Emerging mechanistic insights of selective autophagy in hepatic diseases.

Macroautophagy (hereafter referred to as autophagy), a highly conserved metabolic process, regulates cellular homeostasis by degrading dysfunctional cytosolic constituents and invading pathogens via the lysosomal system. In addition, autophagy selectively recycles specific organelles such as damaged mitochondria (via mitophagy), and lipid droplets (LDs; via lipophagy) or eliminates specialized intracellular pathogenic microorganisms such as hepatitis B virus (HBV) and coronaviruses (via virophagy). Selective autophagy, particularly mitophagy, plays a key role in the preservation of healthy liver physiology, and its dysfunction is connected to the pathogenesis of a wide variety of liver diseases. For example, lipophagy has emerged as a defensive mechanism against chronic liver diseases. There is a prominent role for mitophagy and lipophagy in hepatic pathologies including non-alcoholic fatty liver disease (NAFLD), hepatocellular carcinoma (HCC), and drug-induced liver injury. Moreover, these selective autophagy pathways including virophagy are being investigated in the context of viral hepatitis and, more recently, the coronavirus disease 2019 (COVID-19)-associated hepatic pathologies. The interplay between diverse types of selective autophagy and its impact on liver diseases is briefly addressed. Thus, modulating selective autophagy (e.g., mitophagy) would seem to be effective in improving liver diseases. Considering the prominence of selective autophagy in liver physiology, this review summarizes the current understanding of the molecular mechanisms and functions of selective autophagy (mainly mitophagy and lipophagy) in liver physiology and pathophysiology. This may help in finding therapeutic interventions targeting hepatic diseases via manipulation of selective autophagy.

Sex differences in GABAA receptor subunit transcript expression are mediated by genotype in subjects with alcohol-related cirrhosis of the liver.

Male and female human subjects show contrasting propensities to misuse drugs of addiction, including alcohol. These differences lead to different psychological and neurological consequences, such as the likelihood of developing dependence. The pattern and extent of brain damage in alcohol-use disorder cases also varies with comorbid disease. To explore mechanisms that might underlie these outcomes, we used autopsy tissue to determine mRNA transcript expression in relation to genotype for two GABAA receptor subunit genes. We used quantitative Real-Time PCR to measure GABRA6 and GABRA2 mRNA concentrations in dorsolateral prefrontal and primary motor cortices of alcohol-use disorder subjects and controls of both sexes with and without liver disease who had been genotyped for these GABAA receptor subunit genes. Cirrhotic alcohol-use disorder cases had significantly higher expression of GABRA6 and GABRA2 transcripts than either controls or non-cirrhotic alcohol-use disorder cases. Differences were observed between sexes, genotypes and brain regions. We show that sex differences in subjects with GABRA6 and GABRA2 variants may contribute to differences in susceptibility to alcohol-use disorder and alcohol-induced cirrhosis.

Volume of hippocampal subfields in patients with alcohol dependence.

Alcohol-induced hippocampal atrophy has been well documented in many studies and is known to affect various subfields. Given the functional heterogeneity of these subfields, we investigated the precise effects of alcohol-induced damage in these areas. Twenty-six male patients with alcohol dependence (alcohol group) and twenty-six age-matched male healthy social drinkers were recruited from a mental health hospital and the community respectively, with the aim of comparing the hippocampal subfields between groups. Each participant underwent a 3T MRI scan. Hippocampal subfield volumes were estimated using an automated procedure and drinking history recorded using Lifetime Drinking History, Alcohol Use Disorder Identification Test, and the Brief Michigan Alcoholism Screening Test. The alcohol group showed a lower total hippocampus volume, specifically in the left presubiculum, fimbria, and bilateral subiculum. Regression analysis assessing the influence of age and group showed that group was a more significant factor than age in most subfields. Our findings suggest that alcohol dependence alters hippocampal subfield volumes. Further longitudinal studies on the interaction of structural and neurocognitive changes would improve our understanding of brain structural changes resulting from long-term alcohol consumption.

Dependent heroin use and associated risky behaviour: the role of rash impulsiveness and reward sensitivity.

Impulsive temperament has long been considered as a risk factor for substance use disorders (SUD). Considering the heterogeneity of impulsivity, a biologically-based 2-factor model incorporating reward sensitivity and rash impulsiveness facets, has been proposed. Here we report how these two facets of impulsiveness could be associated with different aspects of dependent heroin use and associated risky behaviour. Two hundred and ninety three dependent heroin users and 232 non-users were assessed on reward sensitivity, rash impulsivity, and the related trait of punishment sensitivity. After adjusting for multiple comparisons, heroin users were found to be more rash-impulsive and reward-sensitive than non-users (p<0.001). Within users, rash impulsivity was associated with high risk behaviour including escalating heroin consumption, injecting heroin use, hazardous drinking, low treatment-seeking and risky sexual behaviour. Reward sensitivity was uniquely associated with early onset of drug use. While greater impulsivity is a common trait in drug users compared with non-users, the use of a 2-factor model of impulsivity provides additional information regarding specific aspects of drug initiation and maintenance that can be targeted in the prevention and treatment of heroin dependence.

