Delayed degradation of Tyr-MIF-1 in neonatal rat plasma.
Peptides like Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) that are administered during the neonatal period can result in biological effects persisting into the adult period. The possibility that Tyr-MIF-1 might have a prolonged half-life in neonatal blood was investigated by HPLC of plasma obtained from 4-day-old rat pups. More than half (65%) of the tritiated Tyr-MIF-1 incubated with neonatal rat plasma at 37 degrees C remained in intact form at 30 min compared with less than a quarter of the Tyr-MIF-1 incubated with adult rat plasma. The calculated half-life of the tetrapeptide incubated in neonatal plasma was 50.2 min, compared with 13.8 min for adult plasma (p < 0.01). The simultaneous addition of Tyr-MIF-1 tritiated on the Tyr and Tyr-MIF-1 tritiated on the Pro showed the formation of equal amounts of the free amino acids Tyr and Pro; this indicates that Tyr-MIF-1 is not a precursor of MIF-1 in neonatal rat plasma. The results show that the degradation of Tyr-MIF-1 is significantly delayed in plasma from neonatal rats, suggesting the possibility that the metabolism of other peptides and different types of compounds also may be delayed during the perinatal period.
Kastin
A J
AJ
VA Medical Center, New Orleans, LA.
Hahn
K
K
Banks
W A
WA
Zadina
J E
JE
D000375:Aging / Q000097:blood*; D000818:Animals; D000831:Animals, Newborn; D001673:Biodegradation, Environmental; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D009075:MSH Release-Inhibiting Hormone / Q000031:analogs & derivatives* / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D014316:Tritium
D014316:Tritium; C036930:tyrosyl-prolyl-leucyl-glycinamide; D009075:MSH Release-Inhibiting Hormone