Early Life Origins of Obesity: Role of Hypothalamic ...iom.nationalacademies.org/~/media/files/activity...BCYF Symposium (05/2010) Early Life Origins of Obesity: Role of Hypothalamic

BCYF Symposium(05/2010)

Early Life Origins of Obesity:

Role of Hypothalamic Programming

Sebastien G. Bouret, Ph.D.

The Saban Research InstituteChildrens Hospital of Los AngelesUniversity of Southern California

USC Keck School of MedicineLos Angeles, CA - USA

A Striking Example of Environmental Control Phenotypic Polymorphism

weight (x2)longevity (x20)

fertility

Queen

Worker

Honey bee larvae with identical DNA

Royal Jelly

Worker Food

ObesityDiabetes

Cardiovascular Risks

Perinatal Food RestrictionPerinatal OverfeedingCatch-up Growth

Early Growth and Later Risk of Diabesity in Humans

Key Role for the Brain in Body Weight Regulation

Reeves, 1969

Hetherington and Ranson, 1940

Hypothalamic Circuits Involved in Appetite Regulation

MCHOX

Bouret,JPGN, 2009

Critical Periods for Hypothalamic Development

?

from Bouret, Forum Nutr, 2010

“Bedside to Bench”: Animal Models of Postnatal Over- and Under-nutrition

• Mechanistic studies can easily be done in animal models

• Brain feeding pathways are highly conserved during evolution

• Studies in the human hypothalamus have been limited in part by instrument resolution

Normal Litter (7)

Mouse Model of Postnatal Over- and Under-nutrition :Divergent Litter Size

Large Litter

Normal Litter

Small Litter

Large Litter (14) undernourished

Small Litter (3) overnourished

Adult Growth of Neonatally Under- and Over-Nourished Animals

SL

NLLL

Normal Litter (7)

Large Litter (14) undernourished

Small Litter (3) overnourished

P4-P22

SL

b

aa

NL LL

Catch-Up Growth

Method to Study Development of Hypothalamic Feeding Circuits

ARH

DiI

adapted from, www.hhmi.org “Science of Fat”

Impact of Early Postnatal Nutrition on Formation of Hypothalamic Neural Projections

SL NL LL

b

a

b

PVH

V3

Underfed (LL) P12

PVH

Overfed (SL) P12

V3

PVH

V3

Normal Fed P12

Secretion Pattern of Peripheral Signals inPostnatally Under- and Over-Nourished Animals

ChemokinesCytokines

Metabolic Hormones

Is Leptin a Signal for Hypothalamic Development ?

LeptinRel

ativ

e Le

vels

Postnatal Age (weeks)

Weaning Puberty

1 2 3 4

Body

Wei

ght

(g)

Postnatal Age (days)7 8 9 10

0

2

4

6

Leptin

Vehicle

11

Caron et al., J Comp Neurol, 2010

Leptin-induced pSTAT3 P10

ARHV3

me

Leptin Receptor mRNA P10

ARH

me

V3

Leptin Deficiency and Hypothalamic Neural Projections

+ / + ob/obP10 P10

PVH PVH

+ / + ob/obAdult Adult

PVH PVH

+/+ ob/ob

V3 V3

ob/ob + leptin

V3

0

5

10

15

20

25

30

0

5

10

15

20

25

30

WT ob/ob ob/ob+

Leptin

PVH

**

AgRP Fiber Density

PVH

PVH

PVH

Adult Treatment

Leptin Acts during a Neonatal Critical Period to Induce its Neurodevelopmental Effects

Neonatal Treatment

ob/ob

PVH PVH

ob/ob + leptin

PVH

DiI Fiber Density

+/+

Bouret et al., Science, 2004

Postnatal Secretion of Metabolic Hormones

Ghrelin

LeptinRel

ativ

e Le

vels

Postnatal Age (weeks)

Weaning Puberty

1 2 3 4

?

adapted from Grove and Cowley, 2005

2

The answer to this latter problem was solved by the discovery and develop-

ment of Spiegelmers (Klussmann et al., 1996; Vater & Klussmann, 2003).

These molecules, which are biostable aptamers, have all of the diversity char-

acteristics of aptamers but possess a structure that prevents enzymatic degra-

dation.

2) Identification of Spiegelmer Products

While aptamers are created from the natural D-nucleotides, which are recog-

nized by the nucleic acid degrading enzymes, a molecule synthesized as the

mirror image L-oligonucleotide will not be degraded by any nucleases since

there are no such enzymes in the body capable of interacting with these un-

natural molecules. As such, the amplification methods used to create large ap-

tamer libraries cannot be employed to synthesize the L-nucleic acid-containing

molecules. However, NOXXON has developed the methods to form high affin-

ity L-oligonucleotide aptamers that possess outstanding binding affinities and

functionality. These molecules are termed “Spiegelmer” from the German

“Spiegel” or mirror.

Figure 1.1 Reciprocal specificities of (D-) aptamers and (L-) Spiegelmers

aptamer •••• naturaltarget

mirror-image •••• mirror-imagetarget aptamer

mirror-image •••• aptamertarget

Spiegelmer •••• naturaltarget

P4-P21

NOX B-11 (SPM) Ghrelin

P4 P21 Adult

birth weaning

Ghrelin Ghrelin

Does Ghrelin Act on Hypothalamic/Metabolic Programming ?

Programming Actions of Ghrelin on MetabolismPre-Weaning Growth Curve Post-Weaning Growth Curve

Adult GlycemiaAdult Food Intake

Long-Term Effects of Postnatal Ghrelin Blockade on Adiposity

Control Anti-Ghrelin

perirenal

visceralsubcutaneous

Postnatal Ghrelin Blockade Increases ARH Neural Projections

Control Anti-GhrelinP12 P12

PVH PVH

Conclusion I

Perinatal Levels of Metabolic Hormones / Perinatal Nutrition

Low High

High

Low

Optimal

Rel

ativ

e R

isk

of D

evel

opm

ent

of M

etab

olic

Dis

ease

in

Adu

lt Li

fe

Abnormal

Optimal

Hyp

otha

lam

ic

Dev

elop

men

t

Conclusion II: Adverse Perinatal Nutritional and Hormonal Environments Increase

the Susceptibility to Adult Metabolic Disease

Postnatal Exposure Adult Exposure

Adapted from Shearman et al., 2006

Conclusion III: Hormonal Programming: Timing is Important!

It is important to determine when key developmental events are particularly sensitive to hormonal signals during restricted ontogenetic periods

Steculorum and Bouret, unpublished