Nicotinamide, neural cells, and Parkinson’s disease: exploring nicotinamide’s effects on proliferation, neuronal differentiation, and neuroprotection within in vitro models

Green, Emma Louise

Abstract

Parkinson’s disease (PD) is characterised by motor symptoms caused by degeneration of dopaminergic neurons in the substantia nigra. The cause remains elusive and current treatments cannot halt or reverse progression. This thesis explores the effects of nicotinamide on cells associated with PD; exploring its roles in the development and protection of dopaminergic neurons, and its influence on microglia.
Nicotinamide was tested on 46C mouse embryonic stem cells. Neural differentiation, indicated by Sox1-GFP expression, was identified by flow cytometry and immunocytochemistry. Neuroprotective effects of nicotinamide were assessed using a 6- hydroxydopamine primary ventral mesencephalon (VM) cell model of PD, and tyrosine hydroxylase (TH) immunocytochemistry to identify dopaminergic neurons. Effects of nicotinamide on Iba1+ microglia were assessed in VM cultures and in isolated rat cortex microglial cultures.
Nicotinamide limited proliferation of 46C cells over 7 days of differentiation. Sox1-GFP expression was lower in nicotinamide-treated cultures compared to control, but peak expression occurred earlier. ß-III-tubulin+ neuron numbers remained unchanged at day 7. In VM cultures, TH+ neuron numbers were higher in nicotinamide-treated cultures at days 1, 4, and 7. However, nicotinamide did not protect TH+ neurons against 6-hydroxydopamine. Nicotinamide treatment showed reversible impairment of Iba1+ microglial proliferation in VM cultures. Lower numbers of Iba1+ microglia were observed in isolated microglial cultures with 10 mM nicotinamide; however, nicotinamide did not prevent granulocyte-macrophage colony-stimulating factor-induced proliferation.
Thus, nicotinamide could be utilised for novel PD treatments including promoting neuronal differentiation and restricting unwanted progenitor cell proliferation in stem cell replacement therapy. Nicotinamide may also enhance dopaminergic differentiation or survival in primary VM cultures. Finally, nicotinamide’s ability to reduce microglial proliferation could be utilised as a novel therapy to slow progression at PD onset or may offer protection from immune rejection in cell replacement therapies.

Citation

Green, E. L. (2021). Nicotinamide, neural cells, and Parkinson’s disease: exploring nicotinamide’s effects on proliferation, neuronal differentiation, and neuroprotection within in vitro models. (Thesis). Keele University

• Thesis Type: Thesis
• Publicly Available Date: May 30, 2023
• Award Date: 2021-03