Long-term administration of soft drink causes memory impairment and oxidative damage in adult and middle-aged rats.

INTRODUCTION: The consumption of soft drinks has increased considerably in recent decades, mainly cola soft drinks. Excessive consumption of cola-based soft drinks is associated with several diseases and cognitive decline, particularly memory impairment. Furthermore, diets with high sugar can promote insulin resistance, metabolic syndrome, and dyslipidemia. AIM: Thus, the present study aimed to evaluate the effect of cola soft drink intake on behavioral alterations and oxidative damage in 2-, 8- and 14- month-old male Wistar rats. METHODS: The soft drink groups drank soft drink and/or water ad libitum during 67 days, the control groups ingested only water. Radial-arm maze and Y-maze were used to evaluate spatial memory, open-field to evaluate the habituation memory, and inhibitory avoidance to evaluate aversive memory. The behavioral tests started at the day 57 and finished at day 67 of treatment. At 68th day, the rats were killed; frontal cortex and hippocampus were dissected to the analysis of antioxidants enzymes catalase (CAT) and superoxide dismutase (SOD); and the oxidative markers thiobarbituric acid reactive substances (TBARS) and dichloro-dihydro-fluorescein diacetate (DCFH) were measured in the hippocampus. RESULTS AND DISCUSSION: The cola-based soft drink intake caused memory impairment in the radial-arm maze, Y-maze task, and open-field in the 2- and 8-month-old rat, but not in the 14-month-old. There were no difference among groups in the inhibitory avoidance test. In the frontal cortex, soft drink intake reduced CAT activity in the 8-month-old rats and SOD activity in the 8- and 14-month-old rats. In the hippocampus, the soft drink increased CAT activity in 2- and 8-month-old rats, increased DCFH levels at all ages, and increased TBARS levels in 2-month-rats. Therefore, the results show that long-term soft drink intake leads to memory impairment and oxidative stress. The younger seems to be more susceptible to the soft drink alterations on behavior; however, soft drink caused alterations in the oxidative system at all ages evaluated.

Folic acid prevents habituation memory impairment and oxidative stress in an aging model induced by D-galactose.

The present study aimed to evaluate the effect of folic acid treatment in an animal model of aging induced by D-galactose (D-gal). For this propose, adult male Wistar rats received D-gal intraperitoneally (100 mg/kg) and/or folic acid orally (5 mg/kg, 10 mg/kg or 50 mg/kg) for 8 weeks. D-gal caused habituation memory impairment, and folic acid (10 mg/kg and 50 mg/kg) reversed this effect. However, folic acid 50 mg/kg per se caused habituation memory impairment. D-gal increased the lipid peroxidation and oxidative damage to proteins in the prefrontal cortex and hippocampus from rats. Folic acid (5 mg/kg, 10 mg/kg, or 50 mg/kg) partially reversed the oxidative damage to lipids in the hippocampus, but not in the prefrontal cortex, and reversed protein oxidative damage in the prefrontal cortex and hippocampus. D-gal induced synaptophysin and BCL-2 decrease in the hippocampus and phosphorylated tau increase in the prefrontal cortex. Folic acid was able to reverse these D-gal-related alterations in the protein content. The present study shows folic acid supplementation as an alternative during the aging to prevent cognitive impairment and brain alterations that can cause neurodegenerative diseases. However, additional studies are necessary to elucidate the effect of folic acid in aging.

The Involvement of NLRP3 on the Effects of Minocycline in an AD-Like Pathology Induced by ß-Amyloid Oligomers Administered to Mice.

Alzheimer's disease (AD) is a neurodegenerative disease which is characterized by progressive memory loss, the accumulation of ß-amyloid peptide (Aß) (mainly Aß1-42), and more recently, by neuroinflammation, which has been highlighted as playing a central role in the development and progress of AD. This study utilized 100-day-old Balb/c mice for the induction of an AD-like dementia model. The animals were administered with Aß1-42 oligomers (400 pmol/site) or artificial cerebrospinal fluid (ACSF) into the left cerebral ventricle. Twenty-four hours after intracerebroventricular administration, the animals were treated with minocycline (50 mg/kg, via oral gavage) for 17 days. The animals' locomotion was evaluated using the open-field test. The spatial memory was tested using the Y-maze, and the aversive memory was evaluated using the inhibitory avoidance task. Treatment with minocycline was shown to improve both spatial and aversive memories in mice that were submitted to the dementia model. In addition, minocycline reduced the levels of Aß and microglial activation in the animals that received the administration of Aß1-42 oligomers. Moreover, the results suggest that the decrease in microglial activation occurred because of a reduction in the levels of toll-like receptors 2 (TLR2) content, and its adapter protein MyD88, as well as a reduction in the levels of the protein NLRP3, which is indispensable in the assembly of inflammasome. These observations were evaluated via immunohistochemistry and confirmed using the Western blot analysis. Treatment with minocycline had no effect in preventing apoptotic morphologic alterations of the neurons. Thus, the anti-inflammatory effect of minocycline involves TLR2 receptors and NLRP3, besides being beneficial by ameliorating memory impairments. Graphical Abstract.

