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Regulation of the Pituitary Gland by Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
β-endorphin is also produced in many brain areas, including the medial basal hypothalamus, thalamus, amygdala, periaqueductal gray, the inferior colliculus, the raphe nucleus, locus ceruleus, several regions of the reticular formation, and the solitary tract. Primarily released in response to pain, β-endorphin reduces the perception of pain by acting on central and peripheral opiate receptors. Whereas it has similar analgesic properties as morphine and codeine, β-endorphin does not lead to addiction or dependence as can be caused by these drugs. The euphoria, or sensation of well-being that often accompanies exercise of sufficient intensity and duration is also attributed to increased β-endorphin release.
Miscellaneous Neuropeptides
Published in Paul V. Malven, Mammalian Neuroendocrinology, 2019
A large precursor for β-endorphin was subsequently identified and found to give rise to a variety of biologically active hormones and neuropeptides (Imura et al., 1982). Figure 5-2 illustrates this precursor, named pro-opiomelanocortin (POMC), and the many important sequences it contains. The C-terminal 91 residues of POMC constitute P-lipotropin, which is located adjacent to the 39 residues of the adenohypophysial hormone ACTH. The N-terminal end of ACTH contains the sequence for α-melanotropin (α-MSH), whereas the related sequences of β-MSH and γ-MSH are located in other parts of POMC (Figure 5-2). Because of sequence identity, the seven residues of ACTH (4–10) are also found in γ-MSH and β-MSH. Therefore, this seven-residue sequence recurs three times in the linear sequence of POMC.
The Pituitary Gland Eva Nagy
Published in Istvan Berczi, Pituitary Function and Immunity, 2019
MSH is secreted by cells located in the pars intermedia of the hypophysis and they are also dispersed in the neurohypophysis in humans. There are three other known substances with MSH activity besides ACTH: α -MSH, β -MSH, and β -LPH (β -lipotropin). The endorphins (α, β, γ) appear to be parts of a larger molecule identical to β -lipotropin. This large peptide molecule also contains a segment identical to β -melanocyte-stimulating hormone, which includes a segment identical to ACTH. The rapid degradation of β -endorphin in the brain raises the possibility that this peptide is acting as a neurotransmitter. α -MSH has not been detected in normal plasma. β -MSH is present in the normal plasma in a concentration of 0.1 ng/mℓ.
Sucrose drinking mimics effects of nucleus accumbens µ-opioid receptor stimulation on fat intake and brain c-Fos-expression
Published in Nutritional Neuroscience, 2022
L.L. Koekkoek, A. Masís-Vargas, T. Kool, L. Eggels, L.L. van der Gun, K. Lamuadni, M. Slomp, C. Diepenbroek, A. Kalsbeek, S.E. la Fleur
While the effects of intra-NAC infusion of DAMGO on fat intake have been well described [9–13], we now show for the first time that a prior bolus of sucrose drinking diminishes this DAMGO-induced increase in fat intake. Sucrose has known analgesic effects [21], which are thought to be due to the release of endogenous opioids [22]. Indeed, sucrose drinking has been found to trigger endogenous opioid release in multiple brain areas, including the dorsal striatum [23] and the NAC [15]. Remarkably, the binding of the endogenous opioids β-endorphin and met-enkephalin can cause the internalization of the μ-opioid receptor [24]. We, therefore, hypothesize that due to the release of endogenous opioids in the NAC upon sucrose drinking and subsequent internalization of the μ-opioid receptor, fewer μ-opioid receptors are available once DAMGO is infused. This reduced availability prevents the increased fat intake that is typically observed upon intra-NAC DAMGO infusion.
Understanding neurobehavioral effects of acute and chronic stress in zebrafish
Published in Stress, 2021
Konstantin A. Demin, Alexander S. Taranov, Nikita P. Ilyin, Anton M. Lakstygal, Andrey D. Volgin, Murilo S. de Abreu, Tatyana Strekalova, Allan V. Kalueff
POMC is also an evolutionary conserved polypeptide found in various species, including humans (Chang, Cochet, & Cohen, 1980) and fishes, such as carp (Arends et al., 1998) and zebrafish (Gonzalez-Nunez, Gonzalez-Sarmiento, & Rodriguez, 2003). In stress, the POMC cleavage by prohormone convertases in cortico- and melanotropic cells of the adenohypophysis generates several important bioactive products that are essential to stress response (Metz, Peters, & Flik, 2006; Morash, MacDonald, Croll, & Anini, 2009). For example, tissue-specific convertases produce ACTH, α- and β-MSH (melanocyte-stimulating hormone) and various endorphins (Gonzalez-Nunez et al., 2003). Likewise, β-endorphin is implicated in the regulation of stress response via the feedback inhibition of CRF expression (Sarkar, Kuhn, Marano, Chen, & Boyadjieva, 2007), also inducing CRF secretion in the isolated rat hypothalamus (Buckingham, 1986). This function of β-endorphin raises the question of direct role of endogenous opioids in stress response, and their potential indirect role (e.g. via the modulation of the stress axis), especially in chronic stress. Supporting the translational relevance of zebrafish models for such studies, their opioidergic system shows a generally high level of conservation, with ∼61% opioid genes being homologous, in humans and zebrafish (Demin et al., 2018).
Rehabilitation of patients with COVID-19
Published in Expert Review of Respiratory Medicine, 2020
Tiantian Sun, Liyun Guo, Fei Tian, Tiantian Dai, Xiaohong Xing, Junqing Zhao, Qiang Li
For mild and moderate signs and symptoms in patients with COVID-19, where there are no contraindications and after professional evaluation, patients can perform breathing guidance exercises and qigong (Baduanjin, simplified Tai Chi, and Liu Zi Jue exercises) [39]. Qigong is a training method that combines sports training, breathing training, and psychological support, which involves a conscious control of one’s breathing to enhance lung function and strengthen muscles through movement of the limbs and trunk. Through meditation, the mind is induced into a relaxed, calm state [49]. Potential mechanisms of action involved with these techniques are considered to bring about a reduction in psychological stress and enhance emotional management through increasing β-endorphin levels and lowering adrenocortical hormone levels [50] and to strengthen recovery of respiratory muscle function, reduce inflammation, and enhance immune function. Although there have been few studies concerning TCM interventions in rehabilitation in the acute respiratory distress infection phase, the results of limited research have shown that Baduanjin, simplified Taijiquan, and Liu Zi Jue exercises can shorten infection duration [51]. Patients requiring isolation at home can contact medical staff through remote mobile devices for rehabilitation training [52–56].