Alcohol - Articles in Press

Alterations of motor performance and brain cortex mitochondrial function during ethanol hangover - Corrected Proof

2012-05-18

Abstract: Ethanol has been known to affect various behavioral parameters in experimental animals, even several hours after ethanol (EtOH) is absent from blood circulation, in the period known as hangover. The aim of this study was to assess the effects of acute ethanol hangover on motor performance in association with the brain cortex energetic metabolism. Evaluation of motor performance and brain cortex mitochondrial function during alcohol hangover was performed in mice 6 hours after a high ethanol dose (hangover onset). Animals were injected i.p. either with saline (control group) or with ethanol (3.8 g/kg BW) (hangover group). Ethanol hangover group showed a bad motor performance compared with control animals (p < .05). Oxygen uptake in brain cortex mitochondria from hangover animals showed a 34% decrease in the respiratory control rate as compared with the control group. Mitochondrial complex activities were decreased being the complex I–III the less affected by the hangover condition; complex II–III was markedly decreased by ethanol hangover showing 50% less activity than controls. Complex IV was 42% decreased as compared with control animals. Hydrogen peroxide production was 51% increased in brain cortex mitochondria from the hangover group, as compared with the control animals. Quantification of the mitochondrial transmembrane potential indicated that ethanol injected animals presented 17% less ability to maintain the polarized condition as compared with controls. These results indicate that a clear decrease in proton motive force occurs in brain cortex mitochondria during hangover conditions. We can conclude that a decreased motor performance observed in the hangover group of animals could be associated with brain cortex mitochondrial dysfunction and the resulting impairment of its energetic metabolism.

Levels of aggressiveness are higher among alcohol-related suicides: Results from a psychological autopsy study - Corrected Proof

Eduardo Chachamovich, Yang Ding, Gustavo Turecki — 2012-05-14

Abstract: Suicide is one of the major causes of deaths worldwide. Several studies have showed that alcohol use disorders (AUD) are associated with suicide ideation, suicide attempts, and suicide completion. The majority of the theoretical conceptualization and the bulk of evidence on suicidal behavior and AUD are based on investigations of nonfatal cases because data on nonfatal suicidal behaviors are more readily available. This study aims to explore demographic, clinical, and behavioral dimensions in a large sample of alcohol-related suicides compared to an age-gender matched sample of non-AUD suicides to identify specific factors associated with AUD suicides. We conducted a psychological autopsy study with 158 pairs of AUD and non-AUD suicides. Findings showed that AUD suicides have lower educational level, more biological children and were more likely to be heavy smokers (OR=3.32). Cases were more likely to have family history of alcohol (OR=1.73) and drug abuse (OR=3.61). Subjects had similar prevalences of depressive disorders, anxiety disorders or psychotic disorders. AUD suicides were more likely to meet criteria for current cocaine abuse/dependence (OR=6.64). With respect to personality disorders, AUD suicides presented higher prevalence of Antisocial Personality Disorder (OR=4.68), and were less likely to meet criteria for Avoidant (OR=0.26) and Obsessive-Compulsive Personality Disorders (OR=0.35). Impulsivity scores were higher in AUD suicides (p=0.18), as well as aggression scores (p<0.001). Results form the conditional logistic regression models showed that cocaine abuse/dependence (OR=4.20) and Antisocial Personality Disorder (OR=6.24) were associated with AUD suicide. After controlling for impulsive-aggressive behaviors, levels of aggression were the only psychopathological feature statistically different between AUD and non-AUD suicides (OR=1.28). In conclusion, higher levels of aggressive behaviors are a specific characteristic of AUD suicides. Apart from substance-related diagnoses, AUD and non-AUD suicides have comparable Axis I psychiatric diagnoses and familial transmission of suicidal behavior.

