Interdependence of Thyroid and Corticosteroid Signaling in Vertebrate Developmental Transitions

Abstract

Post-embryonic acute developmental processes mainly allow the transition from one life stage in a specific ecological niche to the next life stage in a different ecological niche. Metamorphosis, an emblematic type of these post-embryonic developmental processes, has occurred repeatedly and independently in various phylogenetic groups throughout metazoan evolution, such as in cnidarian, insects, molluscs, tunicates, or vertebrates. This review will focus on metamorphoses and developmental transitions in vertebrates, including typical larval metamorphosis in anuran amphibians, larval and secondary metamorphoses in teleost fishes, egg hatching in sauropsids and birth in mammals. Two neuroendocrine axes, the hypothalamic-pituitary-thyroid and the hypothalamic-pituitary-adrenal/interrenal axes, are central players in the regulation of these life transitions. The review will address the molecular and functional evolution of these axes and their interactions. Mechanisms of integration of internal and environmental cues, and activation of these neuroendocrine axes represent key questions in an “eco-evo-devo” perspective of metamorphosis. The roles played by developmental transitions in the innovation, adaptation, and plasticity of life cycles throughout vertebrates will be discussed. In the current context of global climate change and habitat destruction, the review will also address the impact of environmental factors, such as global warming and endocrine disruptors on hypothalamic-pituitary-thyroid and hypothalamic-pituitary-adrenal/interrenal axes, and regulation of developmental transitions.

Evolution, Development and Ecology of Anemonefishes

“…Therefore, CRH, stimulating both the HPI and HPT axes, cross-links environmental stress and TH homeostasis, procuring some developmental plasticity to larvae living in a fluctuating environment. Whether TRH and/or CRH stimulate the HPT axis in teleost fishes remains an open question; the regulation of the HPT axis might be species-specific (Larsen et al 1998;Eales and Himick 1988;Geven et al 2009;Galas et al 2009;Rousseau et al 2021).…”

A Novel Transgenic Model to Study Thyroid Axis Activity in Early Life Stage Medaka

“…1,2 Due to the Hypothalamic−Pituitary−Thyroid (HPT) axis being highly conserved among vertebrates: humans, rodents, amphibians, and fish are all affected by environmental pollutants having common endocrine disrupting properties. 3 In fish, THs play the same essential roles as in other vertebrates including growth and development, differentiation, reproduction, osmoregulation, and feeding/metabolism. 4,5 The World Health Organization (WHO) defines endocrine disruptors as "an exogenous substance or mixture that alters function(s) of the endocrine system and consequently causes adverse effects in an intact organism, or its progeny, or (sub)populations."…”

Maternally transferred thyroid hormones and life‐history variation in birds

“…It is well‐established that in both mammals and birds, THs play a central role in regulating seasonal breeding (Dardente et al, 2014; Nishiwaki‐Ohkawa & Yoshimura, 2016; Shinomiya et al, 2014). THs and glucocorticoids (stress hormones) also have synergistic effects during major life stage transition across vertebrates, such as the smoultification in salmonid fish, metamorphosis in amphibians and fish, hatching in birds and birth in mammals (reviewed in Wada, 2008; Watanabe et al, 2016; Rousseau et al, 2021). Therefore, THs could also play a mediating role in reproductive investment and shape the trade‐offs between survival and reproduction and between current and future reproduction, as has been found for glucocorticoids (Bókony et al, 2009; Casagrande et al, 2018; Hau et al, 2010; Vitousek et al, 2019).…”