Lack of adaptive changes in 5-HT sites in perinatally undernourished rats after chronic stress: opioid influence.
The reactivity of 5-HT receptors following repeated immobilization sessions or after immobilization plus morphine was measured through 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) or 8-hydroxy-2-(dipropyl-amino)tetralin (8-OH-DPAT)-induced serotonergic syndrome in adult rats undernourished at perinatal age. Repeated stress enhanced the scores of forepaw treading and hindlimb abduction elicited by 5-MeODMT in control animals. In a similar way, forepaw treading induced by 8-OH-DPAT was enhanced in chronically stressed control rats. These results indicate the development of supersensitivity in 5-HT1 receptors. Conversely, this effect was not observed in undernourished animals. Morphine injections before each stress session instaured the increased reactivity to 5-HT1 sites in malnourished animals. An injection of naloxone prior to morphine before each stress session fully antagonized the increased behavioral reactivity to 5-MeODMT observed in deprived animals. A possible deficiency in the functional role of the opiate system involved in the process of adaptation to chronic stress in early undernourished rats is suggested.
Keller
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EA
Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
Cancela
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LM
Molina
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VA
Orsingher
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OA
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000222:Adaptation, Physiological; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D004044:Dietary Proteins / Q000008:administration & dosage; D004723:Endorphins / Q000502:physiology*; D005260:Female; D007103:Immobilization / Q000009:adverse effects / Q000502:physiology; D008732:Methoxydimethyltryptamines / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009748:Nutrition Disorders / Q000378:metabolism*; D051381:Rats; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism*; D013312:Stress, Physiological / Q000378:metabolism
D004044:Dietary Proteins; D004723:Endorphins; D008732:Methoxydimethyltryptamines; D011985:Receptors, Serotonin; D009270:Naloxone; D009020:Morphine; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin