Biology subjects

Grant, K. A.

Publications and source records attributed to Grant, K. A..

16 recordsLinked to original sources

bioRxiv2026

The role of serotonin in the orbitofrontal cortex in alcohol consumption

Binge alcohol drinking is a public health concern that can dramatically increase the risk for development of alcohol use disorder (AUD). Continued alcohol drinking in the face of negative consequences is another key feature of AUD. A better understanding of the neural circuitry that regulates these behaviors could provide insight as to novel treatments for AUD. Serotonin is a neurotransmitter that has been implicated in alcohol consumption in both human studies and animal models. The orbitofrontal cortex (OFC) is a brain region that both receives serotonergic input from the dorsal raphe and has been implicated in AUD. However, how volitional alcohol consumption impacts serotonin signaling within the OFC and how this contributes to alcohol related behaviors is unknown. Here, we show that a history of alcohol consumption alters the ability of 5-HT to hyperpolarize OFC pyramidal neurons in mice and monkeys. Consistent with this, a history of binge alcohol consumption decreases the expression of the 5-HT1A but not 5-HT2A receptor in the OFC from mice. Next, we show that deletion of the 5-HT1A receptor from the OFC increased alcohol intake and preference in male, but not female mice. Finally, we found that 5-HT1A receptor deletion led to increased quinine-adulterated alcohol intake, a measure of aversion-resistant drinking, in both male and female mice. Altogether, we identified serotonin signaling in the OFC as key target for modulation of binge and compulsive alcohol consumption.

neuroscience↗

bioRxiv2026

Chronic ethanol self-administration alters dopamine in the caudate nucleus and putamen of rhesus macaques in a sex-dependent manner

Alcohol use disorder (AUD) affects over 28 million people in the U.S and is associated with neurobiological alterations, including in the basal ganglia. Within the basal ganglia, the caudate nucleus (caudate) and putamen are implicated in AUD due to their roles in ethanol reinforcement, with the caudate receiving inputs from cortico-associative areas and the putamen receiving inputs from somatosensory areas, supporting goal-directed and habitual behaviors respectively. These distinct behavioral roles are supported by dopamine signaling, including phasic dopamine, involved in assessing action-outcome associations, and tonic dopamine, which reflects ongoing dopaminergic tone that biases action initiation. Intrastriatal dopamine release is modulated by cholinergic interneurons via nicotinic acetylcholine receptors. Dysregulation of these mechanisms can contribute to the transition from occasional to habitual ethanol drinking. Here, we used in-vitro fast-scan cyclic voltammetry to measure dopamine signaling in male (n=6) and female (n=6) rhesus macaques following six months of ethanol self-administration. In putamen, ethanol increased tonic dopamine in both sexes, with females exhibiting greater release and faster dopamine uptake rates than males. In the caudate, ethanol self-administration enhanced dopamine uptake rates only in males. Phasic dopamine release was enhanced in caudate of both sexes but only putamen in males. nAChR blockade revealed that phasic dopamine release in males, but not females, was dependent on cholinergic modulation. These results demonstrate basal and sex-specific dopamine release and uptake are uniquely altered in rhesus macaque caudate and putamen in conjunction with chronic ethanol drinking.

neuroscience↗

bioRxiv2025

Cross-Species Evidence for Hippocampal CACNA1C as a Therapeutic Target for Alcohol Use Disorder

Context-induced relapse is a major barrier to recovery from alcohol use disorder (AUD). Identifying molecular targets involved in contextual memories associated with alcohol use may serve as novel pharmacotherapies. Our RNAseq profiling study of the hippocampus from rhesus monkeys with chronic alcohol use identified the voltage-gated calcium channel CACNA1C as a promising therapeutic target. However, data regarding CACNA1C expression in AUD and whether inhibition of CACNA1C can attenuate ethanol contextual memories remains limited. We tested the hypothesis that hippocampal CACNA1C expression is increased in human and nonhuman primates (NHPs) with chronic alcohol use. Further, we used a mouse conditioned place preference (CPP) paradigm to test the hypothesis that Nifedipine, a CACNA1C-selective L-type calcium channel antagonist, can attenuate ethanol-induced CPP. CACNA1C mRNA expression was increased in the hippocampus of subjects with AUD (p<0.03). Increased densities of CACNA1C neurons (p<0.01) and glia (p<0.02) were observed in rhesus monkeys with chronic alcohol use. Ethanol-treated mice spent more time in the ethanol-paired chamber compared to the vehicle animals (p<0.04), demonstrating ethanol-induced CPP. This effect was attenuated by Nifedipine, as time spent in the ethanol-paired chamber in the ethanol + Nifedipine group was not significantly different from the vehicle group. These findings demonstrate that chronic alcohol use increases CACNA1C expression in the hippocampus across species and that a CACNA1C subtype-selective antagonist reduces ethanol-induced CPP. Together, these results support CACNA1C as a promising therapeutic target for context-induced relapse in AUD.

