Objective To study the effects of blood-derived monocytes on postoperative cognitive function in cardiopulmonary bypass (CPB) rats.
Methods Thirty-two SPF-grade healthy adult SD male rats, aged 2 months, weighing 350-400 g, were randomly divided into 4 groups: sham operation group+physiological saline (group S), CPB+physiological saline group (group CPB), CPB+PBS liposome group (group CPBP), CPB+disodium chlorophosphate liposome group (group CPBL), 8 rats in each group. The same amount of saline or liposomes were injected into the tail vein of rats in these four groups 48 and 24 hours before operation, respectively. Preoperative water maze experiments were performed 4 times in one day for 5 consecutive days and on the 7th day after operation, and behavioral changes of rats were observed by water maze test. Hippocampus of the rats was taken out after behavioral experiments. Flow cytometry was used to detect the percentage of monocytes in peripheral blood two minutes before administration. ELISA method was used to detect the concentration of peripheral blood brain injury marker S100β and NSE. Real-time quantitative PCR was conducted to detect the expression of cytokine genes such as interleukin-1β (IL-1β), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), and transforming growth factor-β (TGF-β) in hippocampus and the expression of inducible nitric oxide synthase (iNOS). The amount of protein expression of iNOS was further detected by western blot.
Results Compared with group S, the average latent period of rats in groups CPB, CPBP, and CPBL was prolonged, and the number of crossing platforms in these three groups was significantly reduced (P < 0.05). Compared with group S, the concentration levels of S100β and NSE in groups CPB, CPBP, and CPBL were significantly increased, the amount of expression of inflammatory factors IL-1β, IL-10, TNF-α and TGF-β in the hippocampus were significantly increased, and the amount of gene and protein expression of iNOS was increased (P < 0.05). Compared with group CPB, the average latent period in group CPBL was prolonged, the number of crossing the platform was significantly reduced, the number of monacytes in peripheral blood was significantly reduced, the serum concentration level of S100β was significantly increased, the amount of expression in the hippocampus of IL-1β and TNF-α was significantly increased, the amount of expression of IL-10 was significantly reduced, and iNOS gene and protein expression was significantly increased (P < 0.05). Compared with group CPBP, the average latent period in group CPBL was significantly prolonged, the number of crossing the platform was significantly reduced, the number of monocytes in peripheral blood was significantly reduced, the serum concentration level of S100β was significantly increased, the amount of expression in the hippocampus of IL-1β and TNF-α was significantly increased, the amount of expression of IL-10 was significantly reduced, and iNOS gene and protein expression was significantly increased (P < 0.05).
Conclusion The clearance of blood derived monocyte can aggravate the systemic inflammatory response, the activation of M1-type microglia in hippocampus and cognitive dysfunction of rats after CPB. Blood derived monocyte plays an important role in repairing and maintaining cognitive function after injury. |
