Perinatal Supplemental OMEGA-3 Polyunsaturated Fatty Acids Improves Sevoflurane-induced Neurodegeneration And Memory Impairment In Neonatal Rats

Animal studies suggest that neonatal exposure to volatile anesthetics including sevoflurane may cause neuronal apoptosis, impairment of proliferation and differentiation in the developing brain, which leads to functional deficits. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) highly enriched in brain are a family of unsaturated fatty acids that are essential for the anatomical and functional integrity of the brain. Many studies have demonstrated that n-3 PUFAs have anti-apoptotic, anti-oxidant, neurogenesis improvement properties. In this study, we investigated 1) if sevoflurane has significant neurotoxicity in developing brain; 2) if perinatal n-3 PUFAs supplement can improve sevoflurane-induced neurotoxicity and cognitive impairment in neonatal rats.Female Sprague-dawley rats (n=3 each group) were treated with or without an n-3 PUFAs (fish oil) enriched diet from the second day of pregnancy to 7 days after parturition. The offspring rats (P7) were treated with six hours sevoflurane administration (one group without sevoflurane/prenatal n-3 PUFAs supplement as control). The 5-bromodeoxyuridine (Brdu) was injected intraperitoneally during and after sevoflurane anesthesia to assess dentate gyrus (DG) progenitor proliferation. The brain tissues were harvested and fixed at indicated time points. Rats in each group were euthanized 3h (n=3) after anesthesia. Brain tissues were harvested and subjected to Flow cytometric method to detect the reactive oxygen species relative level. And 18h (n=3) after anesthesia, brain tissues of rats in each group were tested the change of cleaved caspase-3 through Western blot and immunohistochemistry respectively. Three days after anesthesia, we observed the BrdU in each group. Morris water maze spatial reference memory, fear conditioning, Morris water maze memory consolidation were tested at P35, P63 and P70 (n=9), respectively.Six hours 3% sevoflurane administration increased the cleaved caspase-3 in the thalamus, parietal cortex but not hippocampus of neonatal rat brain, assessed by immunofluorescence microscopy. What’s more, we found sevoflurane can induce more reactive oxygen species (ROS) in cortex. Sevoflurane anesthesia also decreased the neuronal precursor proliferation of DG in rat hippocampus. However, perinatal n-3 PUFAs supplement could decrease the cleaved caspase-3 and ROS in the cerebral cortex of neonatal rats, assessed by immunoblotting, and mitigate the decrease in neuronal proliferation in their hippocampus. In neurobehavioral studies, compared with control and n-3 PUFAs supplement groups, we did not find significant spatial cognitive deficit and early long-term memory impairment in sevoflurane anesthetized neonatal ones at their adulthood. However, sevoflurane could impair the immediate fear response and working memory and short-term memory. And n-3 PUFAs could improve neurocognitive function in later life after neonatal sevoflurane exposure.Our study demonstrated that neonatal exposure to prolong sevoflurane could impair the immediate fear response, working memory and short-term memory of rat at their adulthood, which may through inducing neuronal oxidation, apoptosis and decreasing neurogenesis. However, these sevoflurane-induced unfavorable neuronal effects can be mitigated by perinatal n-3 PUFAs supplement.