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Title: Elucidating the principal role of cholecystokinin neurons of the ventromedial hypothalamic nucleus in energy homeostasis
Author: Eftychidis, Vasileios
ISNI:       0000 0004 7232 4290
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2017
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The central nervous system (CNS) has a crucial role in the maintenance of energy homeostasis by orchestrating a plethora of signals from peripheral organs about the state of energy stores and the current energy intake needed to match energy expenditure. These signals converge into the hypothalamic regions and its complex local circuitry. CNS-derived cholecystokinin (CCK) is acting at central level to modulate energy balance by regulating the neuronal activity of hypothalamic neuronal populations that regulate food intake, energy storage and consumption. Moreover, our recent published work identifies CCK neurons as key integrators of the neuroendocrine negative feedback of glucocorticoids to the PVN. Glucose sensing neurons of the Ventromedial Hypothalamus (VMH) are integrating energy signals and are essential for mounting a counter-regulatory response and glucose homeostasis. VMH is also important in energy expenditure by regulating body weight and thermogenesis. CCK neurons are present in high density in the VMH.The source of endogenous CCK that acts on distinct neuronal components has not been elucidated. The research so far does not address the purpose of CCK neurons in the hypothalamus and their potential role in the network dynamics regarding energy homeostasis. In this study, we untangle the role of CCK neurons in the VMH nucleus by employing stereotactic intracranial delivery of adeno-associated viruses that result in cell-type specific chemogenetic inhibition or ablation of these neurons. Acute silencing of their neurotransmission with the cre-dependent AAV expression of the chemogenetic tool of Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) increases their daily food intake due to increased meal numbers and eating frequency without meal size or meal duration being affected. CCK ablation by a newly generated double-recombinase-mediated Diphtheria Toxin Receptor (DTR) mouse line or AAV-DTA-mediated ablation resulted in hyperphagia, obesity and hyperglycaemia. We conclude that CCKVMH neurons are implicated in the regulation of food intake, body weight and glucose homeostasis in the adult brain.
Supervisor: Minichiello, Liliana Sponsor: Medical Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Neuroscience ; hypothalamus ; cholecystokinin ; obesity ; hyperglycemia ; appetite ; glucose