Long-term effect of morphine administration in young rats on the analgesic opioid response in adult life.
Neonates, infants and children are often exposed to pain from invasive procedures during intensive care and during the post-operative period. Opioid anesthesia and post-operative opioid analgesia have been used in infants and result in clinical benefits. The objectives of this study were to verify the effect of repeated 5 microg morphine administration (subcutaneous), once a day for 7 days in 8-day-old rats, at P8 until P14. To verify the long-term effect of morphine, the animals were submitted to a second exposure of 5mg/kg (intraperitoneal) of morphine at P80 until P86. Animals that received morphine for 7 days, at P14 did not develop tolerance, however at P80, rats demonstrated greater morphine analgesia. At P86, after 7 days of morphine administration, animals showed classical tolerance. These findings may have important implications for the human neonate, suggesting a possible explanation for the differences in the requirements of morphine observed in the youngest patients.
Rozisky
Joanna Ripoll
JR
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, 90050-170 Porto Alegre, RS, Brazil.
Dantas
Giovana
G
Adachi
Lauren Spezia
LS
Alves
Viviane Soares
VS
Ferreira
Maria Beatriz Cardoso
MB
Sarkis
João José Freitas
JJ
Torres
Iraci Lucena Da Silva
IL
D000367:Age Factors; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000187:drug effects; D004334:Drug Administration Schedule; D004361:Drug Tolerance / Q000502:physiology; D008297:Male; D009020:Morphine / Q000008:administration & dosage*; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D000701:Analgesics, Opioid; D009020:Morphine