Novel Adenosine Analog, N6-(4-Hydroxybenzyl)-Adenosine, Dampens Alcohol Drinking and Seeking Behaviors

A novel monobactam lacking antimicrobial activity, MC-100093, reduces sex-specific ethanol preference and depressive-like behaviors in mice

Several β-lactam derivatives upregulate astrocytic glutamate transporter type 1expression and are known to improve measures in models of mood and alcohol use disorders (AUD) through normalizing glutamatergic states. However, long-term, and high doses of β-lactams may cause adverse side effects for treating mood disorders and AUD. Studies suggest that MC-100093, a novel β-lactam lacking antimicrobial activity, rescues GLT1 expression. Thus, we sought to investigate whether MC-100093 improves affective behaviors and reduces voluntary ethanol drinking. We intraperitoneally administered MC-100093 (50 mg/kg) or vehicle once per day to C57BL/6J male and female mice (8-10 weeks old) over 6 days. We employed the open field test and the elevated plus maze to examine the effect of MC-100093 on anxiety-like behaviors. We assayed MC-100093's effects on depressive-like behaviors using the tail suspension and forced swim tests. Next, utilizing a separate cohort of male and female C57BL6 mice, we assessed the effects MC100093 treatment on voluntary ethanol drinking utilizing the 2-bottle choice continuous access drinking paradigm. After screening and selecting high-drinking mice, we systematically administered MC-100093 (50 mg/kg) or vehicle to the high-drinking mice over 6 days. Overall, we found that MC-100093 treatment resulted in sex-specific pharmacological effects with female mice displaying reduced innate depressive-like behaviors during the tail suspension and force swim testing juxtaposed with male treated mice who displayed no changes in tail suspension and a paradoxical increased depressive-like behavior during the forced swim testing. Additionally, we found that MC100093 treatment reduced female preference for 10% EtOH during the 2-bottle choice continuous access drinking with no effects of MC100093 treatment detected in male mice. Overall, this data suggests sex-specific regulation of innate depressive-like behavior and voluntary EtOH drinking by MC100093 treatment. Western blot analysis of the medial prefrontal cortex and hippocampus revealed no changes in male or female GLT1 protein abundance relative to GAPDH.

N6-substituated adenosine analog J4 attenuates anxiety-like behaviors in mice

RATIONALE

Withdrawal from chronic alcohol exposure produces various physical and mental withdrawal symptoms. Activation of adenosine receptors is known to inhibit withdrawal-induced excitation. However, limited studies investigate how adenosine analogs may prove helpful tools to alleviate alcohol withdrawal-related affective behaviors.

OBJECTIVES

This study aimed to investigate the effects of J4 compared with saline using the mice vapor or voluntary ethanol drinking model on behavioral endpoints representing ethanol-withdrawal negative emotionality commonly observed during abstinence from chronic alcohol use.

METHODS

We subjected C57BL/6 J mice to chronic intermittent ethanol (CIE) exposure schedule to investigate how 72-h withdrawal from alcohol alters affective-like behavior. Next, we determined how treatment with J4, a second-generation adenosine analog, influenced affective behaviors produced by alcohol withdrawal. Finally, we determined how J4 treatment alters voluntary ethanol drinking using the two-bottle-choice drinking paradigm.

RESULTS

Our results show that 72-h withdrawal from chronic intermittent ethanol exposure produces limited affective-like disturbances in male C57BL/6 J mice exposed to 4 cycles ethanol vapor. Most importantly, J4 treatment irrespective of ethanol exposure decreases innate anxiety-like behavior in mice.

CONCLUSIONS

Withdrawal from chronic intermittent ethanol exposure and subsequent behavioral testing 72 h later produces minimal affective-like behavior. J4 treatment did however reduce marble-burying behavior and increased time spent in open arms of the elevated plus maze, suggesting J4 may be useful as a general anxiolytic.

A five-dimensional data collection strategy for multicomponent discovery and characterization in Traditional Chinese Medicine: Gastrodia Rhizoma as a case study

Establishing the identity of bioactive compounds to control the quality of Traditional Chinese Medicines is made more challenging by the complexity of the metabolite matrix, the existence of isomers, and the range of compound concentration and polarity observed between individual samples of the same plant in a multicomponent preparation. In addition, LC-MS analysis has limited capability for the separation and analysis of potentially important trace compounds and isomers, which hinders the comprehensive metabolite characterization of functional foods and Traditional Natural Medicine. To facilitate and improve the chemical composition characterization and enhance metabolite discernment, a comprehensive strategy was developed which integrates ion mobility mass spectrometry (IMS) with offline two-dimensional liquid chromatography based on hydrophilic interaction chromatography (HILIC) and conventional reversed phase (RP) C18 chromatography. Through application of the HILIC × RP offline 2D-LC approach, trace compounds were enriched and separated promoting a more efficient and detailed analysis of the matrix complexity. Comprehensive non-targeted multidimensional data (Rt1D, Rt2D, MS, CCS and MS/MS) and data-independent-acquisition (DIA) mass data of the metabolites in complex food and drug samples were obtained in the IMS-DIA-MS/MS mode on a Waters-SYNAPT G2-Si mass spectrometer with an ESI source. Through the application of high-efficiency neutral loss (NLs) and diagnostic product ions (DPIs) filter strategies, information from DIA mass data permitted the rapid detection and identification of compounds. The identification coverage of metabolites with low-quality MS/MS data was also improved. In the absence of analytical standards, Collision Cross Section (CCS) prediction and matching strategies based on theoretical chemical structures provided a method to distingish isomers. To demonstrate the efficacy of the technique this comprehensive strategy was applied to the compound characterization of Gastrodia Rhizoma (GR). Characterization of 272 compounds was achieved, including 146 unreported compounds. The results affirm that this comprehensive five-dimensional data collection strategy has the capacity to support the in-depth study of the high level of chemical diversity in Traditional Chinese Medicines.

