Effect of Short-Term Desiccation, Recovery Time, and CAPA-PVK Neuropeptide on the Immune System of the Burying Beetle Nicrophorus vespilloides

The allatotropin/orexin system as an example of immunomodulatory properties of neuropeptides

The central nervous system (CNS) plays a critical role in signal integration in animals and allows the orchestration of life processes to maintain homeostasis. Current research clearly shows that inflammatory processes can also be modulated by the CNS via the neuroendocrine system. One of the neuropeptide families that participate in vertebrates in this process is orexins (OXs). Interestingly, our previous results suggested that a similar dependency may also exist between neuropeptides and immune system activity in insects. Due to the structural homology of orexin and allatotropin receptors and the functional similarity between these two neuropeptide families, the main aim of this research was to perform a complex analysis of the relationships between allatotropin (AT) and the insect immune response. Our results revealed functional similarities between vertebrate OXs and insect ATs. Similar effects were observed in the profile of the expression level of the gene encoding the AT precursor in the Tenebrio molitor nervous system and in the general action of Tenmo-AT on selected immune parameters of the tested beetles. Moreover, for the first time in insects, we confirmed the role of cytokines in the modulation of neuroendocrine system by determining the effect of Spätzle-like protein injection on the expression of genes encoding AT precursor and receptor. All these results are important for understanding the evolutionary basis of hormonal regulation of the immune response.

The effect of B-type allatostatin neuropeptides on crosstalk between the insect immune response and cold tolerance

Insects are the largest group of arthropod phyla and are capable of surviving in a variety of environments. One of the most important factors in enabling them to do so is their resistance to temperature stress, i.e., cold tolerance. The neuroendocrine system, together with the immune system, cooperates to regulate a number of physiological processes that are essential for the stability of the organism in stressful conditions. However, to date, no one has studied the effect of insect myoinhibitory peptides (MIPs) on cold stress tolerance and immune system activity. Here, we investigated the effect of Tenmo-MIP 5 (10^-6 M), cold stress (- 5 °C) and a combination of both on the immune response of Tenebrio molitor. All three treatments caused upregulation of immune-related genes (antimicrobial peptides and Toll) and increased phagocytosis activity (by approximately 10%). However, phenoloxidase activity and mortality were increased only after peptide injection and the combination of both treatments. The peptide injection combined with cold stress caused 40% higher mortality than that in the control. Together, our results show the links between cold stress, MIPs activity and the immune response, and to our knowledge, this is the first report showing the effect of MIP on the insect immune system.

Insects as a New Complex Model in Hormonal Basis of Obesity

Nowadays, one of the biggest problems in healthcare is an obesity epidemic. Consumption of cheap and low-quality energy-rich diets, low physical activity, and sedentary work favor an increase in the number of obesity cases within many populations/nations. This is a burden on society, public health, and the economy with many deleterious consequences. Thus, studies concerning this disorder are extremely needed, including searching for new, effective, and fitting models. Obesity may be related, among other factors, to disrupting adipocytes activity, disturbance of metabolic homeostasis, dysregulation of hormonal balance, cardiovascular problems, or disorders in nutrition which may lead to death. Because of the high complexity of obesity, it is not easy to find an ideal model for its studies which will be suitable for genetic and physiological analysis including specification of different compounds’ (hormones, neuropeptides) functions, as well as for signaling pathways analysis. In recent times, in search of new models for human diseases there has been more and more attention paid to insects, especially in neuro-endocrine regulation. It seems that this group of animals might also be a new model for human obesity. There are many arguments that insects are a good, multidirectional, and complex model for this disease. For example, insect models can have similar conservative signaling pathways (e.g., JAK-STAT signaling pathway), the presence of similar hormonal axis (e.g., brain–gut axis), or occurrence of structural and functional homologues between neuropeptides (e.g., neuropeptide F and human neuropeptide Y, insulin-like peptides, and human insulin) compared to humans. Here we give a hint to use insects as a model for obesity that can be used in multiple ways: as a source of genetic and peptidomic data about etiology and development correlated with obesity occurrence as well as a model for novel hormonal-based drug activity and their impact on mechanism of disease occurrence.