Acute hyperinsulinemia inhibits intramyocellular triglyceride synthesis in high-fat-fed obese rats
Hyperinsulinemia is common in obesity, but whether it plays a role in intramyocellular triglyceride (imcTG) buildup is unknown. In this study, hyperinsulinemic-euglycemic clamp experiments were performed in overnight-fasted lean and high-fat-fed obese rats, awake, to determine the effect of insulin...
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| Format: | Article |
| Language: | English |
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Elsevier
2006-12-01
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| Series: | Journal of Lipid Research |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022227520432560 |
| _version_ | 1818728293239619584 |
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| author | ZengKui Guo Lianzhen Zhou Michael D. Jensen |
| author_facet | ZengKui Guo Lianzhen Zhou Michael D. Jensen |
| author_sort | ZengKui Guo |
| collection | DOAJ |
| description | Hyperinsulinemia is common in obesity, but whether it plays a role in intramyocellular triglyceride (imcTG) buildup is unknown. In this study, hyperinsulinemic-euglycemic clamp experiments were performed in overnight-fasted lean and high-fat-fed obese rats, awake, to determine the effect of insulin on imcTG synthesis (incorporation of [14C]glycerol, [14C]glucose, and [3H]oleate). Insulin infusion at 25 (low insulin) and 100 (high insulin) pmol/kg/min increased plasma insulin by 5- and 16-fold, respectively, whereas plasma and intramyocellular glycerol, FFAs, triglycerides, and glucose levels were maintained at their basal levels by co-infusion of exogenous glycerol, FFAs, and triglycerides at fixed rates and glucose at varying rates. In obese rats, insulin suppressed incorporation of glycerol into the imcTG-glycerol moiety dose dependently (P < 0.01–P < 0.001) in gastrocnemius and tibialis anterior, but only the high insulin suppressed it in soleus (P < 0.05). The low insulin suppressed glucose incorporation into imcTG-glycerol in all three muscles (P = 0.01–P < 0.01). However, the low insulin did not affect (P > 0.05) and the high insulin suppressed (P < 0.05–P < 0.01) fatty acid incorporation into imcTG in all three muscles. Insulin also suppressed glycerol incorporation in lean rats (P < 0.01–P < 0.04). On the other hand, imcTG pool size was not affected by insulin (P > 0.05). These observations suggest that acute hyperinsulinemia inhibits imcTG synthesis and thus does not appear to promote imcTG accumulation via the synthetic pathway, at least in the short term. |
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| format | Article |
| id | doaj.art-82afc7bf39964cfc906178814b21d2ac |
| institution | Directory Open Access Journal |
| issn | 0022-2275 |
| language | English |
| last_indexed | 2024-12-17T22:27:41Z |
| publishDate | 2006-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Lipid Research |
| spelling | doaj.art-82afc7bf39964cfc906178814b21d2ac2022-12-21T21:30:19ZengElsevierJournal of Lipid Research0022-22752006-12-01471226402646Acute hyperinsulinemia inhibits intramyocellular triglyceride synthesis in high-fat-fed obese ratsZengKui Guo0Lianzhen Zhou1Michael D. Jensen2Endocrine Research Unit, Mayo Foundation, Rochester, MN 55905Endocrine Research Unit, Mayo Foundation, Rochester, MN 55905Endocrine Research Unit, Mayo Foundation, Rochester, MN 55905Hyperinsulinemia is common in obesity, but whether it plays a role in intramyocellular triglyceride (imcTG) buildup is unknown. In this study, hyperinsulinemic-euglycemic clamp experiments were performed in overnight-fasted lean and high-fat-fed obese rats, awake, to determine the effect of insulin on imcTG synthesis (incorporation of [14C]glycerol, [14C]glucose, and [3H]oleate). Insulin infusion at 25 (low insulin) and 100 (high insulin) pmol/kg/min increased plasma insulin by 5- and 16-fold, respectively, whereas plasma and intramyocellular glycerol, FFAs, triglycerides, and glucose levels were maintained at their basal levels by co-infusion of exogenous glycerol, FFAs, and triglycerides at fixed rates and glucose at varying rates. In obese rats, insulin suppressed incorporation of glycerol into the imcTG-glycerol moiety dose dependently (P < 0.01–P < 0.001) in gastrocnemius and tibialis anterior, but only the high insulin suppressed it in soleus (P < 0.05). The low insulin suppressed glucose incorporation into imcTG-glycerol in all three muscles (P = 0.01–P < 0.01). However, the low insulin did not affect (P > 0.05) and the high insulin suppressed (P < 0.05–P < 0.01) fatty acid incorporation into imcTG in all three muscles. Insulin also suppressed glycerol incorporation in lean rats (P < 0.01–P < 0.04). On the other hand, imcTG pool size was not affected by insulin (P > 0.05). These observations suggest that acute hyperinsulinemia inhibits imcTG synthesis and thus does not appear to promote imcTG accumulation via the synthetic pathway, at least in the short term.http://www.sciencedirect.com/science/article/pii/S0022227520432560muscletriglyceridesinsulinobesity |
| spellingShingle | ZengKui Guo Lianzhen Zhou Michael D. Jensen Acute hyperinsulinemia inhibits intramyocellular triglyceride synthesis in high-fat-fed obese rats Journal of Lipid Research muscle triglycerides insulin obesity |
| title | Acute hyperinsulinemia inhibits intramyocellular triglyceride synthesis in high-fat-fed obese rats |
| title_full | Acute hyperinsulinemia inhibits intramyocellular triglyceride synthesis in high-fat-fed obese rats |
| title_fullStr | Acute hyperinsulinemia inhibits intramyocellular triglyceride synthesis in high-fat-fed obese rats |
| title_full_unstemmed | Acute hyperinsulinemia inhibits intramyocellular triglyceride synthesis in high-fat-fed obese rats |
| title_short | Acute hyperinsulinemia inhibits intramyocellular triglyceride synthesis in high-fat-fed obese rats |
| title_sort | acute hyperinsulinemia inhibits intramyocellular triglyceride synthesis in high fat fed obese rats |
| topic | muscle triglycerides insulin obesity |
| url | http://www.sciencedirect.com/science/article/pii/S0022227520432560 |
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