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Nepetalactone is a name for multiple iridoid analog stereoisomers. Nepetalactones are produced by Nepeta cataria (catnip) and many other plants belonging to the genus Nepeta, in which they protect these plants from herbivorous insects by functioning as . They are also produced by many , in which they are sex pheromones. Nepetalactones are , and cause the behavioral effects that catnip induces in domestic cats. However, they affect visibly only about two thirds of adult cats. They produce similar behavioral effects in many other Felidae, especially in and . In 1941, the research group of Samuel M. McElvain was the first to determine the structures of nepetalactones and several related compounds.
( cis, trans)-Nepetalactone is a colorless oil. Its boiling point is 71 °C at 0.05 mmHg. At 25 °C, its density is 1.0663 g/mL and refractive index 1.4859. (2025). 9781482208689, CRC Press. ISBN 9781482208689
Nepetalactones are also produced by many , in which they function as sex pheromones. The most common isomer in aphids is ( cis, trans)-nepetalactone. Aphids also commonly produce a structurally related (1 R,4a S,7 S,7a R)-nepetalactol, which is also an aphid sex pheromone. Relative concentrations of these two compounds varies among aphid species.
The process starts with geraniol synthase (GES) hydrolyzing GPP to form geraniol which is oxidized into 8-hydrogeraniol by geraniol-8-hydroxylase (G8H) (scheme 1). Geraniol-8-hydroxylase is further oxidized by 8-hydroxygeraniol oxidoreductase (8OG) to produce 8-oxo-geranial which is reduced by iridoid synthase (ISY) and NADPH to form the intermediate 8-oxocitronellyl enol (scheme 2). This intermediate leads to cyclization by a gene cluster which utilizes ISY and major latex-protein-like genes (MLPL) or NEPS homologs. 8-oxocitronellyl enol is cyclized into ( cis, trans)-nepetalactol by MLPL, NEPS1, or NEPS2 and then oxidized by NEPS5 and the cofactor NAD+ to yield ( cis, trans)-nepetalactone (scheme 3). The process can be repeated with 8-oxocitronellyl enol cyclizing into ( cis, cis)-nepetalactol by NEPS3 and oxidation by NEPS1 or NEPS5 and NAD+ to yield ( cis, cis)-nepetalactone (scheme 4). 8-Oxocitronellyl enol can also be cyclized into ( trans, cis)-nepetalactol by NEPS4 and then oxidized by NEPS1 into ( trans, cis)-nepetalactone (scheme 5). It is suggested that the lack of the NEPS1 leads to decay and formation of ( trans, cis)-iridodial.
The effects of nepetalactones begin quickly in domestic cats, and last for 5 to 15 minutes. Cats develop drug tolerance towards nepetalactones after exposure. The tolerance lasts for a few hours.
Lions ( Panthera leo) and jaguars ( Panthera onca) are sensitive to nepetalactones. Their effects can last in them for up to 60 minutes. They also affect leopards ( Panthera pardus). Species exhibiting overall lesser to no sensitivity include tigers ( Panthera tigris), bobcats ( Lynx rufus), cougars ( Puma concolor) or oncillas ( Leopardus tigrinus).
Effects in felines
Duration and efficacy variation
Nepetalactones affect domestic cats via nasal mucosa. Oral ingestion has no effects. They induce noticeable behavioral effects in about two thirds of adult cats. However, all cats are probably affected by them, but the effects in one third of adult cats are less visible. Nepetalactones do not noticeably affect kittens that are less than three months old. Their effects also tend to be less pronounced in neutered cats in comparison to non-neutered cats, but not significantly.
Effects
Two thirds of adult domestic cats begin to lick, sniff, eat, scratch or roll over the nepetalactone source after being exposed to it. They may also begin pawing, shaking their heads, rubbing their cheeks, licking themselves or vocalizing. About one third of adult cats react more passively to nepetalactones, and may assume a sphinx-like posture, decrease vocalization or decrease movement. The effects of nepetalactones are similar in other Felidae.
Mechanism of action
Felidae olfactory receptor exposure to nepetalactones or induces β-endorphin secretion in the blood; this endorphin release in turn activates μ-opioid receptors as an agonist, thus working in a similar manner as morphine or other . Naloxone, a μ-opioid receptor antagonist, is known to block the effects of nepetalactones and nepetalactols in domestic cats, which supports this endorphin related mechanism of action. Repeated exposure to nepetalactones or nepetalactols does not induce opioid withdrawals in Felidae, probably because endogenous β-endorphin secretion is controlled. ( cis, trans)- and ( trans, cis)-nepetalactones have both been shown to function as cat attractants in domestic cats in studies of poor quality. Both isomers occur in catnip for example, but the ( cis, trans)-isomer is the major one.
Evolutionary reasons for the effects
Felidae react to plants that contain nepetalactones by licking them and rubbing them in their fur. Nepetalactones and nepetalactols repel some disease-causing insects. For example, nepetalactols are able to repel Aedes albopictus. The cats typically hunt other animals by stalking them. This requires being still or slow movements, which allow insects to bite the cat more easily. This would make evolutionary pressure select for the behavior of rubbing of natural insect repellent. This was proposed to be the reason for this widely preserved behavioral trait in Felidae in a paper published in 2021.
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