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BioRxiv : the Preprint Server For... Jun 2024Decreased excitability of pyramidal tract neurons in layer 5B (PT5B) of primary motor cortex (M1) has recently been shown in a dopamine-depleted mouse model of...
Decreased cellular excitability of pyramidal tract neurons in primary motor cortex leads to paradoxically increased network activity in simulated parkinsonian motor cortex.
Decreased excitability of pyramidal tract neurons in layer 5B (PT5B) of primary motor cortex (M1) has recently been shown in a dopamine-depleted mouse model of parkinsonism. We hypothesized that decreased PT5B neuron excitability would substantially disrupt oscillatory and non-oscillatory firing patterns of neurons in layer 5 (L5) of primary motor cortex (M1). To test this hypothesis, we performed computer simulations using a previously validated computer model of mouse M1. Inclusion of the experimentally identified parkinsonism-associated decrease of PT5B excitability into our computational model produced a paradoxical increase in rest-state PT5B firing rate, as well as an increase in beta-band oscillatory power in local field potential (LFP). In the movement-state, PT5B population firing and LFP showed reduced beta and increased high-beta, low-gamma activity of 20-35 Hz in the parkinsonian, but not in control condition. The appearance of beta-band oscillations in parkinsonism would be expected to disrupt normal M1 motor output and contribute to motor activity deficits seen in patients with Parkinson's disease (PD).
PubMed: 38948850
DOI: 10.1101/2024.05.23.595566 -
BioRxiv : the Preprint Server For... Jun 2024Distinct basolateral amygdala (BLA) cell populations influence emotional responses in manners thought important for anxiety and anxiety disorders. The BLA contains...
Distinct basolateral amygdala (BLA) cell populations influence emotional responses in manners thought important for anxiety and anxiety disorders. The BLA contains numerous cell types which can broadcast information into structures that may elicit changes in emotional states and behaviors. BLA excitatory neurons can be divided into two main classes, one of which expresses (encoding protein phosphatase 1 regulatory inhibitor subunit 1B) which is downstream of the genes encoding the D1 and D2 dopamine receptors ( and respectively). The role of or BLA neurons in learned and unlearned emotional responses is unknown. Here, we identified that the + and + BLA neuron populations form two parallel pathways for communication with the ventral striatum. These neurons arise from the basal nucleus of the BLA, innervate the entire space of the ventral striatum, and are capable of exciting ventral striatum neurons. Further, through three separate behavioral assays, we found that the + and + parallel pathways bidirectionally influence both learned and unlearned emotional states when they are activated or suppressed, and do so depending upon where they synapse in the ventral striatum - with unique contributions of + and + circuitry on negative emotional states. Overall, these results contribute to a model whereby parallel, genetically-distinct BLA to ventral striatum circuits inform emotional states in a projection-specific manner.
PubMed: 38948716
DOI: 10.1101/2024.06.19.599749 -
BioRxiv : the Preprint Server For... Jun 2024Early diagnosis and biomarker discovery to bolster the therapeutic pipeline for Parkinson's disease (PD) are urgently needed. In this study, we leverage the large-scale...
UNLABELLED
Early diagnosis and biomarker discovery to bolster the therapeutic pipeline for Parkinson's disease (PD) are urgently needed. In this study, we leverage the large-scale whole-blood total RNA-seq dataset from the Accelerating Medicine Partnership in Parkinson's Disease (AMP PD) program to identify PD-associated RNAs, including both known genes and novel circular RNAs (circRNA) and enhancer RNAs (eRNAs). There were 1,111 significant marker RNAs, including 491 genes, 599 eRNAs, and 21 circRNAs, that were first discovered in the PPMI cohort (FDR < 0.05) and confirmed in the PDBP/BioFIND cohorts (nominal < 0.05). Functional enrichment analysis showed that the PD-associated genes are involved in neutrophil activation and degranulation, as well as the TNF-alpha signaling pathway. We further compare the PD-associated genes in blood with those in post-mortem brain dopamine neurons in our BRAINcode cohort. 44 genes show significant changes with the same direction in both PD brain neurons and PD blood, including neuroinflammation-associated genes , , and . Finally, we built a novel multi-omics machine learning model to predict PD diagnosis with high performance (AUC = 0.89), which was superior to previous studies and might aid the decision-making for PD diagnosis in clinical practice. In summary, this study delineates a wide spectrum of the known and novel RNAs linked to PD and are detectable in circulating blood cells in a harmonized, large-scale dataset. It provides a generally useful computational framework for further biomarker development and early disease prediction.
