Figure 2.

Plasma concentrations of alloisoleucine in Zucker and DIO rat models or obesity. Plasma alloisoleucine concentrations in (A) lean and obese Zucker rats fed a low fat (chow) diet or (B) lean and obese Sprague-Dawley DIO rats fed a HF diet as described in the Methods and Procedures. The results are mean ± SE, n=9–10, ** p=0.0051, ns indicates not significant. (C) Schematic summarizing previous findings in these two models related to branched chain amino acids. Zucker rats fed even a low fat diet and SD rats fed a high fat diet have increased caloric and BCAA intake and develop obesity associated with elevated BCAAs albeit BCAA elevations are greater in Zucker compared to DIO rats; both models exhibit impairments in adipose tissue BCAA metabolism that include BCKDC (see Results text statements and References ^{5, 7, 8}). The combination of impaired BCKDC activity in fat ^5,9 and along with ~50% decreased activity in multiple other peripheral tissues ⁸ of the obese Zucker rat is posited to explain the observed elevations in alloisoleucine (A). However in the DIO rat loss of BCKDC in fat ^{7, 9} is compensated for by >50% increase in BCKDC activity in liver as shown by Kadota et al.⁶. Thus no change in alloisoleucine was observed in DIO rats as S-KMV that is not metabolized in fat can circulate to the liver to be metabolized there.