Toxicity Profiles of Kleeb Bua Daeng Formula, a Traditional Thai Medicine, and Its Protective Effects on Memory Impairment in Animals.

Kleeb Bua Daeng (KBD) formula has long been used in Thailand as a traditional herbal medicine for promoting brain health. Our recent reports illustrated that KBD demonstrates multiple modes of action against several targets in the pathological cascade of Alzheimer's disease (AD). The main purpose of the present study was to determine the protective effect and mechanism of KBD in amyloid beta (Aß)-induced AD rats and its toxicity profiles. Pretreatment with the KBD formula for 14 days significantly improved the short- and long-term memory performance of Aß-induced AD rats as assessed by the Morris Water Maze (MWM) and object-recognition tests. KBD treatment increased the activities of the antioxidant enzymes catalase, superoxide dismutase, and glutathione peroxidase; reduced the malondialdehyde content, and; decreased the acetylcholinesterase activity in the rat brain. An acute toxicity test revealed that the maximum dose of 2000 mg/kg did not cause any mortality or symptoms of toxicity. An oral, subchronic toxicity assessment of KBD at doses of 125, 250, and 500 mg/kg body weight/day for 90 days showed no adverse effects on behavior, mortality, hematology, or serum biochemistry. Our investigations indicate that KBD is a nontoxic traditional medicine with good potential for the prevention and treatment of AD.

Clausena Harmandiana root extract attenuated cognitive impairments via reducing amyloid accumulation and neuroinflammation in Aß1-42-induced rats.

BACKGROUND: Alzheimer's disease (AD) pathogenesis is associated with amyloid-ß (Aß)-induced neuroinflammation. In AD, the activation of microglia caused by Aß accumulation is followed by the synthesis and release of pro-inflammatory cytokines, including interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNFα), and ultimately leads to cognitive impairments. Clausena harmandiana (CH) is a medicinal plant in the Rutaceae family and has been used in folk medicine to relieve illnesses such as stomachache and headache, and as a health tonic. Interestingly, CH root extract (CHRE) has several anti-inflammatory and other pharmacological activities, but there are no studies in AD-like animal models. OBJECTIVES: This study aims to evaluate the effects of CHRE on cognitive impairments, increased Aß1-42 protein levels, and neuroinflammation in Aß1-42-induced rats. METHODS: Forty-eight adult male Sprague-Dawley rats (250-300 g) were randomly divided into 6 groups (n = 8) of the sham control, V + Aß, CB + Aß CHRE125 + Aß, CHRE250 + Aß, and CHRE500 + Aß. Sodium carboxymethylcellulose, Celebrex (10 mg/kg BW) and CHRE (125, 250, and 500 mg/kg BW) were given orally or without any treatment for 35 days. On day 21, aggregated Aß1-42 at a concentration of 1 µg/µl were injected into both lateral ventricles (1 µl/side) of all treated rats, while sterilized normal saline were injected to untreated rats. Ten days later, the novel object recognition test was performed to assess their recognition memory. At the end of the test period, an overdose of thiopental sodium (120 mg/kg BW) and transcardial perfusion with 0.9% normal saline solution were used to euthanize all rats. Then Aß1-42 protein levels and the expression of inflammatory markers (CD11b-positive microglia, IL-1ß, and TNFα) were investigated in the cerebral cortex and hippocampus. RESULTS: Pretreatment with CHRE at all doses could attenuate short- and long-term impairments in recognition memory. Additionally, CHRE also inhibited the increase of Aß1-42 protein levels and the expression of inflammatory markers in both brain regions as well as receiving Celebrex. CONCLUSIONS: This suggests that preventive treatment of CHRE might be a potential therapy against cognitive impairments via reducing Aß1-42 protein levels and neuroinflammation caused by Aß1-42.

Hesperidin Reduces Memory Impairment Associated with Adult Rat Hippocampal Neurogenesis Triggered by Valproic Acid.

