Drosophila Melanogaster Mutant For The Dopamine Recycling Pathway Shows Altered Biological Parameters And Increased Lifespan

The ebony and tan genes in Drosophila melanogaster Meigen (Diptera: Drosophilidae) participate in a very peculiar (and exclusive to insects) recycling pathway of neurotransmitters, mainly dopamine (DA) and histamine, in the nervous system and regulate the intensity of tanning in the cuticle. The ebony and tan mutants show altered levels of neurotransmitters, which give rise to developmental and behavioral impairments. The mutant tan lacks N-beta-alanyldopamine hydrolase (NBAD-hydrolase) activity; therefore it is unable to liberate DA from NBAD. Here, we studied developmental traits in tan(1) mutant and previously unknown biological parameters in adult males, such as oxygen consumption, antioxidant capacity, lifespan, and the expression of detoxifying enzymes in the central nervous system. We compared them with those of wt Canton S and the mutant ebony(1). Our results show that although tan(1) mutant had high mortality during the immature stages, adult males had a significantly longer lifespan than wt and ebony(1) mutant; the latter had the shortest lifespan. The longer lifespan of tan(1) was not due to caloric restriction. We found that the nervous system of tan(1) males had a higher antioxidant capacity. After provoking mild oxidative stress by the ingestion of hematoporphyrin, tan(1) males still had a significantly longer lifespan than wt, whereas the ebony(1) mutant had a shorter one. Under these conditions, tan(1) showed an increased expression of catalase mRNA. Our results suggest that lower levels of free DA in the nervous system together with higher antioxidant activities seem to favor an extended lifespan in D. melanogaster tan(1) males.