Complex sentence: At the olfactory epithelium, the nepetalactone binds to one or more olfactory receptors where it probably mimics a cat pheromone, such as the hypothetical "feline facial pheromone" or the cat urine odorant MMB.
Split into simpler sentences: At the olfactory epithelium, the nepetalactone binds to one or more olfactory receptor. Some have speculated that it may mimics a cat pheromone, such as the hypothetical "feline facial pheromone" or the cat urine odorant MMB.