A nuclear hormone receptor nhr-76 programs age-dependent chemotaxis decline in C. elegans

A decline in food-searching behavior of post-reproductive animals can be beneficial for the population and possibly programmed by the genome. We investigated the genetic program of age-dependent decline in chemotaxis behavior toward an odorant secreted from bacterial food in C. elegans. Through a forward genetic screen, we identified a nuclear hormone receptor, nhr-76, whose mutants ameliorate the age-dependent chemotaxis decline. We found that nhr-76 downregulates the expression of the odorant receptor during aging. Because NHR-76 expression and localization did not change during aging, secretion of its hydrophobic ligands might alter the activity of NHR-76 to cause age-dependent chemotaxis decline. Our findings imply that post-reproductive behavioral decline can be genetically programmed.