A new class of weight-loss drugs that suppresses appetite by blocking cannabinoid receptors in the brain should be used with caution in children, U.S. scientists report. In research with mice, they found this class of drugs also suppresses the adaptive rewiring of the brain necessary for neural development in young animals. The findings are in the May 8 issue of Neuron.

One such drug is rimonabant (Acomplia), which was developed by Sanofi-Aventis and is awaiting approval by the U.S. Food and Drug Administration. Other pharmaceutical companies are developing similar drugs. In this study, researchers concluded that a cannabinoid receptor-blocking drug called AM 251 affected experience-dependent cortical plasticity in the brains of juvenile mice. This plasticity is the experience-prompted adaptive rewiring of the brain that plays an critical role in the neural development of young animals. Read more

Breastfeeding doesn’t increase breast sagging, a new study shows. “Expectant mothers should be reassured that breastfeeding does not appear to have an adverse effect upon breast appearance,” report University of Kentucky plastic surgeon Brian Rinker, MD, and colleagues.

They interviewed 132 women who came to their plastic surgery clinic to get breast augmentation or a surgical lift for sagging breasts. The women were 39 years old, on average. The majority 93 patients had had at least one pregnancy. Most of the moms 58% had breastfed at least one child.
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While the rate at which breast cancer tumors grow varies among patients, that growth tends to be faster among younger women, Norwegian researchers report. These findings may help in planning and evaluating screening programs, clinical trials and other studies, the researchers say.

Using a new mathematical model, the scientists were also able to estimate the numbers of breast cancers detectable by mammography. This is a new approach to estimating the growth rate of tumors and the ability of mammograms to find them. “There are enormous implications for the sensitivity of breast cancer screening programs,” lead researcher Harald Weedon-Fekjr, of the Department of Etiological Research, Cancer Registry of Norway, said in a statement. Read more

Japanese researchers using functional magnetic resonance imaging (fMRI) on people being enticed with either monetary or reputational rewards for good deeds done found that both flip on the striatum, the brain’s reward system, in a similar fashion. The study, published in the April 24 issue of Neuron, is consistent with a long-held social psychological theory that people do nice things to others to gain a good reputation or social approval just like they work for salary. It may provide a pivotal step toward a neural explanation for people’s everyday social behaviors.

The researchers’ study on 19 people showed that acquiring a good reputation sent reward-related brain areas, notably the striatum, into overdrive. Many of these areas were also activated when monetary rewards were offered, suggesting that the striatum processes the two in a similar manner. Read more