Time Course of Blood and Brain Cytokine/Chemokine Levels Following Adolescent Alcohol Exposure and Withdrawal in Rats

BACKGROUND

Adolescence is a critical period for neural development, and alcohol exposure during adolescence can lead to an elevated risk for health consequences as well as alcohol use disorders. Clinical and experimental data suggest that chronic alcohol exposure may produce immunomodulatory effects that can lead to the activation of pro-inflammatory cytokine pathways as well as microglial markers. The present study evaluated, in brain and blood, the effects of adolescent alcohol exposure and withdrawal on microglia and on the most representative pro- and anti-inflammatory cytokines and major chemokines that can contribute to the establishing of a neuroinflammatory environment.

METHODS

Wistar rats (males, n = 96) were exposed to ethanol (EtOH) vapors, or air control, for 5 weeks over adolescence (PD22-PD58). Brains and blood samples were collected at 3 time points: (i) after 35 days of vapor/air exposure (PD58); (ii) after 1 day of withdrawal (PD59), and (iii) 28 days after withdrawal (PD86). The ionized calcium-binding adapter molecule 1 (Iba-1) was used to index microglial activation, and cytokine/chemokine responses were analyzed using magnetic bead panels.

RESULTS

After 35 days of adolescent vapor exposure, a significant increase in Iba-1 immunoreactivity was seen in amygdala, frontal cortex, hippocampus, and substantia nigra. However, Iba-1 density returned to control levels at both 1 day and 28 days of withdrawal except in the hippocampus where Iba-1 density was significantly lower than controls. In serum, adolescent EtOH exposure induced a reduction in IL-13 and an increase in fractalkine at day 35. After 1 day of withdrawal, IL-18 was reduced, and IP-10 was elevated, whereas both IP-10 and IL-10 were elevated at 28 days following withdrawal. In the frontal cortex, adolescent EtOH exposure induced an increase in IL-1β at day 35, and 28 days of withdrawal, and IL-10 was increased after 28 days of withdrawal.

CONCLUSION

These data demonstrate that EtOH exposure during adolescence produces significant microglial activation; however, inflammatory markers seen in the blood appear to differ from those observed in the brain.

Fullerene C₆₀ Derivatives Attenuated Microglia-Mediated Prion Peptide Neurotoxicity

Prion disorders are progressive neurodegenerative diseases characterized by extensive neuronal loss, which is linked to the extracellular accumulation of the scrapie isoform (PrPSC) of the normal cellular prion protein (PrPC). As microglial activation is a central event in pathogenesis of prion disease, the strategies that reduce microglial activation may have therapeutic benefits. In this study, the neuroprotective effects of hydroxylated C60(C60-OH) and amino modified-C60(C60-NH2) were evaluated by using PrP(106-126)-stimulated BV-2 cells as a model of activated microglia. Herein, we showed that microglial activation in response to PrP(106-126) was effectively attenuated by pretreatment with C60-OH as compared with C60-NH2. C60-OH significantly inhibited the excessive production of inflammatory mediators, such as prostaglandin E2 (PGE2), nitric oxide (NO), tumor necrosis factors (TNF)-α, interleukin (IL)-1β, and IL-6, and blocked the expression of cyclooxygenase-2 (COX-2) and inducible nitric-oxide synthase (iNOS) in PrP(106-126)-stimulated BV-2 cells. C60-OH exerted anti-inflammatory potential by up-regulating the expression of antioxidant enzymes via activation of nuclear factor erythroid 2-related factor 2 (Nrf2). The inhibitory effect of C60-OH against PrP(106-126)-induced inflammatory response was abolished by siRNA of Nrf2. In addition, conditioned culture media taken from PrP(106-126)-stimulated microglia cause apoptotic neuronal cell death, which was suppressed by pretreatment with C60-OH. Take together, these results suggest that C60-OH protects neuronal cells against PrP(106-126)-mediated neurotoxicity through activation of Nrf2 pathway, and provides evidence that fullerene derivatives may have therapeutic potential in prion diseases.

Scutellarin Ameliorates Learning and Memory Deficit via Suppressing β-Amyloid Formation and Microglial Activation in Rats with Chronic Cerebral Hypoperfusion

Chronic cerebral hypoperfusion is considered as a pivotal factor of cognitive impairment that occurs in cerebrovascular diseases. This study investigated the ameliorating effect of scutellarin (SCT) on spatial cognitive impairment and β-amyloid (Aβ) formation in rats with chronic cerebral hypoperfusion induced by permanent bilateral common carotid artery occlusion (pBCAO). SCT is a flavonoid in medicinal herb of Erigeron breviscapus (vant.) Hand. Mazz. known to have neuroprotective, antioxidative and anti-inflammatory effects. However, the beneficial effect and pivotal mechanism of SCT on cognitive impairment are still unclear. SCT was treated orally with two doses (10 or 30 mg/kg) for 4 weeks. Results of Morris water maze test performed on the ninth week after pBCAO revealed that SCT (30 mg/kg)-treated rats had significantly shortened escape latencies in acquisition training trials, significantly prolonged swimming time at the platform and its surrounding zone, significant increase in memory score, significant reduction in the number of target heading, and significant reduction in the time required for the first target heading during the retention trial compared to rats in the sham-control group. SCT significantly inhibited the production of Aβ(1-40) and Aβ(1–42) in brain tissues. However, SCT significantly upregulated the expression levels of amyloid precursor protein and β-site APP-converting enzyme-1 in the hippocampus. In addition, SCT significantly inhibited the activation of Iba1-expressing microglia in brain tissues. The results suggest that SCT can exert ameliorating effect on spatial cognitive impairment caused by chronic cerebral hypoperfusion through suppressing Aβ formation and microglial activation in brain tissues. Therefore, SCT can be used as a beneficial drug for vascular dementia and Alzheimer's disease.