Ulinastatin attenuates isoflurane-induced cognitive dysfunction in aged rats by inhibiting neuroinflammation and β-amyloid peptide expression in the brain

ABSTRACT

Objective: Postoperative neurocognitive disease (PNCD) in the aged is a major clinical problem with unclear mechanisms. This study was designed to explore the mechanisms for ulinastatin (UTI) to attenuate isoflurane-induced cognitive decline in Fischer-344 rats.

Methods: The rats were divided into four groups: Control (0.9% saline only), Isoflurane (exposure to 1.2% isoflurane), Isoflurane-plus-UTI (exposure to 1.2% isoflurane followed by 100,000 U/kg UTI injection i.v.) and UTI-plus-isoflurane (i.v. of 100,000 U/kg UTI followed by 1.2% isoflurane exposure). After respective tests, the concentrations of tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the brain were determined by ELISA the expression of β-amyloid peptide (Aβ) and cleaved caspase-3 were measured by Western blot. Ratio of apoptotic cells after Barnes maze challenge was assessed by TUNEL assay.

Results: In both Barnes Maze training and challenge, results indicated isoflurane-impaired learning capacity, while pre-and post-treatment with UTI could attenuate this phenomenon. The ratio of apoptotic cells and the expression of cleaved caspase-3 were increased after isoflurane exposure, indicating that isoflurane could induce neuronal apoptosis, while both pre- and post-treatment with UTI could diminish these effects. Moreover, UTI inhibited the expression of TNF-α, IL-1β and Aβ induced by isoflurane in rat brain harvested at 16 h after isoflurane exposure.

Conclusion: These results suggest that UTI inhibits neuronal apoptosis in rat brain by attenuating increased expression of Aβ₄₂ and inflammatory cytokines, which may contribute to its alleviation of isoflurane-induced cognitive dysfunction in rats. Moreover, UTI pre-treatment before isoflurane exposure showed more effective than post-treatment.

KEYWORDS:

• Ulinastatin
• postoperative neurocognitive disease
• isoflurane
• β-amyloid peptide
• inflammatory cytokine

Acknowledgments

This study was supported by grants from the National Science Foundation of China under grant number (81201022); Techpool Research Foundation under grant number (UF201306); National Science Foundation of Guangdong Province under grant number (2018A0303130195) and Guangzhou Science Technology and Innovation Commission under grant number (201704020222).

Author's Contribution

M. Guo and X. Zhu carried out and analysed all data presented in this manuscript. Both authors contributed equally. H. Xu, S. Yang were involved in setting up and carrying out animal experiments; J. Li analysed all data regarding neuroinflammatory pathways; D. Lin designed and oversee the whole project. Z. Zuo reviewed and revised the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Guangzhou Science, Technology and Innovation Commission [201704020222]; National Natural Science Foundation of Guangdong, China [2018A0303130195];The National Science Foundation of China [81201022];Techpool Research Fund [UF201306].

Notes on contributors

Mingyan Guo

Mingyan Guo is an anaesthesiologist at Sun Yat-sen Memorial Hospital, Sun Yat-sen University. His main research focus is on the post-operative cognitive dysfunction under the supervision of Zhiyi Zuo.

Xiaoqiu Zhu

Xiaoqiu Zhu studied medicine at Sun Yat-sen Memorial Hospital, Sun Yat-sen University. He performed animals’ experiment under the supervision of Daowei Lin.

Hui Xu

Hui Xu is an anaesthesiologist at Sun Yat-sen Memorial Hospital, Sun Yat-sen University. His main contribution in this manuscript is to carry out animal experiments.

Shangze Yang

Shangze Yang is an anaesthesiologist at The Eighth Affiliated Hospital, Sun Yat-sen University. He was involved in the planning and executing of all animal experiments.

Zhiyi Zuo

Zhiyi Zuo is the Robert M. Epstein Professor of Anaesthesiology at University of Virginia. He is a neuroanesthesiologist in neuroscience involving using cell cultures and animals.

Daowei Lin

Jin Li is an anaesthesiologist at Sun Yat-sen Memorial Hospital, Sun Yat-sen University. Her main research focus is on neuroinflammation research. She helped in analysing inflammatory-related data in this manuscript.

Daowei Lin is an anaesthesiologist and professor of Sun Yat-sen Memorial Hospital, Sun Yat-sen University. He mainly focused on post-operative cognitive dysfunction using cell cultures and animals.