Role of leptin in modulation of corticotropin-releasing factor neurons in the brain of Xenopus laevis
Year: 2010
Type: dissertation
Abstract: Leptin is a hormone produced by adipocytes that signals to the brain energy stores and acts on hypothalamic feeding control centers to suppress appetite.An important anorexigenic pathway that may mediate leptin actions on feeding involves the stress neuropeptide corticotropin-releasing factor (CRF).CRF is the central mediator of stress responses, controlling the hypothalamic-pituitary-adrenal (HPA) axis.CRF also functions as a neurotransmitter/neuromodulator, influencing stress-related behaviors and feeding.Previous studies in mammals have suggested that leptin's actions on feeding may be mediated by CRF neurons.However, how leptin influences secretion and whether that influence is indirect or direct is unknown.We hypothesize that leptin directly acts on CRF neurons in the anterior preoptic area (POA), a brain region in the frog homologous to the mammalian paraventricular nucleus (PVN).To investigate this hypothesis, leptin's influences on CRF expression were tested and immunohistochemistry was performed to localize leptin receptor and CRF neurons using changes in pSTAT3 immunoreactivity as a proxy for leptin receptor in juvenile Xenopus laevis.Colocalization data obtained using fluorescent and confocal microscopy demonstrated that leptin receptor is expressed on CRF neurons in the POA.The effects of acute leptin injection were examined by injecting frogs with either leptin or saline and performing immunohistochemical analyses for changes in CRF-ir in the POA.A decrease in CRF-ir in parvocellular CRF neurons was observed.We hypothesize that this is due to a leptin-induced secretion of CRF to further modulate feeding.
Author: Choi Li
Language: English
Subfield: Endocrine and Autonomic Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W629252706