Where is Cats Love Catnip Because It Protects Them From

 When exposed to catnip or silver vine, cats engage in some fairly predictable behaviors, such as licking and chewing the leaves, rubbing their heads and faces against the plants, and rolling on the ground. Cats get a real kick out of these plants, but surprising new research points to a more practical purpose than just wanting to get high.

 Nepetalactol—the most potent active ingredient in catnip (Nepeta cataria) and silver vine (Actinidia polygama)—provides cats with a chemical defense against mosquitoes, according to new research published in Science Advances. The discovery could explain why felines, whether domesticated cats or hulking jungle predators, display similar behaviors after being exposed to these plants.

The new research, led by Masao Miyazaki from Iwate University in Japan, offers fresh insights into nepetalactol and how it affects feline behavior and their opioid receptors. That nepetalactol deters mosquitoes is a stunning revelation, and it could result in an entirely new class of insect repellent, according to the researchers. Nepetalactol had previously been associated with mosquito repellent activity, but “our data is the first to show it,” explained Miyazaki in an email.

 What’s more, the new paper is the “first to show that nepetalactol is a potent bioactive compound to cats.” Indeed, it’s no secret that the chemical has some kind of neurological effect on cats, but catnip, a plant from the mint family, and silver vine, a kind of kiwifruit, contain a plethora of other bioactive compounds, such as isoiridomyrmecin, iridomyrmecin, isodihydronepetalactone, and dihydronepetalactone. Miyazaki and his colleagues, including researchers from Nagoya University in Japan and the University of Liverpool in the U.K., focused on nepetalactol because of its suspected potency

The scientists also studied the cats’ reactions to some of the other bioactive agents found in silver vine and found nepetalactol to be the most potent.

“This study has found that...nepetalactol is the major bioactive compound in the leaves of silver vine that induces characteristic rubbing and rolling in cats,” write the authors in their study. “Further, nepetalactol had similar bioactivity in Amur leopard, jaguar, and Eurasian lynx. As most of the [feline] species so far tested have shown positive responses toward catnip (13 of 21 species tested from a total of 41 living species in this family), it is likely that this characteristic response to nepetalactol will also be common across many [felines].”

The group also measured the cats’ endorphin levels both before and after exposure, finding that the feline reaction to nepetalactol is regulated by their opioid system; elevated levels of endorphins were only observed after exposure to nepetalactol. What’s more, when the scientists suppressed their opioid receptors with special drugs, the cats no longer displayed their characteristic behaviors when exposed to the chemical.
 

As for silver vine’s role as a possible mosquito repellant, the researchers found that cats with fur covered in nepetalactol attracted significantly fewer mosquitoes, specifically the species A. albopictus, than the untreated control group—in some cases by as much as half.

“These results show that nepetalactol, transferred to face and head fur by rubbing against silver vine leaves, functions as a repellent against A. albopictus in cats,” the authors write. “This is convincing evidence that the characteristic rubbing and rolling response functions to transfer plant chemicals that provide mosquito repellency to cats.”

This, the authors argue, could explain why the behavior evolved. The cats get high on these plants, roll around in the leaves, and unwittingly become protected against mosquitoes in the process. This theory makes a lot of sense, but scientists now need to explain why this behavior isn’t seen in other animals, and if the repellant action actually happens in nature, not just in a laboratory setting.