OPIOID RECEPTOR INVOLVEMENT IN FOOD INTAKE AND BODY WEIGHT MAINTENANCE: ROLE OF THE MU-1 BINDING SITE.
Item
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Title
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OPIOID RECEPTOR INVOLVEMENT IN FOOD INTAKE AND BODY WEIGHT MAINTENANCE: ROLE OF THE MU-1 BINDING SITE.
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Identifier
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AAI8801734
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identifier
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8801734
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Creator
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MANN, PHYLLIS EDEN.
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Contributor
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Richard J. Bodnar
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Psychology, Psychobiology
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Abstract
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Opiate receptor agonists and antagonists influence feeding behavior. Agonists of each opioid receptor subtype increase feeding. By comparing naloxone, a short-acting opioid receptor antagonist with naloxonazine, an irreversible and highly-selective antagonist of the mu-1 binding site, it is possible to categorize opioid modulation into mu-1-mediated and non-mu-1-mediated actions. The mu-1 site has been implicated in the opioid component modulating free-feeding and deprivation-induced feeding but not glucoprivic feeding. This dissertation further categorizes different feeding models by examining naloxone and naloxonazine effects upon opioid-induced feeding and upon chronic body weight maintenance and food intake in adult, adolescent and dietary obese rats.;The role of the mu-1 binding site in opiate receptor agonist hyperphagia was examined first in adult male rats. Morphine (5 mg/kg, s.c.) hyperphagia was blocked by naloxone (10 mg/kg, s.c. or i.v.) but was potentiated by naloxonazine (10 mg/kg, i.v.). Only naloxone blocked ethylketocyclazocine (EKC) hyperphagia at 2 mg/kg (s.c.) whereas neither blocked EKC hyperphagia at 5 mg/kg. Dynorphin (10 ug, i.c.v.) and D-ala{dollar}\sp2{dollar}-D-leu{dollar}\sp5{dollar}-enkephalin (DADL; 10 ug, i.c.v.) hyperphagia was blocked by naloxone but was unaffected by naloxonazine.;The effects of daily administration of naloxone and naloxonazine in three types of maturational or dietary situations was examined next. In adult rats, naloxone and naloxonazine reduced body weight by 4% and 7%, respectively and food intake by 13% and 22%, respectively over 14 days. In adolescent rats, naloxone and naloxonazine reduced body weight gain by 33% and 53%, respectively and food intake by 14% and 27%, respectively over 14 days. In contrast, neither chronic naloxone nor naloxonazine treatment altered body weight or food intake of rats previously made obese by a "cafeteria" diet.;The use of naloxone and naloxonazine has shown that the mu-1 binding site may be implicated in free-feeding, deprivation-induced feeding and chronic food intake and body weight maintenance suggesting the involvement of the mu-1 site in "long-term" conditions. In contrast, glucoprivic feeding and opioid-induced feeding may be mediated by non-mu-1 binding sites suggesting that other opioid receptor subtypes may be involved in either "short-term" regulatory challenges or stimulatory conditions.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Psychology
