Entry of CART into brain is rapid but not inhibited by excess CART or leptin.
Cocaine- and amphetamine-regulated transcript (CART) is a new anorectic peptide found in the brain and periphery. It is closely associated with leptin, an anorectic agent saturably transported across the blood-brain barrier (BBB). Using multiple time-regression analysis, we found that CART has a rapid rate of entry into brain from blood. However, there was no self-inhibition with CART, even when perfused in blood-free buffer or in fasted mice, showing a lack of saturation. HPLC showed that at least 58% of the injected CART reached brain tissue in intact form, and capillary depletion with and without washout showed that the CART was not bound to endothelial cells or adherent to vascular components. There was no evidence for an efflux system out of the brain for CART. Thus CART can cross the BBB from blood to brain, but its rapid rate of entry is not inhibited by excess CART or leptin.
Kastin
A J
AJ
Veterans Affairs Medical Center, Tulane University School of Medicine, New Orleans, Louisiana 70112-1262, USA.
Akerstrom
V
V
D000418:Albumins / Q000493:pharmacokinetics; D000818:Animals; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000098:blood supply / Q000378:metabolism; D002021:Buffers; D002851:Chromatography, High Pressure Liquid; D005246:Feedback / Q000187:drug effects / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology; D007275:Injections, Intravenous; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D020738:Leptin / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009419:Nerve Tissue Proteins / Q000493:pharmacokinetics*; D000442:Octanols; D012044:Regression Analysis; D013667:Technetium / Q000493:pharmacokinetics; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
D000418:Albumins; D002021:Buffers; D007457:Iodine Radioisotopes; D020738:Leptin; D009419:Nerve Tissue Proteins; D000442:Octanols; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; D013667:Technetium