Catnip, Nepeta cataria, is a member of the mint or Labiatae family. This perennial herb is sometimes known as catnep, catrup, catwort, cataria, or catmint (although there are other plants that also go by these common names). Catnip is indigenous from the eastern Mediterranean region to the eastern Himalayas, but is naturalized over much of North America and is easily grown in most gardens. The generic name Nepeta is said to have been derived from the Italian town Nepete, where catnip was once cultivated. For centuries humans have grown catnip for humans, but the herb is best known for its action on cats.
Nepetalactone is a terpene composed of two isoprene units, with a total of ten carbons. Its chemical structure is similar to that of the valepotriates derived from the herb valerian, which is a mild central nervous system sedative (or stimulant to some persons).
Domestic and many wild cats (including cougars, bobcats, lions, and lynx) respond to the nepetalactone in catnip. However, not all cats react to catnip. The behavior is inherited as an autosomal dominant gene; 10-30% of domestic cats in a population may be unresponsive to nepetalactone. Kittens will not show the behavior until they are at least 6-8 weeks old. In fact, catnip produces an avoidance response in young kittens. The catnip response usually develops by the time a kitten is 3 months old.
When cats smell catnip they exhibit a range of behaviors that may include sniffing, licking and chewing the plant, head shaking, chin and cheek rubbing, head rolling, and body rubbing. This psychosexual reaction lasts for 5-15 minutes and cannot be evoked again for an hour or more after exposure. Cats that react to nepetalactone differ in their individual responses.
The feline receptor for nepetalactone is in the vomeronasal organ, located above the feline palate. The location of the vomeronasal organ may explain why cats do not react from eating gelatin-enclosed capsules of catnip. Nepetalactone must be inhaled for it to reach the receptors in the vomeronasal organ. In cats, the effects of nepetalactone can be moderated by several drugs acting upon the central and peripheral nervous system, and by several environmental, physiological, and psychological factors. The specific mechanism governing these behaviors has not been described.
Herbalists have used catnip for many centuries as a treatment for colic, headache, fever, toothache, colds, and spasms. Catnip is an excellent sleep-inducing agent (as with valerian, in certain individuals it acts as a stimulant). Both people and cats find catnip to be emetic in large doses. It exhibits antibacterial properties and may be useful as an anti-atherosclerotic agent. It is used as an adjunct in treated dysmenorrhea and is given in tincture form to aid amenorrhea. 15th century English cooks would rub catnip leaves on meats before cooking and add it to mixed green salads. Before Chinese tea became widely available, catnip tea was very popular.
Cockroaches and other Insects
There is scientific evidence that catnip and nepetalactone may be effective cockroach repellents. Iowa State University researchers found nepetalactone to be 100x more effective at repelling cockroaches than DEET, a common (and toxic) insect repellent. Purified nepetalactone has also been shown to kill flies. There is also evidence that nepetalactone may serve as an insect sex pheromone in Hemiptera Aphidae (aphids) and a defense substance in Orthoptera Phasmatidae (walking sticks).