sentences:  The uncharged molecule can penetrate the insect blood–brain barrier.Other neonicotinoids have a negatively charged nitro or cyano group, which interacts with a unique, positively charged amino acid residue present on insect, but not mammalian nAChRs.However, the breakdown product desnitro-imidacloprid, which is formed in a mammal's body during metabolism as well as in environmental breakdown of imidacloprid, has a charged nitrogen and shows high affinity to mammalian nAChRs.