neuroscience↗

bioRxiv2025

Altered molecular signaling pathways in the hippocampus of rhesus monkeys following chronic alcohol use

Context-induced relapse is a significant factor limiting recovery from alcohol use disorder (AUD). However, the molecular processes in the hippocampus, a critical region for contextual memory impacted by chronic alcohol use, remain poorly understood. We used a non-human primate model to test the hypothesis that chronic alcohol use impacts hippocampal molecular pathways that may serve as therapeutic targets for context-induced relapse and memory processing issues associated with chronic alcohol use. We conducted RNAseq profiling on hippocampal samples from adult male rhesus monkeys with chronic alcohol use (n=7) and controls (n=5) from the Monkey Alcohol Tissue Research Resource (MATRR). We identified 2,575 differentially expressed genes (DEGs) in subjects with chronic alcohol use, including genes implicated in genome-wide association studies (GWAS) of alcohol dependence, such as GLP2R and GABBR2. Downregulated pathways included chemical synaptic transmission, trans-synaptic signaling, and neuron development, and upregulated pathways involved mitochondrial function. Targeted pathway analysis highlighted significant downregulation of synaptic signaling (e.g., axonal fasciculation) and upregulation of mitochondrial processes (e.g., electron transport). Leading-edge gene analysis revealed several downregulated genes involved in synaptic signaling including GRIN2B, CACNA1C, and NLGN1 as well as upregulated genes such as NDUFS3 and MT-ND1 involved in mitochondrial processes. Drug repurposing analysis identified several targets including epidermal growth factor receptor (EGFR) inhibitors, and L-type calcium channel blockers as potential therapeutic targets. Our results provide critical insights into molecular pathways underlying hippocampal pathology in chronic alcohol use, emphasizing the roles of mitochondrial function, synaptic regulation and calcium channels, and offering potential novel therapeutic targets.

neuroscience↗

bioRxiv2025

Chronic alcohol consumption enhances the differentiation capacity of hematopoietic stem and progenitor cells into osteoclast precursors

Chronic alcohol consumption (CAC) is associated with an enhanced risk of bone fracture, reduced bone density, and osteoporosis. We have previously shown using a rhesus macaque model of voluntary ethanol consumption that CAC induces functional, transcriptomic, and epigenomic changes in hematopoietic stem and progenitor cells (HSPCs) and their resultant monocytes/macrophages, skewing them towards a hyper-inflammatory response. Here, we extended those studies and investigated alterations in osteoclasts, which, in postnatal life, are differentiated from HSPCs and play a critical role in maintaining bone homeostasis. Analysis using spectral flow cytometry revealed a skewing of HSPCs towards granulocyte-monocyte progenitors (GMPs) with the CAC group that was in concordance with an increased number of colony-forming unit-granulocyte/macrophage (CFU-GM). Additionally, HSPCs from animals in the CAC group incubated with M-CSF and RANKL were more likely to differentiate into osteoclasts, as evidenced by increased Tartrate-Resistant Acid Phosphatase (TRAP) staining and bone resorption activity. Moreover, single-cell RNA sequencing of differentiated HSPCs identified three clusters of osteoclast precursors in the CAC group with enhanced gene expression in pathways associated with cellular response to stimuli, membrane trafficking, and vesicle-mediated transport. Collectively, these data show that CAC-derived hematopoietic progenitor cells exhibit a higher capacity to differentiate into osteoclast precursors. These findings provide critical insights for future research on the mechanisms by which CAC disrupts monopoiesis homeostasis and enhances osteoclast precursors, thereby contributing to reduced bone density.