Episodic heavy drinking, problem drinking and injuries – Results of the WHO/NIAAA collaborative emergency room study in South Korea - Corrected Proof

2012-05-11

Abstract: Alcohol is the 5th leading risk factor to the global disease burden and disability and about half of the global alcohol burden was attributable to injuries. Despite a large body of evidence documenting the associations between alcohol and injuries, data from Asian countries including South Korea are sparse. The aim of this study was to investigate the associations between episodic heavy past-year drinking, problem drinking symptomatic of alcohol dependence and alcohol-related and intentional injuries. Data from 1989 injured patients recruited for the WHO/NIAAA Collaborative Study on Alcohol and Injury in South Korea were analyzed with respect to the prevalence rates and associations between injuries and frequency of past-year episodic heavy drinking and problem drinking. In estimating the odds ratios (ORs) and the associated 95% confidence intervals between alcohol intake and injuries multivariable logistic models were employed to adjust for sociodemographic characteristics and selected drinking variables. All analyses were conducted using the SAS 9.2 software. Findings of this study were consistent with prior studies that the risk of alcohol-related or intentional injury was positively associated with the frequency of episodic heavy drinking. The magnitudes of the associations were larger with frequent consumption of 5+ drinks (OR = 4.0 approximately) than with frequent consumption of 12+ drinks (OR = 3.1). Strong associations were also noted between RAPS4-assessed alcohol dependence and alcohol-related and intentional injuries. Further, the prevalence of intentional injury and its association with alcohol increased sharply once the acute alcohol intake exceeded 90 ml. Our results were consistent with prior studies that episodic heavy consumption, acute intoxication and problem drinking are pervasive among emergency room patients. Results of our study also lent support for administering a single-item screener querying consumption of 5+ drinks at a sitting in the past 12 months as a triage tool in Korea.

The α6 nicotinic acetylcholine receptor subunit influences ethanol-induced sedation - Corrected Proof

2012-05-09

Abstract: Alcohol and nicotine are often co-used and data from human and animals studies have demonstrated that common genes underlie responses to these two drugs. Recently, the genes that code for the subunits of the nicotinic acetylcholine receptors have been implicated as a common genetic mediator for alcohol and nicotine responses. The mammalian genes that code for the α6 and β3 subunits of the nicotinic acetylcholine receptor (Chrna6 and Chrnb3, respectively) are located adjacent to each other on human and mouse chromosome 8. These subunits have gained attention as potential regulators of drug behaviors because of their expression in the striatum where they have been shown to modulate dopamine release. Human genetic studies have shown that variation in these genes is associated with alcohol phenotypes. In the current experiments, mice lacking the Chrna6 or Chrnb3 gene were tested for three ethanol behaviors: choice ethanol consumption, ataxia, and sedation. Wildtype (WT), heterozygous (HET), and knockout (KO) mice of each strain went through a standard 2-bottle choice drinking paradigm, the balance beam, and the Loss of Righting Reflex (LORR) paradigm. No genotypic effects on any of the 3 behavioral tasks were observed in Chrnb3 animals. While the Chrna6 gene did not significantly influence ethanol consumption (g/kg) or ataxia, mice lacking the α6 subunit took significantly longer to recover their righting reflex than WT animals. These data provide evidence that receptors containing this subunit modulate the sedative effects of ethanol. Further work examining other models of ethanol consumption and behavioral responses to ethanol is needed to fully characterize the role of these receptor subunits in modulating ethanol responses.

Brief alcohol intervention as pragmatic intervention: Who is voluntarily taking an offered intervention? - Corrected Proof

Gerhard Gmel, Jacques Gaume, Nicolas Bertholet, Jean-Bernard Daeppen — 2012-05-09

Abstract: Brief alcohol interventions (BAI) have shown the potential to decrease problematic alcohol use among adolescents and young adults. Most of the BAI studies have been efficacy trials designed to achieve high internal validity but have raised questions regarding the feasibility of large-scale implementation. Providing interventions for those voluntarily wanting them might offer an alternative, and studies using this design would be more similar to effectiveness studies. The present research compares randomly selected 20-year-old men who took part in a scientific trial (efficacy) with those who voluntarily sought an intervention (effectiveness). Sampling took place during army recruitment procedures that are mandatory for all males in Switzerland. At-risk drinking (20+ drinks per week, or more than one risky drinking occasion of 6+ drinks per month) was determined a posteriori; there was no screening. There were a higher percentage of at-risk drinkers in the volunteer arm at baseline, but at-risk drinkers did not differ from those in the trial arm on any of the assessed alcohol measures. This suggests that offering BAI on a large-scale, voluntary basis may reach at-risk drinkers as effectively as do more scientifically oriented trials, without needing to adhere to screening and stringent research procedures. Nevertheless, BAI was more effective for at-risk drinkers who were invited for trial participation versus those who volunteered. This could be due to behavior that is already consolidated and is difficult to change. Lacking further modifications, real-world implementations of BAI for young men may be less effective than randomized controlled trials designed to test the efficacy of BAI.

