Rozisky JR, Dantas G, Adachi LS, Alves VS, Ferreira MBC, Sarkis JJF, Torres ILDS. Long-term effect of morphine administration in young rats on the analgesic opioid response in adult life.
Int J Dev Neurosci 2008;
26:561-5. [PMID:
18579332 DOI:
10.1016/j.ijdevneu.2008.05.005]
[Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 05/07/2008] [Accepted: 05/10/2008] [Indexed: 11/28/2022] Open
Abstract
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.
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