One-time Exposure to General Anesthetics Alters Nociceptive Response and Nucleotide Hydrolysis in Infant Rats

Abstract

Aims: The objective was to evaluate the single exposure of general anesthetics with or without a surgical procedure at postnatal day 14 (P14) on nociceptive behavioral responses. Furthermore, we evaluated ectonucleotidase activities at P14 and P30. Place of Study: All experiments were performed at the Animal Experimentation Unit of Hospital de Clínicas de Porto Alegre. The Institutional Committee approved the experimental protocol f (GPPG-HCPA protocol No: 08149). Methodology: Fourteen-day-old male Wistar rats were divided into two experimental designs (ED): the 1stED – control (C), isoflurane (ISO), isoflurane/surgery (ISO-SUR) and the 2nd ED – control (C), fentanyl/S(+)-ketamine (FK) and fentanyl/S(+)-ketamine/surgery (FK-SUR). Nociceptive responses were evaluated using the formalin and tail-flick tests, and the ectonucleotidase activities were evaluated by spinal cord synaptosome. All assessments were performed at P14 and P30. Results: The FK and FK-SUR groups displayed an increased latency at P30. For the ectonucleotidase activity analysis, the following results were observed: (a) in the 1st ED, the ISO group displayed a reduction in ATPase and ADPase, and both ISO and ISO-SUR displayed a reduction in AMPase activity at P14; (b) in the 2nd ED, the FK group displayed an increase in AMPase activity at P14 and increased ATPase activity at P30, and both FK and FK-SUR exhibited an increase in AMPase activity at P30. Conclusion: Our results indicate that single administration of general anesthetics at P14 is able to promote changes in the nociceptive response in the intermediate-term, and in the ectonucleotidase activities in the short- and medium-terms.