The role of the blood-brain barrier transporter PTS-1 in regulating concentrations of methionine enkephalin in blood and brain.
Previous studies have suggested that peptide transport system (PTS)-1, a saturable efflux system from brain to blood, regulates the concentration in the brain of methionine enkephalin (Met-Enk), an opiate peptide related to the drinking of ethanol in mice. We determined the relationship of PTS-1 to concentrations of immunoreactive Met-Enk in plasma and whole brain in eight randomly selected strains of mice. An active PTS-1 system could be demonstrated in five of the eight strains. In those five strains, faster efflux rates due to PTS-1 correlated with higher concentrations of Met-Enk in brain and plasma. These concentrations of Met-Enk in brain and plasma were positively correlated in the five strains in which PTS-1 was demonstrable and were inversely correlated in the three strains in which PTS-1 was not demonstrable. The results are consistent with previous observations indicating that the chronic level of brain Met-Enk can set the level of activity of PTS-1 and that, once set, PTS-1 can play a major role in determining the concentrations of Met-Enk in brain and blood.
Banks
W A
WA
Veterans Affairs Medical Center and Tulane University School of Medicine, New Orleans, LA 70146, USA. bbbpts@mailhost.tcs.tulane.edu
Kastin
A J
AJ
D000818:Animals; D001812:Blood-Brain Barrier; D001923:Brain Chemistry; D004744:Enkephalin, Methionine / Q000032:analysis* / Q000097:blood; D026901:Membrane Transport Proteins / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains
D026901:Membrane Transport Proteins; D004744:Enkephalin, Methionine; C043912:peptide permease