Postnatal day 7 ethanol treatment causes persistent reductions in adult mouse brain volume and cortical neurons with sex specific effects on neurogenesis - Corrected Proof

Leon G. Coleman, Ipek Oguz, Joohwi Lee, Martin Styner, Fulton T. Crews — 2012-05-09

Abstract: Ethanol treatment on postnatal day seven (P7) causes robust brain cell death and is a model of late gestational alcohol exposure (). To investigate the long-term effects of P7 ethanol treatment on adult brain, mice received either two doses of saline or ethanol on P7 (2.5 g/kg, s.c., 2 h apart) and were assessed as adults (P82) for brain volume (using postmortem MRI) and cellular architecture (using immunohistochemistry). Adult mice that received P7 ethanol had reduced MRI total brain volume (4%) with multiple brain regions being reduced in both males and females. Immunohistochemistry indicated reduced frontal cortical parvalbumin immunoreactive (PV + IR) interneurons (18–33%) and reduced Cux1+IR layer II pyramidal neurons (15%) in both sexes. Interestingly, markers of adult hippocampal neurogenesis differed between sexes, with only ethanol treated males showing increased doublecortin and Ki67 expression (52 and 57% respectively) in the dentate gyrus, consistent with increased neurogenesis compared to controls. These findings suggest that P7 ethanol treatment causes persistent reductions in adult brain volume and frontal cortical neurons in both males and females. Increased adult neurogenesis in males, but not females, is consistent with differential adaptive responses to P7 ethanol toxicity between the sexes. One day of ethanol exposure, e.g. P7, causes persistent adult brain dysmorphology.

Anti-hepatitis B core positivity as a risk factor for hepatocellular carcinoma in alcoholic cirrhosis: A case–control study - Corrected Proof

2012-05-09

Abstract: Hepatocellular carcinoma (HCC) is occasionally developed in patients with alcoholic cirrhosis. Old age, male gender, lifetime quantity of alcohol, and presence of hepatitis C virus (HCV) infection are risk factors for HCC in alcoholic cirrhosis. In this study, we investigated whether anti-hepatitis B core (HBc) positivity or occult hepatitis B virus (HBV) infection is a risk factor for HCC in patients with alcoholic cirrhosis. Between January 2006 and August 2008, a total of 72 cirrhotic male patients with an initial diagnosis of HCC, hospitalized in three major hospitals in the Incheon area, were enrolled as cases. Another 72 cirrhotic male patients without HCC, who matched the cases by age (±3 years), were enrolled as controls. All cases and controls were negative for hepatitis B surface antigen and anti-HCV, but had history of chronic alcohol intake over 80g per day. The clinical characteristics including presence of anti-HBc or serum HBV DNA (identified by nested polymerase chain reaction) were investigated. The mean age of both the cases and controls was 62±10 years. The basal laboratory data, Child–Pugh scores, total lifetime alcohol intake (1459±1364 versus 1641±1045kg), and detection rates of serum HBV DNA [31.7% (20/63) versus 29.9% (20/67)] of the cases and controls were not significantly different. However, the anti-HBc positivity rate was higher among the cases [86.1% (62/72)] than in the controls [66.7% (48/72); P=0.005] and was the only significant risk factor for HCC (odds ratio; 3.1, 95% confidence interval; 1.354–7.098, P=0.007). Anti-HBc positivity was identified as a risk factor for the development of HCC in patients with alcoholic cirrhosis.

MALAT-1, a non protein-coding RNA is upregulated in the cerebellum, hippocampus and brain stem of human alcoholics - Corrected Proof

