Mechanisms of hypoxia in the hippocampal CA3 region in postoperative cognitive dysfunction after cardiopulmonary bypass

Abstract

Background Postoperative cognitive dysfunction (POCD) is a complication with high morbidity and mortality, commonly observed in the elderly who underwent anesthesia and surgery. The incidence is much higher in cardiac surgery. However, the reason and the mechanism of POCD remains unclear, but cerebral hypoxia is a common neurological complication after cardiac surgery. This study aims to investigate what role cerebral hypoxia plays in the pathogenesis of POCD. Methods The POCD model was established using cardiopulmonary bypass (CPB) surgery. Cognitive function was detected using Y maze and Morris water maze. The hypoxia in central nervous system was assessed using HE staining, western blot, and immunofluorescence. Inflammatory factors in hippocampus and plasma were detected by enzyme-linked immunosorbent assay. Evans blue was used to detect destruction of the blood brain barrier (BBB). Results Cognitive impairment markedly occurred to rats underwent 2-h CPB operation. Cerebral thrombosis and hypoxia occurred in the hippocampal CA3 region of rats after surgery. In addition, microglia in hippocampal was activated and the expression of inflammatory factors such as IL-1β, IL-6 and TNF-α was upregulated. Moreover, the permeability of BBB increased in rats after CPB. Conclusion Hypoxia in hippocampal CA3 region was involved in the occurrence and the mechanism may be associated with neuroinflammation and the damage of BBB.

The Effects of Transfusion on a Neurovascular Unit in an Experiment Using Its Cellular Model

“…The data we obtained correlate with the results of another experiment on rats, in which they studied the effect of cardiopulmonary bypass on them. As a result, they received a rapid increase in the concentration of inflammatory markers and impaired BBB permeability [24]. It is worth noting that in this study, the value of BBB permeability reached a minimum in 3 days after the bypass, but in our study, we measured TER only in the first 24 hours.…”

Effects of regional cerebral oxygen saturation monitoring on postoperative cognitive dysfunction in older patients: a systematic review and meta-analysis

“…It is generally accepted that advanced age, especially pre-existing cognitive impairment, is associated with a high incidence of POCD [37,38]. Episodes of cerebral ischemia and hypoxia have been regarded as the most closely related to POCD among distinct etiological factors [39][40][41]. Compared with younger patients, older patients are more predisposed to perioperative ischemia-induced brain injury, which is partly due to their reduced physiologic cerebrovascular reserve induced by atherosclerosis, hypertension, diabetes, smoking, etc.…”

Kardiyak Cerrahi Sonrası Postoperatif Bilişsel Fonksiyon Bozukluğu; Görülme sıklığı ve Risk Faktörleri

“…İntraoperatif arteriyel hipoksi, hiperoksi ve karbondioksit basıncı düzeyleri de POBB görülme sıklığını etkileyebilir. 36,37 Serebral kan akımı ve oksijen sunumunun yanı sıra, nörobilişsel işlevde serum glukoz düzeylerinin etkili olduğu da bilinmektedir. 38 Bir diğer çalışmada diyabetik olmayan hastalarda intraoperatif hipergliseminin (>200 mg/dL) kötüleşen postoperatif bilişsel işlev ile ilişkili olduğu bildirilmiştir.…”