Y and mitochondrial chromosomes in the heterogeneous stock rat population.

Genome-wide association studies typically evaluate the autosomes and sometimes the X Chromosome, but seldom consider the Y or mitochondrial (MT) Chromosomes. We genotyped the Y and MT Chromosomes in heterogeneous stock (HS) rats (Rattus norvegicus), an outbred population created from 8 inbred strains. We identified 8 distinct Y and 4 distinct MT Chromosomes among the 8 founders.

Acute nicotine activates orectic and inhibits anorectic brain regions in rats exposed to chronic nicotine.

Nicotine use produces psychoactive effects, and chronic use is associated with physiological and psychological symptoms of addiction. However, chronic nicotine use is known to decrease food intake and body weight gain, suggesting that nicotine also affects central metabolic and appetite regulation. We recently showed that acute nicotine self-administration in nicotine-dependent animals produces a short-term increase in food intake, contrary to its long-term decrease of feeding behavior.

Acute nicotine intake increases feeding behavior through decreasing glucagon signaling in dependent male and female rats.

Chronic use of nicotine is known to dysregulate metabolic signaling through altering circulating levels of feeding-related hormones, contributing to the onset of disorders like type 2 diabetes. However, little is known about the acute effects of nicotine on hormonal signaling. We previously identified an acute increase in food intake following acute nicotine, and we sought to determine whether this behavior was due to a change in hormone levels.

Single-nucleus genomics in outbred rats with divergent cocaine addiction-like behaviors reveals changes in amygdala GABAergic inhibition.

The amygdala processes positive and negative valence and contributes to addiction, but the cell-type-specific gene regulatory programs involved are unknown. We generated an atlas of single-nucleus gene expression and chromatin accessibility in the amygdala of outbred rats with high and low cocaine addiction-like behaviors following prolonged abstinence. Differentially expressed genes between the high and low groups were enriched for energy metabolism across cell types.

Chronic administration of a norepinephrine antagonist prevents and partially reverses escalation of cocaine self-administration.

Anxiety is a critical component of the development and maintenance of drug addiction; however, anti-anxiety medications such as benzodiazepines and beta-blockers (β-adrenergic receptor antagonists) are not used for the treatment of substance use disorder, except for the management of acute withdrawal syndrome. Preclinical studies have shown that beta-blockers may reduce stress-induced relapse; however, the effect of beta blockers on the escalation and maintenance of drug intake has not been tested. To address this issue, we chronically administered the β-adrenergic receptor antagonist propranolol during the escalation or maintenance of cocaine intake in a model of extended access (6 h) to cocaine self-administration (0.

Hyperconnectivity of Two Separate Long-Range Cholinergic Systems Contributes to the Reorganization of the Brain Functional Connectivity during Nicotine Withdrawal in Male Mice.

Chronic nicotine results in dependence with withdrawal symptoms on discontinuation of use, through desensitization of nicotinic acetylcholine receptors and altered cholinergic neurotransmission. Nicotine withdrawal is associated with increased whole-brain functional connectivity and decreased network modularity; however, the role of cholinergic neurons in those changes is unknown. To identify the contribution of nicotinic receptors and cholinergic regions to changes in the functional network, we analyzed the contribution of the main cholinergic regions to brain-wide activation of the immediate early-gene Fos during withdrawal in male mice and correlated these changes with the expression of nicotinic receptor mRNA throughout the brain.

Abstinence from Escalation of Cocaine Intake Changes the microRNA Landscape in the Cortico-Accumbal Pathway.

Cocaine administration alters the microRNA (miRNA) landscape in the cortico-accumbal pathway. These changes in miRNA can play a major role in the posttranscriptional regulation of gene expression during withdrawal. This study aimed to investigate the changes in microRNA expression in the cortico-accumbal pathway during acute withdrawal and protracted abstinence following escalated cocaine intake.

Hyperconnectivity of two separate long-range cholinergic systems contributes to the reorganization of the brain functional connectivity during nicotine withdrawal in male mice.

