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Stress Management and Meditation
Published in Mehwish Iqbal, Complementary and Alternative Medicinal Approaches for Enhancing Immunity, 2023
The levels of different hormones alter in reaction to stress. Responses to stress are related to increased secretion of many hormones, including prolactin, catecholamines, glucocorticoids and growth hormones, the outcome of which is to enhance the energy sources' mobilisation and modify the person to their new situation. The pituitary-adrenal axis activation is a renowned reaction of the neuroendocrine system to stress, encouraging endurance. Activation of the pituitary-adrenal axis results in CRF (corticotrophin-releasing factor) secretion from the hypothalamus. Subsequently, corticotropin-releasing factors encourage the pituitary to release adrenocorticotrophin hormone, 3-endorphin and 8-lipotropin. Levels of these hormones in the blood can enhance two to five times in humans during stress (Hargreaves, 1990).
Miscellaneous Neuropeptides
Published in Paul V. Malven, Mammalian Neuroendocrinology, 2019
β-Endorphin Family of EOP. As stated above, the discovery of opioid receptors stimulated the search for opioid bioactivity in various tissue extracts. A protein called β-lipotropin based on its lipid-mobilizing bioactivity had been discovered some years earlier in pituitary extracts of domestic ungulates. When pituitary extracts from camels were examined, they lacked β-lipotropin but contained part of its sequence in a smaller peptide which was originally named C-fragment. This C-fragment derived from the camel pituitary was found to contain opioid bioactivity, and it was assigned a new name, β-endorphin. Although the camel is a physiologically unique species, it was subsequently learned that high levels of β-endorphin in its adenohypophysial tissue were due to postmortem degradation of β-lipotropin and not due to any unique physiology of the camel.
Regulation Of Pro-Opiomelanocortin (Pomc) Biosynthesis In The Amphibian And Mouse Pituitary Intermediate Lobe
Published in Mac E. Hadley, The Melanotropic Peptides, 1988
Y. Peng Loh, Stela Elkabes, Brenda Myers
POMC is processed by a cascade of proteolytic steps beginning with a cleavage at a Lys-Arg pair between the ACTH and β-lipotropin sequence (see Figure 1). This is then followed by the cleavage of the 16K glycopeptide and β-lipotropin, again at Lys-Arg residues to yield ACTH and β-endorphin, respectively.7,50 Recently, an enzyme has been purified from bovine intermediate lobe secretory vesicles that can accomplish these cleavages. The enzyme, named pro-opiomelanocortin-converting enzyme (PCE), has been characterized as an aspartyl protease.51 It has an acidic pH optimum and is a 70,000 mol. wt. glycoprotein. PCE is highly specific for paired basic residues. The enzyme cleaves POMC, as well as the intermediates, 21 to 23K ACTH and β-lipotropin to yield ACTH and P-endorphin, respectively. However, the enzyme does not cleave the Lys-Lys-Arg-Arg residues of ACTH to yield α-MSH,52 nor will it cleave the Lys-Lys pair at the C-terminal portion of β-endorphin to yield truncated forms of β-endorphin found in the intermediate lobe.52 In vitro studies on PCE suggest that the enzyme concentration is important in the regulation of the processing of POMC. Depending on the enzyme concentration used, human β-lipotropin was found to be either fully processed to β-endorphin and β-MSH, or to β-endorphin and γ-lipotropin52 (see Figure 1). Thus, theoretically, by regulating the enzyme to substrate concentration within a secretory vesicle where processing occurs, it may be possible to attenuate the degree of processing and, hence, the end-products generated. The differential processing of β-lipotropin in the intermediate and anterior lobes may be under such a regulatory mechanism.
A mechanistic evaluation of the potential for octamethylcyclotetrasiloxane to produce effects via endocrine modes of action
Published in Critical Reviews in Toxicology, 2021
Several authors have commented on the potential for a number of the effects seen following the exposure to D4 as being secondary to activation of the stress response (e.g. Jean and Plotzke 2017; Dekant et al. 2017a, 2017b; Pauluhn 2021). Virtually any chemical substance will produce a stress response if the body burden approaches the limits that the organism or person can tolerate (e.g. De Boeck et al. 1997; Pruett et al. 2007). This was the case in all of the high dose studies of the effects of D4 (e.g. ≥300 ppm for inhalation exposures) and many of the biological actions that are produced only by high doses of D4 are most probably primarily due to stress-related effects on the female reproductive system. The stress response is a physiological, endocrine-based system that functions to maintain homeostasis in the face of forces that work to alter this state. Stress is commonly defined as a state of real or perceived (psychological) threat to homeostasis. The stress response is mediated by hormones of the hypothalamic-pituitary-adrenal axis (HPA). In this system neurons in the paraventricular nucleus of the hypothalamus respond to stressful stimuli by releasing corticotropin releasing factor (CRF) into the blood traveling to the anterior pituitary gland. CRF stimulates the anterior pituitary to produce proopiomelanocortin, which is fragmented to form adrenocorticotropic hormone, β-endorphin, α- and β-melanocyte stimulating hormone, and β-lipotropin. These are secreted into the general circulation. CRF is also produced and acts in peripheral tissues (Calogero et al. 1996). Adrenocorticotropic hormone induces glucocorticoid synthesis and release from the adrenal cortex. Glucocorticoid levels have been found to be elevated in response to D4 exposure (Wilson 1996; He et al. 2003; Jean and Plotzke 2017). D4, administered to 129 J/C57Bl/6J mice by gavage in corn oil at 3.37 × 10−3 mol/kg/day for 7 days elevated glucocorticoid levels by 6.3* fold (He, et al. 2003).