BCAA Supplementation in Mice with Diet-induced Obesity Alters the Metabolome Without Impairing Glucose Homeostasis - PubMed (original) (raw)

BCAA Supplementation in Mice with Diet-induced Obesity Alters the Metabolome Without Impairing Glucose Homeostasis

Jennifer Lee et al. Endocrinology. 2021.

Abstract

Circulating branched chain amino acid (BCAA) levels are elevated in obese humans and genetically obese rodents. However, the relationship of BCAAs to insulin resistance in diet-induced obese mice, a commonly used model to study glucose homeostasis, is still ill-defined. Here we examined how high-fat high-sucrose (HFHS) or high-fat diet (HFD) feeding, with or without BCAA supplementation in water, alters the metabolome in serum/plasma and tissues in mice and whether raising circulating BCAA levels worsens insulin resistance and glucose intolerance. Neither HFHS nor HFD feeding raised circulating BCAA levels in insulin-resistant diet-induced obese mice. BCAA supplementation raised circulating BCAA and branched-chain α-keto acid levels and C5-OH/C3-DC acylcarnitines (AC) in muscle from mice fed an HFHS diet or HFD, but did not worsen insulin resistance. A set of short- and long-chain acyl CoAs were elevated by diet alone in muscle, liver, and white adipose tissue (WAT), but not increased further by BCAA supplementation. HFD feeding reduced valine and leucine oxidation in WAT but not in muscle. BCAA supplementation markedly increased valine oxidation in muscle from HFD-fed mice, while leucine oxidation was unaffected by diet or BCAA treatment. Here we establish an extensive metabolome database showing tissue-specific changes in mice on 2 different HFDs, with or without BCAA supplementation. We conclude that mildly elevating circulating BCAAs and a subset of ACs by BCAA supplementation does not worsen insulin resistance or glucose tolerance in mice. This work highlights major differences in the effects of BCAAs on glucose homeostasis in diet-induced obese mice versus data reported in obese rats and in humans.

Keywords: BCAAs; acylcarnitines; diet-induced obesity; insulin resistance; metabolic syndrome; metabolomics.

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Figures

Figure 1.

Effect of BCAA supplementation on circulating BCAA levels and insulin resistance in HFHS diet-fed mice. Body weight (A), relative fat mass (B), lean mass (C), and ad libitum-fed glycemia (D) from wild-type female mice fed chow or an HFHS diet with or without BCAA supplementation in water. Chow n = 11, HFHS n = 11, HFHS + BCAA n = 12. Ad libitum-fed plasma BCAAs (isoleucine [ILE], leucine [LEU], and valine [VAL]) (E) and plasma BCKAs (alpha-keto-beta-methylvalerate [KMV], alpha-ketoisocaproate [KIC], and alpha-ketoisovalerate [KIV]) (F) measured at 32 weeks of HFHS diet feeding. Levels of BCAAs (G), and BCKAs (H) from liver, PG WAT, and quadriceps collected from the same mice as profiled in panels A–F. Mice were fasted overnight and refed an HFHS diet for 6 hours prior to the studies. E–H: Chow n = 6, HFHS n = 6, HFHS + BCAA n = 6. I: Glucose tolerance test (13 weeks of treatment) and insulin tolerance test (38 weeks of treatment) (J: left panel, raw values; right panel, normalized to starting glucose levels) performed after a 5-hour food removal in mice fed chow or an HFHS diet with or without BCAA supplementation in water. These are the same mice profiled in panels A–H. Chow n = 6–11, HFHS n = 6–11, HFHS + BCAA n = 6–12. K: Western blots showing protein levels of enzymes that regulate BCAA catabolism with corresponding quantitation by densitometry. Two different blots were run for each protein on a total of 8 to 9 mice. *P < 0.05 vs chow; #P < 0.05 vs HFHS; a, b indicates P < 0.05; ns = not significant. Abbreviations: ACL, ATP citrate lyase; ad-lib, ad libitum; BCAA, branched-chain amino acid; BCKA, branched-chain α-keto acid; BDK, branched-chain α-ketoacid dehydrogenase kinase; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; HFHS, high-fat high sucrose; ns, not significant; p-ACL, phosphorylated ATP citrate lyase; p-ATP, phosphorylated adenosine triphosphate; p-BCKDH, phosphorylated Branched-chain α-ketoacid dehydrogenase; PPM1K, protein phosphatase, Mg2+/Mn2+ Dependent 1K; t-ACL, total ATP citrate lyase; T-BCKDH, total Branched-chain α-ketoacid dehydrogenase.

Figure 2.

Effect of BCAA supplementation on acylcarnitine and acyl CoA levels in metabolic tissues. Levels of acylcarnitines and acyl CoAs in liver (A), gastrocnemius (B), and PG WAT (C) from chow and HFHS-fed wild-type female mice with or without supplemented BCAAs in water (same mice as in Fig. 1, which were on chow and an HFHS diet for 40 weeks). Only metabolites that were significantly changed are shown. Mice were fasted overnight and tissues collected following a 6-hour re-feeding period. n = 6/group. *P < 0.05 vs chow, #P < 0.05 vs HFHS by 1-way ANOVA adjusted for FDR. Abbreviations: ANOVA, analysis of variance; BCAA, branched-chain amino acid; FDR, false discovery rate; PG WAT, perigonadal white adipose tissue.

