Beverly J L, Hrupka B J, Gietzen D W, Rogers Q R
Department of Physiological Sciences, School of Veterinary Medicine, University of California, Davis 95616.
Am J Physiol. 1991 Mar;260(3 Pt 2):R525-32. doi: 10.1152/ajpregu.1991.260.3.R525.
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.
膳食限制氨基酸（DLAA）在梨状前皮质（PPC）中的扩散或代谢可能是将DLAA注入PPC与氨基酸不平衡饮食摄入量增加之间存在时间滞后的原因。将[3H]亮氨酸±[14C]苏氨酸（DLAA）注入PPC的结果表明，其扩散迅速（不到15分钟）且受限（回收标记的85 - 90%距离注射部位小于或等于1毫米）。在注射后的前1.5小时内，3H和14C在三氯乙酸（TCA）可溶部分减少，在TCA不溶部分增加，并且在注射后1.5 - 6小时在TCA不溶部分保持恒定。在注射DLAA后不到或等于30分钟，发现TCA不溶部分中的3H增加了（约50%）。DLAA对TCA可溶部分中的3H没有影响。这些结果表明，PPC内代谢的变化可能是将DLAA注入PPC后进食反应开始延迟的原因。
