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Neuropeptide Regulation of Ion Channels and Food Intake
Published in Tian-Le Xu, Long-Jun Wu, Nonclassical Ion Channels in the Nervous System, 2021
The arcuate nucleus, one of the most popular areas for homeostatic regulation of food intake, is located at the bottom of the hypothalamus around the third ventricle. There are two major populations of neurons in the arcuate nucleus that respond to energy metabolism and act to regulate food intake. The anorexigenic POMC neurons inhibit food intake when they are activated, while the orexigenic AgRP neurons stimulate food consumption when their activity is increased. Optogenetic and chemogenetic activation of AgRP neurons rapidly induces food intake, while stimulation of POMC neurons takes hours to decrease food consumption (Aponte, Atasoy, and Sternson 2011). To sense the energy states of the body, AgRP and POMC neurons in the arcuate nucleus differently respond to the metabolic signals from adipose tissue and gut. Leptin is the satiety signal that arises from adipose tissue and the circulating levels of leptin correlate with adipose mass. The leptin receptors (ObRs) are expressed in many brain regions including the arcuate nucleus for the control of energy and glucose homeostasis (Xu et al. 2018; Varela and Horvath 2012). When leptin level goes up, it stimulates POMC neurons but inhibits AgPR neurons to reduce food intake through the activation of leptin receptors (Varela and Horvath 2012). Ghrelin is another hormone that is released by the stomach In the hungry state. Both AgRP and POMC neurons express ghrelin receptors, which contribute to sense the energy deficit. Increased ghrelin level activates AgRP neurons but inhibits POMC neurons to increase appetite (Cowley et al. 2003).
Distribution and Characteristics of Brain Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
The arcuate nucleus is located near the third ventricle and above the median eminence. It is composed of a diverse population of neurons as well as nonneuronal cells such as astrocytes and tanycytes, which are specialized ependymal cells. The arcuate nucleus contains large amounts of DA and is the origin of the TIDA and THDA neurons that innervate the median eminence and the posterior pituitary, respectively, as discussed in Sections 3.4.3 and 3.4.4. The parvocellular neurons within the arcuate nucleus produce several releasing/inhibiting hormones that include GnRH, GH releasing hormone (GHRH), β-endorphin, melanocyte stimulating hormone (MSH) and somatostatin. In addition, the arcuate nucleus produces a variety of neuromodulators such as kisspeptin, NPY, substance P, Agouti-related peptide (AgRP) and CART (cocaine and amphetamine regulatory transcript). The arcuate nucleus has the highest concentrations of leptin receptors in the brain and as discussed in Chapter 4, it is the best characterized hypothalamic nucleus involved in energy homeostasis.
Effects of Environmental Factors on the Endocrine System
Published in George H. Gass, Harold M. Kaplan, Handbook of Endocrinology, 2020
The arcuate nucleus is situated in the mediobasal hypothalamus just beneath the floor of the third ventricle. It is an important nucleus for reproductive functions such as menstrual cyclicity,5 primarily responsible for GnRH and dopamine. This is a neuronal oscillator responsive to many endogenous factors; one of them has been shown to be estrogen.6 As demonstrated in the rat brain, estrogen is possibly involved in fetal neurogenesis, shaping sex differences in synaptology, postsynaptic membranes, and glia within the arcuate nucleus.
Leptin’s Immune Action: A Review Beyond Satiety
Published in Immunological Investigations, 2023
Alice Abend Bardagi, Clarissa dos Santos Paschoal, Giovanna Ganem Favero, Luisa Riccetto, Maria Luisa Alexandrino Dias, Gil Guerra Junior, Giovanna Degasperi
The arcuate nucleus, located at the base of the hypothalamus (Bouret et al. 2004), expresses a higher density of LepRb in its neurons, suggesting that leptin has a big role in hunger-satiety regulation in this region (Flak and Myers 2016). This nucleus sustains connections with the ventromedial, dorsomedial, and paraventricular nuclei, which also express leptin receptors, implying that they are also involved in modulating the hunger cycle (Perello and Raingo 2013). In the arcuate nucleus, leptin activates POMC-producing neurons. Consequently, POMC is cleaved into alpha-melanocyte-stimulating hormone (α-MSH), which inhibits food intake via melanocortin receptors 3 and 4 (MC3R and MC4R). Leptin also inhibits AgRP, NPY, and GABAergic neurons, thus inhibiting the hunger feeling (Coppari et al. 2005). During fasting periods, the activation of AgRP, NPY, and GABAergic neurons motivate and enable food seeking behaviors; on the other hand, anorexigenic neurons are activated by the increase in leptin blood levels after food intake (Davis et al. 2011).
