Revised powerpoint for SCNC1112 presentation ( Group H2) New slides:

- slide page 7Significance of BAT in infants

- slide page 21Research on Brown Adipose Tissue

Group H2: Shirley Chan Cheuk TingNG Ngan LingGaga Kwok Yiu HeiCelia Kwong Mei YeeTracy So Wai ShuenRita Yuen Kwai Yin

Keeping 'fat' in order to lose weight~

The Brown Fat ~Group H2: Shirley Chan Cheuk TingNG Ngan LingGaga Kwok Yiu HeiCelia Kwong Mei YeeTracy So Wai ShuenRita Yuen Kwai YinRita Yuen Kwai Yin

Our focus- What is Brown Adipose Tissue

(BAT)?- Difference between BAT and

white adipose tissue (WAT)- Mechanism and implications- Scientific research progress of

brown fat

BAT and the societyObesity is a big concern.

Ways of keeping fit?

BAT may help...

Brown fat: Fat that makes you thin http://www.youtube.com/watch?v=VFMLXjWHzYg

Brown Adipose Tissue (BAT)- also named as "Brown Fat"

o brownish: mitochondriao proliferate in response to cold

- present in mammals

- Main function: o generate body heat in animals and newborns

(by burning calories)o regulating heat

- infants: BATo upper half of the spine o towards the shoulders and collar bones

- adults: WATsome BAT: upper chest and neck

Significance of BAT in infants• To balance heat loss and production of infants• large ratio of human brain in infants• lacks of shivering reflexes and ability to produce heat through

physical activity (non-shivering thermogensis)• higher ratio of body surface to body volume• underdeveloped nervous system• Low subcutaneous fat content --> less insulation.• Inability to acquire enough calories-->not enough nutrients for

thermogenesis.• pulmonary problems --> limited consumption

Differences between White adipose Tissue and BAT

• Structure

• Origin

• Developmental pattern

• Location

• Function

• Gene expression

Structure• number of lipid droplet• mitochondrial density• vascularization• uncoupling protein 1

positron emission tomography

Origin• mesodermal stem cell →

adipoblast → white/brown preadipocyte→ mature adipocyte

• BAT has myogenic signature

• not certain- no unique markers- BAT found in WAT in rodents

exopsed to cold

Developmental pattern

• Fetal development: BAT earliero 5% body masso max. BAT at birth

• BAT decreases, WAT increases with agingo BAT decreases→ age-related

decline in thermogenesis→ possible age-related obesity

Location• WAT :- in areas all over the body-subcutaneous,intra-abdominal

depots -->main compartments for fat storage

• BAT :-abundant at birth - in axillary, cervical, perirenal, and

periadrenal regions-present in adulthood but to a lesser

extent

Function• WAT :-protection of internal organ-energy storage-maintaining of constant body temperature

• BAT :- regulation energy balance 50 g of BAT could account for 20% of daily energy expenditureage-related decline in thermogenesis with a reduction in the amount of

functional BAT-regulation of whole-body energy homeostasis e.g.“ectopic brown adipocytes”

Gene expression

UCP-1 gene: Turning "on" and "off"

-fractions isolated from BAT differentiate into UCP-1-expressing cells

-isolates from WAT differentiate into fat without UCP-1

-other stimuli can induce UCP-1 expression or inhibit UCP-1 gene expression

Mechanismstimulate sympathetic nerves to release

catecholamines(Norepinephrine) in BAT

-> stimulates the BAT cells to oxidize substrates more rapidly

-> stimulate proliferation and heat production by brown fat cells

-> Mitochondria proliferate in response to cold, both the concentration of the polypeptide and the binding of purine nucleotides increase.

Thermogenesis

- occur through expression of uncoupling protein-1 (UCP- 1)

--> a 32 kDa protein --> found in the inner membrane --> allows dissipation of the proton electro-

chemical -->expressed in the form of heat

( Cannon and Nedergaard, 2004)

Adverse effects of too much BAT:

1.infants:increase risks for obesity and weight problems in childhood and adulthood

2.adults: BAT usually consider as good fat to help reduce obesity and diabetes but more research is required for discovering if there are adverse effects

How is this related to our current lives?