Rosemarie Kryger, Li Fan, Peter A. Wilce, Vincent Jaquet — 2012-05-07

Abstract: Chronic alcohol intake induces neurochemical adaptative changes in the brain characterised by altered gene expression. A role for non-coding RNAs in alcoholism is beginning to emerge. PCR-differential display using total RNA extracted from brain material of human alcoholics and control cases identified a cDNA fragment corresponding to a section of a known non protein-coding RNA (ncRNA), MALAT-1, (also known as NEAT2). Comparison of mRNA levels of MALAT-1 was performed by northern and dot blot experiments using different regions of brain from human alcoholics and rats chronically treated with ethanol vapours and following withdrawal. A massive increase of MALAT-1 transcripts was detected in cerebellum of human alcoholics and increases were also noted in hippocampus and brain stem, while no significant increase of MALAT-1 expression was noted in frontal or motor cortices. In the rat no significant difference of MALAT-1 ortholog mRNA could be detected in cerebellum. In addition, similarly to humans, no significant increase of MALAT-1 expression was detected in cortex of alcohol-treated rats, however, after 24 h alcohol withdrawal, a significant upregulation of MALAT-1 expression was observed in rat cortex. MALAT-1 is upregulated in specific regions of the human alcoholic brain and following alcohol withdrawal in the rat. As MALAT-1 regulates RNA processing, this suggests that alcohol-induced upregulation of MALAT-1 represents an important novel mechanism for alcohol actions in the CNS.

A comparison of Val81Met and other polymorphisms of alcohol metabolising genes in patients and controls in Northern Spain - Corrected Proof

2012-05-04

Abstract: The aim of this paper is to study polymorphism in the TH, ADH1B, ADH1C, ALDH2 and CYP2E1 genes so as to ascertain whether it is associated with excessive consumption of alcohol. The SNPs rs6356 of TH, rs1229984, rs2066702 of ADH1B; rs698, rs1693482 of ADH1C; rs671 of ALDH2; rs72559710, rs55897648, rs6413419, rs3813867, rs2031920, rs6413432 of CYP2E1 were studied in a sample of 172 high-level patients and 150 fully non-drinkers controls. Genotyping was performed using Rt-PCR with Taqman probes. SNPs located at ALDH2 and CYP2E1 showed no heterozygosity. Frequency distribution showed significant differences between the two groups studied for loci TH and ADH1B. The genotype Val/Val of TH locus increased in risk 1.988 times (95% CI: 1.006–3.930) that the subjects carrying the genotype Met/Met; and the genotype ADH1B*1/*1 of ADH1B locus increased in risk 3.811 times (CI: 1.660–8.749) that the subjects carrying the genotype ADH1B*1/*2. Alleles Val and ADH1B*1 may therefore increase the risk of the onset and development of this illness.

Positive allosteric modulation of the GABAB receptor by GS39783 attenuates the locomotor stimulant actions of ethanol and potentiates the induction of locomotor sensitization - Corrected Proof

Lauren C. Kruse, David N. Linsenbardt, Stephen L. Boehm — 2012-05-04

Abstract: Acute ethanol-induced locomotor stimulation and ethanol-induced locomotor sensitization are two behavioral assays thought to model the rewarding effects of ethanol. Recent evidence suggests that GS39783, a GABAB positive allosteric modulator, may be effective at reducing both the rewarding and reinforcing effects of several drugs of abuse, including ethanol. The goal of this study was to determine if GS39783 was capable of altering acute ethanol-induced stimulation, and the induction and expression of ethanol-induced locomotor sensitization, without effecting basal locomotion levels. Several doses of GS39783 (ranging from 0 to 100 mg/kg, depending on experiment) were tested on adult male DBA/2J mice in four experiments using 3-day basal locomotion and acute ethanol stimulation paradigms, and 14-day induction and expression of ethanol sensitization paradigms. The results of experiment 1 are in agreement with current literature, suggesting that 30 mg/kg doses of GS39783 and lower do not alter basal locomotor activity. In experiment 2, we found that GS39783 significantly decreased acute ethanol stimulation, but only at the 30 mg/kg dose, supporting our hypothesis and other publications suggesting that GABAB receptors modulate acute ethanol stimulation. Contrary to our hypothesis, GS39783 did not alter the expression of locomotor sensitization. Additionally, repeated administration of GS39783 in conjunction with ethanol unexpectedly potentiated ethanol-induced locomotor sensitization. Further study of GS39783 is warranted as it may be a more tolerable treatment for alcoholism than full agonists, due to its behavioral efficacy at doses that lack sedative side effects. Our results add to current literature suggesting that the GABAB receptor system is indeed involved in the modulation of ethanol-induced locomotor stimulation and sensitization.