Effect of S-allylcysteine against diabetic nephropathy via inhibition of MEK1/2-ERK1/2-RSK2 signalling pathway in streptozotocin-nicotinamide-induced diabetic rats
Published in Archives of Physiology and Biochemistry, 2023
V. V. Sathibabu Uddandrao, Brahmanaidu Parim, Ravindarnaik Ramavat, Suresh Pothani, S. Vadivukkarasi, Ponmurugan P, Chandrasekaran P, Saravanan Ganapathy
The proposed investigation uncovered that in the DN control group of rats revealed the polyurea, polydipsia, polyphagia and increased faecal production considerably as indications of DM and its associated complications (Wang-Fischer and Garyantes 2018). This can be explained by reality that the renal tubules are unequipped for taking up the entirety of the glucose separated in the glomeruli. The renal discharge of glucose requires drainage of water and delivers an osmotic diuresis. It can cause lack of hydration, following in obscured vision and dry skin, which is because of swaying in the measure of water and glucose in the focal points of the eye during parchedness. Loss of water causes an increase in the serum extremity that supports the thirst place in the hypothalamus (Leib et al. 2016). The adaptive raise in food intake induced by diminution of energy stores in these animals involves the synchronised regulation of various pathways within the hypothalamic arcuate nucleus (ARC), a region of the brain that acts as an integration centre for peripheral signals of energy condition. Under basal circumstances, leptin and insulin are thought to hold back ARC neurons that coexpress neuropeptide Y and agouti generelated protein, peptides that potentially excite food intake (Schwartz et al. 2003). Additionally, it was likewise discovered that SAC fundamentally diminished the diabetic attributes, for example, polyphagia, polydipsia and polyurea which may be because of the counter diabetic capability of the SAC (Saravanan et al. 2009).
Assessment of acute aerobic exercise in the morning versus evening on asprosin, spexin, lipocalin-2, and insulin level in overweight/obese versus normal weight adult men
Published in Chronobiology International, 2020
Halil İbrahim Ceylan, Özcan Saygın, Ümmühani Özel Türkcü
Obesity is a complex multifactorial health problem involving interaction between factors of genetics, behavior, environment, will power, self-control, appetite regulation, and energy metabolism (Haghshenas et al. 2014; Serter 2003). The physiology of obesity is based on increase in body weight as a result of positive energy balance (WHO 1997). Energy balance control, appetite control, and possible mechanisms of obesity are regulated by the hypothalamus, especially the arcuate nucleus, which is the key site of feedback control of appetite and food intake (Konturek et al. 2005; Suzuki et al. 2010). Appetite control is a complex process that involves communication between the arcuate nucleus of the hypothalamus, gastrointestinal system, and adipose tissue (Stensel 2010). Adipose tissue plays an important role in regulating metabolic activity, systemic energy balance, appetite, satiety, thermogenesis, inflammation, lipid metabolism, and glucose homeostasis by communicating with peripheral organs and brain through adipokines (Luo and Liu 2016; Ramanjaneya et al. 2010; Scheja and Heeren 2019). Therefore, understanding of adipose tissue biology and pathology is of great importance for the prevention and treatment of obesity and obesity-related diseases (Rosen and Spiegelman 2006). Recent studies demonstrated the hormones of asprosin, spexin, lipocalin-2, and insulin that are secreted from adipose tissue play a key role in regulating appetite, satiety, and inflammation. .