By Pat Anson, PNN Editor

A new study may help explain what makes cannabis effective as a pain reliever. It’s not just cannabinoids like cannabidiol (CBD) or tetrahydrocannabinol (THC), but terpenes -- the aromatic compounds that give cannabis its distinctive “skunky” smell. The finding could lead to new ways to boost the potency of cannabis, opioids and other pain-relieving drugs without increasing the dosage.

In experiments on laboratory rodents, scientists at the University of Arizona Health Sciences found that Cannabis terpenes, when used alone, mimic the effects of cannabinoids, including a reduction in pain sensation. When terpenes were combined with a synthetic cannabinoid, the pain-relieving effects were amplified – an “entourage effect” – that reduced pain levels without an increase in euphoria and other side effects.

"A lot of people are taking cannabis and cannabinoids for pain," said lead researcher John Streicher, PhD, a member of the UArizona Health Sciences Comprehensive Pain and Addiction Center and associate professor of pharmacology at the College of Medicine-Tucson.

"We're interested in the concept of the entourage effect, with the idea being that maybe we can boost the modest pain-relieving efficacy of THC and not boost the psychoactive side effects, so you could have a better therapeutic."

Terpenes are found in many plants and are the main component in essential oils. The terpene linalool gives lavender its distinctive floral scent, while citrus trees get their smell from the terpene limonene. Plants create terpenes to lure pollinators, such as birds and insects, and to protect themselves from predators.

Streicher and his colleagues focused on four Cannabis terpenes: alpha-humulene, geraniol, linalool and beta-pinene. They evaluated each terpene alone and in combination with a synthetic cannabinoid that stimulates the body's natural cannabinoid receptors.

In laboratory experiments, researchers found that all four terpenes activated a cannabinoid receptor in the brain, just like THC. The behavioral studies in mice also revealed the terpenes lowered pain sensitivity, reduced pain sensation, lowered body temperature, and reduced movement and catalepsy, a freezing behavior related to the psychoactive effects of cannabinoids.

When terpenes were combined with the synthetic cannabinoid, researchers saw a greater reduction in pain sensation -- demonstrating a terpene/cannabinoid interaction in controlling pain.

"It was unexpected, in a way," said Streicher. "It was our initial hypothesis, but we didn't necessarily expect terpenes, these simple compounds that are found in multiple plants, to produce cannabinoid-like effects."

The study findings were recently published in the journal Scientific Reports. Streicher and his research team still need to confirm if terpenes have an entourage effect when combined with THC and other naturally occurring cannabinoids. Their long-term goal is to develop a dose-reduction strategy that uses terpenes in combination with cannabinoids or opioids to achieve the same levels of pain relief with fewer side effects.

Although the therapeutic benefits of terpenes are not well understood, some cannabis companies are already incorporating them into their products. Lemon Kush, for example, is a hybrid marijuana strain that contains limonene, while the hybrid Blue Dream has a terpene found in blueberries. Terpenes are also being added to chocolate, beverages and many other consumer products.