Adipokinetic hormone affects behaviour in Drosophila
The article in Frontiers in Physiology demonstrates that adipokinetic hormone controls not only energy homeostasis in Drosophila, but also behavioural matters as strength of daily rhythms or negative geotaxis.
Figure: Kaplan-Meier survival curves of w1118-iso, Akh1 and EE-Akh male and female flies under 12 h light:dark (LD) cycles and ad libitum feeding conditions. Log-rank (Mantel-Cox) test revealed significant differences (p<0.0014) between survival curves of male vs female flies of isogenized controls and EE-Akh flies but not between males and females of Akh1 flies. Also no difference in survival curves between males of isogenized controls vs Akh1 flies was recorded. Females however significantly differ in their survival curves among genotypes.
The impact of disruption of adipokinetic hormone (AKH) signalling was studied during aging in Drosophila in a sexually dimorphic manner. A mutant (Akh1) producing a non-functional AKH peptide was compared with isogenized wild-type controls (w1118), and Akh-rescue line where AKH was ectopically expressed in the mutant background (EE-Akh). Longevity, fecundity, and locomotor activity rhythms remained unaffected by lack of AKH signalling. While the strength of rhythms declined in general with age across all fly lines tested this was more so in case of Akh1 flies. Negative geotaxis was significantly impaired in Akh1 flies. Only young Akh1 flies of both sexes and old Akh1 females showed significantly higher body weight compared to age-matched iso-control flies (except in case of EE-Akh). Expression of genes involved in energy homeostasis and aging indicated that dTOR and Akt expression were elevated in Akh1 flies compared to other genotypes, whereas AMPK and dFoxO expression levels were significantly reduced. Multivariate analysis of the distribution of lipid species revealed a significant accumulation of specific diglyceride (DG) and triglyceride (TG) lipid species, irrespective of sex, attributable in part due to lack of AKH. Moreover, irrespective of lack of AKH, older flies of all genotypes accumulated TGs. Taken together, the results strongly suggest that disruption of AKH has very subtle effects on physiology, behaviour and lipid status during aging.
Bednářová A., Tomčala A., Mochanová M., Kodrík D. and Krishnan N. (2018) Disruption of adipokinetic hormone mediated energy homeostasis has subtle effects on physiology, behaviour and lipid status during aging in Drosophila. Front. Physiol. 9, article number 949.