Treatment with valproic acid (VPA) deteriorates hippocampal neurogenesis, which leads to memory impairment. Hesperidin (Hsd) is a plant-based bioflavonoid that can augment learning and memory. This study aimed to understand the effect of Hsd on the impairment of hippocampal neurogenesis and memory caused by VPA. The VPA (300 mg/kg) was administered by intraperitoneal injection twice daily for 14 days, and Hsd (100 mg/kg/day) was administered by oral gavage once a day for 21 days. All rats underwent memory evaluation using the novel object location (NOL) and novel object recognition (NOR) tests. Immunofluorescent staining of Ki-67, BrdU/NeuN, and doublecortin (DCX) was applied to determine hippocampal neurogenesis in cell proliferation, neuronal survival, and population of the immature neurons, respectively. VPA-treated rats showed memory impairments in both memory tests. These impairments resulted from VPA-induced decreases in the number of Ki-67-, BrdU/NeuN-, and DCX-positive cells in the hippocampus, leading to memory loss. Nevertheless, the behavioral expression in the co-administration group was improved. After receiving co-administration with VPA and Hsd, the numbers of Ki-67-, BrdU/NeuN-, and DCX-positive cells were improved to the normal levels. These findings suggest that Hsd can reduce the VPA-induced hippocampal neurogenesis down-regulation that results in memory impairments.

Effect of combined extracts of aged garlic, ginger, and chili peppers on cognitive performance and brain antioxidant markers in Aß-induced rats.

A combination of aged garlic, ginger, and chili peppers extracts (AGC) was studied by high-performance liquid chromatography, 2,2-diphenyl-1-picrylhydrazyl, and ferric-reducing antioxidant assays, and oxidative stress markers were analyzed in Aß1-42-induced rats. The AGC was orally administered to Wistar rats at doses of 125, 250, and 500 mg/kg body weight (AGC125, AGC250, AGC500, respectively) for 64 days. At day 56, Aß1-42 was injected via both sides of the lateral ventricles. The effects of the AGC on spatial and recognition memory were examined using a Morris water maze and novel object recognition tasks. Rats induced with Aß1-42 exhibited obvious cognitive deficits, as demonstrated by their increased escape latency time (ET) and decreased retention time (RT) and percentage of discriminative index (DI). When compared with the control group, all AGC-treated rats showed significantly shorter ETs and higher DIs during the 5-min delay testing phase. Rats treated with AGC250 also had significantly longer RTs. Administration of Aß1-42 significantly increased malondialdehyde (MDA) levels and decreased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels in the rat brain homogenate. Pretreatment with the AGC caused significant increases in SOD, GPx, and CAT activities, as well as a significant decrease in MDA in the rat brain homogenates after Aß-induced neurotoxicity. Our results suggested that an AGC may ameliorate cognitive dysfunction in Aß-treated rats due to its role in the upregulation of SOD, GPx, and CAT.

Asiatic acid protects against cognitive deficits and reductions in cell proliferation and survival in the rat hippocampus caused by 5-fluorouracil chemotherapy.

The chemotherapy drug, 5-fluorouracil (5-FU), has been reported to cause cognitive impairments in cancer patients. The drug also reduces cell proliferation and survival in the brain. Asiatic acid (AA) is a triterpene compound found in Centella asiatica that can protect against reduction of neurogenesis in the hippocampus and memory deficits induced by valproic acid (VPA). In the present study, we investigated the preventive effects of AA on the deficits in spatial working memory and cell proliferation and survival caused by 5-FU chemotherapy in a rat model. Male Sprague Dawley rats received 5-FU (5 i.v. injections, 25 mg/kg) on day 8, 11, 14, 17 and 20 of the study. This was co-administered with AA (30 mg/kg, oral gavage tube) either 20 days before receiving 5-FU (preventive), after receiving 5-FU (recovery), or for the entire period of the experiment (throughout). Spatial working memory was determined using the novel object location (NOL) test and hippocampal cell proliferation and survival of dividing cells were quantified using immunohistochemistry. Rats in the 5-FU alone and recovery groups showed memory deficits in the NOL test and reductions in cell proliferation and cell survival in the subgranular zone (SGZ) of the hippocampal dentate gyrus. Rats in the control, AA alone, and both preventive and throughout co-administration groups, however, did not exhibit these characteristics. The results showed that 5-FU chemotherapy impaired memory and reduced cell proliferation and cell survival in the SGZ of the hippocampal dentate gyrus. However, these impairments in the animals receiving 5-FU chemotherapy were restored to control levels when AA was co-administered before and during 5-FU treatment. These data demonstrate that AA can prevent the spatial working memory and hippocampal neurogenesis impairments caused by 5-FU chemotherapy.