SIGNIFICANCE STATEMENT
Early and accurate diagnosis of Parkinson's disease (PD) is urgently needed. However, biomarkers for early detection of PD are still lacking. Also, the limit of sample size remains one of the main pitfalls of current PD biomarker studies. We employed an analysis of large-scale whole-blood RNA-seq data. By identifying 1,111 significant marker RNAs, we establish a robust foundation for early PD detection, which implicated in neutrophil activation, degranulation, and TNF-alpha signaling, offer unprecedented insights into PD pathogenesis. Our multi-omics machine learning model, boasting an AUC of 0.89, outperforms previous studies, promising a transformative tool for precise PD diagnosis in clinical settings. This study marks a pivotal step toward enhanced biomarker development and early disease prediction.
PubMed: 38948706
DOI: 10.1101/2024.06.18.599639 -
BioRxiv : the Preprint Server For... Jun 2024Relevance-based selectivity and high energy cost are two distinct features of long-term memory (LTM) formation that warrant its default inhibition. Spaced repetition of...
Relevance-based selectivity and high energy cost are two distinct features of long-term memory (LTM) formation that warrant its default inhibition. Spaced repetition of learning is a highly conserved cognitive mechanism that can lift this inhibition. Here, we questioned how the spacing effect integrates experience selection and energy efficiency at the cellular and molecular levels. We showed in that spaced training triggers LTM formation by extending over several hours an increased mitochondrial metabolic activity in neurons of the associative memory center, the mushroom bodies (MBs). We found that this effect is mediated by PKCδ, a member of the so-called 'novel PKC' family of enzymes, which uncovers the critical function of PKCδ in neurons as a regulator of mitochondrial metabolism for LTM. Additionally, PKCδ activation and translocation to mitochondria result from LTM-specific dopamine signaling on MB neurons. By bridging experience-dependent neuronal circuit activity with metabolic modulation of memory-encoding neurons, PKCδ signaling binds the cognitive and metabolic constraints underlying LTM formation into a unified gating mechanism.
PubMed: 38948698
DOI: 10.1101/2023.10.06.561186 -
Kidney Medicine Jul 2024Intradialytic hypotension significantly affects patient safety and clinical outcomes during hemodialysis. Despite various pharmacological and nonpharmacological...
Intradialytic hypotension significantly affects patient safety and clinical outcomes during hemodialysis. Despite various pharmacological and nonpharmacological interventions, effective management remains elusive. In this report, we detail a case of intradialytic hypotension in a male patient in his 40s, undergoing hemodialysis with a history of polycystic kidney disease. Eight years ago, the patient underwent bilateral nephrectomy because of a severe cystic infection, after which his systolic blood pressure (BP) persistently remained at 50-70 mm Hg during dialysis sessions. The initial treatment strategy for hypotension included fludrocortisone, midodrine, and prednisolone, leading to a slight temporary increase in BP, which subsequently declined. As the patient's condition deteriorated, the administration of norepinephrine or dopamine became necessary to sustain BP during dialysis. Given the patient's resistance to these treatments, a daily dose of 25 mg of atomoxetine was introduced. Following this treatment, there was a gradual improvement in the patient's vertigo, weakness, and BP. This case illustrates that low-dose atomoxetine can alleviate symptoms and elevate BP in patients experiencing severe intradialytic hypotension during hemodialysis.
PubMed: 38947771
DOI: 10.1016/j.xkme.2024.100840 -
Cureus May 2024Dyskinetic movements are characterized as hyperkinetic, repetitive movements of the extremities, facial, and oral musculature, most associated with prolonged dopamine D2...