BAT burn stored calories adults lose most BAT to increase metabolic

efficiencysome amount of BAT is found in the bodyactivating BAT may help to alleviate some current

health issues

e.g. weight-loss -->obesitye.g. increase glucose homeostasis --> diabetes

Possible applications:1.Brown Fat Pills with protein (BMP-7) to increase

production of BAT

2.Cold Therapy by triggering cold-induced thermogenesis e.g.Alternating temperature when taking a bath

3. Brown Fat Transplantation by inserting BAT directly

Research on Brown Adipose Tissue• Oxygen consumption rate (OCR) - demonstrates the capacity to burn calories-comparison of OCRs of human BAT cells and mouse constitutive BAT cells + OCRs of human BAT cells and human WAT- the first study to directly measure brown fat cells' OCR

• RESULTS:- the OCR of the human BAT cells from the deep human neck location: nearly 50% of the mouse BAT cells-the OCR of human WAT: only 1/100 of the OCR found in the most active human BAT -brown fat cells have a great capacity to burn fat

• FUNCTIONS:-able to grow new functional brown fat cells (adipocytes) by differentiating precursor cells (preadipocytes) derived from both superficial and deep human neck fat tissue-When stimulated, the cells expressed the same genes as naturally occurring brown fat cells-the first report of the production of brown fat cells (adipogenesis) that can respond to pharmacological stimulation

Current developmentShould we try to increase our brown fat content?

A study by the Universite de Sherbrooke, Canada:

- The more brown fat a person had, the longer it took before he would start to shiver.

- When the brown fat cells were active, the volunteers burned an extra 250 calories; a 1.8 times increase in calorie burning rate.

- did find that lean people have more brown fat than obese individuals

- how humans could increase their brown fat content?

- too early to make any conclusions regarding the weight-loss benefits of brown fat

How is this relevant to weight loss? • CHANGING METABOLISM

Reference ListJ.H. Hagen (1979) Obesity may be due to a malfunctioning of brown fat. Can Med Assoc J. 1979 November 17;

121(10): 1361–1364. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1704532/?page=1

G. Kolata,(2009, April 8) Calorie-Burning Fat? Studies Say You Have It, The New York Times, Retrieved from http://www.nytimes.com/2009/04/09/health/research/09fat.html?_r=1&

P.Seale & M.A.Lazar (2009) Brown Fat in Humans: Turning up the head on obesity, Diabetes July 2009, 58(7), 1452-1484,ldoi: 10.2337/db09-0622, retrieved from http://diabetes.diabetesjournals.org/content/58/7/1482.full.pdf+htm

C. Nordqvist (2012, January 31) What is Brown Fat? What is Brown Adipose Tissue?,Medical News Today, Retrieved from http://www.medicalnewstoday.com/articles/240989.php

B.Canon & J. Nedergaad(2004) Brown Adipose Tissue: Function and Physiological Significance, Physiological Reviews, 84(1), 277-359, retrieved from http://physrev.physiology.org/content/84/1/277.long

S.Gesta & H.T.Yu & C.R. Kahn (2007),Developmental Origin of Fat: Tracking Obesity to Its Source Cell, 131(2), 242-256, retrieved from http://www.sciencedirect.com/science/article/pii/S009286740701272X

D. Hull & M.M.Segall (1966) Distinction of Brown from White Adipose Tissue, Nature 212 , 469-472, doi:10.1038/212469a0

Daniel Cressey ( 2009, Jul 30 ) Fighting fat with fat, Nature News, retrieved fromhttp://blogs.nature.com/news/2009/07/fighting_fat_with_fat.html

B. Sallinen & D. E. Sandberg (2009 June) Brown Fat Controls – PRDM16 and Bone Morphogenetic Protein 7, Growth, Genetics & Hormones, 25(1), retrieved from

http://gghjournal.com/volume25/1/pdf/ab11.pdf

C. Nordqvist (2012, January 25) Brown Fat - Keeps You Warm And Keeps You Slim,Medical News Today, Retrieved from http://www.medicalnewstoday.com/articles/240759.php

J.Mishra (2004) Importance of thermoregulation in the newborn: role of brown fat, Orissa Journal of Medical Biochemistry, Vol 1, retreived from http://www.saihp.org.in/articles/biomerarticle2.pdf

Joslin Diabetes Center (2013, April 22) Scientists Advance Understanding of Human Brown Adipose Tissue and Grow New Cells, Science Daily, Retrieved from http://www.sciencedaily.com/releases/2013/04/130422175840.htm

Reference List

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