The effects of different sevoflurane applications in early and late neonatal periods of rats on learning and memory in preadolescent period

Aim: The aim of this study; to investigate the effects of sevoflurane administration in early and late neonatal periods on neurotoxicity, learning and memory in preadolescence. Methods: 75 newborn male Wistar rats were included in the study and randomized into 5 groups. 2.6% sevoflurane+O2; the group that received once sevoflurane on postnatal 7th day (S1), the group that received repeated doses of sevoflurane on postnatal 7th, 8th and 9th days (S2), the group that received sevoflurane once on postnatal 21st day (S3), the group that received repeated doses of sevoflurane on postnatal 21st, 22nd, 23rd days (S4). On the other hand, only 50% O2 was administered to the Sham group (control group of the study) on the postnatal 7th day. Morris water tank (MST) tests were started on the postnatal 45th day in all groups. Probe trial and then open field tests were performed on the postnatal 50th day. Long Term Potentiation (LTP) records were taken under anesthesia on the postnatal 52nd day and decapitated under anesthesia. Results: In behavioral experiments performed on newborn rats after a single and repeated administration of sevoflurane in the early and late periods, Morris water tank and open field tests, significant differences were found between the groups. In MST tests, it was found that rats in the S1 and S3 groups spent longer time in the target quadrant compared to the Sham group, and the time spent in the target quadrant of the S2 group exposed to repeated anesthesia was shorter than the S1 group. In the open field tests, it was found that the number of squares entered decreased only in the S2 group compared to the Sham group. When the change in LTP recordings compared to the values taken in the baseline recording was examined, the change in EPSP slopes of the S2 (104.37±1.10) and S4 (109.86±4.10) groups decreased significantly compared to the sham (137.39±7.80) group and it was found that there was a significant decrease in PS amplitude in the S2 (108.88±3.85) group compared to the sham (144.68±11.16) group. Conclusion: When learning and memory tests were evaluated; In this study we performed in newborn rats, it was observed that the administration of sevoflurane at a concentration of 2.6% for 2 hours in the early period of the newborn and at repeated doses was neurotoxic and caused learning memory dysfunction. Key Words: Sevoflurane, LTP, Learning, Memory, Rat