Cannabinoids, Rats, and Essential Tremor

Alert readers will instantly note a connection between “Cannabinoids” in the title, and the cannabis plant—better known as marijuana, pot, weed, grass, etc. However, this blog is not about smoking marijuana to get high. Instead, it’s about a natural cannabis plant component called a cannabinoid. With the ever-increasing interest in the health benefits of cannabinoids, it’s not surprising that people with Essential Tremor (ET) are in vigorous dialogue with each other. Some—but by no means the majority—are finding that cannabinoid use helps reduce their tremors.

Cannabinoids are chemical compounds that are unique to cannabis. Sixty-six distinct cannabinoids have been identified and subclassified based on their effect. The type of effect can be stimulating or blocking, and this occurs when they act as chemical messengers by coming into contact with special “receivers” on brain cells called cannabinoid receptors called CB1 and CB2. Cannabinoid receptors are abundant in brain areas that manage motor function, and they play a role in increasing or blocking motor activity depending on the neurotransmitters they receive.i Chemical messengers called agonists have an up-activity effect; those called antagonists have a down-activity effect.

It is thought that cannabinoid receptors may be involved with essential tremor, the involuntary rhythmic shaking motions that can affect hands, head, voice and other body parts. If this is so, can tremor be modulated by deliberately acting on the brain’s cannabinoid receptors in such a way that the tremors become more active or less active.

An experiment with rats

A collaborative research team from England and Iran constructed an experiment designed to prevent “up-activity” messages from influencing CB1 receptors in rats. Since rats don’t naturally get tremors, the researchers first administered a drug that causes tremors to occur. They had special equipment for observing and measuring the tremors. Once they established baseline tremor activity, they gave the rats a drug known to be a CB receptor agonist (up-activity). Sure enough, the tremors got worse.

Then they gave the rats two drugs known to be CB receptor antagonists (down-activity). As hypothesized, the rats’ tremors were diminished. For the team, this was a kind of scientific victor. They had actual physical evidence that tremors can be altered (increased or decreased) by supplying specific chemical messengers to cannabinoid receptors. They concluded, “Our data suggest that CB1 receptor manipulation warrants clinical investigation as a therapeutic approach to protection against behavioural disturbances associated with ET.” In other words, more research into influencing cannabinoid receptors may point to a new line of ET treatment.

A note of caution

Before getting too excited about running out and buying cannabinoid, cannabis supplements, CBN, or any other product, it’s important to remember that a study done with lab animals who had tremors artificially induced doesn’t tell us anything about a similar effect in humans. For one thing, human tremors arise in the brain for unknown reasons, not because of ingesting a tremor-causing agent. For another, even when two people have tremors that appear identical, each person’s brain is unique—which may be why medicines like primidone or propranolol don’t have the same effectiveness for each person.

Scientific research like the study above gives us important puzzle pieces, but we don’t yet have the whole picture. The purpose of this blog is to share what’s going on in the realm of experimental studies. However, we strongly warn you against using yourself as an experiment without first consulting with your own medical team! Remember that the internet contains both information and misinformation. It’s not always clear where the boundary between them lies.

That said, it’s encouraging to know that the search to prevent or cure ET is a global endeavor. While it’s not clear when that day will come, in the meantime there is an excellent treatment called MRI-guided Focused Ultrasound (MRgFUS). It is an outpatient, noninvasive procedure that is safe, effective, and durable. For more information, or to schedule a consultation, contact Sperling Neurosurgery Associates.

iAbbasian H, Whalley B, Sheibani V, Shabana M. Cannabinoid type 1 receptor antagonism ameliorates harmaline-induced essential tremor in rat. Br J Pharmacol. 2016 Nov;173(22):3196-3207.

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