cell biology↗

bioRxiv2025

Phenotypic and Functional Alterations in Peripheral Blood Mononuclear Cell-Derived Microglia in a Primate Model of Chronic Alcohol Consumption

Alcohol-induced dysregulation of microglial activity is associated with neuroinflammation, cognitive decline, heightened risk for neurodegenerative diseases, alcohol dependence, and escalation of alcohol drinking. Given the challenge of longitudinally sampling primary microglia, we optimized an in vitro method to differentiate peripheral blood mononuclear cells (PBMC) from non-human primates (NHP) into microglia-like cells (induced-microglia; iMGL). The iMGLs displayed transcriptional profiles distinct from those of monocyte progenitors and closely resembling those of primary microglia. Notably, morphological features showed that differentiated iMGLs derived from NHPs with chronic alcohol consumption (CAC) possessed a more mature-like microglial morphology. Additionally, dysregulation in key inflammatory and regulatory markers alongside increased baseline phagocytic activity was observed in CAC-derived IMGLs in the resting state. Phenotypic and functional assessments following LPS stimulation indicated the presence of an immune-tolerant phenotype and enrichment of a CD86+ hyper-inflammatory subpopulation in iMGLs derived from ethanol-exposed animals. Collectively, these findings demonstrate that in vitro differentiation of PBMC offers a minimally invasive approach to studying the impact of CAC on microglial function revealing that CAC reshapes both functional and transcriptional profiles of microglia.

neuroscience↗

bioRxiv2024

Chronic alcohol consumption alters sex-dependent BNST neuron function in rhesus macaques

Repeated alcohol drinking contributes to a number of neuropsychiatric diseases, including alcohol use disorder and co-expressed anxiety and mood disorders. Women are more susceptible to the development and expression of these diseases with the same history of alcohol exposure as men, suggesting they may be more sensitive to alcohol-induced plasticity in limbic brain regions controlling alcohol drinking, stress responsivity, and reward processing, among other behaviors. Using a translational model of alcohol drinking in rhesus monkeys, we examined sex differences in the basal function and plasticity of neurons in the bed nucleus of the stria terminalis (BNST), a brain region in the extended amygdala shown to be a hub circuit node dysregulated in individuals with anxiety and alcohol use disorder. We performed slice electrophysiology recordings from BNST neurons in male and female monkeys following daily "open access" (22 hr/day) to 4% ethanol and water for more than one year or control conditions. We found that BNST neurons from control females had reduced overall current density, hyperpolarization-activated depolarizing current (Ih), and inward rectification, as well as higher membrane resistance and greater synaptic glutamatergic release and excitatory drive, than those from control males, suggesting that female BNST neurons are more basally excited than those from males. Chronic alcohol drinking produced a shift in these measures in both sexes, decreasing current density, Ih, and inward rectification and increasing synaptic excitation. In addition, network activity-dependent synaptic inhibition was basally higher in BNST neurons of males than females, and alcohol exposure increased this in both sexes, a putative homeostatic mechanism to counter hyperexcitability. Altogether, these results suggest that the rhesus BNST is more basally excited in females than males and chronic alcohol drinking produces an overall increase in excitability and synaptic excitation. These results shed light on the mechanisms contributing to the female-biased susceptibility to neuropsychiatric diseases including co-expressed anxiety and alcohol use disorder.

neuroscience↗

bioRxiv2024

Synchrony between midbrain gene transcription and dopamine terminal regulation is modulated by chronic alcohol drinking

Alcohol use disorder is marked by disrupted behavioral and emotional states which persist into abstinence. The enduring synaptic alterations that remain despite the absence of alcohol are of interest for interventions to prevent relapse. Here, 28 male rhesus macaques underwent over 20 months of alcohol drinking interspersed with three 30-day forced abstinence periods. After the last abstinence period, we paired direct sub-second dopamine monitoring via ex vivo voltammetry in nucleus accumbens slices with RNA-sequencing of the ventral tegmental area. We found persistent augmentation of dopamine transporter function, kappa opioid receptor sensitivity, and dynorphin release - all inhibitory regulators which act to decrease extracellular dopamine. Surprisingly, though transcript expression was not altered, the relationship between gene expression and functional readouts of these encoded proteins was highly dynamic and altered by drinking history. These results outline the long-lasting synaptic impact of alcohol use and suggest that assessment of transcript-function relationships is critical for the rational design of precision therapeutics.

neuroscience↗

bioRxiv2023

Recurrent activity within microcircuits of macaque dorsolateral prefrontal cortex tracks cognitive flexibility

Human and non-human primate data clearly implicate the dorsolateral prefrontal cortex (dlPFC) as critical for advanced cognitive functions1,2. It is thought that intracortical synaptic architectures within dlPFC are the integral neurobiological substrate that gives rise to these processes, including working memory, inferential reasoning, and decision-making3-7. In the prevailing model, each cortical column makes up one fundamental processing unit composed of dense intrinsic connectivity, conceptualized as the canonical cortical microcircuit3,8. Each cortical microcircuit receives sensory and cognitive information from a variety of sources which are represented by sustained activity within the microcircuit, referred to as persistent or recurrent activity4,9. Via recurrent connections within the microcircuit, activity can propagate for a variable length of time, thereby allowing temporary storage and computations to occur locally before ultimately passing a transformed representation to a downstream output4,5,10. Competing theories regarding how microcircuit activity is coordinated have proven difficult to reconcile in vivo where intercortical and intracortical computations cannot be fully dissociated5,9,11,12. Here, we interrogated the intrinsic features of isolated microcircuit networks using high-density calcium imaging of macaque dlPFC ex vivo. We found that spontaneous activity is intrinsically maintained by microcircuit architecture, persisting at a high rate in the absence of extrinsic connections. Further, using perisulcal stimulation to evoke persistent activity in deep layers, we found that activity propagates through stochastically assembled intracortical networks, creating predictable population-level events from largely non-overlapping ensembles. Microcircuit excitability covaried with individual cognitive performance, thus anchoring heuristic models of abstract cortical functions within quantifiable constraints imposed by the underlying synaptic architecture.

neuroscience↗

bioRxiv2023

Chronic alcohol consumption dysregulates innate immune response to SARS-CoV-2 in the lung

Alcohol consumption is widespread with over half of the individuals over 18 years of age in the U.S. reporting alcohol use in the last 30 days. Moreover, 9 million Americans engaged in binge or chronic heavy drinking (CHD) in 2019. CHD negatively impacts pathogen clearance and tissue repair, including in the respiratory tract, thereby increasing susceptibility to infection. Although, it has been hypothesized that chronic alcohol consumption negatively impacts COVID-19 outcomes; the interplay between chronic alcohol use and SARS-CoV-2 infection outcomes has yet to be elucidated. Therefore, in this study we investigated the impact of chronic alcohol consumption on SARS-CoV-2 anti-viral responses in bronchoalveolar lavage cell samples from humans with alcohol use disorder and rhesus macaques that engaged in chronic drinking. Our data show that in both humans and macaques, the induction of key antiviral cytokines and growth factors was decreased with chronic ethanol consumption. Moreover, in macaques fewer differentially expressed genes mapped to Gene Ontology terms associated with antiviral immunity following 6 month of ethanol consumption while TLR signaling pathways were upregulated. These data are indicative of aberrant inflammation and reduced antiviral responses in the lung with chronic alcohol drinking.

immunology↗

bioRxiv2023

Integrated single cell analysis shows chronic alcohol drinking disrupts monocyte differentiation in the bone marrow niche

Chronic alcohol drinking rewires circulating monocytes and tissue-resident macrophages towards heightened inflammatory states with compromised anti-microbial defenses. As these effects remain consistent in short-lived monocytes after a 1-month abstinence period it is unclear whether these changes are restricted to the periphery or mediated through alterations in the progenitor niche. To test this hypothesis, we profiled monocytes/macrophages and hematopoietic stem cell progenitors (HSCP) of the bone marrow compartment from rhesus macaques after 12 months of ethanol consumption using a combination of functional assays and single cell genomics. Bone marrow-resident monocytes/macrophages from ethanol-consuming animals exhibited heightened inflammation. Differentiation of HSCP in vitro revealed skewing towards monocytes expressing neutrophil-like markers with heightened inflammatory responses to bacterial agonists. Single cell transcriptional analysis of HSCPs showed reduced proliferation but increased inflammatory markers in mature myeloid progenitors. We observed transcriptional signatures associated with increased oxidative and cellular stress as well as oxidative phosphorylation in immature and mature myeloid progenitors. Single cell analysis of the chromatin landscape showed altered drivers of differentiation in monocytes and progenitors. Collectively, these data indicate that chronic ethanol drinking results in remodeling of the transcriptional and epigenetic landscapes of the bone marrow compartment leading to altered functions in the periphery.

