Effects of different ratios of medicine dosage for isoflurane and propofol on postoperative cognitive function of rats with mild cognitive impairment

Abstract

Objective To evaluate the effects of different ratios of medicine dosage for isoflurane and propofol on postoperative cognitive function of rats with mild cognitive impairment (MCI). Methods Healthy male Wistar rats, aged 16-18 months, were used in the study.MCI model was established by occlusion of bilateral common carotid arteries.One hundred and fifty rats with MCI were divided into 5 groups (n=30 each) using a random number table: sham operation group (group S), isoflurane group (group I), propofol group (group P) and different ratios of medicine dosage for isoflurane and propofol groups (IP1, 2 groups). The rats inhaled 1.9% isoflurane for 3 h in group I. Propofol 40 mg·kg-1·h-1 was infused intravenously for 3 h in group P. The rats inhaled 1.0% isoflurane, and propofol 20 mg·kg-1·h-1 was infused intravenously for 3 h in group IP1.The rats inhaled 1.4% isoflurane, and propofol 10 mg·kg-1·h-1 was infused intravenously for 3 h in group IP2.After disappearance of eyelash reflex, open reduction and internal fixation was performed after tibial fracture was induced.On 7 days after operation, contextual fear conditioning test and Y maze test were used to assess the cognitive function, and hippocampal tissues were obtained to count the viable neurons (using Nissl′s staining) and CCAAT/enhancer-binding protein homologous protein (CHOP) and caspase-12 positive neurons (by immunofluorescence) in hippocampal CA1 region. Results Compared with group S, the rate of time spent in N arm, the rate of time spent freezing, and the number of viable neurons were significantly decreased, and the number of CHOP and caspase-12 positive neurons were significantly increased in IP2, I and P groups (P 0.05). Compared with group IP1, the rate of time spent in N arm, the rate of time spent freezing, and the number of viable neurons were significantly decreased, and the number of CHOP and caspase-12 positive neurons was significantly increased in IP2, I and P groups (P<0.05). Compared with group IP2, the rate of time spent in N arm, the rate of time spent freezing, and the number of viable neurons were significantly decreased, and the number of CHOP and caspase-12 positive neurons was significantly increased in I and P groups (P<0.05). Conclusion Combination of 1.0% isoflurane and propofol 20 mg·kg-1·h-1 does not aggravate the postoperative cognitive dysfunction of the rats with MCI. Key words: Propofol; Isoflurane; Cognition disorders; Postoperative complications