Effects of Physical Activity and Ginkgo Biloba on Cognitive Function and Oxidative Stress Modulation in Ischemic Rats

Ginkgo biloba L. Prevents Hypobaric Hypoxia-Induced Spatial Memory Deficit Through Small Conductance Calcium-Activated Potassium Channel Inhibition: The Role of ERK/CaMKII/CREB Signaling

Hypobaric hypoxia (HH) is a stressful condition, which is more common at high altitudes and can impair cognitive functions. Ginkgo biloba L. leaf extract (GBE) is widely used as herbal medicine against different disorders. Its ability to improve cognitive functions, reduce oxidative stress, and promote cell survival makes it a putative therapeutic candidate against HH. The present study has been designed to explore the effect of GBE on HH-induced neurodegeneration and memory impairment as well as possible signaling mechanisms involved. 220–250 gm (approximately 6- to 8-week-old) Sprague Dawley rats were randomly divided into different groups. GBE was orally administered to respective groups at a dose of 100 mg/kg/day throughout the HH exposure, i.e., 14 days. Memory testing was performed followed by hippocampus isolation for further processing of different molecular and morphological parameters related to cognition. The results indicated that GBE ameliorates HH-induced memory impairment and oxidative damage and reduces apoptosis. Moreover, GBE modulates the activity of the small conductance calcium-activated potassium channels, which further reduces glutamate excitotoxicity and apoptosis. The exploration of the downstream signaling pathway demonstrated that GBE administration prevents HH-induced small conductance calcium-activated potassium channel activation, and that initiates pro-survival machinery by activating extracellular signal–regulated kinase (ERK)/calmodulin-dependent protein kinase II (CaMKII) and the cAMP response element–binding protein (CREB) signaling pathway. In summary, the current study demonstrates the beneficial effect of GBE on conditions like HH and provides various therapeutic targets involved in the mechanism of action of GBE-mediated neuroprotection.

Neuroprotective effects of Tiliacora triandra leaf extract in a mice model of cerebral ischemia reperfusion

OBJECTIVE

The present study investigated possible neuroprotective effects of ethanolic extract of Tiliacora triandra leaf against cerebral ischemic-reperfusion injury in mice.

MATERIALS AND METHODS

Forty male Institute of Cancer Research (ICR) mice were randomly divided into five groups: (1) Sham + 10% Tween 80, (2) bilateral common carotid artery occlusion (BCCAO) + 10% Tween 80, (3) BCCAO + T. triandra 300 mg/kg, (4) BCCAO + T. triandra 600 mg/kg and (5) BCCAO + quercetin 10 mg/kg. Cerebral ischemic-reperfusion (IR) was induced by 30 min of BCCAO followed by 45 min of reperfusion. After IR induction, total brain protein, calcium, malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), and reduced glutathione (GSH), as well as brain infraction and histopathological changes in vulnerable brain areas, such as the cerebral cortex and hippocampus, were evaluated.

RESULTS

The results showed that 2 weeks of pretreatment with T. triandra leaf extract at doses of 300 and 600 mg/kg significantly reduced calcium and MDA, but increased GSH and SOD and CAT activities. The extract significantly attenuated brain infarction and neuronal death in the cerebral cortex and hippocampus.

CONCLUSION

We demonstrated the neuroprotective effects of T. triandra leaf extract against cerebral IR injury in mice.

The neuroprotective mechanisms of ginkgolides and bilobalide in cerebral ischemic injury: a literature review

The incidence and mortality of strokes have increased over the past three decades in China. Ischemic strokes can cause a sequence of detrimental events in patients, including increased permeability and dysfunction of the blood-brain barrier, brain edema, metabolic disturbance, endoplasmic reticulum stress, autophagy, oxidative stress, inflammation, neuron death and apoptosis, and cognitive impairment. Thrombolysis using recombinant tissue plasminogen activator (rtPA) and mechanical embolectomy with a retrievable stent are two recognized strategies to achieve reperfusion after a stroke. Nevertheless, rtPA has a narrow therapeutic timeframe, and mechanical embolectomy has limited rates of good neurological outcomes. EGb761 is a standardized and extensively studied extract of Ginkgo biloba leaves. The ginkgolides and bilobalide that constitute a critical part of EGb761 have demonstrated protective properties towards cerebral injury. Ginkgolides include Ginkgolide A (GA), Ginkgolide B (GB), Ginkgolide C (GC), Ginkgolide J (GJ), Ginkgolide K (GK), Ginkgolide L (GL), and Ginkgolide M (GM). This review seeks to elucidate the neuroprotective effects and mechanisms of ginkgolides, especially GA and GB, and bilobalide in cerebral injury following ischemic strokes.

Endurance training on rodent brain antioxidant capacity: A meta-analysis

The influence of physical exercise on brain antioxidant defense mechanisms has been studied. Nevertheless, the effect of training volume on the brain`s redox balance remains unclear. In this meta-analysis, we compared the effect of training volume on antioxidant enzymatic resource and lipid peroxidation on various brain regions. The activities of the enzymes glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) and the levels of thiobarbituric acid reactive substances (TBARS) were also evaluated. The effects of training periods (weeks) and exercise duration were compared. Meta-analysis revealed that protocols over 8 weeks were associated with an increase in SOD (p =  0.0008) and CAT activities (p =  0.0001). Exercise durations for 30 and 60 min were associated with higher CAT activity (p =  0.04). Joint analysis revealed that moderate physical exercise over 4 and 8 weeks promoted a healthy enzymatic balance. However, high volumes of exercise over 8 weeks were associated with the increased antioxidant enzymatic activity, indicating higher reactive oxygen species (ROS) levels. The data also indicated that there is still limited research and inaccurate information, on the safety conditions of training periods that simulate tests of ultra resistance in humans.