Green tea extract improves high fat diet-induced hypothalamic inflammation, without affecting the serotoninergic system

• Published in: The Journal of nutritional biochemistry 2014-10, Vol.25 (10), p.1084-1089
• Main Authors: Okuda, Marcos H., Zemdegs, Juliane C.S., de Santana, Aline A., Santamarina, Aline B., Moreno, Mayara F., Hachul, Ana C.L., Santos, Bruno dos, Nascimento, Claudia M. Oller do, Ribeiro, Eliane B., Oyama, Lila M.
• Format: Article
• Language: English
• Subjects: Adiponectin - blood; Adipose Tissue - drug effects; Adipose Tissue - metabolism; Animals; Blood Glucose - metabolism; Body Weight - drug effects; Cholesterol - blood; Diet, High-Fat - adverse effects; Enzyme-Linked Immunosorbent Assay; Fasting; Glucose Tolerance Test; Green tea extract; High-fat diet; Hypothalamus; Hypothalamus - drug effects; Hypothalamus - metabolism; Hypothalamus - pathology; I-kappa B Proteins - genetics; I-kappa B Proteins - metabolism; Inflammation - drug therapy; Inflammation - pathology; Insulin - blood; Interleukin-6 - blood; Male; Mice; Neuroinflammation; NF-kappa B p50 Subunit - genetics; NF-kappa B p50 Subunit - metabolism; NF-KappaB Inhibitor alpha; Plant Extracts - pharmacology; Serotonin; Tea - chemistry; Toll-Like Receptor 4 - genetics; Toll-Like Receptor 4 - metabolism; Triglycerides - blood
• ISSN: 0955-2863; 1873-4847
• DOI: 10.1016/j.jnutbio.2014.05.012

To investigate possible mechanisms of green tea’s anti-obesity and anti-diabetic effects in the hypothalamus, the central regulator of metabolism, of mice fed with high-fat diet (HFD), we analyzed proteins of the toll-like receptor 4 (TLR4) pathway and serotoninergic proteins involved in energy homeostasis. Thirty-day-old male Swiss mice were fed with HFD rich in saturated fat and green tea extract (GTE) for 8 weeks. After that, body weight and mass of fat depots were evaluated. Oral glucose tolerance test was performed 3 days prior to euthanasia; serum glucose, insulin and adiponectin were measured in fasted mice. Hypothalamic TLR4 pathway proteins, serotonin receptors 1B and 2C and serotonin transporter were analyzed by Western blotting or enzyme-linked immunosorbent assay. A second set of animals was used to measure food intake in response to fluoxetine, a selective serotonin reuptake inhibitor. Mice fed with HFD had increased body weight and mass of fat depots, impaired oral glucose tolerance, elevated glucose and insulin and decreased adiponectin serum levels. TLR4, IκB-α, nuclear factor κB p50 and interleukin 6 were increased by HFD. Concomitant GTE treatment ameliorated these parameters. The serotoninergic system remained functional after HFD treatment despite a few alterations in protein content of serotonin receptors 1B and 2C and serotonin transporter. In summary, the GTE attenuated the deleterious effects of the HFD investigated in this study, partially due to reduced hypothalamic inflammation.