Dyskinetic movements are characterized as hyperkinetic, repetitive movements of the extremities, facial, and oral musculature, most associated with prolonged dopamine D2 receptor blockade. In rare instances, dyskinetic movements can be brought on by selective serotonin reuptake inhibitor (SSRI) usage via an indirect D2 blockade mechanism, mimicking the D2 blockade observed with dopamine receptor blocking agents (DRBAs), such as in first-generation antipsychotics. This mimicked D2 blockade by SSRIs is said to be due to increased tonic inhibition by serotonin on dopaminergic neurons in the dopaminergic pathways of the brain, specifically the nigrostriatal pathway. In this case report, we look at a patient with a history of cerebral palsy who developed acute dyskinetic movements after short-term citalopram usage. The objective is to bring attention to the possible extrapyramidal side effects (EPS) of SSRI usage.
PubMed: 38947732
DOI: 10.7759/cureus.61364 -
Research Square Jun 2024The consumption of alcohol and caffeine affects the lives of billions of individuals worldwide. Although recent evidence indicates that caffeine impairs the reinforcing...
The consumption of alcohol and caffeine affects the lives of billions of individuals worldwide. Although recent evidence indicates that caffeine impairs the reinforcing properties of alcohol, a characterization of its effects on alcohol-stimulated mesolimbic dopamine (DA) function was lacking. Acting as the pro-drug of salsolinol, alcohol excites DA neurons in the posterior ventral tegmental area (pVTA) and increases DA release in the nucleus accumbens shell (AcbSh). Here we show that caffeine, via antagonistic activity on A2A adenosine receptors (A2AR), prevents alcohol-dependent activation of mesolimbic DA function as assessed, in-vivo, by brain microdialysis of AcbSh DA and, in-vitro, by electrophysiological recordings of pVTA DA neuronal firing. Accordingly, while the A1R antagonist DPCPX fails to prevent the effects of alcohol on DA function, both caffeine and the A2AR antagonist SCH 58261 prevent alcohol-dependent pVTA generation of salsolinol and increase in AcbSh DA in-vivo, as well as alcohol-dependent excitation of pVTA DA neurons in-vitro. However, caffeine also prevents direct salsolinol- and morphine-stimulated DA function, suggesting that it can exert these inhibitory effects also independently from affecting alcohol-induced salsolinol formation or bioavailability. Finally, untargeted metabolomics of the pVTA showcases that caffeine antagonizes alcohol-mediated effects on molecules (e.g. phosphatidylcholines, fatty amides, carnitines) involved in lipid signaling and energy metabolism, which could represent an additional salsolinol-independent mechanism of caffeine in impairing alcohol-mediated stimulation of mesolimbic DA transmission. In conclusion, the outcomes of this study strengthen the potential of caffeine, as well as of A2AR antagonists, for future development of preventive/therapeutic strategies for alcohol use disorder.
PubMed: 38946995
DOI: 10.21203/rs.3.rs-4289552/v1 -
Behavioural Brain Research Jun 2024Major depressive disorder (MDD) affects millions of people worldwide, with women at a higher risk during the childbearing age. Vortioxetine (VOX) and Vilazodone (VLZ)...
Major depressive disorder (MDD) affects millions of people worldwide, with women at a higher risk during the childbearing age. Vortioxetine (VOX) and Vilazodone (VLZ) are newer antidepressants with improved therapeutic profile commonly used, but their safety during pregnancy and long-term effects on offspring are poorly understood due to paucity of literature in preclinical and clinical studies. This study aimed to investigate whether prenatal exposure to VOX and VLZ impacts depressive- and anxiety-like neurobehavioral alterations in offspring, focusing on neurotransmitter-mediated mechanisms. Pregnant Wistar dams received either VOX or VLZ, 1mg/day and 2mg/day of the drug orally from gestation day (GD) 6 to 21. The dams naturally delivered their offspring and reared until they reached postnatal day (PND) 21. Offspring of both sexes were tested for display of depressive-and anxiety-like behaviors from PND 56 to 70. After PND 70, offspring were sacrificed, and their brains were collected to estimate neurotransmitter levels. As per protocol, controls were maintained simultaneously for each experimental design. Prenatal exposure to VOX or VLZ induced an increased state of depressive- and anxiety-like behaviors in both male and female offspring. Additionally, neurotransmitter (serotonin, dopamine, and nor-epinephrine) levels in the prefrontal cortex region of the brain were substantially reduced in exposed offspring. No sex specific neurobehavioral and neurochemical implications were observed in the present study. Our findings suggest that prenatal exposure to VOX and VLZ disrupts neurochemical balance in the fetal brain, leading to long-lasting neurobehavioral impairments in offspring of both sexes.
