Mild thiamine deficiency and chronic ethanol consumption modulate acetylcholinesterase activity change and spatial memory performance in a water maze task

Alteration of the α5 GABA receptor and 5HTT lead to cognitive deficits associated with major depressive-like behaviors in a 14-day combined stress rat model

INTRODUCTION

Current models used to study the pathophysiology of major depressive disorder (MDD) are laborious and time consuming. This study examined the effect of a 14-day combined stress model (CS; corticosterone injection and restraint stress) in male Sprague-Dawley rats and also compare the effect of CS versus 28-day corticosterone treatment on depressive-like behaviour and cognitive deficits.

MATERIEL AND METHODS

Depressive-like behaviours and cognitive deficits were assessed in the forced swim test (FST), sucrose preference (SPT), Morris water maze (MWM) and novel object recognition (NORT) tests. Real-time PCR and ELISA were respectively used to detect expression of the serotonin transporter (5-HTT), serotonin 1 A receptor (5-HT1A), α5 GABAA receptor, and the concentrations of corticosterone (plasma), GABA and acetylcholinesterase (AChE) in the hippocampus and Prefrontal cortex (PFC).Results CS group showed increased immobility time in the FST, time to reach the MWM platform, higher corticosterone level, and increased expressions of hippocampal and PFC 5-HT1A and α5 GABAA receptors, and AChE compared to their control groups. In contrast, reductions in SPT ratio, discrimination index in NORT, time in target quadrant, and hippocampal 5-HTT expression was noted relative to their control group. Compared to the 28-day corticosterone only group, PFC 5-HT1A, Hippocampal 5-HTT were reduced, while PFC 5-HTT, Hippocampal α5 GABAA receptors, and AChE concentrations were higher in the CS group.

CONCLUSION

Our CS model induced depressive-like behaviour with early cognitive deficits in rats affecting both hippocampus and PFC. The CS model may be useful in investigating new and comprehensive treatment strategies for MDD.

A Pivotal Role for Thiamine Deficiency in the Expression of Neuroinflammation Markers in Models of Alcohol-Related Brain Damage

BACKGROUND

Alcohol-related brain damage (ARBD) is associated with neurotoxic effects of heavy alcohol use and nutritional deficiency, in particular thiamine deficiency (TD), both of which induce inflammatory responses in brain. Although neuroinflammation is a critical factor in the induction of ARBD, few studies have addressed the specific contribution(s) of ethanol (EtOH) versus TD.

METHODS

Adult rats were randomly divided into 6 conditions: chronic EtOH treatment (CET) where rats consumed a 20% v/v solution of EtOH for 6 months; CET with injections of thiamine (CET + T); severe pyrithiamine-induced TD (PTD); moderate PTD; moderate PTD during CET; and pair-fed controls. After the treatments, the rats were split into 3 recovery phase time points: the last day of treatment (time point 1), acute recovery (time point 2: 24 hours posttreatment), and delayed recovery (time point 3: 3 weeks posttreatment). At these time points, vulnerable brain regions (thalamus, hippocampus, frontal cortex) were collected and changes in neuroimmune markers were assessed using a combination of reverse transcription polymerase chain reaction and protein analysis.

RESULTS

CET led to minor fluctuations in neuroimmune genes, regardless of the structure being examined. In contrast, PTD treatment led to a profound increase in neuroimmune genes and proteins within the thalamus. Cytokine changes in the thalamus ranged in magnitude from moderate (3-fold and 4-fold increase in interleukin-1β [IL-1β] and IκBα) to severe (8-fold and 26-fold increase in tumor necrosis factor-α and IL-6, respectively). Though a similar pattern was observed in the hippocampus and frontal cortex, overall fold increases were moderate relative to the thalamus. Importantly, neuroimmune gene induction varied significantly as a function of severity of TD, and most genes displayed a gradual recovery across time.

CONCLUSIONS

These data suggest an overt brain inflammatory response by TD and a subtle change by CET alone. Also, the prominent role of TD in the immune-related signaling pathways leads to unique regional and temporal profiles of induction of neuroimmune genes.

Combined corticosterone treatment and chronic restraint stress lead to depression associated with early cognitive deficits in mice

Many models, such as chronic mild stress, chronic stress or chronic corticosterone injections are used to induce depression associated with cognitive deficits. However, the induction period in these different models is still long and face constraints when it is short such as in the chronic mild stress done in a minimum period of 21 days. This study aimed to characterize a model of depression with early onset cognitive deficit. 14 days combined chronic injection of corticosterone followed by 2 h restraint stress using a restrainer was used to induce depression with early cognitive deficit onset. The forced swim test, sucrose test and plasma corticosterone concentration were used to assess depression-like characteristics. The Morris water maze, novel object recognition task, as well as hippocampal acetylcholinesterase activity were used to assess cognitive deficit. The combined corticosterone injection + chronic restraint stress group presented with marked depression-like behaviour and a higher plasma corticosterone concentration compared to corticosterone injection alone and restraint stress alone. It also showed an alteration in the learning process, memory deficit as well as increased acetylcholinesterase activity compared to corticosterone injection and restraint stress alone groups. These findings suggest that the combined corticosterone administration and chronic restraint stress can be used not only as an animal model for severe depression, but also for depression with early onset cognitive deficit.

