Behaviorally-related expression differences of nutrient-sensing cells in the honey bee brain

Nutrition is an important factor regulating the age-related division of labor in the honey bee, Apis mellifera. Bees transition from working in the hive (including “nursing” the brood) to foraging outside, and this transition involves a major loss of abdominal lipids. Gene expression studies in our laboratory have suggested that nutritional inputs are integrated in both the brain and peripheral adipose tissue to regulate division of labor. To better understand this process, we used laser capture microdissection and microarray analysis to profile nurse and forager bee gene expression in the pars interecrebralis (PI), the brain region most closely associated with nutrient-sensing in other insect species. There were differences in expression for thousands of genes, and Gene Ontology analyses indicated that the list of differentially expressed genes was enriched for those involved in translation, phototransduction, ATP synthase electron transport and oxidation reduction. In addition, several nutrition- and locomotion-related neuropeptides were upregulated in forager PI, including an insulin-like peptide, neuropeptide F and tachykinin. Based on comparisons of gene expression, the PI showed a stronger response to experimental diet manipulations than did the whole brain, suggesting a central role for this brain region in regulating nutritionally-mediated division of labor.