Unlabelled: Chronic nicotine results in dependence with withdrawal symptoms upon discontinuation of use, through desensitization of nicotinic acetylcholine receptors and altered cholinergic neurotransmission. Nicotine withdrawal is associated with increased whole-brain functional connectivity and decreased network modularity, however, the role of cholinergic neurons in those changes is unknown. To identify the contribution of nicotinic receptors and cholinergic regions to changes in the functional network, we analyzed the contribution of the main cholinergic regions to brain-wide activation of the immediate early-gene FOS during withdrawal in male mice and correlated these changes with the expression of nicotinic receptor mRNA throughout the brain.

Glucocorticoid Receptor-Regulated Enhancers Play a Central Role in the Gene Regulatory Networks Underlying Drug Addiction.

Substance abuse and addiction represent a significant public health problem that impacts multiple dimensions of society, including healthcare, the economy, and the workforce. In 2021, over 100,000 drug overdose deaths were reported in the US, with an alarming increase in fatalities related to opioids and psychostimulants. Understanding the fundamental gene regulatory mechanisms underlying addiction and related behaviors could facilitate more effective treatments.

Leptin Protects Against the Development and Expression of Cocaine Addiction-Like Behavior in Heterogeneous Stock Rats.

Cocaine affects food intake, metabolism and bodyweight. It has been hypothesized that feeding hormones like leptin play a role in this process. Preclinical studies have shown a mutually inhibitory relationship between leptin and cocaine, with leptin also decreasing the rewarding effects of cocaine intake.

Cannabidiol reduces withdrawal symptoms in nicotine-dependent rats.

Rationale: Cannabidiol (CBD) reduces craving in animal models of alcohol and cocaine use and is known to modulate nicotinic receptor function, suggesting that it may alleviate symptoms of nicotine withdrawal. However, preclinical evaluation of its efficacy is still lacking.

Objectives: The goal of this study was to test the preclinical efficacy of a chronic CBD treatment in reducing nicotine dependence using measures of withdrawal symptoms including somatic signs, hyperalgesia, and weight gain during acute and protracted abstinence.

The Cocaine and Oxycodone Biobanks, Two Repositories from Genetically Diverse and Behaviorally Characterized Rats for the Study of Addiction.

The rat oxycodone and cocaine biobanks contain samples that vary by genotypes (by using genetically diverse genotyped HS rats), phenotypes (by measuring addiction-like behaviors in an advanced SA model), timepoints (samples are collected longitudinally before, during, and after SA, and terminally at three different timepoints in the addiction cycle: intoxication, withdrawal, and abstinence or without exposure to drugs through age-matched naive rats), samples collected (organs, cells, biofluids, feces), preservation (paraformaldehyde-fixed, snap-frozen, or cryopreserved) and application (proteomics, transcriptomics, microbiomics, metabolomics, epigenetics, anatomy, circuitry analysis, biomarker discovery, etc.Substance use disorders (SUDs) are pervasive in our society and have substantial personal and socioeconomical costs. A critical hurdle in identifying biomarkers and novel targets for medication development is the lack of resources for obtaining biological samples with a detailed behavioral characterization of SUD.

Validation of a nicotine vapor self-administration model in rats with relevance to electronic cigarette use.

The debate about electronic cigarettes is dividing healthcare professionals, policymakers, manufacturers, and communities. A key limitation in our understanding of the cause and consequences of vaping is the lack of animal models of nicotine vapor self-administration. Here, we developed a novel model of voluntary electronic cigarette use in rats using operant behavior.

Nociceptin attenuates the escalation of oxycodone self-administration by normalizing CeA-GABA transmission in highly addicted rats.

Approximately 25% of patients who are prescribed opioids for chronic pain misuse them, and 5 to 10% develop an opioid use disorder. Although the neurobiological target of opioids is well known, the molecular mechanisms that are responsible for the development of addiction-like behaviors in some but not all individuals are poorly known. To address this issue, we used a unique outbred rat population (heterogeneous stock) that better models the behavioral and genetic diversity that is found in humans.

