Lambs provide crucial link in understanding obesity

March 14, 2011, Wiley

The research, published today in The Journal of Physiology, shows a definite link between maternal and offspring obesity and is the first demonstration that this is the case in mammals which bear 'mature offspring' – as humans do.

Professor Peter Nathanielsz, lead author of the research, said: "A relationship between maternal and offspring obesity has been clearly identified in rodents but as their young are born immature, it was not clear whether the findings would apply to humans.

"Lambs offer a more similar model to understand the mechanism of human obesity as they are born at a more advanced level of maturity – equivalent to humans."

For 60 days before conception and throughout their pregnancy Nathanielsz and his team at the Center for Pregnancy and Newborn Research, University of Texas and the University of Wyoming, fed sheep either a normal diet or one that produces obesity. The appetite and weight gain of their offspring were then monitored for a further 19 months.

By taking frequent blood samples from the newborn lambs, the team were able to monitor levels of hormones that are known to affect developmental programming – in particular the hormone leptin. Leptin is produced by adipose fat cells and regulates appetite. In lambs born of normal weight mothers, there was a peak in leptin in the sixth to ninth days of life but this peak did not occur in lambs born to obese ewes.

"The neonatal peak in leptin plays a central role in the development of areas of the brain that regulate appetite. We have found that an absence of this peak in lambs born to obese mothers seems to predispose them to increased appetite and obesity in later life."

Blood samples taken from one day old lambs also found that cortisol levels were up to 50% higher in obese sheep, leading the team to suspect that exposure to higher levels of cortisol in the womb may prevent the normal leptin rise in lambs of obese mothers.

"We propose that cortisol prepares fetal adipose tissue to secrete leptin – and that this process seems to be disrupted in lambs born to obese mothers. The nutrient excess present in the blood of obese mothers throughout gestation seems to inhibit the post-natal leptin peak – which likely has important consequences for the development of the lamb."

"Given the epidemic of obesity both in the developed and developing world, the search for environmental factors occurring around the time of birth which predispose of overweight mothers to lifelong obesity is important.

"Seeing these hormonal change in lambs, in addition to what we have already found with rodents, is advancing our understanding of what programmes appetite. We are getting closer to understanding what causes obesity in humans." concluded Nathanielsz.

Related Stories

Recommended for you

Researchers illustrate how muscle growth inhibitor is activated, could aid in treating ALS

January 19, 2018
Researchers at the University of Cincinnati (UC) College of Medicine are part of an international team that has identified how the inactive or latent form of GDF8, a signaling protein also known as myostatin responsible for ...

Bioengineered soft microfibers improve T-cell production

January 18, 2018
T cells play a key role in the body's immune response against pathogens. As a new class of therapeutic approaches, T cells are being harnessed to fight cancer, promising more precise, longer-lasting mitigation than traditional, ...

Weight flux alters molecular profile, study finds

January 17, 2018
The human body undergoes dramatic changes during even short periods of weight gain and loss, according to a study led by researchers at the Stanford University School of Medicine.

Secrets of longevity protein revealed in new study

January 17, 2018
Named after the Greek goddess who spun the thread of life, Klotho proteins play an important role in the regulation of longevity and metabolism. In a recent Yale-led study, researchers revealed the three-dimensional structure ...

The HLF gene protects blood stem cells by maintaining them in a resting state

January 17, 2018
The HLF gene is necessary for maintaining blood stem cells in a resting state, which is crucial for ensuring normal blood production. This has been shown by a new research study from Lund University in Sweden published in ...

Magnetically applied MicroRNAs could one day help relieve constipation

January 17, 2018
Constipation is an underestimated and debilitating medical issue related to the opioid epidemic. As a growing concern, researchers look to new tools to help patients with this side effect of opioid use and aging.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.