Using the blood-sucking kissing bug, Rhodnius prolixus as an experimental model, we have studied the involvement of
insulin-like peptides (ILPs) and
adipokinetic hormone (AKH) signaling in carbohydrate metabolism, focusing on the regulation of the
trehalose-specific facilitated transporter (Rhopr-TRET), particularly in the ovaries. We find that
trehalose stores in ovaries increase after feeding, synchronously with the beginning of vitellogenesis, but that the transcript expression of
enzymes involved in
trehalose synthesis show no changes between unfed and blood-fed animals. However, an eightfold increase in Rhopr-TRET transcript expression is observed in the ovaries post-blood meal. In vivo and ex vivo assays using exogenous
insulins and Rhopr-AKH, reveal that Rhopr-TRET is up-regulated in ovaries by both
peptide families. In accordance with these results, when ILP and AKH signaling cascades are impaired using RNA interference, Rhopr-TRET transcript is down-regulated. In addition,
trehalose injection induces an up-regulation of Rhopr-TRET transcript expression and suggests an activation of
insulin signaling. Overall, the results support the hypothesis of a direct
trehalose uptake by ovaries from the hemolymph through Rhopr-TRET, regulated by ILP and/or AKH. We also show that Rhopr-TRET may work cooperatively with AKH signaling to support the release of
trehalose from the ovaries into the hemolymph during the unfed (starved) condition. In conclusion, the results indicate that in females of R. prolixus,
trehalose metabolism and its hormonal regulation by ILP and AKH play critical roles in adapting to different nutritional conditions and physiological states.