Estradiol Increases Fenfluramine-Induced Anorexia

The ovarian hormone estradiol plays an important role in the control of food intake in the female rat. For example, ovariectomized (OVX) rats display hyperphagia and excessive weight gain in the absence of estradiol replacement and ovarian-intact rats display an estrous-related decrease in food inta...

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Other Authors: Rivera, Heidi M. (authoraut)
Format: Others
Language:English
English
Published: Florida State University
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Online Access:http://purl.flvc.org/fsu/fd/FSU_migr_etd-1858
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spelling ndltd-fsu.edu-oai-fsu.digital.flvc.org-fsu_1763302020-06-05T03:08:37Z Estradiol Increases Fenfluramine-Induced Anorexia Rivera, Heidi M. (authoraut) Eckel, Lisa (professor directing thesis) Overton, Michael (committee member) Contreras, Robert (committee member) Licht, Barbara (committee member) Department of Psychology (degree granting department) Florida State University (degree granting institution) Text text Florida State University Florida State University English eng 1 online resource computer application/pdf The ovarian hormone estradiol plays an important role in the control of food intake in the female rat. For example, ovariectomized (OVX) rats display hyperphagia and excessive weight gain in the absence of estradiol replacement and ovarian-intact rats display an estrous-related decrease in food intake. Estradiol's ability to decrease food intake appears to be indirect. Several groups have demonstrated that estradiol increases the hypophagic effect of cholecystokinin (CCK), a gut peptide implicated in the physiological control of meal size. Because the involvement of CCK cannot entirely account for the hypophagic effect of estradiol, other peptide or neurotransmitter systems may participate in the estrogenic control of food intake. The goal of this thesis was to investigate the hypothesis that estradiol may interact with the serotonin (5-HT) system to inhibit food intake in the female rat. In two studies, food intake was monitored in male and female rats (Study 1), and in OVX rats with and without estradiol replacement (Study 2), following acute administration of fenfluramine (FEN), a serotonin (5-HT) receptor agonist that has been used extensively to investigate the contribution of endogenous 5-HT to the control of food intake. Study 1 demonstrated that FEN-induced anorexia was sexually dimorphic and varied across the estrous cycle. Both the magnitude and duration of FEN-induced anorexia was greater in female rats, relative to male rats. The magnitude of FEN-induced anorexia was also greater in estrous rats, relative to diestrous rats. Thus, FEN-induced anorexia appears to be modulated by gonadal hormone status. These effects may be mediated by estradiol since female rats have higher levels of estradiol than male rats and because estradiol secretion is increased prior to estrus. Study 2 was designed as a direct test of this hypothesis. The results of Study 2 demonstrated that FEN-induced anorexia was greater in estradiol-treated OVX rats, relative to oil-treated OVX rats. Thus, FEN-induced anorexia is modulated by estradiol treatment in OVX rats. Together, my findings indicate that both endogenous and exogenous estradiol increases FEN-induced anorexia. Because FEN increases 5-HT neurotransmission, my data suggest that estradiol interacts with the 5-HT system to decrease meal size in female rats. A Thesis Submitted to the Department of Psychology in Partial Fulfillment of the Requirements for the Degree of Master of Science. Spring Semester, 2006. February 10, 2006. Feeding Behavior, Fenfluramine, Serotonin, Estrogen Includes bibliographical references. Lisa Eckel, Professor Directing Thesis; Michael Overton, Committee Member; Robert Contreras, Committee Member; Barbara Licht, Committee Member. Psychology FSU_migr_etd-1858 http://purl.flvc.org/fsu/fd/FSU_migr_etd-1858 This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. http://diginole.lib.fsu.edu/islandora/object/fsu%3A176330/datastream/TN/view/Estradiol%20Increases%20Fenfluramine-Induced%20Anorexia.jpg
collection NDLTD
language English
English
format Others
sources NDLTD
topic Psychology
spellingShingle Psychology
Estradiol Increases Fenfluramine-Induced Anorexia
description The ovarian hormone estradiol plays an important role in the control of food intake in the female rat. For example, ovariectomized (OVX) rats display hyperphagia and excessive weight gain in the absence of estradiol replacement and ovarian-intact rats display an estrous-related decrease in food intake. Estradiol's ability to decrease food intake appears to be indirect. Several groups have demonstrated that estradiol increases the hypophagic effect of cholecystokinin (CCK), a gut peptide implicated in the physiological control of meal size. Because the involvement of CCK cannot entirely account for the hypophagic effect of estradiol, other peptide or neurotransmitter systems may participate in the estrogenic control of food intake. The goal of this thesis was to investigate the hypothesis that estradiol may interact with the serotonin (5-HT) system to inhibit food intake in the female rat. In two studies, food intake was monitored in male and female rats (Study 1), and in OVX rats with and without estradiol replacement (Study 2), following acute administration of fenfluramine (FEN), a serotonin (5-HT) receptor agonist that has been used extensively to investigate the contribution of endogenous 5-HT to the control of food intake. Study 1 demonstrated that FEN-induced anorexia was sexually dimorphic and varied across the estrous cycle. Both the magnitude and duration of FEN-induced anorexia was greater in female rats, relative to male rats. The magnitude of FEN-induced anorexia was also greater in estrous rats, relative to diestrous rats. Thus, FEN-induced anorexia appears to be modulated by gonadal hormone status. These effects may be mediated by estradiol since female rats have higher levels of estradiol than male rats and because estradiol secretion is increased prior to estrus. Study 2 was designed as a direct test of this hypothesis. The results of Study 2 demonstrated that FEN-induced anorexia was greater in estradiol-treated OVX rats, relative to oil-treated OVX rats. Thus, FEN-induced anorexia is modulated by estradiol treatment in OVX rats. Together, my findings indicate that both endogenous and exogenous estradiol increases FEN-induced anorexia. Because FEN increases 5-HT neurotransmission, my data suggest that estradiol interacts with the 5-HT system to decrease meal size in female rats. === A Thesis Submitted to the Department of Psychology in Partial Fulfillment of the Requirements for the Degree of Master of Science. === Spring Semester, 2006. === February 10, 2006. === Feeding Behavior, Fenfluramine, Serotonin, Estrogen === Includes bibliographical references. === Lisa Eckel, Professor Directing Thesis; Michael Overton, Committee Member; Robert Contreras, Committee Member; Barbara Licht, Committee Member.
author2 Rivera, Heidi M. (authoraut)
author_facet Rivera, Heidi M. (authoraut)
title Estradiol Increases Fenfluramine-Induced Anorexia
title_short Estradiol Increases Fenfluramine-Induced Anorexia
title_full Estradiol Increases Fenfluramine-Induced Anorexia
title_fullStr Estradiol Increases Fenfluramine-Induced Anorexia
title_full_unstemmed Estradiol Increases Fenfluramine-Induced Anorexia
title_sort estradiol increases fenfluramine-induced anorexia
publisher Florida State University
url http://purl.flvc.org/fsu/fd/FSU_migr_etd-1858
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