NCBS team uncovers how the brain postpones hunger

When we go hungry, we have the ability to ignore the urge to eat so that we can carry out the task at hand.

How the brain coordinates this response to nutritional stress so that the body can function normally is not understood very well. Now, researchers from the National Centre for Biological Sciences (NCBS), Bengaluru, have discovered some clues to this question through their research on fruit flies.  From the time they hatch out of eggs, fruit flies undergo three major stages in their lives - larva, pupa and adult stages. Integrating nutrition sensing with these developmental steps is important. The larva must know when it has enough resources to pupate and make the transformation into an adult, the study said. When deprived of food, pupation can often be postponed until enough reserves have been accumulated.

However, there are exceptions to this – when faced with protein deprivation towards the end of their larval lives, fruit fly larvae are able to push themselves to pupate.

Prof Gaiti Hasan’s team from NCBS has now uncovered the fact that this happens due to an integrative circuit of nerve cells in fruit fly brains that allow them to ignore the lack of proteins in their food to enter the pupal stage. The circuit Hasan’s group has discovered consists of three types of nerve cells – one set senses and reports the lack of protein in food, a second set integrates this input with metabolic information and the third set controls the hormonal signals necessary to begin pupation.

The “integrator circuit” linking nutrition and development that they have uncovered could be similar in insects and mammals, the study said. The study has been published in the international journal eLife this month.