Neurohormonal regulation of reproduction and feeding in the desert locust Schistocerca gregaria

In the desert locust Schistocerca gregaria (Orthoptera), several neurohormones are known to play a role in the regulation of the female reproductive physiology. In this study we concentrate on Neuropeptide F (NPF) and on the Ovary Maturating Parsins (OMP) in order to further analyze their physiological role. By means of the S. gregaria EST database and 3’-RACE (Rapid Amplification of cDNA Ends), the precursor cDNA sequences for these neurohormones were obtained. Interestingly, two very similar S. gregaria precursors were found, each encoding a CRF-like diuretic hormone (DH) as well as one of both large Scg-OMP isoforms. By means of quantitative “real-time” RT-PCR, the tissue-specific expression of these precursors was examined. The main expression was always seen in the central nervous system, while the NPF precursor was also expressed in the digestive system (mainly in the midgut). By means of feeding experiments (combined with RNAi knockdown and peptide injections), we were able to show that NPF increased food intake while the CRF-like DH decreased food intake. By means of RNAi, as well as peptide injections, the physiological effects of the studied neurohormones were further analyzed. For this, the effects on several transcript levels (neuropeptide precursors, biosynthetic enzymes, etc.) as well as certain hormone titers and other reproductive parameters were evaluated (e.g. the effect of NPF on male reproductive physiology). Taken together, our data show that the NPF and CRF-like DH/OMP signaling systems are involved in the regulation of food intake, as well as in several physiological processes related to reproduction (and probably also related to the first effect). Based on these functions, these signaling systems may represent interesting targets for locust pest management.status: publishe