NEONATAL MONOSODIUM GLUTAMATE: BEHAVIORAL CHARACTERIZATION OF NOCICEPTIVE AND STRESS RESPONSE ALTERATIONS IN THE RAT.
Item
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Title
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NEONATAL MONOSODIUM GLUTAMATE: BEHAVIORAL CHARACTERIZATION OF NOCICEPTIVE AND STRESS RESPONSE ALTERATIONS IN THE RAT.
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Identifier
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AAI8409379
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identifier
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8409379
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Creator
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BADILLO DE MARTINEZ, DIANA.
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Contributor
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Richard Bodnar
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Date
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1984
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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, Physiological
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Abstract
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Neonatal administration of monosodium glutamate (MSG) produces in rats neurotoxic degeneration of the medial basal hypothalamus (MBH), particularly the arcuate nucleus and median eminence and depletes these structures of neuropeptides and neurotransmitters. This treatment produces multiple neuroendocrine and behavioral disturbances, including attenuations in cold water swim (CWS) and morphine analgesia. The first experiment examined whether MSG-induced alterations in stress analgesia were accompanied by alterations in other stress responses. MSG rats showed attenuated analgesia and hypothermia following CWS, potentiated 2-DG analgesia and reduced 2-DG hyperphagia. Locomotor activity changes failed to account for response differences following either manipulation. Therefore, it appears that MSG treatment alters a number of stress responses and that interpretation of the analgesic alterations in terms of a specific role for the circumventricular system in certain pain-inhibitory systems should be considered in light of the multi-faceted effects of MSG. Since MSG treatment destroys beta-endorphin cells, but increases opiate receptors and reduces morphine analgesia on the jump test, but increases morphine analgesia on the hot-plate, the second experiment assessed the test-specific effects of MSG upon morphine analgesic and locomotor dose-response curves as well as changes in analgesia, thermoregulation and body weight following chronic morphine treatment. Test-specific and gender-specific effects were observed in MSG-treated rats following actue morphine injections. While male MSG animals showed lowered morphine analgesia on the jump test and increased analgesia on the hot-plate test, the MSG females displayed potentiated analgesia on both tests following high morphine dose, but attenuated hot-plate analgesia following a low dose. Moreover, HMSG treatment altered morphine tolerance more on the jump test, than on the hot-plate test. MSG also disrupted other morphine coping behaviors since decreased hyperthermia and increased weight loss accompanied the alterations in analgesia in MSG-treated rats. The third experiment assessed the relationship between early MSG-induced endocrine imbalances and the development of nociceptive thresholds. Nociceptive thresholds, body weight and lengths were measured at various critical ages. MSG-treated rats were shorter, weighed more and after sexual maturity, their nociceptive thresholds were test-specifically altered. Long standing MSG-induced hormonal changes are suggested to influence these basal nociceptive effects.
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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
