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  • The presence of ghrelin s mRNA in

    2022-05-13

    The presence of ghrelin's mRNA in the eye and the presence of ghrelin in the aqueous humor, along with a decrease of its levels in glaucoma, suggest a local role for this peptide in the ocular tissue [8], [16], [18]. There is no available data regarding the presence of GHSR-1 in the anterior segment. Our results demonstrate the expression of ghrelin in the ciliary processes, at the ciliary epithelium. Moreover, ghrelin did not colocalize with VECs marker. These results indicate a local production of ghrelin by the ciliary processes of normal Wistar rats, which is in agreement with previous studies where ghrelin's mRNA was identified in the non-pigmented ciliary epithelium [18]. Contractile elements have been described at the scleral spur. These elements present some characteristics of both vascular smooth muscle cells and myofibroblasts [20]. Once relaxation of the trabecular meshwork contractile elements occurs, there is a decrease in trabecular resistance, with a consequent increase in aqueous humor outflow [21], [26]. Nitric oxide has been involved in the modulation of isolated trabecular meshwork strips tonus, leading to their relaxation [25]. As ghrelin's hypotensive effect in our model seems to be associated with nitric oxide, the presence of GHSR-1 in the trabecular meshwork may suggest that this route may also be modulated by ghrelin.
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    Introduction Obesity is a global health concern due, in part, to changes in diet and lifestyle and is a major risk factor for a variety of clinical conditions including cardiovascular disease, type II diabetes, and metabolic syndrome (Mark, 2006). One hallmark of obesity is the dysregulation of the hypothalamic centers that control feeding behavior, energy expenditure, and the peripheral hormones that mediate the communication between the body and the Pirinixic Acid mg (Cai and Liu, 2011). Normally, neuronal populations in the hypothalamus regulate energy homeostasis by responding to circulating nutrients as well as appetite-regulating hormones such as leptin, insulin, and ghrelin (Gao and Horvath, 2007). The incidence of metabolic disorders associated with obesity exhibit clear sex differences with premenopausal women having fewer metabolic disorders than men. However, metabolic disorders increase dramatically in postmenopausal women (Ford, 2005, Loucks et al., 2007). The loss of the reproductive steroid 17β-estradiol (E2) is, in part, the major cause of these effects, especially on body weight gain (Rachoń and Teede, 2010, Stefanska et al., 2015). In ovariectomized rodent models, E2 regulates many aspects of energy homeostasis through both peripheral actions and central mechanisms (reviewed in Mauvais-Jarvis et al., 2013, Roepke, 2009, Shi et al., 2009). E2 suppresses feeding and fat accumulation and augments energy expenditure and activity. To control energy homeostasis, E2 primarily uses the nuclear steroid receptor, ERα, which is highly expressed in the hypothalamus (Roepke, 2009). Total body knockout of ERα or deletion in specific hypothalamic neurons produces an obese phenotype with hyperphagia, higher visceral adiposity, and lower activity and energy expenditure in mice (Geary et al., 2001, Heine et al., 2000, Mamounis et al., 2014, Musatov et al., 2007, Xu et al., 2011). Among the hypothalamic areas involved in energy homeostasis, the arcuate nucleus (ARC) is of special interest as it is an integration center for homeostatic signals from the periphery and the central nervous system (CNS). The “first order” ARC neurons central to the control of energy homeostasis are the proopiomelanocortin (POMC) and neuropeptide Y (NPY) neurons (Gao and Horvath, 2007). POMC and NPY neurons have opposing actions in the control of energy homeostasis. POMC neurons are anorexigenic primarily through the actions of α-melanocyte-stimulating hormone (α-MSH) via melanocortin receptors (MC3/4) expressed throughout the hypothalamus (Dietrich and Horvath, 2013). NPY neurons are orexigenic primarily through the actions of its neuropeptides, NPY and agouti-related peptide (AgRP), an antagonist for the MC4 receptors. Thus, the actions of POMC and NPY/AgRP neurons are important for the hypothalamic control of feeding and energy expenditure (Gao and Horvath, 2007).