Early Metabolic Programming and Calorie Restriction

Amanda and Kiana

Outline

1. Review and Introduction2. Methods3. Results4. Conclusions

Diet and Development

• Pancreatic islets and the hypothalamus mature after birth

• Previous work suggests that early overnutrition leads to metabolic problems in adult rats

What is the effect of calorie restriction on rats that consumed a high-carbohydrate diet early in development?

NPY and POMC

-Increased NPY encourages more food intake-Increased POMC causes satiation-Both of these hormones are regulated by leptin-Located in the arcuate nucleus of the hypothalamus

Schwartz et al. (2000)

Critical Periods of Development

Gestation

Birth

Postnatal-weaning

Brain Development

Development of the Hypothalamus

9-10 weeks

11-14 weeks

15-17 weeks 18-23

weeks

Earliest evidence of NPY neurons at 21 weeks in humans

24-32 weeks

34 weeks to birth

Koutcherov et al. (2002)

Development of the Hypothalamus

Bouret and Simerly (2004)

Development of the hypothalamus in wild-type (WT) and leptin-deficient mice

Pancreatic Islets-Parasympathetic nervous system increases insulin secretion-Parasympathetic nerves are cholinergic- Beta cells within the islet secrete insulin

-Sympathetic nervous system inhibits glucose-related insulin secretion-Sympathetic nerves are adrenergic

Ahren (2000)

Development of the Pancreatic Islets

Development of the Pancreatic Islets in Mice

Cabrera-Vasquez et al. (2009)

Development of the Pancreatic Islets

Cabrera-Vasquez et al. (2009)

Expression of pro-NGF (a Nerve Growth Factor Precursor) in Mouse Pancreatic Islets

Development of the Pancreatic Islets

Signalling Pathways

JAK-STAT Pathway-Stat3 has effects on gene transcription and downregulates the effect of leptin via Socs3-Socs3 is also triggered by inflammation, which can be triggered by diet

Morton and Schwartz (2011)

Signalling Pathways

IRS-PI3K Pathway-Stat3 effects on gene transcription can also be activated through this pathway-Socs3 can affect leptin and insulin signalling

Morton and Schwartz (2011)

Early Diet Influences on Metabolism

STEP 1: Dietary assignments• Postnatal Day 4• Group 1: Motherfed (MF)

• natural rearing on mother’s high fat milk• Group 2: High Carbohydrate (HC)

• artificial rearing on high carb milk

AL - Ad libitum• Unlimited access to food and allowed to eat at will

Postnatal Diets During Suckling Period

MFMother-fed (Control)

HCHigh-Carbohydrate

STEP 2: Change in diet• Postnatal Day 24• Group 1: MF weaned off milk

• standard rat chow ad libitum• Group 2: HC weaned off milk

• standard rat chow ad libitum• Group 3: High Carbohydrate/Pair-fed (HC/PF)

• pair-fed standard rat chowPF - Paired-feeding

HC/PF pups were force fed standard rat chow to match the caloric intake of their paired MF pup

Purpose: to control for caloric intake between the rat pairs

STEP 3: Freedom in feeding• Postnatal Day 90• Group 4: High Carbohydrate/Pair-fed → Ad

libitum (HC/PF/AL)• switch from pair-feeding to free-feeding

Purpose: to observe the effects of caloric restriction on adult-onset obesity

End of Experiment Measures

• Postnatal Day 140• Brains and pancreases dissections• Serum collection for insulin and leptin

concentrations at basal (5.5mM) and max stimulatory (16.7mM) levels

• Insulin secretion 5.5mM glucose alone, +Acetylcholine, and +Oxymetazoline

• mRNA levels of Npy, Pomc, Lepr, Socs3, Stat3

Body Weight Gains of Postnatal Days 24-140

Day 24-52: consistent increase, but no significant difference in body weight change between groups

Day 52-94: consistent increase, HC rats gained significantly more weight than MF and HC/PF

Day 94-108: MF and HC/PF start to level off, HC/PF/AL and HC both increasing

Day 108-140: HC/PF/AL catch up to HC

Srinivasan (2013)

Food Intake by Week

Significant increase at week 12 in HC rats allowed to feed ad libitum No difference between HC and HC/PF/AL

Srinivasan (2013)

Results: Serum Insulin and Leptin

Serum Insulin Levels Serum Leptin Levels

Calorie restriction in adulthood can help maintain a normal metabolic profile.

Islet Response to Glucose

Despite a normal metabolic profile, response of the HC\PF islets to glucose is not normal

Islet Responses

-Acetylcholine application increases insulin production more in the three experimental groups-Oxymetazoline inhibited insulin secretion less in the three experimental groups-Calcium deprivation shows insulin signaling in pancreatic islets is disrupted in experimental groups

mRNA ExpressionExpressed Protein

Pattern Interpretation

NPY HC, HC Pair-fed, and HC/PF/AL pattern together

Metabolic programming

Pomc HC, HC Pair-fed, and HC/PF/AL pattern together

Metabolic programming

Lepr HC and HC/PF/AL pattern together, Mother-fed and pair-fed pattern together

Caloric intake

Stat3 No significant differences between groups with possible trends

Inconclusive

Socs3 HC, HC Pair-fed and HC/PF/AL pattern together

Metabolic Programming

Conclusions

• Calorie restriction creates a similar metabolic profile between MF and HC rats

• Calorie restriction does not change hypothalamic and pancreatic islet signals that lead to obesity in HC rats

• Early high-carb feeding leads to permanent changes in metabolic regulation

• These changes can be modulated by calorie restriction, but not reversed

Works CitedAhren, B. (2000). “Autonomic Regulation of Islet Hormone Secretion -

Implications for Health and Disease.” Diabetologia, 43, p. 393-410. DOI: 10.1007/s001250051322

Bear, M., Connors, B.W., and Paradiso, M.A. (2007). Neuroscience: Exploring the Brain (3rd ed.). Philadelphia, PA: Lippincott Williams & Wilkins.

Bouret, S.G., and Simerly, R.B. (2004). “Minireview: Leptin and Development of Hypothalamic Feeding Circuits.” Endocrinology, 145(6), p. 2621-2626. DOI: 10.1210/en.2004-0231.

Cabrera-Vasquez, S., Navarro-Tableros, V., Sanchez-Soto, C., Gutierrez-Ospina, G., and Hiriart, M. (2009). “Remodelling Sympathetic Innervation in Rat Pancreatic Islets Ontogeny.” BMC Developmental Biology, 9(34), n.p. DOI: 10.1186/1471-213X-9-34.

Works CitedKoutcherov, Y., Mai, J.K., Ashwell, K.W.S., and Paxinos, G. (2002).

“Organization of Human Hypothalamus in Fetal Development.” The Journal of Comparative Neurology, 446, p. 301-324. DOI: 10.1002/cne.10175.

Morton, G.J, and Schwartz, M.W. (2011). “Leptin and Central Nervous System Control of Glucose Metabolism.” Physiological Reviews, 91, p. 389-411. DOI: 10.1152/physrev.00007.2010

Schwartz, M.W., Woods, S.C., Porte Jr., D., Seeley, R.J., and Baskin, D.G. (2000). “Central Nervous System Control of Food Intake.” Nature, 404, p. 661-71. DOI: 10.1038/35007534.

Srinivasan, M., S. Mahmood, and M.S. Patel. (2012). “Metabolic Programming Effects Initiated in the Suckling Period Predisposing for Adult-onset Obesity Cannot Be Reversed by Calorie Restriction.” AJP: Endocrinology and Metabolism 304.5 : E486-494. DOI: 10.1152/ajpendo.00519.2012.