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.
Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
E A
EA
Keller
L M
LM
Cancela
V A
VA
Molina
O A
OA
Orsingher
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