The role of WGA for decreasing the accumulation of Aβ: A new approach to promote transsynaptic transport of Aβ in the rat

Wheat germ agglutinin (WGA) has been known to be transported easily to terminals from neuronal cell bodies and pass through synapses. In the present fluorescent experiments, coinjection of fluorescent WGA (FWGA) with F-Amyloid-β (FAβ) into one side of the vagus nerve (VN) at the cervical portion of the rats resulted in heavy labeling of these substances in the nodose ganglion (NG) and nucleus of solitary tract (NST) ipsilaterally compared to each injection of FWGA and FAβ. It was of interest that the labeling is characterized by existence in cytoplasm of neurons of the NG and NST. Further observations by the laser scanning confocal microscope showed that co-localization of FWGA and FAβ is present in close vicinity to the nucleus of neurons of the NST. In the immunohistochemical electron microscopic experiments, co-injection of WGA with Aβ resulted in heavy accumulation of reaction product (RP) in axon terminals and dendrites in the neuropil of the NST. The majority of these terminals and dendrites indicated to contain large-sized RP (0.20-0.40 μm in diameter) in addition to small(0.03-0.09 μm) and medium-sized RP (0.10-0.15 μm) found in the case of injection of Aβ. Interestingly, large-sized RP transported to neurons of the NST formed a complex with the same-sized RP. The present findings might indicate that WGA is a valuable tool to decrease the accumulation of Aβ by transsynaptic transport and offers new perspectives for its application in the Alzheimer’s disease.