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1.
Lactational Amenorrhea: Neuroendocrine Pathways Controlling Fertility and Bone Turnover.
Calik-Ksepka, A, Stradczuk, M, Czarnecka, K, Grymowicz, M, Smolarczyk, R
International journal of molecular sciences. 2022;(3)
Abstract
Lactation is a physiological state of hyperprolactinemia and associated amenorrhea. Despite the fact that exact mechanisms standing behind the hypothalamus-pituitary-ovarian axis during lactation are still not clear, a general overview of events leading to amenorrhea may be suggested. Suckling remains the most important stimulus maintaining suppressive effect on ovaries after pregnancy. Breastfeeding is accompanied by high levels of prolactin, which remain higher than normal until the frequency and duration of daily suckling decreases and allows normal menstrual function resumption. Hyperprolactinemia induces the suppression of hypothalamic Kiss1 neurons that directly control the pulsatile release of GnRH. Disruption in the pulsatile manner of GnRH secretion results in a strongly decreased frequency of corresponding LH pulses. Inadequate LH secretion and lack of pre-ovulatory surge inhibit the progression of the follicular phase of a menstrual cycle and result in anovulation and amenorrhea. The main consequences of lactational amenorrhea are connected with fertility issues and increased bone turnover. Provided the fulfillment of all the established conditions of its use, the lactational amenorrhea method (LAM) efficiently protects against pregnancy. Because of its accessibility and lack of additional associated costs, LAM might be especially beneficial in low-income, developing countries, where modern contraception is hard to obtain. Breastfeeding alone is not equal to the LAM method, and therefore, it is not enough to successfully protect against conception. That is why LAM promotion should primarily focus on conditions under which its use is safe and effective. More studies on larger study groups should be conducted to determine and confirm the impact of behavioral factors, like suckling parameters, on the LAM efficacy. Lactational bone loss is a physiologic mechanism that enables providing a sufficient amount of calcium to the newborn. Despite the decline in bone mass during breastfeeding, it rebuilds after weaning and is not associated with a postmenopausal decrease in BMD and osteoporosis risk. Therefore, it should be a matter of concern only for lactating women with additional risk factors or with low BMD before pregnancy. The review summarizes the effect that breastfeeding exerts on the hypothalamus-pituitary axis as well as fertility and bone turnover aspects of lactational amenorrhea. We discuss the possibility of the use of lactation as contraception, along with this method's prevalence, efficacy, and influencing factors. We also review the literature on the topic of lactational bone loss: its mechanism, severity, and persistence throughout life.
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Neuroendocrine and Metabolic Effects of Low-Calorie and Non-Calorie Sweeteners.
Moriconi, E, Feraco, A, Marzolla, V, Infante, M, Lombardo, M, Fabbri, A, Caprio, M
Frontiers in endocrinology. 2020;:444
Abstract
Since excessive sugar consumption has been related to the development of chronic metabolic diseases prevalent in the western world, the use of sweeteners has gradually increased worldwide over the last few years. Although low- and non-calorie sweeteners may represent a valuable tool to reduce calorie intake and prevent weight gain, studies investigating the safety and efficacy of these compounds in the short- and long-term period are scarce and controversial. Therefore, future studies will need to elucidate the potential beneficial and/or detrimental effects of different types of sweeteners on metabolic health (energy balance, appetite, body weight, cardiometabolic risk factors) in healthy subjects and patients with diabetes, obesity and metabolic syndrome. In this regard, the impact of different sweeteners on central nervous system, gut hormones and gut microbiota is important, given the strong implications that changes in such systems may have for human health. The aim of this narrative review is to summarize the current evidence for the neuroendocrine and metabolic effects of sweeteners, as well as their impact on gut microbiota. Finally, we briefly discuss the advantages of the use of sweeteners in the context of very-low calorie ketogenic diets.
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3.
Neuroendocrine Factors and Head and Neck Squamous Cell Carcinoma: An Affair to Remember.
