Flipping the On-Off Switch for Eating

This week an article was published that shows when a specific set of brain cells is activated, the animal eats whether they’re already fed or not (see the video above; “The Inhibitory Circuit Architecture of the Lateral Hypothalamus Orchestrates Feeding” published September 27, 2013 in Science). The target location of these neurons, the hypothalamus, has been known to be important in the control of eating behaviors but the precise brain circuitry driving the three “F”s – fighting, feeding and sex – has not been shown. The new research describes what looks to be a key piece of brain circuitry involved in eating behaviors.

The scientists genetically manipulated neurons in a structure known as the bed nucleus of the stria terminalis so that, when light was shined on them through fiber optics, they became electrically active and released their inhibitory chemicals (neurotransmitters) onto target neurons in the lateral hypothalamus. This decreased (inhibited) the activity of excitatory neurons in the lateral hypothalamus that contained a specific protein known as the vesicular glutamate transporter-2 protein. The result was a dramatic increase in feeding behavior.

In other words, excitatory neurons in the lateral hypothalamus seem to suppress feeding behavior. Decrease the activity of those neurons and feeding behavior is turned on. They appear to act as an on-off switch for eating. The potential therapeutic importance of these neurons is clear, especially in the United States with the highest rate of obesity in the world. However, recent public exposure of processed food industry practices presents troubling ethical dilemmas.

Last week I attended a lecture by the journalist Michael Moss where he talked about his new book “Salt Sugar Fat: How the Food Giants Hooked Us.” Moss states that much of the problem with obesity in the United States is due to the abundance of cheap, calorie-rich, processed food. He goes further and presents evidence that the companies producing processed foods use scientific research data to design the food they market to be maximally attractive to consumers. Makes sense. A company wants to sell product. Best if it sells a lot of product over and over again. The dilemma arrises when we contemplate when a line is crossed from making extraordinarily attractive food to creating additive substances.

It would be interesting to feed the mouse in the video above sugary cereal to see if this same “switch” was turned on. The research team may have begun describing part of the very circuit activated when a person experiences pleasure, termed bliss in the industry, that companies target when developing a product. It’s interesting that funding for the study included drug and alcohol abuse agencies. This is a complex, fascinating, and very important topic. I highly recommend reading “Salt Sugar Fat: How the Food Giants Hooked Us.”