FEB 19, 2016 8:59 AM PST

How Does Smoking Protect You From Parkinson's Disease?

WRITTEN BY: Cassidy Reich
Approximately one million people in the U.S. have Parkinson’s Disease (PD), a progressive neurodegenerative disorder characterized by the loss of dopamine-producing neurons in a brain region called the substantia nigra. While certain drugs and treatments, like L-DOPA and deep brain stimulation, can alleviate the motor symptoms of PD, there are no therapies that can slow down disease progression. The primary symptoms of PD are related to motor control, such as tremors and difficulty initiating voluntary movements, but there are many other nonmotor symptoms associated with this complex disease. Depression, sleep issues, and, as the disease progresses, dementia are also symptoms of PD.
 

Similar to Alzheimer’s, the majority of PD cases are sporadic, with no inherited genetic cause. Even though researchers don’t know exactly what causes PD, epidemiological studies over the past 60 years have revealed a crazy correlation between smoking and risk of PD.

Smoking cigarettes, a habit that everyone agrees is terrible for your health, can reduce your risk of developing PD by about 2-fold.

Why is this the case? Over 50 epidemiological studies have been done, and we know it’s not because people who smoke don’t live long enough to develop PD. Nicotine has actually be shown to be neuroprotective against PD, making this observation causative, not just correlational.
Nicotine binds nicotinic acetylcholine receptors (nAChRs) that are located presynaptically on dopaminergic neurons to stimulate dopamine release. And by binding to nAChRs, nicotine also causes Ca2+ influx into the neuron which could elicit more neuroprotective gene expression through a second messenger signaling cascade.
 
However, a recent paper published in The Journal of Neuroscience details a very physiological,”inside out” mechanism of neuroprotection. The experiments in this paper were done on cultured dopaminergic neurons and they used a very interesting model of PD. Since PD is a progressive disorder that occurs over many years, the researchers used a model of sustained endoplasmic reticulum (ER) stress like you would see in the early stages of disease progression instead of outright cell death. The concentration of nicotine used, 200 nM, is also significant because it is below the concentration needed to activate the nAChRs that are located on dopaminergic neurons. Nicotine is actually capable of diffusing through the cell membrane to reach the intracellular organelles, like the ER. Basically, this study showed that chronic nicotine exposure, at levels too low to activate most nAChRs, attenuated the ER stress and also suppressed the pro-apoptotic unfolded protein response (UPR) pathway through a process called “pharmacological chaperoning”. The nicotine made dopaminergic neurons that looked like the early stages of PD healthy again.

This is most likely not the only way nicotine elicits neuroprotection against PD, but it is important to unravel the different pathways to find new targets for treatments. And because nicotine has been shown to be neuroprotective, these pathways could offer a means of preventing disease onset.

Sources: NIH and Journal of Neuroscience
About the Author
Cassidy is a curious person, and her curiosity has led her to pursue a PhD in Pharmacology at the New York University Sackler Institute of Biomedical Sciences. She likes to talk about science way too much, so now she's going to try writing about it.
You May Also Like
JUL 20, 2022
Cannabis Sciences
Why Health Experts Consider Delta 8 THC Dangerous
JUL 20, 2022
Why Health Experts Consider Delta 8 THC Dangerous
Delta 8 is booming in popularity, but health experts are concerned. Here's why.
JUL 23, 2022
Drug Discovery & Development
No Evidence for Depression and Serotonin Activity Link
JUL 23, 2022
No Evidence for Depression and Serotonin Activity Link
A new review study found that there is no clear evidence that serotonin levels or serotonin activity are responsible for ...
JUL 27, 2022
Neuroscience
What is Trigeminal Neuralgia?
JUL 27, 2022
What is Trigeminal Neuralgia?
Trigeminal neuralgia is an extremely painful disorder that usually impacts the lower face and jaw, but may also involve ...
AUG 10, 2022
Health & Medicine
Blood Vessel Disease May Worsen Cognition in Alzheimer's Disease
AUG 10, 2022
Blood Vessel Disease May Worsen Cognition in Alzheimer's Disease
A new study from a group of Alzheimer’s disease researchers at Augusta University is highlighting the importance o ...
AUG 04, 2022
Health & Medicine
Researchers Investigate Memory Strategy to Slow Cognitive Decline
AUG 04, 2022
Researchers Investigate Memory Strategy to Slow Cognitive Decline
A team of researchers from University of Michigan and Penn State College of Medicine compared two mnemonic strategies fo ...
SEP 21, 2022
Neuroscience
What We Can Learn From Brain Asymmetry
SEP 21, 2022
What We Can Learn From Brain Asymmetry
A study published in eLife examined the subtle differences in functional organization between the left and right side of ...
Loading Comments...