Solomon, I, Voiculescu, VM, Caruntu, C, Lupu, M, Popa, A, Ilie, MA, Albulescu, R, Caruntu, A, Tanase, C, Constantin, C, et al
Disease markers. 2018;:9787831
Abstract
Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive malignancies. Therefore, the major goal of cancer treatment is inhibition of tumor cell growth and of metastasis development. In order to choose the best management option for HNSCC patients, we need to identify reliable prognostic factors and to develop new molecular techniques in order to obtain a better understanding of therapy resistance. By acting as neurohormones, neurotransmitters, or neuromodulators, the neuroendocrine factors are able to signal the maintenance of physiological homeostasis or progression to malignant disease. Certain neuropeptides possess strong antitumor properties acting as tumor suppressors and immunomodulators, providing additional benefits for future potential therapeutic strategies. In light of the current understanding, cancer starts as a localized disease that can be effectively treated if discovered on proper time. Unfortunately, more than often cancer cells migrate to the surrounding tissues generating distant metastases, thus making the prognosis and survival in this stage much worse. As cellular migration is mandatory for tumor invasion and metastasis development, searching for alternate controllers of these processes, such as the neuroendocrine factors, it is an active tremendous task.
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4.
The 2016 ESPEN Sir David Cuthbertson lecture: Interfering with neuroendocrine and metabolic responses to critical illness: From acute to long-term consequences.
Van den Berghe, G
Clinical nutrition (Edinburgh, Scotland). 2017;(2):348-354
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5.
Steroids and Autoimmunity.
Trombetta, AC, Meroni, M, Cutolo, M
Frontiers of hormone research. 2017;:121-132
Abstract
From the middle of the 19th century, it is known that endocrine and immune systems interact bi-directionally in different processes that ensure organism homeostasis. Endocrine and nervous systems have a pivotal role in the balancing of pro- and anti-inflammatory functions of immune system, and constitute a complex circadian neuroendocrine network. Autoimmune diseases have in fact a complex pathogenic origin in which the importance of endocrine system was demonstrated. In this chapter, we will mention the structure and function of steroidal hormones involved in the neuroendocrine immune network and we will address the ways in which endocrine and immune systems influence each other, in a bi-directional fashion. Adrenal hormones, sex hormones, vitamin D, and melatonin and prolactin importantly all contribute to the homeostasis of the immune system. Indeed, some of the steroidal hormone activities determine inhibition or stimulation of immune system components, in both physiological (i.e. suppression of an unwanted response in pregnancy, or stimulation of a protective response in infections) and pathological conditions. We will finally mention the rationale for optimization of exogenous administration of glucocorticoids in chronic autoimmune diseases, and the latest developments concerning these drugs.
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6.
Neuroendocrine regulation of energy balance: Implications on the development and surgical treatment of obesity.
Farias, G, Netto, BDM, Bettini, SC, Dâmaso, AR, de Freitas, ACT
Nutrition and health. 2017;(3):131-146
Abstract
INTRODUCTION Obesity, a serious public health problem, occurs mainly when food consumption exceeds energy expenditure. Therefore, energy balance depends on the regulation of the hunger-satiety mechanism, which involves interconnection of the central nervous system and peripheral signals from the adipose tissue, pancreas and gastrointestinal tract, generating responses in short-term food intake and long-term energy balance. Increased body fat alters the gut- and adipose-tissue-derived hormone signaling, which promotes modifications in appetite-regulating hormones, decreasing satiety and increasing hunger senses. With the failure of conventional weight loss interventions (dietary treatment, exercise, drugs and lifestyle modifications), bariatric surgeries are well-accepted tools for the treatment of severe obesity, with long-term and sustained weight loss. Bariatric surgeries may cause weight loss due to restriction/malabsorption of nutrients from the anatomical alteration of the gastrointestinal tract that decreases energy intake, but also by other physiological factors associated with better results of the surgical procedure. OBJECTIVE This review discusses the neuroendocrine regulation of energy balance, with description of the predominant hormones and peptides involved in the control of energy balance in obesity and all currently available bariatric surgeries. CONCLUSIONS According to the findings of our review, bariatric surgeries promote effective and sustained weight loss not only by reducing calorie intake, but also by precipitating changes in appetite control, satiation and satiety, and physiological changes in gut-, neuro- and adipose-tissue-derived hormone signaling.
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Taurine, energy drinks, and neuroendocrine effects.
