Intestinal Transit Time and Cortisol-Mediated Stress in Zebrafish

Abstract

Intestinal motility, the spontaneous and rhythmic smooth muscle contraction, is a complex process that is regulated by overlapping and redundant regulatory mechanisms. Primary regulators intrinsic to the gastrointestinal tract include interstitial cells of Cajal, enteric neurons, and smooth muscle cells. Extrinsic primary regulators include the autonomic nervous system, immune system, and the endocrine system. Due to this complexity, a reductionist approach may be inappropriate if the ultimate goal is to understand motility regulation in vivo. Motility can be directly visualized in intact zebrafish, with intact regulatory systems, because larvae are transparent. Intestinal motility can therefore be measured in a complete system. However, the intestinal tract may respond to external influences, such as handling, which may invoke a stress response and influence intestinal transit. We used SR4G transgenic zebrafish, which express green fluorescent protein following activation of glucocorticoid receptors, and showed that handling required for the intestinal motility assay induces stress. Separate experiments showed that exogenous application of hydrocortisone did not influence intestinal transit, suggesting that handling may not interfere with transit measurements in intact zebrafish larvae. These experiments contribute to further development of the zebrafish model for intestinal motility research.

Glucocorticoid receptor activities in the zebrafish model: a review

“…The SR4G reporter demonstrated that handling zebrafish larvae during the execution of the intestinal transit assay induces an increase in cortisol secretion (Brady et al 2017) and in vivo confirmed the interaction between methylmercury, an environmental contaminant, and the Gr, previously suggested by molecular dynamics simulations. Moreover, this interaction was found to have a role in the developmental neurotoxic effects determined by this molecule (Spulber et al 2018).…”

Bioresorbable and degradable behaviors of PGA: Current state and future prospects

“…[ 136 ] In smooth muscle, spontaneous rhythmic muscular contraction is regulated for supporting intestinal motility. [ 137 ] In response to intestinal distension, active contractile forces are generated by intestinal wall motions incorporating coordinated circular and longitudinal muscular motions. [ 138 ] Therefore, the scaffold should be subjected to the same mechanical environment following the type of the engineered tissue during the experimental research. Universalizing PGA scaffolds in varied fields of tissue engineering application Besides, the applicability of the PGA scaffold should be made universal that it can be applied to most of the human tissues.…”

The gut–brain axis in vertebrates: implications for food intake regulation

“…yellow-legged gull, Larus michahellis: Noguera et al, 2018) and fish (rainbow trout: Rosengren et al, 2018) it has been reported that hormonal manipulation of the HPA-HPI axis can significantly alter intestinal microbiota. However, it is difficult to make generalisations given the small number of species assessed, as, for instance, no effects of HPI manipulation were observed in the zebrafish gastrointestinal tract (Brady et al, 2017).…”