Sodium butyrate improves memory and modulates the activity of histone deacetylases in aged rats after the administration of d-galactose.

Aging is a complex biological process. Epigenetic alterations have been related to both aging and memory decline. Included amongst these alterations is histone acetylation, which may play a crucial role in aging. Thus, the aims of the present study were to standardize the animal model of d-galactose (d-gal), and to evaluate the effects caused by sodium butyrate (SB), which is a histone deacetylase inhibitor on memory, the modulation of histone deacetylases (HDACs), and also DNA damage in 2, 6 or 16-month-old Wistar rats which were subjected to administrations of d-gal. To help choose the best dose of d-gal for the induction of the aging model, we performed a dose-response curve (100, 200 or 300 mg/kg). d-Gal was administered orally to the 2-month-old rats for a period of 30 days. After this, d-gal (200 mg/kg) or water were administered to the 2, 6 or 16-month-old rats for a period of 30 days. On the 24th day, treatment was started with SB (600 mg/kg) intraperitoneally, for a period of 7 days. SB was able to reverse the damage to habituation memory caused by d-gal in the 2 and 6-month-old rats, but was unable to reverse the damage in the 16 month-old animals. In addition, SB was able to reverse the damage caused by natural aging in the 16-month-old animals. In the inhibitory avoidance task, SB improved the damage caused by d-gal in the 2, 6 and 16-month-old animals and had the same result against the effects of natural aging in the 16-month-old rats. Moreover, d-gal caused an increase in the level of HDACs activity in the 16-month-old animals, and SB was able to reverse this effect in the frontal cortex and hippocampus. The 16-month-old animals showed an increase in the frequency of DNA damage in peripheral blood, and SB was able to reduce this damage. Moreover, d-gal caused an increase in the index and frequency of DNA damage in the 2 and 6-month-old animals, and treatment with SB was able to prevent this damage. Thus, the present study showed the protective effects of SB on the memory of naturally aged and d-gal induced aging in rats. Therefore, the present study shows new findings for the use of SB in aging.

Minocycline reduces inflammatory parameters in the brain structures and serum and reverses memory impairment caused by the administration of amyloid ß (1-42) in mice.

Alzheimer's disease (AD) is a neurodegenerative disorder and the most common type of age-related dementia. Cognitive decline, beta-amyloid (Aß) accumulation, neurofibrillary tangles, and neuroinflammation are the main pathophysiological characteristics of AD. Minocycline is a tetracycline derivative with anti-inflammatory properties that has a neuroprotective effect. The aim of this study was to evaluate the effect of minocycline on memory, neurotrophins and neuroinflammation in an animal model of AD induced by the administration of Aß (1-42) oligomer. Male BALB/c mice were treated with minocycline (50mg/kg) via the oral route for a total of 17days, 24h after intracerebroventricular administration of Aß (1-42) oligomer. At the end of this period, was performed the radial maze test, and 24h after the last minocycline administration, serum was collected and the cortex and hippocampus were dissected for biochemical analysis. The administration of minocycline reversed the memory impairment caused by Aß (1-42). In the hippocampus, minocycline reversed the increases in the levels of interleukin (IL-1ß), Tumor Necrosis Factor- alpha (TNF-α) and, IL-10 caused by Aß (1-42). In the cortex, AD-like model increase the levels of IL-1ß, TNF-α and, IL-4. Minocycline treatment reversed this. In the serum, Aß (1-42) increased the levels of IL-1ß and IL-4, and minocycline was able to reverse this action, but not to reverse the decrease of IL-10 levels. Minocycline also reversed the increase in the levels of Brain-derived neurotrophic factor (BDNF) in the hippocampus caused by Aß (1-42), and reduced Nerve Growth Factor (NGF) increases in the total cortex. Therefore, our results indicate that minocycline causes improvements in the spatial memory, and cytokine levels were correlated with this effect in the brain it. Besides this, minocycline reduced BDNF and NGF levels, highlighting the promising effects of minocycline in treating AD-like dementia.