Adipose tissue as an endocrine organ

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Adipose tissue as an endocrine organ

• Assaf Rudich, MD, PhD,
• The S. Daniel Abraham for Health Nutrition,
• Department of Clinical Biochemistry,
• Faculty of Health Science,
• Ben-Gurion University of the Negev,
• Beer-Sheva

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Adipose tissue is (also) a secretory organ!

• Adipose tissue is the major site of energy
  storage, in the form of triglycerides.
• Triglyceride storage and release are tightly
  regulated by hormones.
• Yet, In addition
• Non-peptide bioactive compounds, such as FFA also
  act through receptors (and are thus both
  metabolic agents as well as hormones).
• 30 of expressed genes in adipocytes are
  potentially secreted proteins!

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Peptides
Leptin
TNF, IL6, MCP1 Complement
Adiponectin Resistin
Angiotensinogen PAI-1, TF
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Non-Peptides
CNS Development Food intake Energy
expenditure Autonomic activity Reproductive
Fuel metabolism FFA release Fat
metabolism Glucose homeostasis
Inflammation immunity
Pancreatic Beta-cells
Vascular Thrombosis Vascular tone
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Agenda

• Adipose tissue as an endocrine organ

Adipose tissue as an endocrine organ
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1. Organ or Organs Apples pears
Upper body (android, central) obesity is more
correlated to the metabolic syndrome than lower
body (gynoid) obesity

• Depot-specific differences in adipose tissue
• Anatomical (visceral fat draines to the portal
  system).
• Secretory function.
• Sensitivity to metabolic cues (lipolytic and
  anti-lipolytic)
• Fat tissue cellular composition?

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2. Cellular composition of adipose tissue
relevance for its endocrine function
Omental fat biopsy from an obese
woman Immuohistochemistry for the macrophage
marker CD68
(H. Redel, H. Oz, E. Avinoach, N. Sion-Vardi, I.
Harman-Boehm, N. Bashan, A. Rudich)
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Macrophages may be major players in the secretory
function of adipose tissue, particularly in
Obesity
Small adipocytes
Large adipocytes
(JCI 112 1785-8, 2003)
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Endocrine Function definitions
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Specific fat-derived hormones (adipokines)

• Specific Major target(s) alterations
• hormone in obesity
• Leptin Brain, other.. Resistance
• Adiponectin Liver, Endothelium, Deficiency
• Muscle(?), Brain? ( resistance)
• Resistin Liver Increased
• Visfatin Liver? Increased
• NEFA (FFA) Liver, Muscle, Brain? Increased