
PubMed: 38824710
DOI: 10.1016/j.psychres.2024.115989 -
Scientific Reports May 2024Voriconazole is a second-generation azole used to treat serious fungal infections. Visual hallucinations constitute a representative adverse event caused by...
Association between voriconazole-induced visual hallucination and dopamine in an analysis of the food and drug administration (FDA) adverse event reporting system database.
Voriconazole is a second-generation azole used to treat serious fungal infections. Visual hallucinations constitute a representative adverse event caused by voriconazole. However, its mechanism of action remains unclear. In patients with schizophrenia or Parkinson's disease, the frequency of visual hallucinations is associated with brain dopamine levels. This study investigated the frequency of visual hallucinations in patients treated with voriconazole alone or in combination with dopaminergic medicines or dopamine antagonists, using data collected from the Food and Drug Administration Adverse event Reporting System (FAERS). The frequency of visual hallucinations with voriconazole alone and in combination with a dopaminergic medicine (levodopa) or dopamine antagonists (risperidone and chlorpromazine) was compared using data from the FAERS between 2004 and 2023, using the reporting odds ratio (ROR) with relevant 95% confidence intervals (CI). The reference group comprised patients who had been administered voriconazole without dopaminergic medication or dopamine antagonists. Of the patients, 22,839, 90,810, 109,757, 6,435, 20, 83, and 26, respectively were treated with voriconazole, levodopa, risperidone, chlorpromazine, voriconazole plus levodopa, voriconazole plus risperidone, and voriconazole plus chlorpromazine. The occurrence of visual hallucinations increased when used in combination with levodopa (ROR = 12.302, 95% CI = 3.587-42.183). No increase in incidence was associated with the concomitant use of dopamine antagonists (risperidone, ROR = 1.721, 95% CI = 0.421-7.030; chlorpromazine, ROR = none, 95% CI = none). Dopaminergic medicine may increase the risk of visual hallucinations in patients treated with voriconazole. Whether voriconazole positively modulates dopamine production warrants further investigation using a translational research approach.
Topics: Humans; Voriconazole; Hallucinations; United States; United States Food and Drug Administration; Male; Female; Aged; Middle Aged; Dopamine; Levodopa; Adult; Antifungal Agents; Adverse Drug Reaction Reporting Systems; Chlorpromazine; Risperidone; Dopamine Antagonists; Parkinson Disease; Young Adult; Adolescent; Databases, Factual
PubMed: 38822123
DOI: 10.1038/s41598-024-63504-y -
Brain Stimulation 2024Dopaminergic neurons in the ventral tegmental area (VTA) are crucially involved in regulating arousal, making them a potential target for reversing general anesthesia....
BACKGROUND
Dopaminergic neurons in the ventral tegmental area (VTA) are crucially involved in regulating arousal, making them a potential target for reversing general anesthesia. Electrical deep brain stimulation (DBS) of the VTA restores consciousness in animals anesthetized with drugs that primarily enhance GABA receptors. However, it is unknown if VTA DBS restores consciousness in animals anesthetized with drugs that target other receptors.
OBJECTIVE
To evaluate the efficacy of VTA DBS in restoring consciousness after exposure to four anesthetics with distinct receptor targets.
METHODS
Sixteen adult Sprague-Dawley rats (8 female, 8 male) with bipolar electrodes implanted in the VTA were exposed to dexmedetomidine, fentanyl, ketamine, or sevoflurane to produce loss of righting, a proxy for unconsciousness. After receiving the dopamine D1 receptor antagonist, SCH-23390, or saline (vehicle), DBS was initiated at 30 μA and increased by 10 μA until reaching a maximum of 100 μA. The current that evoked behavioral arousal and restored righting was recorded for each anesthetic and compared across drug (saline/SCH-23390) condition. Electroencephalogram, heart rate and pulse oximetry were recorded continuously.
RESULTS
VTA DBS restored righting after sevoflurane, dexmedetomidine, and fentanyl-induced unconsciousness, but not ketamine-induced unconsciousness. D1 receptor antagonism diminished the efficacy of VTA stimulation following sevoflurane and fentanyl, but not dexmedetomidine.
CONCLUSIONS
Electrical DBS of the VTA restores consciousness in animals anesthetized with mechanistically distinct drugs, excluding ketamine. The involvement of the D1 receptor in mediating this effect is anesthetic-specific.
Topics: Animals; Ventral Tegmental Area; Sevoflurane; Rats, Sprague-Dawley; Dexmedetomidine; Male; Fentanyl; Rats; Female; Unconsciousness; Deep Brain Stimulation; Consciousness; Ketamine; Anesthetics, Inhalation
PubMed: 38821397
DOI: 10.1016/j.brs.2024.05.012 -
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 Clinical Psychopharmacology
Topics: Humans; Antipsychotic Agents; Lurasidone Hydrochloride; Asthma; Piperazines; Female; Male; Schizophrenia; Adult
PubMed: 38820328
DOI: 10.1097/JCP.0000000000001871