1. به نام خدا

2. FOOD INTAKE AND APPETITE
CONTROL OF
FOOD INTAKE AND APPETITE

3. What’s the underlying cause?
Fast forward 15 years to 2030 Humans are sicker than ever
Life expectancy has decreased and productivity is down
What’s the underlying cause?
Obesity

4. Traditionally, a distinction has been made between homeostatic & nonhomeostatic control of appetite and food intake

5. Deviation from homeostatic control
physiologic
nonphysiologic
obesity

6. CENTRAL CONTROLS OF FOOD INTAKE AND APPETITE
Coordination by the
Hypothalamus

7. The hypothalamus is widely recognized as the in the control of food intake and appetite
“gate keeper”

8. the lateral hypothalamus as the “hunger center” and the medial hypothalamus as the “satiety center”

9. A network of communication among the gut, pancreas, adipose tissue, brainstem, and hypothalamus is well established

10. Additionally, further communication
exists between the
hypothalamus and higher cortical centers pertaining to food memory of food, with resulting overall coordinated
control of food intake

11. Role of the Brainstem
is the main organ responsible for facilitating the communication between peripheral signals of food intake and hypothalamic nuclei

12. The arcuate nucleus (ARC) is thought to be the main hypothalamic
area controlling food intake

13. Within the ARC, two groups of neurons are pivotal in regulating food intake
One group of neurons contains neuropeptide Y (NPY), and most of these also contain Agouti-related peptide (AgRP)
The second group is formed by neurons containing pro-opiomelanocortin (POMC)
Activation of these neurons
enhances food ntake
(orexigenic)
Activation of these neurons reduces food intake (anorexigenic)

14. NPY is the most powerful central stimulant of appetite

15. Neuropeptides Implicated in the Control of Food Intake
Agouti-Related Peptide
Cocaine- and Amphetamine-Regulated Transcript
Hypothalamic Releasing Hormones
Orexins
Melanin-Concentrating Hormone
Brain-Derived Neurotrophic Factor
Ciliary Neurotrophic Factor
Central Neurotransmitters

16. PERIPHERAL CONTROLS OF FOOD INTAKE AND APPETITE
Nutrient, hormonal signals from the gastrointestinal system, endocrine organs, and adipose tissue
all have essential roles in influencing food intake and appetite

17. hunger (orexigenic signals)
These peripheral signals target areas of the hypothalamus to regulate appetite They include signals conveying a feeling of fullness (satiety signals)
and
hunger (orexigenic signals)

18. These signals can control
meal size
&
meal number

19. Orosensory and Optic Stimuli
Neural Signals
Orosensory and Optic Stimuli
Orosensory and optic stimuli provide the brain with
sensory information regarding the nature of food
These stimuli include
appearance, taste, smell, and textural stimuli

20. to continue or to stop eating
The information is used by the brain to decision
to eat or not eat
to continue or to stop eating

21. Gastric Distention
Volume-related postprandial gastric distention results in satiety during a meal
bariatric surgical

22. Nutrient Signals
Most nutrient signals exert their effects on the gastrointestinal
system and the brain and induce the
secretion of gastrointestinal hormones and appetite regulation

23. Gut Hormones the largest endocrine organ
secretes more than 30 different regulatory
peptide hormones
• digestion and absorption
• affect short-term feelings of hunger and satiety

24. These hormones are the subject of extensive research, given their potential as physiologic antiobesity therapies

25. Cholecystokinin (CCK)
It is released postprandially
slowed gastric emptying
CCK reduces food intake

26. Ghrelin Increases appetite “hunger hormone”
considered as one of the most powerful physiologic orexigenic agents
increases food intake and body weight in rodents
Plasma ghrelin levels are also noted to increase on weight loss (regain weight )

27. Peptide YY (PYY) released postprandially
PYY administration decreases food intake
Obese patients demonstrate a blunted postprandial rise in PYY
PYY-based antiobesity agents are currently under development

28. Glucagon-like Peptide-1(GLP-1)
reduces food intake
released postprandially
reduces gastric emptying
analogs of GLP-1 are used in the treatment of type 2 diabetes
currently undergoing clinical trials for the treatment of obesity

29. Pancreatic Hormones
major function is to control glucose homeostasis (Insulin & Glucagon)
pancreatic polypeptide and amylin, also affect appetite ( are satiety signal and reduces food intake)

30. Hormones from Adipose Tissue (leptin)
a circulating protein produced by adipocytes (fat cells)
is a signal from the adipose tissue to the brain that reflects the state of energy stores
increased by overfeeding
absence of leptin lead to severe obesity
Leptin acts on ARC LepR to stimulate POMC neurons and inhibit NPY/AgRP neurons to decrease food intake

31. Other Hormones
Thyroid hormones, gonadal steroids and glucocorticoids regulate metabolic rate, reproductive state and stress responses, respectively
These processes rely on adequate
energy supplies. Therefore, it is not surprising that hormones regulating these processes are also involved in the
endocrine regulation of appetite

32. Signals from the Immune System
Anorexia or decreased food intake during infectious,
inflammatory, and neoplastic disease states is very evident.
Anorexia appears to result from the action of cytokines in the brain

33. The word “hedonic” relates to pleasant (or unpleasant) sensations
Hedonic Mechanisms
The word “hedonic” relates to pleasant (or unpleasant) sensations
visual, smell, and taste signals can override satiety signals to maintain
food intake

34. CONCLUSION The regulation of food intake and appetite occurs through
the integration of various
central and peripheral signals

35. of food, and numerous environmental and emotional factors
These signals interact at the level of the brainstem and hypothalamus to produce an overall response of hunger or fullness
Additionally,
these neuronal networks are hugely modified by other influences such as sensory inputs, food memory, rewarding aspects
of food, and numerous environmental and emotional factors

36. This modification is a particular feature of modern human eating behavior and may underpin the dysregulation of energy balance that is responsible for the current obesity epidemic

37. By means of ever-expanding current research , it is hoped that our understanding of the complex and intricate signaling pathways governing appetite control will improve and pave the way for better antiobesity drug treatments

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