Effects of Aged Garlic Extract on Cholinergic, Glutamatergic and GABAergic Systems with Regard to Cognitive Impairment in Aß-Induced Rats.

Alzheimer's disease (AD) has been linked to the degeneration of central cholinergic and glutamatergic transmission, which correlates with progressive memory loss and the accumulation of amyloid-ß (Aß). It has been claimed that aged garlic extract (AGE) has a beneficial effect in preventing neurodegeneration in AD. Therefore, the objective of this study was to investigate the effects of AGE on Aß-induced cognitive dysfunction with a biochemical basis in the cholinergic, glutamatergic, and GABAergic systems in rats. Adult male Wistar rats were orally administered three doses of AGE (125, 250, and 500 mg/kg) daily for 65 days. At day 56, they were injected with 1 µL of aggregated Aß (1-42) into each lateral ventricle, bilaterally. After six days of Aß injection, the rats' working and reference memory was tested using a radial arm maze. The rats were then euthanized to investigate any changes to the cholinergic neurons, vesicular glutamate transporter 1 and 2 proteins (VGLUT1 and VGLUT2), and glutamate decarboxylase (GAD) in the hippocampus. The results showed that AGE significantly improved the working memory and tended to improve the reference memory in cognitively-impaired rats. In addition, AGE significantly ameliorated the loss of cholinergic neurons and increased the VGLUT1 and GAD levels in the hippocampus of rat brains with Aß-induced toxicity. In contrast, the VGLUT2 protein levels did not change in any of the treated groups. We concluded that AGE was able to attenuate the impairment of working memory via the modification of cholinergic neurons, VGLUT1, and GAD in the hippocampus of Aß-induced rats.

Neuroprotective Effects of Aged Garlic Extract on Cognitive Dysfunction and Neuroinflammation Induced by ß-Amyloid in Rats.

Neuroinflammation is pathological evidence of Alzheimer's disease (AD) that likely starts as a host defense response to the damaging effects of the ß-amyloid (Aß) deposits in the brain. The activation of microglia may promote the neurodegenerative process through the release of proinflammatory cytokines, such as interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNFα), which may lead to neuronal damage and eventual death. Aged garlic extract (AGE) has been reported to have multiple biological activities, including anti-inflammatory effects. Therefore, the objective of this study was to investigate the effect of AGE on Aß (1-42)-induced cognitive dysfunction and neuroinflammation. Adult male Wistar rats were given AGE (125, 250, and 500 mg/kg BW, body weight), orally administered, daily for 56 days. They were then injected with 1 µL of aggregated Aß (1-42) into the lateral ventricles; bilaterally. Seven days later, their recognition memory was evaluated using a novel object recognition (NOR) test. Then the rats were sacrificed to investigate the alteration of microglia cells, IL-1ß and TNFα in the cerebral cortex and hippocampus. The results indicated that AGE at doses of 250 and 500 mg/kg BW significantly improved short-term recognition memory in cognitively impaired rats. In addition, AGE significantly minimized the inflammatory response by reducing the activation of microglia and IL-1ß to the levels found in the control, which is similar to the results found in Celebrex-treated rats. In conclusion, AGE may be useful for improving the short-term recognition memory and relieve the neuroinflammation in Aß-induced rats.

Kaempferia parviflora extract ameliorates the cognitive impairments and the reduction in cell proliferation induced by valproic acid treatment in rats.