Pain response in heroin users: personality, abstinence, and modulation by benzodiazepines.

We compared cold-pain responses among male current opioid users with and without concurrent benzodiazepine use, long-term ex-users, and healthy controls. Forty-eight current opioid users (14 concurrently using benzodiazepines), 34 ex-users (abstinent for ≥1 y) and 63 controls received cold-pressor tests. Pain threshold (first reporting pain) and pain tolerance (total immersion time) were recorded. Pain thresholds were similar in ex-users and current users; pain tolerance was similar in ex-users and controls. Net pain tolerance (endurance) in ex-users was intermediate between the other two groups. Current users showed higher pain threshold and shorter pain tolerance than controls (p<0.05). Current users not co-using benzodiazepines showed the lowest pain tolerance and net pain tolerance, and differed significantly from controls, ex-users, and current users co-using benzodiazepines (p<0.05). Neuroticism was higher in current users than in the other two groups (p<0.001), extraversion marginally lower (p<0.05); net pain tolerance differences remained significant after controlling for these. Benzodiazepine use modulates pain tolerance in opioid users. Pain responses altered by opioid use may partially recover with abstinence.

Patterns of substance use in male incarcerated drug users in Sri Lanka.

INTRODUCTION AND AIMS: The number of illicit drug users incarcerated in Sri Lanka has been growing over the last decade. This paper presents drug-use characteristics and risk-taking behaviours among a group of male incarcerated drug users. DESIGN AND METHODS: An interviewer-administered structured questionnaire was completed by 278 drug users in three prisons in Sri Lanka. RESULTS: The majority (81.3%) of interviewees were aged 25-45 years. Most of them had received low levels of education, and experienced childhood delinquency and a deprived upbringing. Drug use was largely initiated during early adolescence, then continued to chronicity and the development of drug dependence. There was a high incidence (25-35%) of family history of drug abuse. Heroin (98%) and cannabis (54%) were the main drugs of abuse in the past 30 days. Polydrug use was common (75% in the past 12 months). Tobacco and alcohol use were widespread. The prevalence of intravenous drug use was higher than officially reported (15.8% vs. 1%). There was a high prevalence (53%) of risk-taking sexual behaviour. DISCUSSION AND CONCLUSION: The pattern of drug use was similar to those reported in nearby countries. However, the increasing prevalence of injecting drug use and risk-taking sexual behaviour is a concern. There is an urgent need to develop effective treatment strategies and to prevent the spread of HIV and hepatitis in Sri Lanka.

Regional expression of dopamine D1 and D2 receptor proteins in the cerebral cortex of asphyxic newborn infants.

Dopamine D(1) and D(2) receptor protein expression was examined by Western blotting in newborn infants dying from cerebral asphyxia between 31 and 42 weeks' gestation, and matched controls. Frontal, occipital, temporal, and motor cortex tissue samples were obtained at autopsy (median postmortem interval 35 hours) and frozen for storage at -80 degrees C. A total of 2 immunoreactive bands were detected with each primary antibody in infant brain, whereas a single band was present in adult human and rat tissue. Immunoreactivity varied between cortical areas for both receptors, but their regional patterns differed significantly. D(1) protein levels were higher in motor and temporal cortex than in frontal or occipital cortex. D(2) protein showed graded expression frontal > motor > occipital > temporal cortex. Asphyxia cases showed lower expression of the upper D(2) immunoreactive band, but no difference in regional pattern. Lower D(2) receptor expression may attenuate stress responses and underlie increased vulnerability to hypoxia at birth.

Dopamine receptor D4 gene -521C/T polymorphism is associated with opioid dependence through cold-pain responses.

Heroin users exhibit abnormal pain sensitivity called opioid-induced hyperalgesia that may weaken their determination to abstain. The dopamine receptor D4 gene (DRD4) is associated with heroin dependence; one of its polymorphisms is a C/T variation 521 bp upstream to the gene (-521C/T). We investigated whether this polymorphism was related to opioid dependence through modulation of cold-pain responses. We recruited 84 heroin-dependent Chinese male subjects and 168 healthy male Chinese controls. Genotyping was performed by PCR-RFLP. A significantly higher T allele frequency was observed in the heroin group (P= 0.041). Of the cohort recruited, 43 current heroin users and 66 controls were further subjected to a cold-pressor test (CPT) to determine their pain threshold and tolerance. TT controls demonstrated a significantly lower pain threshold than did their CC/CT counterparts (P= 0.022) and TT opioid users (P= 0.006). Moreover, CC/CT controls had a significantly higher pain tolerance than TT controls (P= 0.042) and CC/CT opioid users (P= 0.010). The data suggest that DRD4-521C/T plays an important role in opioid dependence through modulating cold-pain responses. TT individuals might have a higher tendency to use opioids because they experience pain less strongly after chronic opioid use.