Neural Mechanisms Underlying the Rewarding and Therapeutic Effects of Ketamine as a Treatment for Alcohol Use Disorder

Alcohol use disorder (AUD) is the most prevalent substance use disorder and causes a significant global burden. Relapse rates remain incredibly high after decades of attempting to develop novel treatment options that have failed to produce increased rates of sobriety. Ketamine has emerged as a potential treatment for AUD following its success as a therapeutic agent for depression, demonstrated by several preclinical studies showing that acute administration reduced alcohol intake in rodents. As such, ketamine's therapeutic effects for AUD are now being investigated in clinical trials with the hope of it being efficacious in prolonging sobriety from alcohol in humans (ClinicalTrials.gov, Identifier: NCT01558063). Importantly, ketamine's antidepressant effects only last for about 1-week and because AUD is a lifelong disorder, repeated treatment regimens would be necessary to maintain sobriety. This raises questions regarding its safety for AUD treatment since ketamine itself has the potential for addiction. Therefore, this review aims to summarize the neuroadaptations related to alcohol's addictive properties as well as ketamine's therapeutic and addictive properties. To do this, the focus will be on reward-related brain regions such as the nucleus accumbens (NAc), dorsal striatum, prefrontal cortex (PFC), hippocampus, and ventral tegmental area (VTA) to understand how acute vs. chronic exposure will alter reward signaling over time. Additionally, evidence from these studies will be summarized in both male and female subjects. Accordingly, this review aims to address the safety of repeated ketamine infusions for the treatment of AUD. Although more work about the safety of ketamine to treat AUD is warranted, we hope this review sheds light on some answers about the safety of repeated ketamine infusions.

Chronic Alcohol Exposure Induces Aberrant Mitochondrial Morphology and Inhibits Respiratory Capacity in the Medial Prefrontal Cortex of Mice

Alcohol use disorder (AUD) is characterized as a chronic, relapsing disease with a pattern of excessive drinking despite negative consequences to an individual’s life. Severe chronic alcohol use impairs the function of the medial prefrontal cortex (mPFC), which contributes to alcohol-induced cognitive and executive dysfunction. The mPFC contains more mitochondria compared to other cortical areas, which suggests mitochondrial damage may occur in AUD and trigger subsequent behavior change. Here, we identified morphological and functional changes in mitochondria in the mPFC in C57BL6/J mice after 8 h of withdrawal from chronic intermittent alcohol (CIA) exposure. Three-dimensional serial block-face scanning electron microscopy (SBFSEM) reconstruction revealed that CIA exposure elongated mPFC mitochondria and formed mitochondria-on-a-string (MOAS). Furthermore, alcohol significantly affected mitochondrial bioenergetics, including oxidative phosphorylation and electron transport, with inhibited aerobic respiration in mPFC mitochondria after CIA exposure. We also found decreased expression of fusion (mitofusin 2, Mfn2) and increased fission (mitochondrial fission 1 protein, Fis1) proteins in the mPFC of alcohol-treated mice. In sum, our study suggests that CIA exposure impairs mitochondrial dynamics and function in the mPFC.

Astrocytic equilibrative nucleoside transporter type 1 upregulations in the dorsomedial and dorsolateral striatum distinctly coordinate goal-directed and habitual ethanol-seeking behaviours in mice

Two distinct dorsal striatum regions, dorsomedial striatum (DMS) and dorsolateral striatum (DLS), are attributed to conditioned goal-directed and habitual reward-seeking behaviours, respectively. Previously, our study shows that the ethanol-sensitive adenosine transporter, equilibrative nucleoside transporter 1 (ENT1), regulates ethanol-drinking behaviours. Although ENT1 is expressed in both neurons and astrocytes, astrocytic ENT1 is thought to regulate adenosine levels in response to ethanol. However, the role of DMS and DLS astrocytic ENT1 in goal-directed and habitual ethanol-seeking is not well known. Here, we identified whether the upregulation of astrocytic ENT1 in the DMS and DLS differentially regulates operant seeking behaviours towards the 10% sucrose (10S); 10% ethanol and 10% sucrose (10E10S); and 10% ethanol (10E) in mice. Using 4 days of random interval (RI), mice exhibited habitual seeking for 10S, but goal-directed seeking towards 10E10S. Using the same mice conditioned with 10E10S, we examined 10E-seeking behaviour on a fixed ratio (FR) for 6 days and RI for 8 days. On the other hand, during FR and the first 4 days of RI schedules, mice showed goal-directed seeking for 10E, whereas mice exhibited habitual seeking for 10E during the last 4 days of RI schedule. Interestingly, DMS astrocytic ENT1 upregulation promotes shift from habitual to goal-directed reward-seeking behaviours. By contrast, DLS astrocytic ENT1 upregulation showed no effects on behavioural shift. Taken together, our findings demonstrate that DMS astrocytic ENT1 contributes to reward-seeking behaviours.