Proposed mechanisms of neuroprotection for nicotine in Parkinson's disease

Parkinson's disease (PD) is a neurological disorder that is characterized by the death of dopaminergic neurons in the substantia nigra. Despite extensive research, the exact cause of PD is unknown, and current treatment options are centered on symptom management rather than disease modification. Most, though not all, epidemiologic studies have demonstrated reduced risk of development of PD among smokers, generating interest in nicotine, a key component of tobacco. Many preclinical investigations have investigated nicotine's neuroprotective properties, especially through its interaction with nicotinic acetylcholine receptors in the central nervous system. Nicotine has been linked to a variety of cellular activities, including neurotransmitter release, neuronal survival, and anti-inflammatory responses. Animal studies in PD models have indicated that nicotine administration can attenuate the degeneration of dopaminergic neurons and ameliorate behavioral abnormalities. Clinical investigations evaluating nicotine as a treatment for PD have yielded mixed results in terms of efficacy. Thus, central questions remain about the effects of nicotine in patients with established PD, and neither nicotine nor smoking are recommended for treatment or prevention of PD. Further research on the multiple proposed mechanisms of nicotine is required, with particular emphasis on elucidating symptomatic versus neuroprotective effects. The aim of this scoping review is to provide a comprehensive discussion of the proposed mechanisms of neuroprotection for nicotine in Parkinson's disease.