Significance of hypothalamic-pituitary-adrenal axis to adapt to climate change in livestock

Abstract

Climate, which includes many atmospheric parameters such as temperature, humidity, wind speed and solar radiation can affect in many ways any animal’s ability to survive and produce. Adaptation involves the technique to adapt a species to its environment. Biological adaptation to thermal stress is accompanied by changes in protein, membrane lipid, and metabolic rate. Production of heat shock protein (HSP) is a cellular and tissue defense response to thermal stress. Hypothalamus, blood, thyroid, liver, lungs, heart, skin, cell and different axis play an important role in the process of attaining homeostasis by the animal. Hypothalamicpituitary-adrenal (HPA) axis, somatotrophic axis, lactotrophic axis, gonadotrophic axis and thyrotropic axis are the different axis involved in adaptation. One of the best, consistent and spontaneous response to stress is the activation of the HPA axis. The HPA axis get activated when an animal receives stress through various sense organs. Activation of HPA results in secretion of steroid hormones from the adrenal gland. Activation of pituitary component of HPA axis can be mediated by several neuroendocrine hormones such as corticotropin releasing hormone (CRH) and adreno corticotrophic hormone (ACTH). Secretion of steroids from the adrenal cortex is stimulated by ACTH from the anterior pituitary. The endocrine action of ACTH, CRH and Vasopressin (VP) mediate glucocorticoid secretion from the adrenal cortex. International Research Journal of Agricultural and Food Sciences Article Number: PRJA97540518 Copyright ©2017 Author(s) retain the copyright of this article Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution 4.0 International License. Glucocorcoids activation plays a vital role in inducing hepatic gluconeogenesis to support the adaptation process. Glucocorticoids also stimulate the synthesis of epinephrine from the adrenal medulla. All these findings indicates the crucial role played by HPA axis in controlling the neuroendocrine mechanisms that regulate the complex adaptive responses of livestock to environmental challenges.