High-fat Diet-induced Ultradian Leptin and Insulin Hypersecretion are Absent in Obesity-resistant Rats*
| Autor: | Pushpa S. Kalra, Michael G. Dube, Rita Torto, Effiong E. Otukonyong, Satya P. Kalra |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Leptin
Periodicity medicine.medical_specialty Peptide Hormones Endocrinology Diabetes and Metabolism medicine.medical_treatment Medicine (miscellaneous) Biology Statistics Nonparametric Energy homeostasis Feedback Rats Sprague-Dawley Eating Endocrinology Internal medicine Insulin Secretion medicine Hyperinsulinemia Animals Cluster Analysis Insulin Obesity Ultradian rhythm Body Weight digestive oral and skin physiology Public Health Environmental and Occupational Health medicine.disease Dietary Fats Ghrelin Circadian Rhythm Rats Female medicine.symptom Weight gain hormones hormone substitutes and hormone antagonists Food Science Hormone |
| Zdroj: | Obesity Research. 13:991-999 |
| ISSN: | 1071-7323 |
| Popis: | Objective: Sprague-Dawley rats fed a high-fat diet (HFD) are either obesity prone (OP) or obesity resistant (OR). We tested the hypothesis that differences in the ultradian rhythmic patterns of insulin and ghrelin in OP vs. OR rats promote obesity in OP rats. Research Methods and Procedures: Rats were fed regular chow or an HFD, and ultradian fluctuations in leptin, insulin, and ghrelin were analyzed in blood samples collected at 5-minute intervals from intrajugular cannulae of freely moving rats. Results: Regular chow feeding resulted in a slow weight gain accompanied by small increases in insulin and leptin and a decrease in ghrelin discharge, with only the pulse amplitude significantly altered. Similar changes were observed in OR rats, despite HFD consumption. In contrast, OP rats exhibited a high rate of weight gain and marked hyperinsulinemia, hyperleptinemia, and hypoghrelinemia; amplitude was altered, but frequency was stable. In a short-term experiment, HFD elicited similar secretory patterns of smaller magnitude even in the absence of weight gain. Discussion: We showed that three hormonal signals of disparate origin involved in energy homeostasis were secreted in discrete episodes, and only the pulse amplitude component was vulnerable to age and HFD consumption. Increases in insulin and leptin and decreases in ghrelin pulse amplitude caused by HFD were exaggerated in OP rats relative to OR rats and preceded the weight increase. These findings show that a distinct genetic predisposition in the endocrine organs of OR rats confers protection against high-fat intake-induced ultradian hypersecretion of obesity-promoting hormonal signals. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text