The interaction of chronic restraint stress and voluntary alcohol intake: Effects on spatial memory in male rats - Corrected Proof

Juan L. Gomez, Michael J. Lewis, Victoria N. Luine — 2012-05-04

Abstract: Alcohol consumption and exposure to stressful life events activate similar neural pathways and thus result in several comparable physiological and behavioral effects. Alcoholics in treatment claim that life stressors are the leading cause of continued drinking or relapse. However, few studies have investigated the interactive effects of stress and alcohol on cognitive behavior. The effects of restraint stress, alcohol, and stress in combination with alcohol were examined on a spatial memory test, the object placement (OP) task. In addition, intake levels were measured to determine if stress altered general consumption of alcohol. Male Sprague-Dawley rats were assigned to one of four conditions: no alcohol/no stress control (CON), stress alone (STR), alcohol alone (ALC), and STR+alcohol (STR+ALC). Following each restraint stress bout, the STR+ALC and the ALC groups were given access to 8% alcohol for 1h using the two-bottle choice limited access paradigm. As predicted, the STR+ALC group significantly increased alcohol consumption, while the ALC group had consistent drinking over the 10-day treatment. On the OP task, STR and ALC groups performed at chance levels, whereas the CON and STR+ALC groups significantly discriminated between objects in the new and old locations. These data show that stress increases alcohol intake and the intake of alcohol is associated with reduction of the stress-induced impairment of spatial memory. The data have important implications for the development of alcohol abuse and its treatment.

Ethanol protects from injury due to ischemia and reperfusion by increasing vascularity via vascular endothelial growth factor - Corrected Proof

2012-05-04

Abstract: The cardioprotective effects of moderate ethanol consumption have been known for years and have generally been ascribed to long-term effects of alcohol on blood lipids. However, other mechanisms, particularly ethanol-induced increase in blood vessel density, may also be involved. Our goal was to understand the relationship between ethanol consumption, new blood vessel formation in vivo and protection from injury due to ischemia and ischemia/reperfusion. Using paired ethanol fed and control rats, we assessed capillary density in the heart, brain and skeletal muscle by immunostaining and quantified expression of vascular endothelial growth factor (VEGF) by Western blot analysis and immunocytochemistry. Numbers of vessels were significantly increased in the brain, heart and skeletal muscle of animals fed ethanol-rich diets. VEGF (and its receptors) were upregulated in these organs. These effects were very rapid: highly significantly increased vascularization was seen within 2 weeks of commencing alcohol feeding. A neutralizing VEGF antibody, bevacizumab, inhibited new blood vessel formation induced by moderate doses of ethanol. Ethanol consumption increased vascularization and promoted skeletal muscle regeneration following hindlimb ischemia; these effects were prevented by bevacizumab. Finally, ethanol consumption protected myocardium following experimental ischemia/reperfusion. Conclusion: Experimental ethanol ingestion rapidly increases VEGF production, significantly increasing the capillary bed in the heart, brain, and skeletal muscle. Moreover, the ethanol-induced increase of blood vessel density is protective against ischemic events (i.e., hindlimb ischemia and myocardium ischemia/reperfusion) and promotes skeletal muscle regeneration.

Increased amplitude of P3 event-related potential in young binge drinkers - Corrected Proof

2012-03-29

Abstract: The aim of the present study was to determine how binge drinking (BD) affects brain functioning in male and female university students during the performance of a visual discrimination task. Thirty two binge drinkers and 53 controls (non binge drinkers), with no history of other drug use, personal or family history of alcoholism or psychopathological disorders, were selected. Event-related potentials (ERPs) were recorded during the performance of a visual oddball task. The latency and amplitude of the N2 and P3b components of the ERPs were analyzed. There were no differences between the groups in behavioral measures, but P3b amplitudes were significantly larger in binge drinkers than controls. This may suggest the presence of anomalies in neural processes mediating attention processing, or an imbalance (increased) of neuronal activity in P3b generators caused by the presence of BD pattern for a long time.

