title: Episodic secretion of opioid activity in human plasma and monkey CSF: evidence for a diurnal rhythm.
mesh_terms: D000328:Adult; D000818:Animals; D002940:Circadian Rhythm; D004723:Endorphins / Q000097:blood / Q000134:cerebrospinal fluid / Q000378:metabolism*; D006801:Humans; D008253:Macaca mulatta; D008297:Male; D011869:Radioligand Assay
chemical_list: D004723:Endorphins