Systemic Administration of the Cyclin-Dependent Kinase Inhibitor (S)-CR8 Selectively Reduces Escalated Ethanol Intake in Dependent Rats.

Background: Chronic exposure to ethanol (EtOH) and other drugs of abuse can alter the expression and activity of cyclin-dependent kinase 5 (CDK5) and its cofactor p35, but the functional implication of CDK5 signaling in the regulation of EtOH-related behaviors remains unknown. In the present study, we sought to determine whether CDK5 activity plays a role in the escalation of EtOH self-administration triggered by dependence.

Methods: We tested the effect of systemically administered (S)-CR8, a nonselective CDK inhibitor, on operant responding for EtOH or saccharin, a highly palatable reinforcer, in adult male Wistar rats.

Tsix-Mecp2 female mouse model for Rett syndrome reveals that low-level MECP2 expression extends life and improves neuromotor function.

Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by a mutation in the X-linked methyl-CpG-binding protein 2 (MECP2). There is currently no disease-specific treatment, but MECP2 restoration through reactivation of the inactive X (Xi) has been of considerable interest. Progress toward an Xi-reactivation therapy has been hampered by a lack of suitable female mouse models.

A Thiolactone Strategy for Straightforward Synthesis of Disulfide-Linked Side-Chain-to-Tail Cyclic Peptides Featuring an N-Terminal Modification Handle.

The development of straightforward and versatile peptide cyclisation methods is highly desired to meet the demand for more stable peptide-based drugs. Herein, a new method for the synthesis of side-chain-to-tail cyclic peptides with the simultaneous introduction of an N-terminal handle, based on the introduction of an N-terminal thiolactone building block, is described. A primary amine liberates a homocysteine analogue from the thiolactone building block, which further enables cyclisation of the peptide through disulfide-bond formation with a C-terminal cysteamine.

A mixed modality approach towards Xi reactivation for Rett syndrome and other X-linked disorders.

The X-chromosome harbors hundreds of disease genes whose associated diseases predominantly affect males. However, a subset, including neurodevelopmental disorders, Rett syndrome (RTT), fragile X syndrome, and CDKL5 syndrome, also affects females. These disorders lack disease-specific treatment.

A high-throughput small molecule screen identifies synergism between DNA methylation and Aurora kinase pathways for X reactivation.

X-chromosome inactivation is a mechanism of dosage compensation in which one of the two X chromosomes in female mammals is transcriptionally silenced. Once established, silencing of the inactive X (Xi) is robust and difficult to reverse pharmacologically. However, the Xi is a reservoir of >1,000 functional genes that could be potentially tapped to treat X-linked disease.

Triplex crosslinking through furan oxidation requires perturbation of the structured triple-helix.

Short oligonucleotides can selectively recognize duplexes by binding in the major groove thereby forming triplexes. Based on the success of our recently developed strategy for furan-based crosslinking in DNA duplexes, we here investigated for the first time the use of the furan-oxidation crosslink methodology for the covalent locking of triplex structures by an interstrand crosslink. It was shown that in a triplex context, although crosslinking yields are surprisingly low (to nonexistent) when targeting fully complementary duplexes, selective crosslinking can be achieved towards mismatched duplex sites at the interface of triplex to duplex structures.

DNA interstrand cross-link formation using furan as a masked reactive aldehyde.

This unit describes a method for interstrand cross-linking between a furan-modified oligonucleotide and its unmodified complement. The synthesis of two furan-modified phosphoramidites, selected based on high cross-linking yield versus improved cross-linking selectivity, is described. The methods allow gram-scale synthesis starting from stable and readily available furan derivatives.

Toxicity inspired cross-linking for probing DNA-peptide interactions.

A cross-linking methodology for the study of DNA-protein interactions is described. The method is inspired by the metabolic activation of furans causing toxic DNA damage, including DNA-protein cross-links (DPC). The furan moiety, representing a latent functionality, is easily incorporated into oligonucleotides, and can be activated on demand to release a reactive aldehyde.