Protective effects of Astragalus kahiricus root extract on ethanol-induced retrograde memory impairments in mice

Repeated pre-exposure to morphine inhibited the amnesic effect of ethanol on spatial memory: Involvement of CaMKII and BDNF

Evidence has suggested that addiction and memory systems are related, but the signaling cascades underlying this interaction have not been completelyealed yet. The importance of calcium-calmodulin-dependent protein kinase II (CaMKII) and brain-derived neurotrophic factor (BDNF) in the memory processes and also in drug addiction has been previously established. In this present investigation, we examined the effects of repeated morphine pretreatment on impairment of spatial learning and memory acquisition induced by systemic ethanol administration in adult male rats. Also, we assessed how these drug exposures influence the expression level of CaMKII and BDNF in the hippocampus and amygdala. Animals were trained by a single training session of 8 trials, and a probe test containing a 60-s free-swim without a platform was administered 24 h later. Before training trials, rats were treated with a once-daily subcutaneous morphine injection for 3 days followed by a 5-day washout period. The results showed that pre-training ethanol (1 g/kg) impaired spatial learning and memory acquisition and down-regulated the mRNA expression of CaMKII and BDNF. The amnesic effect of ethanol was suppressed in morphine- (15 mg/kg/day) pretreated animals. Furthermore, the mRNA expression level of CaMKII and BDNF increased significantly following ethanol administration in morphine-pretreated rats. Conversely, this improvement in spatial memory acquisition was prevented by daily subcutaneous administration of naloxone (2 mg/kg) 15 min prior to morphine administration. Our findings suggest that sub-chronic morphine treatment reverses ethanol-induced spatial memory impairment, which could be explained by modulating CaMKII and BDNF mRNA expressions in the hippocampus and amygdala.

Portulaca oleracea L. (purslane) improves the anti-inflammatory, antioxidant and autophagic actions of metformin in the hippocampus of diabetic demented rats

Great body of evidence links cognitive decline to diabetes/insulin resistance. In this study the effect of Portulaca oleracea (PUR) (100 mg/kg), Metformin (MET) (200 mg/kg), a first line diabetes mellitus type 2 therapy, and their combination on cognitive function and hippocampal markers in diabetic rats were assessed. Male rats were injected with streptozotocin (30 mg/kg on two successive weeks) followed by 4 weeks of treatment. Possible antioxidant, anti-inflammatory, and autophagy enhancing mechanisms of these drugs were investigated in the hippocampal tissue using spectrophotometry, ELISA, and western blotting. Diabetic rats suffered significant cognitive impairment in Morris's water maze, hippocampal TBARS elevation, GSH depletion, and SOD upregulation. In addition, diabetes promoted the secretion of hippocampal inflammatory cytokines, TNF-α and IL-1β, and depleted anti-inflammatory cytokines as IL-10. Such detrimental changes were reversed by MET and/or PUR. Notably, AMPK was upregulated by diabetes, then restored to normal by MET and/or PUR. The pattern of change in AMPK expression was concomitant with changes in oxidative and inflammatory burden. Hence, AMPK is believed to be a key mediator in most of the measured pre-AD markers in this study. However, from our results, PUR is believed to have non-AMPK dependent actions as well. In conclusion, antidiabetic agents as metformin and purslane extract proved to be invaluable in addressing the cognitive decline and hippocampal changes that arise as a complication of diabetes. They mainly acted through AMPK pathway; however, their usefulness was not limited to AMPK pathways since their combination was suggested to have a different mechanism.

Metformin improved memory impairment caused by chronic ethanol consumption during adolescent to adult period of rats: Role of oxidative stress and neuroinflammation

OBJECTIVE

Adolescence is a crucial time for brain maturation. We investigated the protective effects of metformin (Met) on behavioral changes, oxidative stress, tumor necrosis factor alpha (TNF-α) and nitrite in adulthood induced by ethanol (Eth) consumption during adolescent to adult period of rats.

MATERIALS AND METHODS

The adolescence male rats (21 days old) were treated as: 1) Control, 2) Eth (Eth in drinking water (20 %)), 3-5) Eth-Met50, 100 and 150 mg/kg (Eth in drinking water and Met (50, 100, or 150 mg/kg). After 5 weeks treatment, Morris water maze (MMW) and passive avoidance (PA) tests were done.

RESULTS

The latency in the MWM test was higher and the latency to enter the dark chamber in the PA test was lower in the Eth group than in control. In Eth-Met100 and 150 groups, they were less than the Eth group. Malondialdehyde (MDA) and nitrite concentration in the hippocampus and cortex of the Eth group were higher than the control group. The thiol content and catalase and superoxide dismutase (SOD) activities in hippocampal and cortical tissues of the Eth group reduced compared to the control group. TNF-α was higher in hippocampal tissues of Eth group animals. Met reversed all of these effects.

CONCLUSION

Our findings showed that the protective effects of Met against chronic Eth consumption induced learning and memory impairment were accompanied by decreasing of TNF-a, nitrite and oxidative stress in adolescent rats.