Researchers have found a mechanism by which stress increases food drive in rats. The discovery published online in The Journal Neuron, could provide important insight into why stress is thought to be one of the underlying contributors of obesity.

The brain normally produces neurotransmitters: chemicals released by the brain to communicate with cells. Endocannabinoids is a neurotransmitter chemical that sends signals to control appetite.

The study found that when food is not present, a stress response temporality causes malfunction in the brain, blocking the endocannabinoids ability to regulate food intake, enhancing the drive for food.

The researchers also discovered that when they blocked the effects of stress hormones in the brain, the absence of food caused no change in the neural circuitry.

Researchers Jaideep Bains, Ph.D. and Quentin Pittman, Ph.D., looked specifically at nerve cells (neurons) in the region of the brain called the hypothalamus. The hypothalamus is the area of the brain that produces hormones to regulate hunger, thirst, moods, and sleep. This structure has been identified as the primary region responsible for the brain's response to stress.

"These findings could help explain how the cellular communication in our brains may be overridden in the absence of food. Interestingly, these changes are driven not necessarily by the lack of nutrients, but rather by the stress induced by the lack of food," said Bains.

The research laid the foundation for future studies to investigate the use of therapies that affect food intake. The research highlights the importance of food availability to our nervous system.

"For example, if we elect to pass over a meal, the brain appears to simply increase the drive in pathways leading to increased appetite," explains Pittman. "Furthermore, the fact that the lack of food causes activation of the stress response might help explain the relationship between stress and obesity."

“The absence of food clearly brings about dramatic changes in the way our neurons communicate with each other," says Pittman.