Pretreatment with Rhodiola rosea extract reduces cognitive impairment induced by intracerebroventricular streptozotocin in rats: implication of anti-oxidative and neuroprotective effects.

OBJECTIVE: To investigate the pretreatment effects of Rhodiola rosea (R. rosea) extract on cognitive dysfunction, oxidative stress in hippocampus and hippocampal neuron injury in a rat model of Alzheimer's disease (AD). METHODS: Male Sprague-Dawley rats were pretreated with R. rosea extract at doses of 1.5, 3.0, and 6.0 g/kg for 3 weeks, followed by bilateral intracerebroventricular injection with streptozotocin (1.5 mg/kg) on days 1 and 3. Behavioral alterations were monitored after 2 weeks from the lesion using Morris water maze task. Three weeks after the lesion, the rats were sacrificed for measuring the malondialdehyde (MDA), glutathione reductase (GR) and reduced glutathione (GSH) levels in hippocampus and histopathology of hippocampal neurons. RESULTS: The MDA level was significantly increased while the GR and GSH levels were significantly decreased with striking impairments in spatial learning and memory and severe damage to hippocampal neurons in the model rat induced by intracerebroventricular injection of streptozotocin. These abnormalities were significantly improved by pretreatment with R. rosea extract (3.0 g/kg). CONCLUSION: R. rosea extract can protect rats against cognitive deficits, neuronal injury and oxidative stress induced by intracerebroventricular injection of streptozotocin, and may be used as a potential agent in treatment of neurodegenerative diseases such as AD.

[Inhibitive effects of Panax notoginseng saponins on expression of Abeta(1-40), Abeta(1-42) protein in SAMP8's brain].

OBJECTIVE: To observe inhibitive effects of Panax notoginseng saponins on expression of Abeta(1-40), Abeta(1-42) protein in SAMP8's brain. METHODS: Amount of Abeta(1-40), Abeta(1-42 immuno-positive neurons was detected in parietal cortex and hippocamp in their brains under high power lens (40 x) by immunohistochemistry analysis. RESULTS: PNS could reduce the amount of Abeta(1-40), Abeta(1-42) protein in parietal cortex and hippocamp. CONCLUSION: PNS can reduce the amount of Abeta(1-40), Abeta(1-42) protein in SAMP8's brain.

Mitochondrial protective and anti-apoptotic effects of Rhodiola crenulata extract on hippocampal neurons in a rat model of Alzheimer's disease.

In our previous study, we found that the edible alcohol extract of the root of the medicinal plant Rhodiola crenulata (RCE) improved spatial cognition in a rat model of Alzheimer's disease. Another study from our laboratory showed that RCE enhanced neural cell proliferation in the dentate gyrus of the hippocampus and prevented damage to hippocampal neurons in a rat model of chronic stress-induced depression. However, the mechanisms underlying the neuroprotective effects of RCE are unclear. In the present study, we investigated the anti-apoptotic effect of RCE and its neuroprotective mechanism of action in a rat model of Alzheimer's disease established by intracerebroventricular injection of streptozotocin. The rats were pre-administered RCE at doses of 1.5, 3.0 or 6.0 g/kg for 21 days before model establishment. ATP and cytochrome c oxidase levels were significantly decreased in rats with Alzheimer's disease. Furthermore, neuronal injury was obvious in the hippocampus, with the presence of a large number of apoptotic neurons. In comparison, in rats given RCE pretreatment, ATP and cytochrome c oxidase levels were markedly increased, the number of apoptotic neurons was reduced, and mitochondrial injury was mitigated. The 3.0 g/kg dose of RCE had the optimal effect. These findings suggest that pretreatment with RCE prevents mitochondrial dysfunction and protects hippocampal neurons from apoptosis in rats with Alzheimer's disease.

[Effects of the Panax notoginseng saponins on the level of synaptophysin protein in brain in rat model with lesion of Meynert].

OBJECTIVE: To observe the protective effect of Panax notoginseng saponins (PNS) on the level of synaptophysin ptotein in brain in rat model with Alzheimer's disease (AD). METHOD: The AD rat models were established by intra-peritoneal injection of D-galactose combined with excitatory neurotoxin ibotenic acid injection into bilateral nbM. The activity and content of synaptophysin protein in brain were determined by immunohistochemistry analysis. RESULT: PNS could reduce the lesion of level of synaptophysin protein in brain, as compared with those of model group's rats. CONCLUSION: PNS plays a protective role by reducing down of the level of synaptophysin protein in brain in lesion of AD animal model.

Neuroprotective effect of preadministration with Ganoderma lucidum spore on rat hippocampus.

The aim of this study was to investigate if preadministration with Ganoderma lucidum spore (GLS) could (1) alleviate oxidative stress and mitochondrial dysfunction in rat hippocampus of intracerebroventricular (ICV) injection of streptozotocin (STZ), (2) protect neurons from apoptosis, and (3) improve cognitive dysfunction. Three groups of Sprague-Dawley rats were preadministrated with GLS at doses of 2.0, 4.0 and 8.0 g/kg, respectively, for 3 weeks before the ICV STZ injury. Thereafter the rats were operated with ICV STZ (1.5 mg/kg) bilaterally on days 1 and 3. The behavioral alterations, oxidative stress indexes, ATP, cytochrome oxidase (CytOx), and histopathology of hippocampal neurons were studied. The results showed that ICV STZ model rats exhibited a significant increase of malondialdehyde (MDA), a significant decrease of glutathione reductase (GR), reduced glutathione (GSH), ATP and CytOx, accompanied with marked impairments in spatial learning and memory, and severe damage of hippocampal neuron. In conclusion, preadministration with GLS at dose of 8.0 g/kg in ICV STZ rats significantly reversed these abnormalities. In conclusion, preadministration with GLS might protect hippocampus from oxidative impairment and energy metabolism disturbance of ICV STZ. This may also provide useful information for future research on the pathogenesis and prevention of Alzheimer's disease (AD).

Protective effects of a Rhodiola crenulata extract and salidroside on hippocampal neurogenesis against streptozotocin-induced neural injury in the rat.

Previously we have demonstrated that a Rhodiola crenulata extract (RCE), containing a potent antioxidant salidroside, promotes neurogenesis in the hippocampus of depressive rats. The current study was designed to further investigate the protective effect of the RCE on neurogenesis in a rat model of Alzheimer's disease (AD) induced by an intracerebroventricular injection of streptozotocin (STZ), and to determine whether this neuroprotective effect is induced by the antioxidative activity of salidroside. Our results showed that pretreatment with the RCE significantly improved the impaired neurogenesis and simultaneously reduced the oxidative stress in the hippocampus of AD rats. In vitro studies revealed that (1) exposure of neural stem cells (NSCs) from the hippocampus to STZ strikingly increased intracellular reactive oxygen species (ROS) levels, induced cell death and perturbed cell proliferation and differentiation, (2) hydrogen peroxide induced similar cellular activities as STZ, (3) pre-incubation of STZ-treated NSCs with catalase, an antioxidant, suppressed all these cellular activities induced by STZ, and (4) likewise, pre-incubation of STZ-treated NSCs with salidroside, also an antioxidant, suppressed all these activities as catalase: reduction of ROS levels and NSC death with simultaneous increases in proliferation and differentiation. Our findings indicated that the RCE improved the impaired hippocampal neurogenesis in the rat model of AD through protecting NSCs by its main ingredient salidroside which scavenged intracellular ROS.