Caption: Mouse neurons (purple), with their nuclei (blue) and primary cilia (green). Credit: Yi Wang, Vaisse Lab, UCSF
Obesity involves the complex interplay of diet, lifestyle, genetics, and even the bacteria living in the gut. But there are other less-appreciated factors that are likely involved, and a new NIH-supported study suggests one that you probably never would have imagined: antenna-like sensory projections on brain cells.
The study in mice, published in the journal Nature Genetics , suggests these neuronal projections, called primary cilia, are a key part of a known “hunger circuit,” which receives signals from other parts of the body to control appetite. The researchers add important evidence in mouse studies showing that changes in the primary cilia can produce a short circuit, impairing the brain’s ability to regulate appetite and leading to overeating and obesity.
Credit: Zhang, Y.V., Aikin, T.J., Li, Z., and Montell, C., University of California, Santa Barbara
It’s a problem that parents know all too well: a child won’t eat because their oatmeal is too slimy or a slice of apple is too hard. Is the kid just being finicky? Or is there a biological basis for disliking food based on its texture? This image, showing the tongue (red) of a fruit fly (Drosophila melanogaster), provides some of the first evidence that biology could indeed play a role .
The image shows a newly discovered mechanosensory nerve cell (green), which is called md-L, short for multidendritic neuron in the labellum. When the fly extends its tongue to eat, the hair bristles (short red lines) on its surface bend in proportion to the consistency of the food. If a bristle is bent hard enough, the force is detected at its base by one of the arms of an md-L neuron. In response, the arm shoots off an electrical signal that’s relayed to the central part of the neuron and onward to the brain via the outgoing informational arm, or axon.
Marie Bragg is a first-generation American, raised by a mother who immigrated to Florida from Trinidad. She watched her uncle in Florida cope effectively with type 2 diabetes, taking prescription drugs and following doctor-recommended dietary changes. But several of her Trinidadian relatives also had type 2 diabetes, and often sought to manage their diabetes by alternative means—through home remedies and spiritual practices.
This situation prompted Bragg to develop, at an early age, a strong interest in how approaches to health care may differ between cultures. But that wasn’t Bragg’s only interest—her other love was sports, having played on a high school soccer team that earned two state championships in Florida. That made her keenly aware of the sway that celebrity athletes, such as Michael Jordan and Serena Williams, could have on the public, particularly on young people. Today, Bragg combines both of her childhood interests—the influence of celebrities and the power of cultural narratives—in research that she is conducting as an Assistant Professor of Population Health at New York University Langone Medical Center and as a 2015 recipient of an NIH Director’s Early Independence Award.
For some people, the smell of Mom’s home-baked pie, the sight of an ice cream truck, or the sound of sizzling French fries can trigger a feeding frenzy. But others find it much easier to resist such temptations. What’s the explanation?
You might think it’s sheer willpower. But a recent study in the journal Molecular Psychiatry suggests the answer to what fuels susceptibility to food cues may be far more complex, related to subtle differences in brain chemistry .