Nepetalactone is the oil in catnip that binds to protein receptors in the cat's nasal passages and provides stimulation in sensory neurons. The sensory neurons then signal the neurons in the olfactory bulb, which subsequently affects regions in the brain that enable or inhibit behavior.
The symptoms of a cat that has been affected by catnip include persistent rubbing, rolling around, salivation and vocalizations. These behaviors last approximately 10 minutes. The cat is immune to the effects of catnip for around 30 minutes following the initial exposure. Between 70 and 80 percent of cats are prone to the effects of catnip, and the response is hereditary. Kittens under the age of six weeks are not capable of being affected by catnip.