title: Individual variability in Tyr-Gly-Gly formation from enkephalin hydrolysis in mouse plasma.
abstract: We examined the effects of captopril (an angiotensin-converting enzyme inhibitor) and phosphoramidon (a selective enkephalinase inhibitor) on Tyr-Gly-Gly production during Met-enkephalin hydrolysis in plasma samples taken from individual outbred Swiss-Webster and inbred C57BL/6J and DBA/2J mice. Discriminant analysis procedures identified three distinct plasma profiles of Tyr-Gly-Gly production in all strains of mice: a captopril-sensitive/phosphoramidon-insensitive profile, a captopril-insensitive/phosphoramidon-sensitive profile, and a moderate captopril and phosphoramidon sensitivity profile. The abilities of captopril and phosphoramidon to inhibit Tyr-Gly-Gly production in the same mouse plasma sample were highly inversely correlated (r = -0.938). Plasma of Swiss-Webster mice whose cages and bedding had been changed 24 h prior to sample collection was significantly more likely to exhibit the captopril-sensitive/phosphoramidon-insensitive profile than the plasma of mice whose cages/bedding had not been changed for at least 5 days. The results suggest that environmental novelty may dramatically alter the activity of a plasma dipeptidyl carboxypeptidase system, and thereby regulate behavioral and physiological responses to novel experiences.
authors.affiliation: Department of Psychology, University of California, Berkeley 94720.
authors.forename: G
authors.initials: G
authors.lastname: Schulteis
authors.forename: W A
authors.initials: WA
authors.lastname: Rodriguez
authors.forename: S B
authors.initials: SB
authors.lastname: Rodriguez
authors.forename: J L
authors.initials: JL
authors.lastname: Martinez
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002216:Captopril / Q000494:pharmacology; D016002:Discriminant Analysis; D004744:Enkephalin, Methionine / Q000097:blood*; D006020:Glycopeptides / Q000494:pharmacology; D006868:Hydrolysis; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D015260:Neprilysin / Q000037:antagonists & inhibitors; D009842:Oligopeptides / Q000097:blood*
chemical_list: D006020:Glycopeptides; D009842:Oligopeptides; C044757:tyrosyl-glycyl-glycine; D004744:Enkephalin, Methionine; D002216:Captopril; D015260:Neprilysin; C008890:phosphoramidon