Mice choose sex over food, scientists uncover the reasons why

Sex or food? It’s an old-age question that friends ask each other at parties, but in mice models, it’s the foundation of some pretty interesting research, and it could have implications for how we treat obesity.

“We can only pursue one behavior at a time, so our brain has to somehow compute what will be the most rewarding behavior, or what is our most urgent need,” told Technology Networks on Thursday Dr. Tatiana Korotkova, a neuroscientist at the University Clinic Cologne in Germany and the lead of the new study.

To understand which innate needs take precedence in mice, Korotkova and her team studied neurons within the lateral hypothalamus, a brain region commonly known as the “feeding center” because it’s responsible for appetite and thirst.

Weighing hunger against sex

“Animals continuously weigh hunger and thirst against competing needs, such as social contact and mating, according to state and opportunity. Yet neuronal mechanisms of sensing and ranking nutritional needs remain poorly understood,” wrote the researchers in their study.

“Here, combining calcium imaging in freely behaving mice, optogenetics, and chemogenetics, we show that two neuronal populations of the lateral hypothalamus guide increasingly hungry animals through behavioral choices between nutritional and social rewards.”

The team found that increased food consumption was marked by increasing inhibition of a leptin receptor-expressing (LepRLH) subpopulation at a fast timescale. In other words, LepRLH neurons limited feeding or drinking and promoted social interaction despite hunger or thirst but only in moderate cases.

“We have this system which can only regulate moderate hunger, but not strong hunger,” explained Korotkova. “This circuit might contribute to why diets don’t work: it’s not a problem to reduce your food intake for a short time, but it doesn't work if you try to do it for longer.”

The team proceeded to stimulate the mice’s NtsLH neurons and found that it resulted in an increase in drinking behavior at the expense of socializing.

“We usually think about neurons having a particular function, but we found that one cell can actually encode multiple different stimuli,” said Korotkova to Technology Networks. “This makes a lot of sense biologically because behaviors need to be coordinated, and it’s much more efficient to coordinate behaviors with the same cell than by many different cell types somehow communicating with each other.”

The study was published in Cell Metabolism.

Abstract:

Animals continuously weigh hunger and thirst against competing needs, such as social contact and mating, according to state and opportunity. Yet neuronal mechanisms of sensing and ranking nutritional needs remain poorly understood. Here, combining calcium imaging in freely behaving mice, optogenetics, and chemogenetics, we show that two neuronal populations of the lateral hypothalamus (LH) guide increasingly hungry animals through behavioral choices between nutritional and social rewards. While increased food consumption was marked by increasing inhibition of a leptin receptor-expressing (LepRLH) subpopulation at a fast timescale, LepRLH neurons limited feeding or drinking and promoted social interaction despite hunger or thirst. Conversely, neurotensin-expressing LH neurons preferentially encoded water despite hunger pressure and promoted water seeking, while relegating social needs. Thus, hunger and thirst gate both LH populations in a complementary manner to enable the flexible fulfillment of multiple essential needs.