Impulsivity in Hong Kong-Chinese club-drug users.

To investigate the relationship between personality, club-drug use and high-risk drug-related behaviour, 360 club-drug users and 303 non-drug users in Hong Kong were assessed on measures of two impulsivity dimensions, reward drive and rash impulsivity, and a related trait of punishment sensitivity. The most frequently used drugs were ketamine, ecstasy, and cannabis, with the majority of participants using two or more drugs on any one occasion. Club-drug users were more rash-impulsive and reward-driven, and less punishment-sensitive than non-drug users (p<0.001). Rash impulsivity, but not reward drive or punishment sensitivity, was significantly (p<0.001) associated with risky drug-related behaviour. There was no association between any personality traits and preferred drug. These findings suggest that, while those who use club drugs are generally more impulsive and less punishment-sensitive, some discrete facets of impulsivity are associated with differing patterns of drug-use behaviour.

Association analysis of GABA receptor subunit genes on 5q33 with heroin dependence in a Chinese male population.

GABAA receptor subunit genes clustered on 5q33 play a role in the development of alcoholism and methamphetamine use disorder without psychosis. The present study explored the possible contribution of the same subunit genes to the development of heroin dependence. Single nucleotide polymorphisms (SNPs) of the GABAA receptor subunits GABRB2, GABRA6, GABRA1, and GABRG2 were examined in 178 male Han Chinese heroin-dependent and 170 male control subjects. A significant difference in allele frequency for the SNP rs211014 in the GABAAgamma2 receptor subunit gene between cases and controls was identified (P = 0.015). A possible mechanism for the involvement of the GABA receptor subunit genes on 5q33 in the development of heroin dependence is discussed.

Development of a postnatal 3-day-old rat model of mild hypoxic-ischemic brain injury.

Improvements in both obstetric and paediatric care have been responsible for a continuing reduction in mortality in extremely premature infants. However, higher survival rates have been at the expense of more long-term neurological damage. Various animal models have been developed to study the effect of hypoxic-ischemic insults on the brain. However, established models like the postnatal day 7 rat model represent damage found in term infants rather than in preterm infants of 24-28 weeks' gestation, and produce a severe form of injury resulting in high mortality rates. In this study we developed a reliable model of minor hypoxic-ischemic brain injury in postnatal day 3 rats. At this maturity, the pattern of damage represents that expected in a preterm infant suffering a non-lethal perinatal insult. We found that minor changes in duration of insult and both temperature and humidity produced wide fluctuations in the degree of injury observed. By maintaining strict control over experimental conditions including duration of insult, temperature and humidity, we produced a reliable model of minor injury primarily affecting all five areas of the cerebral cortex, and also the thalamus (area 7) and basal ganglia (area 8). Differences were significant compared to normal controls and sham-operated animals (p<0.05). These areas represent the primary motor, insular, visual and temporal cortices. The overall mortality rate in this study was 12.3%.

A Selective Regional Response of Cultured Astrocytes to Methamphetaminea.

Methamphetamine (METH) has long-lasting neurotoxic effects on the dopamine and forebrain serotonin systems. It was reported that METH would induce the release of glutamate within the striatum and that it also caused astrogliosis. The mechanisms of this release and subsequent neurotoxicity are not well defined. The aim of this study was to examine the response of cultured astrocytes after METH-induced injury. Astrocytes were cultured from neonatal C57B1/6 mice brains. Cells were obtained from the mesencephalon, striatum and cortex in order to examine any regional differences. Cells were treated with 4 mM METH for 4, 8, 12, 24 and 48 hr. Lactate dehydrogenase (LDH) levels were used as a measure of cell viability. At various time points, Western blot analyses were performed to study the change in GFAP and vimentin (markers for astrogliosis) levels. Change in glutamine synthase (GS), the enzyme that catalyzes the synthesis of glutamine from glutamate and ammonia in astrocytes, was also examined. The results showed that METH caused marked astrogliosis in striatal and mesencephalic astrocytes. Cells were transformed from protoplasmic (inactive) to fibrous (reactive) form after 48 hr treatment. There were also large amounts of vacuoles present in the cytoplasm of these cells. LDH results showed that there was only slight increase in enzyme levels after 48 hr treatment suggesting that the astrogliosis observed was not due to the decrease in cell viability. The amount of GS were depleted more rapidly in striatal astrocytes (50% of control by 8 hr treatment) followed by mesencephalic astrocytes (reaching 10% of control by 48 hr treatment). Cortical astrocytes showed only a 48% depletion by 48 hr treatment, indicating that they are more resistant to METH-induced toxicity. The rapid depletion of GS obtained in striatal and mesencephalic astrocytes suggested that astrocytes of the dopaminergic system are more sensitive to METH-induced injury. This may be due to the direct effects of METH-induced oxidative stress on the mitochondria of these cells resulting in GS depletion and astrogliosis.