Acupuncture has been reported to be beneficial in treating cognitive impairment in various pathological conditions. This review describes the effort to understand the signaling pathways that underlie the acupunctural therapeutic effect on cognitive function. We searched the literature in 12 electronic databases from their inception to November 2013, with full text available and language limited to English. Twenty-three studies were identified under the selection criteria. All recruited animal studies demonstrate a significant positive effect of acupuncture on cognitive impairment. Findings suggest acupuncture may improve cognitive function through modulation of signaling pathways involved in neuronal survival and function, specifically, through promoting cholinergic neural transmission, facilitating dopaminergic synaptic transmission, enhancing neurotrophin signaling, suppressing oxidative stress, attenuating apoptosis, regulating glycometabolic enzymes and reducing microglial activation. However, the quality of reviewed studies has room for improvement. Further high-quality animal studies with randomization, blinding and estimation of sample size are needed to strengthen the recognition of group differences.
Nitric oxide (NO) is a well-known vaso-dilator but its regulation in the retina is unclear. This study was conducted to quantify total NO production and retinal ganglion cell (RGC) loss in an experimental glaucoma model. Three quarters of the peri-limbal/episcleral drainage vessels and anterior angle (right eyes) of Sprague-Dawley rats were thermally blocked using laser irradiation, while the left eyes served as controls. We measured the intraocular pressure (IOP) of both eyes using a digital tonometer (Tonopen) 21, 28 and 35 days after the laser treatment. After 35 days, we determined the total NO level in retinas and remaining ocular tissues for the laser-treated and control eyes using a spectro-photometric assay. The viable RGC numbers were also determined by counting the cell bodies stained retrogradely by fluoro-gold. The laser treatment significantly increased the IOP 2.0-2.6x throughout the whole periodof measurements (P<0.0001). The mean total RGC number decreased significantly from 98725+/-5383 (+/-S.E. (M.)) to 69276+/-5592, or 29.8% reduction, in the laser-treated eyes after 35 days (P=0.008). The mean total NO level in the laser-treated retina was significantly increased by 2.4x compared with controls (P=0.016), but no significant difference was found in the eyecups (P>0.05). Laser treatment resulted in significant IOP elevation and RGC loss, suggesting that thermal coagulation of the perilimbal region may provide an alternate protocol for glaucoma study. NO level was increased by two-fold in the retina but not in other ocular tissues. Since NO is capable of producing powerful peroxynitrite anions and hydroxyl radicals, elevated level of NO has a potential role in glaucoma.
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