Download PG1006 Lecture 15 Adipose Tissue Dr. Neil Docherty

PG1006
Lecture 15
Adipose Tissue
Dr. Neil Docherty
My Teaching Objec/ves 1.  To describe the distribu0on and cellular nature of dipose 0ssue 2.  To explain the role of white adipose 0ssue in metabolism 3.  To present the heat genera0ng func0on of brown adipose 0ssue 4.  To make the link between obesity, inflamma0on and metabolic dysregula0on. Adipose Tissue Loose connec0ve 0ssue populated mainly by lipid accumula0ng adipocytes White Adipose Tissue
Brown Adipose Tissue
White Adipose Tissue (WAT)
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White (20-­‐25% of total body weight) Superficial depot (subcutaneous) Visceral fat depots (peri-­‐renal,mesenteric) Bone marrow Breast 0ssue Hormone responsive to
• insulin,
• glucocorticoids,
• growth hormone
• Noradrenaline (see later)
Brainstorm three purposes of WAT
given its nature
WAT Adipocyte Features
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White adipocytes  uniocular cells –  Large lipid droplet surrounded by thin cytoplasm –  FlaLened, eccentric nuclei. –  ~0.1mm in diameter. –  Fat stored as triglycerides and cholesterol ester. –  Secrete hormones or adipocytokines e.g) lep0n White Adipose Tissue (TEM) Note size comparison
with macrophage
And fibroblast
Lipid and Glucose Trafficking To and From The Adipocyte
Role of Noradrenaline (Norepinephrine)
Lep/n-­‐An Adipose Hormone •  Energy intake and expenditure –  Appe0te, metabolism. •  Discovered in obese mice (ob/ob). •  white and brown adipose 0ssue, ovaries, placenta, skeletal muscle, bone marrow, pituitary and liver. •  Absence leads to uncontrolled food intake obesity. –  BUT ↑ lep0n, ↑ obesity lep0n densensi0sa0on Leptin is an Anorexigenic Hormone
Acts on receptors in hypothalamus
Reduces neuropeptide Y release
Brown adipose /ssue Mul0locular cells Polyglonal shape Considerable cytoplasm ScaLered lipid droplets Round central nucleus Brown colour from mitochondria Used to generate heat Brown Adipose Tissue (TEM) Brown adipose /ssue and Heat Produc/on •  Can dissipate stored energy as heat –  Neonates, small mammals, hiberna0ng animals. –  25% b.w. in neonates. •  Cells express mitochondrial uncoupling protein 1 (UCP1) –  Can uncouple oxida0ve phosphoryla0on to generate heat rather than ATP. Importance in Neonates: • 
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↑ body surface:body volume ↑ propor0onal surface area of the head ↓ musculature, ↓ shivering. ↓ thermal insula0on The nervous system is not fully developed Adipose /ssue macrophages •  Obesity associated with chronic low grade inflamma0on. infiltra0on of macrophages. Adipose Tissue Macrophages and Metabolic Dysregula/on Your Learning from Today Should focus on being able to;
1.  Describe the distribu0on and cellular nature of adipose 0ssue 2.  Explain the role of white adipose 0ssue in metabolism 3.  Discuss the mechanism and role of heat genera0on in brown adipose 0ssue 4.  Link obesity, inflamma0on and metabolic dysregula0on.