Caine, JJ, Geracioti, TD
Cleveland Clinic journal of medicine. 2016;(12):895-904
Abstract
Taurine is an amino acid found abundantly in brain, retina, heart, and reproductive organ cells, as well as in meat and seafood. But it is also a major ingredient in popular "energy drinks," which thus constitute a major source of taurine supplementation. Unfortunately, little is known about taurine's neuroendocrine effects. The authors review the sparse data and provide a basic background on the structure, synthesis, distribution, metabolism, mechanisms, effects, safety, and currently proposed therapeutic targets of taurine.
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8.
Neuroendocrine adaptations to bariatric surgery.
Dixon, JB, Lambert, EA, Lambert, GW
Molecular and cellular endocrinology. 2015;:143-52
Abstract
The global epidemic of obesity and its related disease in combination with robust physiological defence of intentional weight loss generates a pressing need for effective weight loss therapies. Bariatric surgery, which works very effectively at delivering substantial sustained weight loss, has been an enigma with respect to mechanism of action. Naive concepts of restriction and malabsorption do not explain the efficacy of the most commonly used bariatric procedures. This century has seen increased interest in unravelling the mystery of the mechanisms underlying surgery associated weight loss with a focus on integrative gastrointestinal (GI) physiology, gut-brain signalling, and beyond weight loss effects on metabolism. GI interventions, some very minor, can alter GI wall stretch and pressure receptors; a range of GI hormones affecting hunger and satiety; bile acid metabolism and signalling; the characteristics of GI microbiome; portal vein nutrient sensing; and circulating concentrations of amino acids. Understanding the mechanisms involved should present targets for less invasive effective therapies.
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9.
Neuroendocrine circuits governing energy balance and stress regulation: functional overlap and therapeutic implications.
Ulrich-Lai, YM, Ryan, KK
Cell metabolism. 2014;(6):910-25
Abstract
Significant comorbidities between obesity-related metabolic disease and stress-related psychological disorders suggest important functional interactions between energy balance and brain stress integration. Largely overlapping neural circuits control these systems, and this anatomical arrangement optimizes opportunities for mutual influence. Here we first review the current literature identifying effects of metabolic neuroendocrine signals on stress regulation, and vice versa. Next, the contributions of reward-driven food intake to these metabolic and stress interactions are discussed. Lastly, we consider the interrelationships between metabolism, stress, and reward in light of their important implications in the development of therapies for metabolism- or stress-related disease.
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10.
Food cues do not modulate the neuroendocrine response to a prolonged fast in healthy men.
Snel, M, Wijngaarden, MA, Bizino, MB, van der Grond, J, Teeuwisse, WM, van Buchem, MA, Jazet, IM, Pijl, H
Neuroendocrinology. 2012;(4):285-93
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Abstract
INTRODUCTION Dietary restriction benefits health and increases lifespan in several species. Food odorants restrain the beneficial effects of dietary restriction in Drosophila melanogaster. We hypothesized that the presence of visual and odorous food stimuli during a prolonged fast modifies the neuroendocrine and metabolic response to fasting in humans. SUBJECTS AND METHODS In this randomized, crossover intervention study, healthy young men (n = 12) fasted twice for 60 h; once in the presence and once in the absence of food-related visual and odorous stimuli. At baseline and on the last morning of each intervention, an oral glucose tolerance test (OGTT) was performed. During the OGTT, blood was sampled and a functional MRI scan was made. RESULTS The main effects of prolonged fasting were: (1) decreased plasma thyroid stimulating hormone and triiodothyronine levels; (2) downregulation of the pituitary-gonadal axis; (3) reduced plasma glucose and insulin concentrations, but increased glucose and insulin responses to glucose ingestion; (4) altered hypothalamic blood oxygenation level-dependent (BOLD) signal in response to the glucose load (particularly during the first 20 min after ingestion); (5) increased resting energy expenditure. Exposure to food cues did not affect these parameters. CONCLUSION This study shows that 60 h of fasting in young men (1) decreases the hypothalamic BOLD signal in response to glucose ingestion; (2) induces glucose intolerance; (3) increases resting energy expenditure, and (4) downregulates the pituitary-thyroid and pituitary-gonadal axes. Exposure to visual and odorous food cues did not alter these metabolic and neuroendocrine adaptations to nutrient deprivation.