PubMed: 38945303
DOI: 10.1016/j.bbr.2024.115128 -
Behavioural Brain Research Jun 2024Controlled nigrostriatal dopamine release supports effective limb use during locomotion coordination that becomes compromised after this pathway deteriorates in...
Controlled nigrostriatal dopamine release supports effective limb use during locomotion coordination that becomes compromised after this pathway deteriorates in Parkinson's Disease (PD). How dopamine release relates to active ongoing behavior control remains unknown. Restoring proper release strategy appears important to successful PD treatment with transplanted dopamine-producing stem cells. This is suggested by apparently distinct behavioral support from tonic or phasic release and corresponding requirements of requisite afferent control exhibited by intact nigrostriatal neurons. Our laboratory previously demonstrated that transplanted dopaminergic cells can elicit skilled movement recovery known to depend on phasic dopamine release. However, efforts to measure this movement-related dopamine release yielded seemingly paradoxical, incongruent results. In response, here we explored whether those previous observations derived from rapid reuptake transport into either transplanted cells or residual, lesion-surviving terminals. We confirmed this using minimal reuptake blockade during intrastriatal microdialysis. After unilateral dopamine depletion, rats received transplants and were subjected to our swimming protocol. Among dopamine-depleted and transplanted rats, treatment supported restoration of limb movement symmetry. Interestingly, subsequent reuptake-restricted microdialysis confirmed distinct swimming-induced dopamine increases clearly occurred among these lesioned/transplanted subjects. Thus, phasic firing control appears to contribute to transplant-derived recovery in Parkinsonian animals.
PubMed: 38945302
DOI: 10.1016/j.bbr.2024.115121 -
European Journal of Pharmacology Jun 2024Bitter taste receptors (TAS2Rs) and their downstream signaling pathways are expressed not only in the oral tissues but also in extraoral tissues. Emerging data has...
AIMS
Bitter taste receptors (TAS2Rs) and their downstream signaling pathways are expressed not only in the oral tissues but also in extraoral tissues. Emerging data has demonstrated the beneficial effect of ghrelin in neurodegenerative diseases. Gaining more insight into the interaction between TAS2Rs and gut hormones may expand their therapeutic applications. Herein, we aimed to assess the possible effect of TAS2R activation by denatonium benzoate (DB) in modulating functional and neurobiochemical alterations in a model of Parkinson's disease (PD).
MAIN METHODS
PD model was induced by daily injection of rotenone (2 mg/kg). Rats received DB (5 mg/kg), atenolol (10 mg/kg), or both concomitantly with rotenone, daily for 28 days. Evaluation of the motor abnormalities and histological examination of brain tissues were conducted. In addition, striatal dopamine contents, immunohistochemical expression of tyrosine hydroxylase, plasma ghrelin level, and biochemical analysis of markers of inflammation and oxidative stress were assessed.
KEY FINDINGS
Treatment with DB increased serum levels of ghrelin and striatal dopamine contents with consequent amelioration of oxidative stress and attenuation of inflammatory cytokines. Moreover, DB treatment significantly ameliorated motor disturbance and histological abnormalities compared to untreated rats. Atenolol inhibited ghrelin release and abolished the positive effect of DB suggesting the involvement of ghrelin on such effects.
SIGNIFICANCE
The current study suggests that TAS2Rs agonists are promising candidates for ameliorating rotenone-induced PD pathology in rats, an action that could be linked to the enhancement of ghrelin release with consequent antioxidant and anti-inflammatory activities.
PubMed: 38945288
DOI: 10.1016/j.ejphar.2024.176802