Tachykinin-related peptides modulate immune-gene expression in the mealworm beetle Tenebrio molitor L.

Tachykinins (TKs) are a group of conserved neuropeptides. In insects, tachykinin-related peptides (TRPs) are important modulators of several functions such as nociception and lipid metabolism. Recently, it has become clear that TRPs also play a role in regulating the insect immune system. Here, we report a transcriptomic analysis of changes in the expression levels of immune-related genes in the storage pest Tenebrio molitor after treatment with Tenmo-TRP-7. We tested two concentrations (10(-8) and 10(-6) M) at two time points, 6 and 24 h post-injection. We found significant changes in the transcript levels of a wide spectrum of immune-related genes. Some changes were observed 6 h after the injection of Tenmo-TRP-7, especially in relation to its putative anti-apoptotic action. Interestingly, 24 h after the injection of 10(-8) M Tenmo-TRP-7, most changes were related to the regulation of the cellular response. Applying 10(-6) M Tenmo-TRP-7 resulted in the downregulation of genes associated with humoral responses. Injecting Tenmo-TRP-7 did not affect beetle survival but led to a reduction in haemolymph lysozyme-like antibacterial activity, consistent with the transcriptomic data. The results confirmed the immunomodulatory role of TRP and shed new light on the functional homology between TRPs and TKs.

Automated summary

This study conducted a transcriptomic analysis to investigate the changes in the expression levels of immune-related genes in the storage pest Tenebrio molitor after treatment with Tenmo-TRP-7. The results revealed that Tenmo-TRP-7 regulates immune-related genes and provides new evidence for the functional homology between TRPs and TKs.