title: Opioid activity of synthetic and naturally occurring enkephalin peptides.
mesh_terms: D000700:Analgesics; D000818:Animals; D001921:Brain / Q000378:metabolism; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011957:Receptors, Opioid / Q000378:metabolism; D013329:Structure-Activity Relationship; D013997:Time Factors
chemical_list: D000700:Analgesics; D004723:Endorphins; D004745:Enkephalins; D011957:Receptors, Opioid