John Hughes (born 6 January 1942)[2] is a British neuroscientist who shared the 1978 Albert Lasker Award for Basic Medical Research for the discovery of met-enkephalin and leu-enkephalin.
[3][4][5] This discovery demonstrated that opiate drugs exert their effects on the human brain by mimicking endogenous neurotransmitters, the opioid peptides.
Kosterlitz had developed assays for responses to opiate drugs, using pieces of guinea pig intestine and mouse vas deferens.
"[10] He would bicycle daily to a slaughterhouse, where he would trade bottles of whiskey to the butchers in exchange for pig heads, and he subsequently prepared brain extracts using acetone.
[9] After testing many samples in Kosterlitz's assays, the two scientists were able to isolate and identify two peptides, met- and leu-enkephalin, as naturally occurring molecules from the brain, that have activity resembling opioids.