EDITORIAL published: 24 September 2019 doi: 10.3389/fendo.2019.00652 Editorial: Comparative Endocrine Stress Responses in Vertebrates Lluis Tort 1*, John F. Cockrem 2 and Edward J. Narayan 3,4 1 Department Cell Biology, Physiology and Immunology, Universitat Autonoma de Barcelona, Barcelona, Spain, 2 School of Veterinary Science, Massey University, Wellington, New Zealand, 3 School of Science and Health, Western Sydney University, Penrith, NSW, Australia, 4 School of Agriculture and Food Sciences, The University of Queensland, Gatton, QLD, Australia Keywords: editorial, stress, responses, endocrine, vertebrates Editorial on the Research Topic Comparative Endocrine Stress Responses in Vertebrates The stress response in vertebrates is characterized by involving physiological regulatory systems and a number of organs, tissues, and effector pathways in order to both respond to the stressor effects and overcome the situation and recover homeostasis. Although differences in specific mechanisms are encountered in different animal groups and even between interspecies and intraspecies, the stress response involves an endocrine activation in all groups of vertebrates. Since an increasing number of scientific works are currently published in this field, the idea of collecting and reviewing such advances originated the initiative of a Topic Collection on the Comparative Stress responses in Vertebrates. In the following set of papers, the readers will find out an interesting update of the latest work in the field of the endocrine responses to stress in vertebrates, from general approaches to specific contributions and methodological updates.Of course, it is not intended that this Topic collection be exhaustive or complete, as many untreated aspects could be added, and some vertebrate groups are not well-represented into the collection, but this overview is anyway Edited and reviewed by: interesting to show what are some of the current working areas in this field. Cunming Duan, Among the general approaches presented in this Topic collection, a novel contribution is University of Michigan, United States the concept of stressotope by Balasch and Tort, linking the adaptive set of responses of the *Correspondence: animal to particular biotopes associated with specific conditioning factors involving the maximum Lluis Tort overall stress responses across immune-neuroendocrine relevant physiological levels and scenarios, lluis.tort@uab.es including the characterization of behavioral response. In relation with this stressotope concept, the work by Sánchez-Vázquez et al., deep into the Specialty section: relationship among factors regulating the circadian rhythms in animals particularly under stress This article was submitted to situations, showing that not only a number of specific environmental factors are connected Experimental Endocrinology, to circadian rhythms, but also that the proper oscillations of the environmental factors are a section of the journal significantly involved. Frontiers in Endocrinology In another of the works in this Topic, Gómez-Boronat et al., investigating in daily cycles, Received: 03 September 2019 demonstrate that the misalignment of external cues such as day-night photocycles and feeding time Accepted: 06 September 2019 may temporarily alter fish homeostasis, thus involving a stress situation for the animals. Published: 24 September 2019 Other contributions make relevant insights in the comparative approach of endocrine stress Citation: regulation in vertebrates. In the first one, Narayan and Vanderneut provided invaluable insights Tort L, Cockrem JF and Narayan EJ into how wild koalas respond physiologically to environmental trauma and disease, a species not (2019) Editorial: Comparative Endocrine Stress Responses in often represented in the scientific literature of comparative stress responses. In addition, this paper Vertebrates. includes an applied aspect on how methods of care, husbandry, and treatment can be used to reduce Front. Endocrinol. 10:652. the impacts of stressors with the ultimate aim of increasing the rehabilitation possibilities and future doi: 10.3389/fendo.2019.00652 release of this species in the wild. Frontiers in Endocrinology | www.frontiersin.org 1 September 2019 | Volume 10 | Article 652 Tort et al. Editorial: Comparative Endocrine Stress Responses in Vertebrates In another paper, Höglund et al. show the role of Tryptophan they show how significant can be the species-specific molecular and the associated metabolic pathways in the regulation of and neuro-regional differences between two similar species serotonergic activity in the fish brain, a key mechanism intimately sharing many environmental and geographical conditions. This associated to stress and behavioral responses of animals. points out how important can be the variability of specific Numerous studies have shown that elevated dietary Trp has a mechanisms between species, even from close-related groups, suppressive effect on aggressive behavior and post-stress plasma though sharing the basic patterns of molecular and endocrine cortisol concentrations in vertebrates. These effects are believed molecules and pathways. to be mediated by the brain serotonergic system, even though Finally, regarding key methodological contributions, the mechanisms involved are not well-understood. paper by Aerts rises the importance of the methodological aspects Also regarding key components in the diet, the work associated to the molecules currently chosen to define a stressed by Herrera et al., have looked at the studies on stress status. He demonstrates that it is pivotal to know the involved attenuation in animals through diet or supplement components. regulatory molecules and to understand how these molecules Other than the development of new technologies to monitor are synthesized, regulated, and excreted, together with how these and improve environmental conditions of farmed animals, molecules grasp their actions on a plethora of biological processes particularly fish, beneficial additives in the daily meal have in many organs and tissues. been included in order to mitigate the effects of husbandry Collectively, the Topic highlights current research areas and stressors. Immunological, nutritional, and metabolic changes future directions in the dynamic field of vertebrate stress have been assessed in these trials, always associated to endocrine endocrinology. Beyond theoretical knowledge, the field of regulation. The biochemical and physiological functionality of research provides powerful tools to enable researchers to make those feed additives may strongly affect the stress response and, objective assessments of the physiological state of animals, to even, such additives may act as neurotransmitters, hormone understand how animals respond to environmental change and precursors, energy substrates, or cofactors implying multi- human interventions. systematic and multi-organic responses that modify the response to stress. AUTHOR CONTRIBUTIONS Suarez-Bregua et al. focused their approach in a less studied area in lower vertebrates as the endocrine relationship between All authors listed have made a substantial, direct and intellectual glucocorticoid metabolism and the parathyroid hormone family contribution to the work, and approved it for publication. peptides. The paper deeps into the response driven by these hormones and other key regulators of mineral homeostasis in Conflict of Interest: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a connection with bone remodeling processes, which involves potential conflict of interest. important consequences in terms of harmonic growth and skeletal deformities. Copyright © 2019 Tort, Cockrem and Narayan. This is an open-access article A more specific comparative work on the stress and endocrine distributed under the terms of the Creative Commons Attribution License (CC BY). responses is presented by a group of researchers from Greece, The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original Norway, and The Netherlands. Thus, Samaras et al. focus on publication in this journal is cited, in accordance with accepted academic practice. the differential responses between two close warm water marine No use, distribution or reproduction is permitted which does not comply with these aquacultured species, sea bass, and sea bream. In this paper, terms. Frontiers in Endocrinology | www.frontiersin.org 2 September 2019 | Volume 10 | Article 652