immunology↗

bioRxiv2021

Chronic ethanol drinking in non-human primates induces inflammatory cathepsin gene expression in alveolar macrophages accompanied by functional defects

Chronic alcohol drinking is associated with increased susceptibility to viral and bacterial respiratory pathogens. Investigating the effects of alcohol on the lung is challenging in humans because of the complexity of human drinking behavior and the challenge of obtaining samples. In this study, we utilize a rhesus macaque model of voluntary ethanol self-administration to study the effects of alcohol on the lung in a physiologically and genetically relevant model. We report a heightened activation and inflammatory state in alveolar macrophages (AM) obtained from ethanol drinking animals that is accompanied by increased chromatin accessibility in intergenic regions that regulate inflammatory genes and contain binding motifs for transcription factors AP-1, IRF8, and NFKB p-65. In line with these transcriptional and epigenetic changes at basal state, AM from ethanol drinking animals generate elevated inflammatory mediator responses to LPS and respiratory syncytial virus (RSV). Analysis using scRNA-Seq revealed heterogeneity in lung-resident macrophage and monocyte populations, including increased abundance of activated and cathepsin-expressing clusters and accelerated differentiation with ethanol. Finally, functional assays show increased mitochondrial content in AM from ethanol drinking animals, which is associated with observed increased ROS and decreased phagocytosis capacity. This comprehensive epigenomic, transcriptional and functional profiling of lung macrophages after ethanol drinking in macaques provides previously unidentified mechanisms of ethanol induced infection susceptibility in patients with alcohol use disorders.

immunology↗

bioRxiv2021

Exploratory extracellular vesicle-bound miRNA profiling to identify candidate biomarkers of chronic alcohol drinking in non-human primates

BackgroundLong-term alcohol drinking is associated with numerous health complications including susceptibility to infection, cancer, and organ damage. However, due to the complex nature of human drinking behavior, it is challenging to determine whether alcohol use should be considered a risk factor during diagnosis and treatment. We lack reliable biomarkers of alcohol use that could be used to determine drinking behavior prior to signs of overt organ damage. Recently, extracellular vesicle-bound microRNA (EV-miRNA) have been discovered to be consistent biomarkers of conditions including cancer and liver disease. MethodsIn this study, we profiled the plasma EV-miRNA content by miRNA-Seq from 80 non-human primates after 12 months of voluntary ethanol drinking. ResultsWe identified a list of up- and downregulated EV-miRNA candidate biomarkers of both heavy drinking as well as those positively correlated with ethanol dose. We further overexpressed these candidate miRNA in control primary peripheral immune cells to assess potential functional mechanisms of these EV-miRNA. We identified that overexpression of miR-155, miR-154, miR-34c, miR-450a, and miR-204 led to increased inflammatory TNF or IL-6 production in PBMC after stimulation. ConclusionThis exploratory study identified several EV-miRNA that could serve as biomarkers of long-term alcohol drinking as well as provided a mechanism for alcohol-induced peripheral inflammation.

molecular biology↗

bioRxiv2021

Transcriptional, epigenetic, and functional reprogramming of blood monocytes in non-human primates following chronic alcohol drinking

