Neuroprotective Effects of OMO within the Hippocampus and Cortex in aD-Galactose and A_25-35-Induced Rat Model of Alzheimer's Disease

Morinda officinalisF.C. How. (Rubiaceae) is a herbal medicine. It has been recorded that its oligosaccharides have neuroprotective properties. In order to understand the oligosaccharides extracted fromMorinda officinalis(OMO), a systematic study was conducted to provide evidence that supports its use in neuroprotective therapies for Alzheimer's disease (AD). AD rat models were prepared withD-galactose and A beta(25-35). The following groups were used in the present experiment: normal control group, sham-operated group, model group, Aricept group, OMO low-dose group, OMO medium-dose group, and OMO high-dose group. The effects on behavioral tests, antioxidant levels, energy metabolism, neurotransmitter levels, and AD-related proteins were detected with corresponding methodologies. AD rats administered with different doses of OMO all exhibited a significant (P<0.05) decrease in latency and an increase (P<0.05) in the ratio of swimming distance to total distance in a dose-dependent manner in the Morris water maze. There was a significant (P<0.05) increase in antioxidant enzyme activities (SOD, GSH-Px, and CAT), neurotransmitter levels (acetylcholine,gamma-GABA, and NE and DA), energy metabolism (Na+/K+-ATPase), and relative synaptophysin (SYP) expression levels in AD rats administered with OMO. Furthermore, there was a significant (P<0.05) decrease in MDA levels and relative expression levels of APP, tau, and caspase-3 in AD rats with OMO. The present research suggests that OMO protects againstD-galactose and A beta(25-35)-induced neurodegeneration, which may provide a novel strategy for improving AD in clinic.