Neuroprotective effects of resveratrol in Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder, which is commonly seen in older individuals. This is characterized by cognitive dysfunction, which leads to dementia. Pharmacological treatments for AD are mainly targeted on its symptoms like memory loss and cognitive impairment. The pathophysiology involved in AD is intra-neuronal accumulation of hyper-phosphorylated tau protein as neurofibrillary tangle and extra cellular beta amyloid plaque deposition, which is due to oxidative stress. Here we review the neuro-protective effects of Resveratrol (RSV) and its treatment efficacy in AD. RSV is a naturally available polyphenolic compound, which has antioxidant, anti-cancerous, anti-inflammatory and anti-aging properties. RSV crosses blood brain barrier and exerts its antioxidant effect by enhancing the anti-oxidant enzymes. RSV is involved in Sirtuin (SIRT1) mediated lifespan extension activity. RSV has reduced glial activation and helped in increasing the hippocampal neurogenesis. RSV was able to decrease the expression of amyloid precursor protein, along with improvement of spatial working memory. Since RSV acts as an antioxidant, it can be safely used as oral drug.

Anxiolytic activity of aqueous extract of Camellia sinensis in rats.

OBJECTIVES: The present study was undertaken to evaluate anxiolytic effect of Camellia sinensis (CS) and possible mechanism on acute and chronic administration in rats. MATERIALS AND METHODS: Eight groups of rats with six in each group were used. Group I served as control. Group II received diazepam (1 mg/kg). Groups III, IV, and V received CS in doses of 3.3, 16.5, and 33 mg/kg, respectively. Three pharmacologically validated experimental models - elevated plus maze (EPM), light and dark box (LDB), and open field tests (OFT) - were employed. Each animal was tested initially in the EPM and then in the LDB, followed by the OFT in a single setting. In EMP, number of entries into, time spent in, and number of rears in each arm in a 5-min period were noted. In LDB, number of entries and time spent in bright arena, number of rears, and duration of immobility were noted. In OFT, number of peripheral and central squares crossed, time spent, and number of rears in central squares were observed for a 5-min period. One-way ANOVA followed by post hoc least significant difference test was performed. RESULTS: In EPM and LDB, CS at 3.3, 16.5, and 33 mg/kg (acute and chronic models) increased the number of entries and time spent and rearing in the open arms and bright arena, respectively, compared to control. In the OFT, CS at 16.5 and 33 mg/kg significantly increased the number of squares crossed, time spent, and the number of rears in the central squares compared to control. Anxiolytic effect was dose dependent in EPM and LDB and CS at 33 mg/kg showed better anxiolytic activity compared to diazepam (1 mg/kg) in all models. Flumazenil (0.5 mg/kg) and bicuculline (1 mg/kg) completely inhibited while picrotoxin (1 mg/kg) partially inhibited the anxiolytic effect of CS. Diazepam and CS at 33 mg/kg reduced the locomotor activity in rats. CONCLUSION: CS has dose-dependent anxiolytic activity which is comparable to diazepam. Anxiolytic action of CS is likely mediated through GABAA-benzodiazepine receptor - Cl - channel complex - since flumazenil and bicuculline inhibited the anxiolytic effect.

Analgesic effect of extracts of Alpinia galanga rhizome in mice.

OBJECTIVE: To evaluate the analgesic effect of extracts of Alpinia galanga (AG) rhizome in mice and elucidate the possible mechanism for its analgesic action. METHODS: Analgesic action of extracts of AG rhizome was studied in three experimental models of nociception. Albino mice of both sexes weighing 25 to 30 g were used in this study. For the hot-plate test, mice in the five groups with six in each received three different doses of ethanolic extracts of dried rhizome of AG suspended in 2% gum acacia orally, morphine subcutaneously and 2% gum acacia orally, respectively. Reaction time was observed after administration of vehicle or drugs. For the hot-plate test after naloxone pretreatment, mice in the five groups received naloxone subcutaneously 30 min prior to the administration of vehicle or drugs and reaction time was observed as explained above. In the writhing test, writhes were induced by injecting acetic acid intraperitoneally in another 30 mice which were randomly allocated to five groups of six in each and received three different doses of ethanolic extracts of dried rhizome of AG suspended in 2% gum acacia, aspirin suspended in 2% gum acacia and 2% gum acacia orally, respectively. The mice were observed individually for a period of 15 min and the number of writhes was recorded for each animal. RESULTS: AG treatment significantly increased the latency period in the hot-plate test at all three doses at 30, 60, 90 and 120 min time intervals compared with control group (P<0.05 or P<0.01). Naloxone pretreatment significantly reduced the latency period in hot-plate test for both AG and morphine groups as compared with corresponding groups that did not receive naloxone pretreatment (P<0.05 or P<0.01). AG at all doses significantly reduced the number of writhes compared with control group (P<0.01). CONCLUSION: The study confirmed the analgesic effect of AG rhizome and hence justified its use in ethnomedicine for the treatment of pain due to various causes. The probable mechanism of its analgesic action may be central as well as peripheral.

Analgesic effect of extracts of Alpinia galanga rhizome in mice / 中西医结合学报

To evaluate the analgesic effect of extracts of Alpinia galanga (AG) rhizome in mice and elucidate the possible mechanism for its analgesic action.