"Toluene is found in paint thinners, varnishes and even nail polish remover. Researchers from the University of Arizona and the National Institute of Drug Abuse (NIDA) demonstrate that toluene directly stimulates dopamine neurons causing dopamine release. Dopamine is a neurotransmitter and is released by reward centers in the brain causing a feeling of euphoria. The results suggest that the brain likely also interprets sniffing toluene as rewarding which can result in further abuse and possibly future use of other drugs.
Besides showing where in the brain toluene acts, the researchers also demonstrate that, surprisingly, toluene substances are most effective when used at low concentrations. Since toluene is rapidly absorbed in the brain, this might explain why the preferred mode of delivery is by "huffing" or "sniffing". Sniffing is frequently considered a harmless recreational or party drug but unlike other drugs, even a single session of inhaling the compound can disrupt heart rhythms
enough to cause cardiac arrest and lower oxygen levels enough to cause suffocation".
Macrocycles, flexibility and biological activity: A tortuous pairing
6 hours ago in The Curious Wavefunction