Obesity in mice can be ameliorated by transplantation of hypothalamic neurons

The db/db mouse is widely employed as model of morbid obesity and its main feature is that it lacks of the receptor of a hormone called leptin. This hormone plays a major role in the hypothalamus, were things like sleep, thirst, body temperature, and hunger are regulated.

In a recent study published in Science, Czupryn et al., showed that increasing leptin-receptor containing neurons in the hypothalamus could work to help db/db mice to reduce weight. They took newborn db/db mice and controls, and gave them an implant of neurons containing the leptin receptor. After the mice grew up, the authors found that the neurons were able to express the leptin receptor in the hypothalamus. The result was a lower body weight in mice treated with the leptin expressing neurons compared to non-treated db/db mice, but not as low as control mice.

Still, though it’s not the whole answer, it’s an interesting start to understanding not only the role of the hypothalamus in obesity and type 2 diabetes, but also how we might be able to change receptors in the brain to restore leptin sensitivity, and decrease sever obesity and the type 2 diabetes that often goes with it.

Source: Scientific American and
Czupryn, A., Zhou, Y., Chen, X., McNay, D., Anderson, M., Flier, J., & Macklis, J. (2011). Transplanted Hypothalamic Neurons Restore Leptin Signaling and Ameliorate Obesity in db/db Mice Science, 334 (6059), 1133-1137

Are diet and exercise enough to lose weight and keep it low?

A new study, published in The New England Journal of Medicine, shows that regaining weight after a period of diet and exercise may be inevitable due to hormones.

Australian researchers found that after losing weight, hormone levels - particularly those that influence hunger - shifted in the body, leading to increase appetites and weight regain.

The study involved 50 adults with a body mass index (BMI) between 27 and 40, who were on a diet and exercise for 10 weeks. After an initial loss scientists found that the levels of appetite-regulating hormones changed, resulting in a regain of 1/3 of the lost weight over the course of a year.

The results of the Australian study corroborate findings in another paper released earlier this year, in which researchers from Spain confirmed that people with high levels of the hormone leptin and low levels of ghrelin are more likely to gain the weight they lost.

Instead of playing the diet and exercise message on repeat - an ineffective longterm weight loss strategy for some - the Spanish authors suggested that endocrinologists and nutritionists consider the possibility of hormonal imbalances when developing weight loss strategies.

Source: http://www.nydailynews.com/life-style/health/diet-exercise-fight-obesity-study-article-1.971052#ixzz1cjDgPJ3S

Obese adolescents and the risk of breast cancer

According to a recent review, adolescent girls and in high risk of developing breast cancer.

Breast cancer, the second most common cause of cancer death in women, is strongly associated with obesity; this relationship is particularly true in postmenopausal breast cancer. There are many factors that many explain the relationship between adiposity and breast cancer. Obesity is related to elevated levels of insulin and leptin, and lower levels of adiponectin. Hyperinsulinemia may impact and affect tumorigenesis. Peripheral aromatization of androgens in adipose tissue is enhanced by leptin, leading to greater estrogen levels.Adipocytokines may participate as cancer promoters and regulators, and participate in regulation of sex steroids by interleukins 4 and 6 (Il-4, Il-6). Increased serum levels of leptin and resistin, and decreased levels of adiponectin, were related to tumor metastasis.

From: In-Iw and Biro. Adolescent Women and Obesity. Journal of Pediatric and Adolescent Gynecology