Investigating neurodegeneration in the retina of tau P301L mice

Abstract

Neurodegeneration is a collective term for the progressive loss of structure, function or even death of neurons. This includes diseases like Alzheimer’s disease, frontotemporal dementia, Parkinson’s disease and motor neuron disease. Recent researches have shown great interest in the role of tau proteins, which have versatile functions including microtubule stabilization and signal relay in the central nervous system.

Retina and optic nerve, being part of the central nervous system, can also be affected by similar processes. In neurodegenerative diseases visual disturbances including difficulties in reading and finding object, depth perception, perceiving structure from motion, color recognition and impairment in spatial contrast sensitivity have all been observed. Some of these defects may be attributed to changes at ocular level.

The effect of tau mutation was investigated in this study utilizing a transgenic P301L tau mice model. Morphometric analysis has been utilized to quatify the neurodegenerative changes, including the thickness of inner nuclear layer(INL), density of retinal ganglion cells(RGCs) and size of RGCs. Retinal sections stained by hematoxylin and eosin(H&E) were analyzed. Comparisons were made between the P301L tau mice and the control mice in addition to comparisons between different age groups.

The study found that there was a significant decrease of thickness of INL of P301L tau mice when compared with control mice. The effect was more pronounced in the peripheral area and the effect increased with age. Regarding density of RGCs, P301L tau mice showed a similar age-related decline as control mice. And regarding the size of RGCs, the RGCs from P301L tau mice increased in size with age and the RGCs from control mice decreased in size with age.