Changes in cytokine levels during admission and mortality in acute alcoholic hepatitis - Corrected Proof

2012-03-26

Abstract: Cytokine levels are raised in acute alcoholic hepatitis. However, there are disparate results regarding the duration of altered plasma levels, and there are also discrepancies about the relation of changes during the first 15 days after admission with short-term (in-hospital) or long-term mortality. In 56 patients with acute alcoholic hepatitis we found that IL-8, IL-4, Interferon-γ (IFN-γ), malondialdehyde and C-reactive protein remained higher in patients than in 18 age- and sex-matched controls at admission, at the 7th day and at the 15th day after admission. Moreover, IL-4 levels (and to a lesser extent, IL-10 and IFN-γ ones) increased along the three determinations. However, comparing patients who died during the admission with those who did not, there were no statistically significant differences, but there was a nearly significant trend for MDA (Z = 1.89; p = 0.059), with higher levels among those who died. When changes between the first and the second determinations were compared with long-term survival, only IL-8 and IFN-γ showed a relation with mortality. IFN-γ values increased among those who survived and decreased among those who died (p = 0.048). IFN-γ values at the first determination also showed a relation with long-term mortality, especially when patients with IFN-γ values in the first quartile were compared with those of the 4th one (log rank = 5.64; p = 0.018; Breslow = 4.64; p = 0.031). Besides Interferon-γ, only C-reactive protein showed differences between the first and the 4th quartile regarding mortality (Log rank = 4.50; p = 0.034; Breslow 4.33; p = 0.038). In contrast with other studies, no relation was found between TNF-α or IL-6 and mortality.

Effect of l-cysteine on acetaldehyde self-administration - Corrected Proof

2012-03-22

Abstract: Acetaldehyde (ACD), the first metabolite of ethanol, has been implicated in several behavioural actions of alcohol, including its reinforcing effects. Recently, we reported that l-cysteine, a sequestrating agent of ACD, reduced oral ethanol self-administration and that ACD was orally self-administered. This study examined the effects of l-cysteine pre-treatment during the acquisition and maintenance phases of ACD (0.2%) self-administration as well as on the deprivation effect after ACD extinction and on a progressive ratio (PR) schedule of reinforcement. In a separate PR schedule of reinforcement, the effect of l-cysteine was assessed on the break-point produced by ethanol (10%). Furthermore, we tested the effect of l-cysteine on saccharin (0.2%) reinforcement. Wistar rats were trained to self-administer ACD by nose poking on a fixed ratio (FR1) schedule in 30-min daily sessions. Responses on an active nose-poke caused delivery of ACD solution, whereas responses on an inactive nose-poke had no consequences. l-cysteine reduced the acquisition (40 mg/kg), the maintenance and the deprivation effect (100 mg/kg) of ACD self-administration. Furthermore, at the same dose, l-cysteine (120 mg/kg) decreased both ACD and ethanol break point. In addition, l-cysteine was unable to suppress the different responses for saccharin, suggesting that its effect did not relate to an unspecific decrease in a general motivational state. Compared to saline, l-cysteine did not modify responses on inactive nose-pokes, suggesting an absence of a non-specific behavioural activation. Taken together, these results could support the hypotheses that ACD possesses reinforcing properties and l-cysteine reduces motivation to self-administer ACD.

Influence of chronic ethanol intake on mouse synaptosomal aspartyl aminopeptidase and aminopeptidase A: Relationship with oxidative stress indicators - Corrected Proof

2012-03-22

Abstract: Aminopeptidase A (APA) and aspartyl aminopeptidase (ASAP) not only act as neuromodulators in the regional brain renin-angiotensin system, but also release N-terminal acidic amino acids (glutamate and aspartate). The hyperexcitability of amino acid neurotransmitters is responsible for several neurodegenerative processes affecting the central nervous system. The purpose of the present work was to study the influence of chronic ethanol intake, a well known neurotoxic compound, on APA and ASAP activity under resting and K+-stimulated conditions at the synapse level. APA and ASAP activity were determined against glutamate- and aspartate-β-naphthylamide respectively in mouse frontal cortex synaptosomes and in their incubation supernatant in a Ca2+-containing or Ca2+-free artificial cerebrospinal fluid. The neurotoxic effects were analyzed by determining free radical generation, peroxidation of membrane lipids and the oxidation of synaptosomal proteins. In addition, the bioenergetic behavior of synaptosomes was analyzed under different experimental protocols. We obtained several modifications in oxidative stress parameters and a preferential inhibitor effect of chronic ethanol intake on APA and ASAP activities. Although previous in vitro studies failed to show signs of neurodegeneration, these in vivo modifications in oxidative stress parameters do not seem to be related to changes in APA and ASAP, invalidating the idea that an excess of free acidic amino acids released by APA and ASAP induces neurodegeneration.