Neural and hormonal control of visceral systems

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Our long-term goals are to study how cells, tissues and organ systems in insects are regulated and integrated by neurons and neuroendocrine pathways that utilize a variety of neuroactive chemicals (neuropeptides and amines), G-protein coupled receptors (GPCRs) and second messengers. We are interested in how these systems participate in successful behaviours; including aspects of reproduction, digestion, circulation of nutrients and waste, and ecdysis behaviour. We have observed that some neuroactive chemicals are expressed in a variety of cell types and so it is possible that these neuroactive chemicals might in themselves represent functional units that interact to bias the insect towards a new functional state or behaviour. In addition, these neuroactive chemicals are also components of the brain-gut axis, and therefore serve as a link between the endocrine / neural system of the digestive tract, the neuroendocrine system, the central nervous system (CNS), and circulation of haemolymph (blood) and neurohormones. The research objects of the proposed research program lie in the following areas: 1) to define the integrative neuroendocrine control of reproductive structures and associated visceral tissues (eg. digestive, cardiac) in the agricultural pest Locusta migratoria and in the medically-important vector of Chagas’ disease, Rhodnius prolixus; and 2) to define the integrative control of ecdysis behaviour (shedding of the exoskeleton) through the coordinated action of neuropeptides on CNS and associated peripheral systems (cardiac, digestive, skeletal muscle). Our scientific approach is holistic and incorporates multi-facetted aspects from gene to behaviour. We define the neural substrates and circuits (including their neuroactive chemicals and receptors) used in the integrative control of these behaviours using a variety of techniques including molecular biology, pharmacology, neurophysiology, physiological assays, peptide isolation, neural mapping, and immunohistochemistry. Novelty and expected significance: Our long term goal is to study how cells communicate with one another in order to produce an appropriate physiological and behavioral output. We identify and define the interactions between the diverse neurochemicals which are used in our model systems, and also look at interactions / coordination of organ systems. The importance of research into insects lies increasingly in the testing and demonstration of universal principles of neural organization and functioning, while identifying unique features for target of novel pest control strategies. For example, just like the pharmaceutical industry, the agrochemical industry is targeting neuroactive chemicals and GPCRs for novel pest control strategies due to the ever increasing resistance to the current generation of pesticides. The future is hopeful, especially for neuropeptides, where the intrinsic problems associated with their use have been overcome. This need for control is particularly relevant for our model insects, L. migratoria and R. prolixus. Locusts are agricultural pests, eating or destroying crops and affecting over 20% of the earth’s land and more than 65 of the world’s poorest countries. Their swarms lead to devastating consequences in many developing countries. The medically-important insect, R. prolixus, is the vector of human Chagas disease, and whilst once considered to be confined to the Americas, Chagas disease now occurs throughout the World due to human migration and blood transfusions. For example, it is estimated that 300,000 people are infected in the USA, 50,000 in Spain and 2,000 in Canada. Therefore, this research, as outlined above, has the potential to discover lead compounds that can be developed into bio-pesticides in the future.