One Fish, Two Fish, Drunk Fish, Stoned Fish

What do you get when you take a Lego figurine, a one-inch fish native to the freshwaters of the Indian sub-continent and place it in a testing pool called “the arena” — where it is microdosed it with LSD?

For researchers in the Department of Psychology at MacEwan University, it could potentially lead to novel treatments for humans dealing with mental illness and chronic alcoholism.

Research on zebrafish — so-called because of the distinct black and white stripes along its body — has been on-going since the early 1980s. But, their popularity as a vertebrate model organism (which are organisms, such as lab mice, used by scientists to study various biological functions and processes and model human diseases) has increased exponentially since 2013, when their genome was fully sequenced. It was found that around 70 per cent of human genes have a corresponding gene in zebrafish.

Dr. Trevor Hamilton is the lead neuroscience and behavioural researcher at the eponymous Hamilton Research Lab at MacEwan’s City Centre Campus. He and collaborator Dr. Melike Schalomon, who is the current dean of Arts and Science, have researched zebrafish for close to a decade.

“Zebrafish are becoming a very popular model organism for medical research,” says Hamilton. “Primarily, there’s a variety of reasons, but one is they are able to reproduce very quickly. And a lot of people, myself included, are interested in transgenerational work. There’s also a huge variety of scientific tools that have become available. Everything from genetic tools to tools for neural imaging. So, you can use tools to manipulate genetics, I recently had a collaboration with Ted Allison at the University of Alberta, where he modified prion proteins, to make a potential model of Alzheimer’s disease in zebrafish. We tested those fish in our lab with learning and memory tests that we developed and found an age-related memory decline in the mutant zebrafish, consistent with a model of Alzheimer’s disease in the rodents. Just an example of zebrafish research and how the goal isn’t necessarily to eliminate rodent research, but to complement it.

“They’re also easier to use, I would argue, and easier to store. And it’s relatively cheaper to maintain and feed the fish.”

Another reason why zebrafish are ideal for his particular research, specifically behavioural research into mental disorders and addictions, is that they are very social, and in their natural settings are always found in shoals. “We use a variety of tests to measure basic movement, anxiety-like behaviour, boldness, and different types of memory, like episodic and object recognition memory,” Hamilton says.

An example is using a “novel object approach test” in which a Lego figurine is the novel object – never before seen by the fish.

Hamilton also dispels a myth. “Goldfish memory” is often used to describe a scatterbrained and forgetful individual based on the ( assumption that fish memory doesn’t extend beyond a few seconds. Research by Hamilton unequivocally proves that’s not the case.

“We have performed food-based reinforcement memory tests and shown that yellow cichlids can remember the cues associated with food reward for at least 12 days. We have also shown that zebrafish have a capable object recognition memory system that is enhanced by nicotine,” he says.

He also points to anecdotal evidence of sockeye salmon, who return from the oceans to the same freshwaters where they were spawned.

Unlike past researchers, Hamilton and his team have developed a method that allows them to administer fish with more precise doses of pharmacological substances, mimicking human consumption patterns. Some of the research, that tested the effects of substances such as nicotine and alcohol, brought results that are consistent with those found in humans.

“We have shown that zebrafish experience ethanol and nicotine-induced withdrawal after repeated exposures. This was shown via an increase in anxiety-like behaviour during drug withdrawal.”

And Hamilton’s team researched the behavioural effects of alcohol withdrawal. They set up a rectangular arena, the testing aquarium where fish behaviour is observed, with one side lined with white walls, and the other with dark – a common behavioural test called the light/dark test that is captured using motion-tracking software. Adult zebrafish displaying increased anxiety spend more time on the dark side, while those with reduced anxiety spend more time on the light side. They found that repeated doses of alcohol, even at a moderate level, showed greater change in behaviour than infrequent doses at a larger level. That indicates withdrawal from chronic drinking displays more significant, though reversible, behavioural changes than withdrawal from binge drinking.

Their future research includes microdosing fish with LSD and other psychedelic compounds such as psilocybin (magic mushrooms) and MDMA, to examine whether these compounds can help with alcohol and nicotine withdrawal. This has significant human implications in treating alcohol and tobacco dependence, which cause both serious harm to the health of the users and a huge cost burden to health-care systems. Their most recent study showed no behavioural changes in the fish microdosed with LSD, indicating lesser addictive potential and withdrawal symptoms – an encouraging discovery that could eventually lead to these substances being readopted as radical treatment to help humans with addiction.

Using LSD and other psychedelic compounds to battle addiction and various mental disorders was pioneered by English psychiatrist Humphry Osmond (with frequent collaborator Dr. Abram Hoffer) after he moved to Saskatchewan in the early 1950s and conducted human trials on volunteers. He even coined the term psychedelic (from Greek for “mind-manifesting”) in 1957 and famously opened the doors of perception, in a manner of speaking, for British novelist Aldous Huxley. Osmond administered the writer with mescaline in 1953, a psychedelic experience Huxley would later describe in his 1954 book, The Doors Of Perception.

LSD was also clinically tested on humans by both the CIA and the United States government in the 1950s and ‘60s, as well as by Harvard clinical psychologist Timothy Leary (who coined the slogan “turn on, tune in, drop out”), before it became demonized towards the end of the 1960s and became part of the larger war on drugs. Since the 1990s there has been a revival in studying the potential therapeutic benefits of hallucinogenic drugs.