THC-rich cannabis is well known to bring relief for some chronic pain sufferers. But the downside, off putting for many users and a barrier to more widespread legalization, are the side effects that can come from the fact that THC is psychoactive. For many it causing significant side effects such as memory issues, sleepiness or irritability.
Now, scientists have developed a peptide that’s been shown in animal studies to allow THC to fight pain without the side effects.
The researchers from Spain and Portugal, had previously identified two peptides that disrupt an interaction between a receptor that's the target of THC and another receptor that binds serotonin, which regulates learning, memory and other cognitive functions. When the researchers injected these peptides into the brains of mice, the mice had fewer memory problems caused by THC.
In the current study, reported in the Journal of Medicinal Chemistry the team, led by Rafael Maldonado and David, the experiment was refined by improving the peptides to make them smaller, more stable, and able to cross the blood-brain barrier when consumed orally.
The researchers then gave the new, most promising peptide — an orally active 16-residue peptide — to the mice orally, along with a THC injection, before testing the mice's pain threshold and memory.
Mice treated with both THC and the optimized peptide reaped the pain-relieving benefits of THC and also showed improved memory compared with mice treated with THC alone.
Another encouraging finding was that multiple treatments with the peptide did not promote an immune response, which would be an unwanted response in a potential new drug candidate.
Together these positive findings suggest that this optimized peptide has potential in the development of an effective THC-rich cannabis medicine, but without the unwanted cognitive side effects. "Our efforts have culminated in the identification of an ideal candidate for cannabis-based pain management,” the researchers concluded.