The physiology of how catnip gets cats high has mostly been a scientific mystery. But now, researchers from Japan's Iwate University have determined that catnip, and also silver vine, activate the opioid systems in the feline brain similarly to how heroin and morphine works on humans. Interestingly, it also turns out that the compound in catnip that attracts cats, nepetalactone, happens to repel mosquitos. The researchers have since patented a new nepetalactone-based insect repellent. From Science:
The researchers measured beta-endorphins—one of the hormones that naturally relieves pain and induces pleasure by activating the body's opioid system—in the bloodstreams of five cats 5 minutes before and after exposure [to nepetalactone]. The researchers found that levels of this "happiness hormone" became significantly elevated after exposure to nepetalactol compared with controls. Five cats that had their opioid systems blocked did not rub on the nepetalactol-infused pouches[…]
The researchers speculate that cat ancestors might have rubbed their bodies against the plants by chance, enjoyed the feeling, and kept doing it. It is not clear, though, whether it was the euphoric response—or the insect-repelling properties of the plant—that kept them rolling
"The characteristic response of domestic cats to plant iridoids allows them to gain chemical defense against mosquitoes" (Science Advances)