Chronic heavy drinking (CHD) of alcohol is a known risk factor for increased susceptibility to bacterial and viral infection as well as impaired wound healing. Evidence suggests that these defects are mediated by a dysregulated inflammatory response originating from myeloid cells, notably monocytes and macrophages, but the mechanisms remain poorly understood. Our ability to study CHD is impacted by the complexities of human drinking patterns and behavior as well as comorbidities and confounding risk factors for patients with alcohol use disorders. To overcome these challenges, we utilize a translational rhesus macaque model of voluntary ethanol self-administration that closely recapitulates human drinking patterns and chronicity. In this study, we examined the effects of CHD on blood monocytes and alveolar macrophages in control and CHD female macaques after 12 months of daily ethanol consumption. While monocytes from CHD female macaques generated a hyper-inflammatory response to ex vivo LPS stimulation, their response to E.Coli was dampened. In depth scRNA-Seq analysis of purified monocytes revealed significant shifts in classical monocyte subsets with accumulation of cells expressing markers of hypoxia (HIF1A) and inflammation (NFkB signaling pathway) in CHD macaques. The increased presence of monocyte subsets poised to generate a hyperinflammatory response was confirmed by the epigenetic analysis which revealed higher accessibility of promoter regions that regulate genes involved in cytokine signaling pathways. Finally, alveolar macrophages (AM) from the same animals produced higher levels of inflammatory mediators in response to LPS stimulation, but reduced ability to phagocytose bacteria. Collectively, data presented in this manuscript demonstrate that CHD primes monocytes and tissue-resident macrophages towards a more hyper-inflammatory immune response with compromised functional abilities, which could be used in diagnostic purposes or preventative measures for patients with alcohol use disorders.

immunology↗

bioRxiv2019

Cross-species epigenetic regulation of nucleus accumbens KCNN3 transcript variants by excessive ethanol drinking and dependence

The underlying genetic and epigenetic mechanisms driving functional adaptations in neuronal excitability and excessive alcohol intake are poorly understood. Given that small-conductance Ca2+-activated K+ (KCa2 or SK) channels encoded by the KCNN family of genes have emerged from preclinical studies as a crucial target that contributes to heavy drinking and alcohol-induced functional neuroadaptations, we performed a cross-species analysis of KCNN3 methylation, gene expression, and polymorphisms of alcohol-drinking monkeys and alcohol dependent mice. Because of the alternative promoters in KCNN3, we analyzed expression of the different transcript variants that when translated influence surface trafficking and function of KCa2 channels. In heavy drinking rhesus macaques and alcohol dependent C57BL/6J mice, bisulfite sequencing analysis of the nucleus accumbens revealed a differentially methylated region in exon 1A of KCNN3 that overlaps with a predicted promoter sequence. The hypermethylation of KCNN3 in monkey and mouse accumbens paralleled an increase in expression of alternative transcript variants that encode apamin-insensitive and dominant-negative KCa2 channel isoforms. A polymorphic repeat in macaque KCNN3 encoded by exon 1 did not correlate with alcohol drinking. At the protein level, KCa2.3 channel expression in the accumbens was significantly reduced in very heavy drinking monkeys. Together, our cross-species findings on epigenetic dysregulation of KCNN3 by heavy alcohol drinking and dependence represent a complex mechanism that utilizes alternative promoters to impact firing of accumbens neurons. Thus, these results provide support for hypermethylation of KCNN3 by excessive alcohol drinking as a possible key molecular mechanism underlying harmful alcohol intake and alcohol use disorder.

neuroscience↗

bioRxiv2018

Maternal Circulating MicroRNAs Control the Placental Response to Alcohol

Prenatal Alcohol exposure (PAE), like other pregnancy complications, can result in placental insufficiency and fetal growth restriction, though the linking causal mechanisms are unclear. We previously identified 11 gestationally-elevated maternal circulating miRNAs that predicted infant growth deficits following PAE. Here, we investigated whether these HEamiRNAs contribute to the pathology of PAE, by inhibiting trophoblast epithelial-mesenchymal transition (EMT), a pathway critical for placental development. We now report for the first time, that PAE inhibits expression of placental pro-EMT pathway members in both rodents and primates, and that HEamiRNAs collectively, but not individually, mediate placental EMT inhibition. HEamiRNAs collectively, but not individually, also inhibited cell proliferation and the EMT pathway in cultured trophoblasts, while inducing cell stress, and following trophoblast syncytialization, aberrant endocrine maturation. Moreover, a single intra-vascular administration of the pooled murine-expressed HEamiRNAs, to pregnant mice, decreased placental and fetal growth and inhibited expression of pro-EMT transcripts in placenta. Our data suggests that HEamiRNAs collectively interfere with placental development, contributing to the pathology of PAE, and perhaps also, to other causes of fetal growth restriction. SummaryMaternal gestational circulating microRNAs, predictive of adverse infant outcomes including growth deficits, following prenatal alcohol exposure, contribute to placental pathology by impairing the EMT pathway in trophoblasts.

developmental biology↗