Effects of sesamin on Aβ1-42-induced oxidative stress and LTP impairment in a rat model of Alzheimer's disease

Cacao consumption improves passive avoidance memory impairment in a rat model of Alzheimer's disease: the role of hippocampal synaptic plasticity and oxidative stress

Introduction: Alzheimer's disease (AD) causes progressive loss of cognitive function and synaptic plasticity, which is the most common form of dementia. The present study was designed to scrutinize the effects of cacao on passive avoidance memory function and to identify the roles of hippocampal synaptic plasticity and oxidative stress in an AD rat model induced by unilateral intracerebroventricular (UICV) injection of amyloid-beta (Aβ). Methods: Oral administration of cacao (500 mg/kg/ day) was given for 2 consecutive months. A memory retention test was conducted 24 h after passive avoidance training was completed. Subsequently, the amplitude of population spike (PS) and slope of field excitatory postsynaptic potentials (fEPSPs) were assessed at hippocampal long-term potentiation (LTP) in perforant pathway-dentate gyrus (PP-DG) synapses. Moreover, total thiol group (TTG) and malondialdehyde (MDA) concentrations were evaluated in the plasma. Furthermore, compact Aβ plaques were detected in the hippocampal DG by performing Congo red staining. Results: As a result of AD induction, passive avoidance memory was impaired; also, reduced fEPSP slopes, PS amplitudes, and content of TTG, and increase in MDA levels in the rats were observed. In contrast, cacao treatment ameliorated passive avoidance memory impairment, improved hippocampal LTP impairment, modulated oxidative-antioxidative status, and delayed Aβ plaques production in AD rats. Disscussion: Conclusively, cacao alleviates Aβ-induced cognitive deficit, probably by the amelioration of hippocampal LTP impairment, modulation of oxidative-antioxidative status, and inhibition of Aβ plaque accumulation.

Sesamin mitigates lead-induced behavioral deficits in male rats: The role of oxidative stress

Lead (Pb) is a well-known toxic pollutant that has negative effects on behavioral functions. Sesamin, a phytonutrient of the lignan class, has shown neuroprotective effects in various neurological disorder models. The present study was undertaken to evaluate the putative protective effects of sesamin against Pb-induced behavioral deficits and to identify the role of oxidative stress in male rats. The rats were exposed to 500 ppm of Pb acetate in their drinking water and simultaneously treated orally with sesamin at a dose of 30 mg/kg/day for eight consecutive weeks. Standard behavioral paradigms were used to assess the behavioral functions of the animals during the eighth week of the study. Subsequently, oxidative stress factors were evaluated in both the cerebral cortex and hippocampal regions of the rats. The results of this study showed that Pb exposure triggered anxiety-/depression-like behaviors and impaired object recognition memory, but locomotor activity was indistinguishable from the normal control rats. These behavioral deficiencies were associated with suppressed enzymatic and non-enzymatic antioxidant levels, and enhanced lipid peroxidation in the investigated brain regions. Notably, correlations were detected between behavioral deficits and oxidative stress generation in the Pb-exposed rats. Interestingly, sesamin treatment mitigated anxio-depressive-like behaviors, ameliorated object recognition memory impairment, and modulated oxidative-antioxidative status in the rats exposed to Pb. The results suggest that the anti-oxidative properties of sesamin may be one of the underlying mechanisms behind its beneficial effect in ameliorating behavioral deficits associated with Pb exposure.