Hi—love your site! I’m an MD/PhD student in the Bronx, and I have a quicky catnip question for you. I’ve read your Jan 20 ’04 post, and like most of the sources I’ve found on the internet so far, it mentions the vomeronasal organ as the site of action of catnip, attributing the smell of the substance as what the cats are after. Do you know of any research showing catnip receptors inside cats’ brains? I guess because the vomeronasal organ in humans is nonexistent, I’m just having a hard time wrapping my mind around the idea of the smell itself of a substance being the only mechanism behind such a consistent, stereotyped behavior across individual animals, without some sort of direct action inside the brain itself. But I guess that’s why I’m not a cat. ;) Thanks for your help!
C., Albert Einstein College of Medicine
Hello and thank you! I am so glad you enjoy my website.
You know, I have searched all over several scientific databases, but I can't find any reputable articles on catnip or nepetalactone's (which is 80-95% of catnip oil) interaction with human or cat brain receptors. There is an article (Aydin et. al., ) suggesting interactions with rodent brain opioid receptors. But you are absolutely right, it does bind to receptors in the cat's VNO, or vomeronasal organ.
As you already know, the existence of this pheromone sensor in people's sniffers has been hotly debated. But cats have it, and I am guessing that once nepetalactone binds its receptor in cat's VNO, the VNO then sends signals to the cat brain. So, your question is really, where do those signals go? I don't know...but hopefully no one will discomfort any cats to find out.
Some cats also love the herb valerian in the same, silly way, and it has valepotriates, chemicals that resemble nepetalactone. One of our own cats, Alberio, LOVES to stick her nose in our peppermint tea, regardless of brand, and ignores all our other herbal teas. I have not seen other cats do this. Since catnip is a mint, I wonder if Alby has a VNO receptor mutation which causes her to respond to similar molecules in peppermint. She is an odd little thing, psychologically, so this seems not out of the question.
There is evidence that suggests that humans actually respond to pheromones, but where are our VNOs? These organs in other animals respond to sex hormones, and also respond to simple "come here" or "go away" pheromone messages. But the dogma is that we humans don't have a VNO in our noses. Not wanting to feel left out at the animal pheromone party, I suppose, the hunt has been on to find our VNOs.
One new idea is that we humans sense pheromones with our mundane little noses. But scientists have not completely ruled out the possibility of human VNOs existing, either. (Besli et. al., Wysoki et al., Zosel et. al.) There are traces of them, but their efferent nerves appear to dead end and fail to reach the brain, from what I understand. Failing that, to my mind nepatalactone so resembles valepotriates in valerian, that I have to supsect they could do the same thing, and possibly sedate us by enhancing the binding of the inhibitory neurotransmitter GABA to its receptor.
I hope that helps!