Posted By cYw26 on Sep 5, 2014 | 5 comments

Jack always said the ocean was his first love. Every chance he had as a young boy, he would hop a ride on his father’s little skipper to go diving or snorkeling, or maybe just to spend an hour bobbing on the waves. Now Jack teaches his grandchildren to love the ocean as he does, pulling out his well-worn field guides and pronouncing each creature’s scientific name as if introducing an old friend.

One day, Jack noticed a slight tremor in his left hand. It was so faint he would have thought he imagined it, except for the subtle sloshing of the ice tea in his glass. A few weeks later he began feeling extremely fatigued, but brushed it off, telling himself he was just getting older. He started to get worried when he realized he was slurring his speech, stumbling over words as if his tongue couldn’t keep up with his brain. To dispel his own anxiety and at the urging of his children, Jack scheduled an appointment with his doctor for later that month; his body had other ideas. That weekend while snorkeling, Jack’s legs cramped up, and he began to sink. He woke up coughing on the deck, surrounded by the worried faces of his loved ones.

Shell of the omaria cone snail, whose venomous bite could hold the key to treating many neurological diseases.
(By permission of Phil Camill)

Weeks of tests and scans followed, never yielding a definitive answer. Finally Jack’s 65th birthday came and brought a devastating diagnosis – Parkinson’s disease. The doctor said “progressive neurological disorder” so matter-of-factly, as if it didn’t mean Jack couldn’t scuba dive or snorkel anymore, or that he couldn’t be trusted to go out alone on his boat, or that daily activities like dressing, eating, bathing and writing “might someday become difficult.” It was all because his neurons were breaking down and dying, his doctor said, leaving Jack with a serious lack of dopamine, a chemical messenger vital in maintaining normal brain function. The doctor had no explanation – maybe it was genetics, maybe exposure to certain environmental toxins – either way, there was nothing that could be done to stop the disease. Medicines currently available would only slow it down (“Parkinson’s disease,” 2014).

Jack left the doctor’s office with a sense of helplessness. He felt his first glimmer of hope when his his oldest grandson stopped by with some amazing information.

“Grandpa, you’ll never guess who popped up during my search for Parkinson’s research,” the youngster said with a rare look of delight in his eyes.

“Who?” Jack queried, not quite following.

“Conus omaria, that sea snail we sometimes see when we’re diving, the one you always tell me not to touch because its bite is super poisonous. It turns out one of those dangerous neurotoxins in the cone snail’s venom called alpha conotoxin Om1A is helping researchers at the University of Utah develop new drugs to treat Parkinson’s!” the boy announced triumphantly (“A new tool against brain disease,” 2006).

Throughout the brain and the rest of the nervous system are receptors called nicotinic acetylcholine receptors, which are an important part of healthy brain function. Alpha conotoxin Om1A fits very tightly into the nicotinic receptors that trigger the release of dopamine and serotonin, two neurotransmitters involved in many neurological diseases. Being able to activate or block specific these receptors would open up a whole new world of medical treatments for diseases such as Parkinson’s, mood disorders, nicotine and alcohol addiction, and possibly even schizophrenia (Yuhas, 2013).

Researchers at the University of Utah tested many toxins in the omaria cone snail’s venom and found that Om1A is unique because it fits tightly into some receptors but not others (Siegel, 2006). This desirable attribute is beneficial because if a drug can be developed to mimic the shape of the toxin, it will be less likely to bind with the wrong receptor and cause unwanted side effects. The researchers produced a detailed picture of both the receptor ‘locks’ and the toxin ‘key.’ By locating the points of contact between the toxin and the receptor, scientists will be able to design a drug to fit exactly into the receptor, triggering the release of needed neurotransmitters (Bingham, 2010).

“Lock” and “key” model; the purple represents the potential drug and the grey represents the receptor.
By Bensaccount at en.wikipedia [Public domain], from Wikimedia Commons

In Brief:

• Nicotine receptors throughout the nervous system control the release of neurotransmitters, which allow cells to communicate.
• A lack of certain neurotransmitters, like dopamine or serotonin, can cause neurological diseases, such as Parksinson’s disease, Alzheimer’s disease, schizophrenia, and depression.
• A specific toxin from the venom of the omaria cone snail, Conus omaria, fits tightly into some of these receptors, but not all, giving it potential as a model for new drugs to trigger the release of needed neurotransmitters and treat these various neurological diseases.

Works Cited

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