Abstract: The process of neurite outgrowth and branching is a crucial aspect of neuronal development and regeneration. Axons and dendrites, sometimes referred to as neurites, are extensions of a neuron’s cellular body that are used to start networks. Here we explored the effects of diethyl (3,4-dihydroxyphenethylamino)(quinolin-4-yl) methylphosphonate (DDQ) on neurite developmental features in HT22 neuronal cells. In this work, we examined the protective effects of DDQ on neuronal processes and synaptic outgrowth in differentiated HT22 cells expressing mutant Tau (mTau) cDNA. To investigate DDQ characteristics, cell viability, biochemical, molecular, western blotting, and immunocytochemistry were used. Neurite outgrowth is evaluated through the segmentation and measurement of neural processes. These neural processes can be seen and measured with a fluorescence microscope by manually tracing and measuring the length of the neurite growth. These neuronal processes can be observed and quantified with a fluorescent microscope by manually tracing and measuring the length of the neuronal HT22. DDQ-treated mTau-HT22 cells (HT22 cells transfected with cDNA mutant Tau) were seen to display increased levels of synaptophysin, MAP-2, and β-tubulin. Additionally, we confirmed and noted reduced levels of both total and p-Tau, as well as elevated levels of microtubule-associated protein 2, β-tubulin, synaptophysin, vesicular acetylcholine transporter, and the mitochondrial biogenesis protein–peroxisome proliferator-activated receptor-gamma coactivator-1α. In mTau-expressed HT22 neurons, we observed DDQ enhanced the neurite characteristics and improved neurite development through increased synaptic outgrowth. Our findings conclude that mTau-HT22 (Alzheimer’s disease) cells treated with DDQ have functional neurite developmental characteristics. The key finding is that, in mTau-HT22 cells, DDQ preserves neuronal structure and may even enhance nerve development function with mTau inhibition.

Key words: diethyl (3,4- dihydroxyphenethylamino) (quinolin-4-yl) methylphosphonate (DDQ),  hippocampal neuronal cells,  HT22,  neurite outgrowth,   neuronal development,  small molecule