**6. Conclusion and outlook**

Recently *Drosophila* has emerged as a model to study intestinal infection and pathology because of conservation between *Drosophila* and mammalian intestinal pathophysiology, regeneration, and signaling pathways that control them. Real time and other *Drosophila* assays provide the complex cellular composition of a real intestine and opportunities to assess toxicity in a whole organism at a relatively low cost compared to mammalian system. Its simpler cellular structure, flexibility to doing screening, availability of molecular markers and other genetic tools adds up to its value as an ideal model system to study intestine. Also, it has been shown that human intestinal pathogens can cause intestinal pathology in flies as well.

In the recent past, data from the intestinal mechanisms found in flies have been shown to be active in mammals, and may therefore become relevant in the context of human pathologies including diabetes, obesity, neurodegenerative diseases, gastrointestinal cancers, or aging. Parallel findings of communication between gut and brain via neuropeptides in *Drosophila* and humans highlight on the importance of GBA in maintaining health. Identification of neural circuitries is of prime importance to apprehend more about the link between the gut and brain and their link with metabolic and neurodegenerative diseases. Greater understanding of gut-brain feeding circuits, paracrine signaling of peptides and physical communication via neural circuitries will establish their functioning in several metabolic disorders, neurological syndromes, aging and cardiovascular diseases. Research using flies on specific gut regions, cell types during various developmental stages and on stem cell biology and aging have been conducted so far. Other functions including role of unidentified taste receptors in the gut, their connection with the brain mediating nutrient digestion and transport, or organs such as the crop and the proventiculus, remain poorly characterized. Deeper understanding is required on the function of gut brain neural connectivity and to investigate what may be their key role in human or insect (patho)physiology concerning feeding behavior and appetitive learning. Techniques like *in vivo* CRISPR transcriptional activation (CRISPRa) and interference (CRISPRi) approaches [288, 305], to allow tightly regulated and reversible promoter activation and blocking in fly gut can be fruitful for future studies.

Developing new techniques and behavioral assays can help us explore physiological drives: what is the gut function to maintain the overall health of the animal. It would be interesting to find out the key intestinal sensors. How the physical association between gut and brain via neural micro circuits regulate decisions regarding nutrition, hunger and satiety is under question. Better "holistic" and quantitative methods, integration of spatial and temporal information about genetic events more comprehensively are required, so that cause and effect can be uncoupled in a physiological context [306]. We anticipate and hope that fly models of intestinal pathology, in addition to uncovering newly identified genes (chemosensory and others) and basic biology mechanisms will emphasize the most conserved aspects of human intestinal biology. As a result, fly will contribute to translational research investigating drug effects, and microbial and host genetic component analyses, leading to biological findings that are broadly applicable to human health and disease.

*Gut Feeding the Brain:* Drosophila *Gut an Animal Model for Medicine to Understand… DOI: http://dx.doi.org/10.5772/intechopen.96503*
