Nicotine may protect the brain from manganese and iron metal trace elements thought to be involved in the onset of Parkinson’s disease, a study based on a disease cell model reported.
Parkinson’s is characterized by the gradual loss of dopaminergic neurons in the substantia nigra — a region of the brain responsible for movement control — leading to motor and cognitive impairments.
Although the exact causes of Parkinson’s are not
yet fully understood, scientists believe the accumulation of metal trace elements, such as manganese and iron, could play a role in its onset. At low concentrations, these elements are crucial for cell growth and physiological functions; indeed, they are important for all growth and healthy workings of the body. But at high levels, they become toxic, and have been associated with several neurodegenerative disorders, including Parkinson’s.
Nicotine, a potent stimulant originally found in plants that activates the nicotinic acetylcholine receptor (nAChR) in the brain, has been shown to protect dopaminergic neurons from damage caused by different types of toxins. However, no study had addressed possible neuroprotective effects of nicotine against specific metal trace elements.
The new study from Howard University College of Medicine examined the effects of nicotine on toxic manganese and iron elements in a neuroblastoma cell line (SH-SY5Y), a standard in vitro model to study Parkinson’s disease cells, due to their dopaminergic activity.
When researchers exposed SH-SY5Y cells to high concentrations of manganese or iron for a day, toxicity levels increased by 30% and 35%, respectively. Pretreatment with nicotine was seen to completely prevent these toxic effects.
As expected, nicotine’s neuroprotective properties against toxic trace elements were lost when researchers used different types of nicotinic receptor antagonists (molecules that block the activity of nAChRs). This was true for “dihydro-beta erythroidine (DHBE), a selective alpha4-beta2 subtype antagonist and methyllycaconitine (MLA), a selective alpha7 antagonist,” the study noted.
“In summary, the results of this study provide evidence for neuroprotective effects of nicotine against toxicity induced by Mn [manganese] or Fe [iron] in a cellular model of PD [Parkinson’s disease],” the researchers wrote.
“Moreover, both high and low affinity nicotinic receptors (i.e., alpha4-beta2 and alpha7 subtypes) appear to mediate the effects of nicotine. Thus, utility of nicotine or nicotinic agonists in trace element-induced Parkinson-like syndrome may be suggested,” they concluded.