Spatial navigation deficits in amnestic mild cognitive impairment with neuropsychiatric comorbidity

AIMS

To find out whether neuropsychiatric comorbidity (comMCI) influences spatial navigation performance in amnestic mild cognitive impairment (aMCI).

METHODS

We recruited aMCI patients with (n = 21) and without (n = 21) neuropsychiatric comorbidity or alcohol abuse, matched for global cognitive impairment and cognitively healthy elderly participants (HE, n = 22). They completed the Mini-Mental State Examination and a virtual Hidden Goal Task in egocentric, allocentric, and delayed recall subtests.

RESULTS

In allocentric navigation, aMCI and comMCI performed significantly worse than HE and similarly to each other. Although aMCI performed significantly worse at egocentric navigation than HE, they performed significantly better than patients with comMCI.

CONCLUSIONS

Despite the growing burden of dementia and the prevalence of neuropsychiatric symptoms in the elderly population, comMCI remains under-studied. Since trials often assess "pure" aMCI, we may underestimate patients' navigation and other deficits. This finding emphasizes the importance of taking account of the cognitive effects of psychiatric disorders in aMCI.

Interactions between chronic ethanol consumption and thiamine deficiency on neural plasticity, spatial memory, and cognitive flexibility

BACKGROUND

Many alcoholics display moderate to severe cognitive dysfunction accompanied by brain pathology. A factor confounded with prolonged heavy alcohol consumption is poor nutrition, and many alcoholics are thiamine deficient. Thus, thiamine deficiency (TD) has emerged as a key factor underlying alcohol-related brain damage (ARBD). TD in humans can lead to Wernicke Encephalitis that can progress into Wernicke-Korsakoff syndrome and these disorders have a high prevalence among alcoholics. Animal models are critical for determining the exact contributions of ethanol (EtOH)- and TD-induced neurotoxicity, as well as the interactions of those factors to brain and cognitive dysfunction.

METHODS

Adult rats were randomly assigned to 1 of 6 treatment conditions: chronic EtOH treatment (CET) where rats consumed a 20% v/v solution of EtOH over 6 months; severe pyrithiamine-induced TD (PTD-moderate acute stage); moderate PTD (PTD-early acute stage); moderate PTD followed by CET (PTD-CET); moderate PTD during CET (CET-PTD); and pair-fed (PF) control. After recovery from treatment, all rats were tested on spontaneous alternation and attentional set-shifting. After behavioral testing, brains were harvested for determination of mature brain-derived neurotrophic factor (BDNF) and thalamic pathology.

RESULTS

Moderate TD combined with CET, regardless of treatment order, produced significant impairments in spatial memory, cognitive flexibility, and reductions in brain plasticity as measured by BDNF levels in the frontal cortex and hippocampus. These alterations are greater than those seen in moderate TD alone, and the synergistic effects of moderate TD with CET lead to a unique cognitive profile. However, CET did not exacerbate thalamic pathology seen after moderate TD.

CONCLUSIONS

These data support the emerging theory that subclinical TD during chronic heavy alcohol consumption is critical for the development of significant cognitive impairment associated with ARBD.

Change in psychiatric symptomatology after benfotiamine treatment in males is related to lifetime alcoholism severity

BACKGROUND

Severe alcoholism can be associated with significant nutritional and vitamin deficiency, especially vitamin B1 (thiamine) which is associated with neurological deficits impacting mood and cognition. Alcohol consumption was reduced among female but not male alcoholics after supplementation with the high potency thiamine analog benfotiamine (BF). We examined the relationship between lifetime alcoholism severity, psychiatric symptoms and response to BF among the alcohol dependent men from this cohort.

METHODS

Eighty-five adult men (mean age=48±8 years) meeting DSM-IV-TR criteria for a current alcohol use disorder who were abstinent <30days participated in a randomized, double-blind, placebo-controlled trial of 600mg BF vs placebo (PL) for 6 months. Psychometric testing included a derived Lifetime Alcoholism Severity Score (AS), Symptom Checklist 90R (SCL-90R), and the Barratt Impulsivity Scale (BIS) at baseline and at 6 months.

RESULTS

Baseline SCL-90-R scale scores for men with high alcoholism severity (AS≥24; N=46 HAS) were significantly greater than for men with low alcoholism severity (AS<24; N=39 LAS), but BIS scores did not differ. MANOVA modeling at follow-up (N=50 completed subjects) identified a significant treatment effect (F=2.5, df=10, p<0.03) and treatment×alcoholism severity level interaction (F=2.5, dfnum=10, dfden=30, p<0.03) indicating reduced SCL-90-R scores among BF treated, HAS males. Above normal plasma thiamine levels at follow-up predicted reduced depression scores in a BF-treated subset (F=3.2, p<0.09, N=26).

CONCLUSION

BF appears to reduce psychiatric distress and may facilitate recovery in severely affected males with a lifetime alcohol use disorder and should be considered for adjuvant therapy in alcohol rehabilitation.

TRIAL REGISTRATION

#NCT00680121 High Dose Vitamin B1 to Reduce Abusive Alcohol Use.