DEVELOPMENT OF ENDORPHINERGIC CONTROL OF FOOD INTAKE IN RATS.
Item
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Title
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DEVELOPMENT OF ENDORPHINERGIC CONTROL OF FOOD INTAKE IN RATS.
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Identifier
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AAI8222922
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identifier
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8222922
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Creator
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AROYEWUN, OLADIPUPO OLATOKUNBO.
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Contributor
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Gordon A. Barr
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Date
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1982
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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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The pure opiate antagonist, naloxone, has been found to reduce deprivation-induced feeding in adult animals. This effect presumably reflects the blockade of opiate receptors by naloxone and the attendant pertubation of activity in endogenous opioid systems involved in food consumption. The aims of these experiments were to determine the developmental age of inception as well as the pharmacological and behavioural mechanisms of naloxone's anorexigenic action. Towards this end, altricial infant rats were used as subjects. The experimental approach involved specifying a series of behavioural and pharmacological elements that would characterise naloxone's anoretic action independently of toxic or narcotic effects.;The major findings of this study are as follows: (1) Naloxone hydrochloride (5-30 mg/kg), or its structural congener naltrexone (10-50 mg/kg) given intraperitoneally to rats had no effect on the milk consumed by 3, 10 and 12 day olds. Naloxone attenuated food intake beginning 14 days postpartum and in a dose-related manner. (2) Naloxone had no effect on the latency of eating but hastened the early cessation of feeding in 14 day olds. (3) The relationship between the ontogeny of opiate receptors and feeding behaviour was examined by exposing developing rats to antenatal morphine. While no shift in the time-course occurred, a change in naloxone dose-response curves for feeding modulation was apparent in the 14 day-olds. (4) Morphine treatment during the first 5 days of postnatal life accelerated the functional maturation of the system supporting naloxone's effect. Rats were responsive to naloxone at 10, 12 and 14 days of age. (5) Chronic pretreatment with naltrexone potentiated naloxone's anorexigenic effect only at 14 days postpartum.;These findings suggest that naloxone, and, by inference, the endogenous opioid system, may not participate in the feeding of the young before their second week of birth; support the contention that naloxone's effects are mediated by the opiate-receptor mechanisms; and extend observations in adults to preweanling rats that endogenous opioid system may mediate feeding and appetite. The findings also suggest a 'satiety' mode of food-intake modulation for naloxone, and by inference, an 'anti-satiety' mode of food intake regulatory control for the endogenous opioid systems.
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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