Kaempferia parviflora is a herbal plant whose rhizomes are used in traditional medicine. Investigations of this plant have shown it to have antidepressant activity and to improve learning and memory in animal models. The aim of the present investigation was to determine whether K. parviflora could protect the brain from the impairments in cognition and hippocampal neurogenesis which are caused by valproic acid (VPA). Male Sprague Dawley rats (180-200g) were given once daily K. parviflora extract (100mg/kg) via oral gavage for 21 days. Rats received twice daily intraperitoneal injections of valproic acid (300mg/kg) from days 8 to 21 of the experiment. Spatial memory was tested using the novel object location (NOL) test five days after the end of treatment. Cell proliferation in the sub granular zone (SGZ) of the dentate gyrus was quantified by immunohistochemistry and levels of doublecortin (DCX) were determined by Western blotting. Co-treatment of VPA and K. parviflora prevented the cognitive decline and reduction in proliferating cells caused by VPA. Furthermore, co-treatment significantly increased DCX protein levels within the hippocampus. These findings demonstrate that K. parviflora is able to prevent the brain from VPA-induced the impairments of spatial memory and proliferating cells within the SGZ.

Asiatic Acid Prevents the Deleterious Effects of Valproic Acid on Cognition and Hippocampal Cell Proliferation and Survival.

Valproic acid (VPA) is commonly prescribed as an anticonvulsant and mood stabilizer used in the treatment of epilepsy and bipolar disorder. A recent study has demonstrated that VPA reduces histone deacetylase (HDAC) activity, an action which is believed to contribute to the effects of VPA on neural stem cell proliferation and differentiation which may explain the cognitive impairments produced in rodents and patients. Asiatic acid is a triterpenoid derived from the medicinal plant Centella asiatica. Our previous study has shown that Asiatic acid improves working spatial memory and increases cell proliferation in the sub granular zone of the hippocampal dentate gyrus. In the present study we investigate the effects of Asiatic acid in preventing the memory and cellular effects of VPA. Male Spraque-Dawley rats were orally administered Asiatic acid (30 mg/kg/day) for 28 days, while VPA-treated animals received injections of VPA (300 mg/kg) twice a day from Day 15 to Day 28 for 14 days. Spatial memory was determined using the novel object location (NOL) test and hippocampal cell proliferation and survival was quantified by immuostaining for Ki-67 and Bromodeoxyuridine (BrdU), respectively. The results showed that VPA-treated animals were unable to discriminate between objects in familiar and novel locations. Moreover, VPA significantly reduced numbers of Ki-67 and BrdU positive cells. These results indicate that VPA treatment caused impairments of spatial working memory, cell proliferation and survival in the subgranular zone (SGZ) of the hippocampal dentate gyrus (DG). However, these abnormalities were restored to control levels by co-treatment with Asiatic acid. These data demonstrate that Asiatic acid could prevent the spatial memory and neurogenesis impairments caused by VPA.

Purple rice berry is neuroprotective and enhances cognition in a rat model of Alzheimer's disease.

Alzheimer's disease, a neurodegenerative disease characterized by progressive memory loss and cognitive impairment, is the most common type of dementia in aging populations due to severe loss of cholinergic neurons in a specific area. Oxidative stress is known to be involved in the pathogenesis of this condition. Therefore, the cognition-enhancing and neuroprotective effects of rice berry (Oryza sativa), a purple-pigmented rice that is rich in antioxidant substances, was evaluated. Young adult male Wistar rats, weighing 180-220 g, were orally given rice berry once daily at doses of 180, 360, and 720 mg/kg of body weight for a period of 2 weeks before and 1 week after the induction of memory deficit and cholinergic lesions with AF64A, a specific cholinotoxin, via bilateral intracerebroventricular administration. One week following AF64A administration the rats were evaluated for spatial memory, neuron density, acetylcholinesterase activity, and hippocampal lipid peroxidation products. Our results showed that rice berry could significantly prevent memory impairment and hippocampal neurodegeneration in hippocampus. Moreover, it also decreased hippocampal acetylcholinesterase activity and lipid peroxidation product formation. These results suggest that rice berry has potential as an effective agent for neurodegeneration and memory impairment in Alzheimer's disease.