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: Jeremy McIntyre, University of Florida College of Medicine, Gainesville
You’ve probably learned the hard way about how the grocery list can go out the window when you go shopping on an empty stomach. Part of the reason is that our sense of smell intensifies when we’re hungry, making the aroma of freshly baked cookies, fried chicken, and other tempting goodies even more noticeable. And this beautiful micrograph helps to provide a biological explanation for this phenomenon.
The image, which looks like something that Van Gogh might have painted, shows a thick mesh of neurons in a small cross section of a mouse’s olfactory bulb, a structure located in the forebrain of all vertebrates (including humans!) that processes input about odors detected by the nose. Here, you see specialized neurons called mitral cells (red) that can receive signals from the hypothalamus, a brain region known for its role in hunger and energy balance. Also fluorescently labeled are receptors that detect acetylcholine signals from the brain (green) and the nuclei of all cells in the olfactory bulb (blue).