We tested the hypothesis that the effects of traumatic brain injury, surgery and sevoflurane interact to induce neurobehavioral abnormalities in adult male rats and/or in their offspring (an animal model of intergenerational perioperative neurocognitive disorder).
Sprague-Dawley male rats (F0 generation) underwent a traumatic brain injury on postnatal day 60 that involved craniectomy (surgery) under 3% sevoflurane for 40 min followed by 2.1% sevoflurane for 3 h on postnatal days 62, 64, and 66 (injury group). The surgery group had craniectomy without traumatic brain injury, whereas the sevoflurane group had sevoflurane only. On postnatal day 90, F0 males and control females were mated to generate offspring (F1 generation).
Acutely, F0 injury rats exhibited the greatest increases in serum corticosterone and interleukins 1β and 6, and activation of the hippocampal microglia. Long term, compared to controls, F0 injury rats had the most exacerbated corticosterone levels at rest (2.21 ± 0.64 vs. 7.28 ± 1.95 ng/ml, n = 8 – 7; P < 0.001) and 10 min after restraint (133.12 ± 33.98 vs. 232.83 ± 40.71 ng/ml, n =8 – 7; P < 0.001), increased interleukins 1β and 6, and reduced expression of hippocampal glucocorticoid receptor (Nr3c1) (0.53 ± 0.08 fold change relative to control, P < 0.001, n = 6) and brain-derived neurotrophic factor genes. They also exhibited greater behavioral deficiencies. Similar abnormalities were evident in their male offspring, whereas F1 females were not affected. The reduced Nr3c1 expression in F1 male, but not female, hippocampus was accompanied by corresponding Nr3c1 promoter hypermethylated CpG sites in F0 spermatozoa and F1 male, but not female, hippocampus.
These findings in rats suggest that young adult males with traumatic brain injury are at an increased risk of developing perioperative neurocognitive disorder, as are their unexposed male but not female offspring.