Cognitive impairment and changes of red blood cell components and serum levels of IL-6, IL-18, and L-tryptophan in methamphetamine abusers

The deficit in cognitive function is more concerning in methamphetamine (MA) users. The cognitive deficit was suspected to be the consequence of neuroinflammation-induced neurological dysregulation. In addition, activating the key enzyme in the tryptophan metabolic pathway by pro-inflammatory cytokines results in metabolite toxicity, further generating cognitive impairments. However, the evidence for the role of neuroinflammation and tryptophan metabolites involved in MA-induced cognitive deficit needs more conclusive study.

OBJECTIVES

This retrospective study aimed to determine blood-inflammatory markers, tryptophan metabolite-related molecules, and cognitive function in MA abusers compared to healthy control (HC) participants.

METHODS

The cognitive functions were evaluated using Stroop, Go/No-Go, One Back Task (OBT), and Wisconsin Card Sorting Test-64 (WCST-64). Blood samples were analyzed for complete blood count (CBC) analysis, serum inflammatory cytokines interleukin (IL)-6 and IL-18 and tryptophan metabolites.

RESULTS

MA group exhibited poor cognitive performance in selective attention, inhibition, working memory, cognitive flexibility, concept formation and processing speed compared to HC. Reduction in red blood cell (RBC) components but induction in white blood cells (WBCs) and IL-6 were observed in MA abusers, which might indicate anemia of (systemic chronic low-grade) inflammation. In addition, the depletion of precursor in the tryptophan metabolic pathway, L-tryptophan was also observed in MA users, which might represent induction in tryptophan metabolites.

CONCLUSION

These findings emphasize that blood biomarkers might be a surrogate marker to predict the role of neuroinflammation and abnormal tryptophan metabolite in MA-induced cognitive impairments.

Aluminum chloride-induced amyloid β accumulation and endoplasmic reticulum stress in rat brain are averted by melatonin

Accumulation of aluminium (Al) in the brain is known to be a toxic insult that result in neurodegenerative diseases and melatonin is known to have neuroprotective role. The present study was designed to investigate the neuroprotective effects of melatonin for aluminium chloride (AlCl₃)-induced neurotoxicity in rats. Twelve-week old male Wistar rats were orally received 175 mg/kg AlCl₃ with or without 5 mg/kg melatonin intraperitoneal pretreatment. Group 3 intraperitoneally recieved 5 mg/kg melatonin and group 4 rats were orally treated with saline solution for 8 weeks. A series of behavioral tests, biochemical analysis and expression of AD-associated proteins in the brain were determined after 7 weeks of all treatments. Our results indicated that AlCl₃ treatment tends to induce memory and cognitive impairment. However, melatonin treatment attenuated amyloid beta (Aβ) (1-42) level by decreasing β-secretase, augmented low-density lipoprotein receptor-related protein 1, and neprilysin protein expression. Moreover, AlCl₃ -induced endoplasmic reticulum (ER) stress and oxidative stress was attenuated by melatonin supplementation. In conclusion, these findings demonstrate a protective role of melatonin against Aβ peptide accumulation, ER stress and oxidative stress in the AlCl₃ -treated AD model. Hence, the melatonin supplement might be an alternative way to alleviate the development of AD.