AJP - Regulatory, Integrative and Comparative Physiology, Vol 260, Issue 3 525-R532, Copyright © 1991 by American Physiological Society
Distribution of dietary limiting amino acid injected into the prepyriform cortex
J. L. Beverly, B. J. Hrupka, D. W. Gietzen and Q. R. Rogers
Department of Physiological Sciences, School of Veterinary Medicine, University of California, Davis 95616.
Diffusion or metabolism of the dietary limiting amino acid (DLAA) in the
prepyriform cortex (PPC) may account for the time lag between injection of
the DLAA into the PPC and the increase in intake of an amino
acid-imbalanced diet. Results from the injection of [3H]Leu +/- [14C]Thr
(DLAA) into the PPC indicated rapid (less than 15 min) and limited
diffusion (85-90% of recovered label was less than or equal to 1 mm from
the injection site). 3H and 14C decreased in the trichloroacetic acid
(TCA)-soluble fraction and increased in the TCA-insoluble fraction during
the first 1.5 h and remained constant in the TCA-insoluble fraction 1.5-6 h
after injection. An increase (approximately 50%) in 3H in the TCA-insoluble
fraction was found less than or equal to 30 min after injection of the
DLAA. There was no affect of the DLAA on 3H in the TCA-soluble fraction.
These results indicated that a change in metabolism within the PPC may be
responsible for the delay in onset of the feeding response after injection
of the DLAA into the PPC.
