Insect adipokinetic hormones (AKHs) are short peptides produced in the corpora cardiaca and are responsible for mobilizing energy stores from the fat body to the hemolymph. Three related peptides, AKH1, AKH2, and AKH/corazonin-related peptide (ACP) as well as three AKH receptors have been reported in Bombyx mori. AKH1 and AKH2 are specific for the AKHR1 receptor, whereas ACP interacts with the other two AKHRs. To assess the effect of the two silkworm AKHs and ACP in the regulation of energy homeostasis we examined the expression pattern of the three peptides and their receptors as well as their effect on the level of carbohydrates and lipids in the hemolymph. Our results support the hypothesis that only AKH1 and AKH2 peptides together with the AKHR1 receptor are involved in the maintenance of energy homeostasis. Because Bombyx AKHR1 (BmAKHR1) seems to be a true AKHR we generated its mutation. The BmAKHR1 mutant larvae display significantly lower carbohydrate and lipid levels in the hemolymph and reduced sensitivity to starvation. Our study clarifies the role of BmAKHR1 in energy homeostasis.

• Keywords
• BMSK0010951, Bommo-AKH1, Bommo-AKH2, NM_001043584, TALEN, silkworm, targeted mutagenesis,
• MeSH
• Bombyx growth & development   metabolism   MeSH
• Energy Metabolism MeSH
• Hemolymph metabolism   MeSH
• Insect Hormones genetics   metabolism   MeSH
• Insect Proteins genetics   metabolism   MeSH
• Pyrrolidonecarboxylic Acid analogs & derivatives   metabolism   MeSH
• Larva metabolism   MeSH
• Lipids analysis   MeSH
• Mutagenesis MeSH
• Neuropeptides genetics   metabolism   MeSH
• Oligopeptides genetics   metabolism   MeSH
• Protein Isoforms genetics   metabolism   MeSH
• Receptors, Glucagon genetics   metabolism   MeSH
• Gene Expression Regulation MeSH
• Carbohydrates analysis   MeSH
• Signal Transduction * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• adipokinetic hormone MeSH Browser
• corazonin protein, insect MeSH Browser
• Insect Hormones MeSH
• Insect Proteins MeSH
• Pyrrolidonecarboxylic Acid MeSH
• Lipids MeSH
• Neuropeptides MeSH
• Oligopeptides MeSH
• Protein Isoforms MeSH
• Receptors, Glucagon MeSH
• Carbohydrates MeSH

Insect adipokinetic hormones (AKHs) are neuropeptides with a wide range of actions, including the control of insect energy metabolism. These hormones are also known to be involved in the insect defence system against toxins and pathogens. In this study, our aim was to demonstrate whether the application of external AKHs significantly enhances the efficacy of the entomopathogenic fungus Isaria fumosorosea in a model species (firebug Pyrrhocoris apterus) and pest species (Egyptian cotton leafworm Spodoptera littoralis and pea aphid Acyrthosiphon pisum). It was found that the co-application of Isaria with AKHs significantly enhanced insect mortality in comparison to the application of Isaria alone. The mode of action probably involves an increase in metabolism that is caused by AKHs (evidenced by the production of carbon dioxide), which accelerates the turnover of Isaria toxins produced into the infected insects. However, several species-specific differences probably exist. Intoxication by Isaria elicited the stimulation of Akh gene expression and synthesis of AKHs. Therefore, all interactions between Isaria and AKH actions as well as their impact on insect physiology from a theoretical and practical point of view need to be discussed further.

• Keywords
• AKH, carbon dioxide production, entomopathogen, insect pest, metabolism, mortality,
• Publication type
• Journal Article MeSH

The impact of disruption of adipokinetic hormone (AKH) signaling 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 signaling. 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, behavior and lipid status during aging.

• Keywords
• AKH signaling, adipokinetic hormone, aging, energy homeostasis, lipid status, senescence,
• Publication type
• Journal Article MeSH

Insects, like other organisms, must deal with a wide variety of potentially challenging environmental factors during the course of their life. An important example of such a challenge is the phenomenon of oxidative stress. This review summarizes the current knowledge on the role of adipokinetic hormones (AKH) as principal stress responsive hormones in insects involved in activation of anti-oxidative stress response pathways. Emphasis is placed on an analysis of oxidative stress experimentally induced by various stressors and monitored by suitable biomarkers, and on detailed characterization of AKH's role in the anti-stress reactions. These reactions are characterized by a significant increase of AKH levels in the insect body, and by effective reversal of the markers-disturbed by the stressors-after co-application of the stressor with AKH. A plausible mechanism of AKH action in the anti-oxidative stress response is discussed as well: this probably involves simultaneous employment of both protein kinase C and cyclic adenosine 3',5'-monophosphate pathways in the presence of extra and intra-cellular Ca(2+) stores, with the possible involvement of the FoxO transcription factors. The role of other insect hormones in the anti-oxidative defense reactions is also discussed.

• Keywords
• AKH gene, FoxO, adipokinetic hormones (AKH), anti-oxidative mechanisms, free radicals, insect endocrine system, insecticide, oxidative stress, signaling pathway,
• MeSH
• Insecta metabolism   MeSH
• Insect Hormones metabolism   MeSH
• Pyrrolidonecarboxylic Acid analogs & derivatives   metabolism   MeSH
• Oligopeptides metabolism   MeSH
• Oxidative Stress * MeSH
• Signal Transduction MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• adipokinetic hormone MeSH Browser
• Insect Hormones MeSH
• Pyrrolidonecarboxylic Acid MeSH
• Oligopeptides MeSH