Figure 3.

Effect of BCAA supplementation on analytes derived from BCAA catabolism in HFHS diet-fed mice. BCAAs and downstream analytes in liver, gastrocnemius, and PG WAT from chow or HFHS-fed wild-type female mice with or without BCAAs supplemented in water (same mice as in Fig. 1, which were on a chow and HFHS diet for 40 weeks). Mice were fasted overnight and tissues collected following 6 hours of re-feeding. n = 6/group. *P < 0.05 vs chow; #P < 0.05 vs HFHS. Abbreviations: BCAA, branched-chain amino acid; HFHS, high-fat high sucrose; PG WAT, perigonadal white adipose tissue; TCA, tricarboxylic acid cycle.

Figure 4.

Effect of BCAA supplementation on TCA cycle intermediate levels in metabolic tissues. Amino acids and TCA cycle analytes from liver (A) and gastrocnemius (B) from chow or HFHS-fed wild-type female mice with or without BCAAs supplemented in water (same mice as in Figs. 1–3). Mice were fasted overnight and tissues were collected following 6 hours of re-feeding. n = 6/group. *P < 0.05 vs chow; #P < 0.05 vs HFHS. Abbreviations: BCAA, branched-chain amino acid; TCA, tricarboxylic acid.

Figure 5.

BCAA supplementation in another model of diet-induced obese mice does not worsen glucose homeostasis. Body weight (A), relative fat and lean mass (B), cumulative food intake (C), and cumulative water intake (D) from wild-type male mice fed chow and an HFD with or without BCAA supplementation in water. Glucose tolerance test (9 weeks of treatment) (E) and insulin tolerance test (14 weeks of treatment) (F) performed in mice following a 5-hour food removal. A–F: Chow n = 5, HFD and HFD + BCAA n = 12 per group. Terminal serum levels of BCAAs (valine and leu/ile) (G) and BCKAs (KIV, KIC, and KMV) (H) from 19-week-old mice fasted overnight and refed HFD for 6 hours prior to studies. BCAA levels from liver (I), gastrocnemius (J), and PG WAT (K), and BCKA levels from liver (L), gastrocnemius (M), and PG WAT (N) collected from mice in the 6-hour re-fed state following an overnight fast. G–N: Chow n = 4; HFD and HFD + BCAA n = 6 per group. *P < 0.05 vs chow, #P < 0.05 vs HFD. Oxidation of valine (O) and leucine (P) in PG WAT, SQ WAT, and EDL and soleus muscle explants. O–P: Chow n = 4–8, HFD and HFD + BCAA n = 6–12 per group. Q: KIV oxidation in liver, PG WAT, and quadriceps lysates. n = 11–12 per group. *P < 0.05 vs chow; #P < 0.05 vs HFD. Abbreviations: BCAA, branched-chain amino acid; BCKAs, branched-chain α-ketoacids; EDL, extensor digitorum longus; HFD, high fat diet; KIC, alpha-ketoisocaproic acid; KIV, alpha-ketoisovalerate; KMV, alpha-keto-beta-methylvalerate; leu/ile, leucine/isoleucine; PG WAT, perigonadal white adipose tissue; SQ WAT, subcutaneous white adipose tissue.

Figure 6.

Effect of BCAA supplementation on acylcarnitine and acyl CoA levels in serum and metabolic tissues from HFD-fed mice. Levels of acylcarnitines and acyl CoAs in serum (A), liver (B), gastrocnemius (C), and PG WAT (D) from chow and HFD-fed wild-type male mice supplemented with or without BCAAs in water. Mice were fasted overnight and tissues were collected following a 6-hour re-feeding period. Chow n = 4, HFD and HFD + BCAA n = 6 per group. *P < 0.05 vs chow; #P < 0.05 vs HFD. One-way ANOVA adjusted for FDR. Abbreviations: ANOVA, analysis of variance; BCAA, branched-chain amino acid; FDR, false discovery rate; HFD, high fat diet.

Figure 6.

Figure 7.

Effect of BCAA supplementation on analytes derived from BCAA catabolism in HFD-fed mice. BCAAs and downstream analytes in liver, gastrocnemius, and PG WAT from chow and HFD-fed wild-type male mice with or without BCAAs supplemented in water. Mice were fasted overnight and tissues were collected following a 6-hour re-feeding period. Chow n = 4, HFD and HFD + BCAA n = 6 per group. *P < 0.05 vs chow; #P < 0.05 vs HFD. Abbreviations: BCAA, branched-chain amino acid; HFD, high fat diet; PG WAT, perigonadal white adipose tissue.

Figure 8.

Effect of BCAA supplementation on levels of TCA cycle intermediates in HFD-fed mice. Amino acids and TCA cycle analytes from liver (A) and gastrocnemius (B) from chow or HFD-fed wild-type female mice supplemented with or without BCAAs in water (same mice as in Figs. 5–7). Mice were fasted overnight and tissues were collected following 6 hours of re-feeding. Chow n = 4, HFD and HFD + BCAA n = 6 per group. *P < 0.05 vs chow; #P < 0.05 vs HFD. Abbreviations: BCAA, branched-chain amino acid; HFD, high fat diet; TCA, tricarboxylic acid.

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BCAA Supplementation in Mice with Diet-induced Obesity Alters the Metabolome Without Impairing Glucose Homeostasis - PubMed (original) (raw)