Aging differentially affects the loss of neuronal dendritic spine, neuroinflammation and memory impairment at rats after surgery.

Zhongcong Xie,Yuan Le,Qin Liao,Jianbin Tong,Chang Tan,Mingchao Peng,Shuli Liu,Wen Ouyang,Kaiming Duan

doi:10.1371/journal.pone.0106837

Zhongcong Xie, Yuan Le

Open Access

https://doi.org/10.1371/journal.pone.0106837

Copy DOI

Journal: PloS one	Publication Date: Sep 8, 2014
Citations: 51	License type: CC BY 4.0

Affiliation: Third Xiangya Hospital, Central South University

Abstract

It is known that age is an important factor for postoperative cognitive dysfunction (POCD) and the patients with POCD suffer from the impairment of multiple brain regions and multiple brain functions. However currently animal studies of POCD mainly focus on hippocampus region, therefore in this study we performed partial hepatectomy in young adult and aged rats to test the questions (1) whether POCD in animals involves other brain areas besides hippocampus; (2) how age influences POCD of young adult and aged animals. We found that (1) in young adult rats, the memory was not significantly affected (P>0.05) 1d, 3d and 7d after partial hepatectomy, but was significantly impaired (p<0.001) in aged rats 1d and 3d post-surgery; (2) in young adult rats, the surgery did not significantly affect the densities of dendritic spines of neurons at CA1, dentate gyrus (DG) and cingulate cortex (P>0.05, respectively) 1d and 3d post-surgery, but the spine densities at CA1 and DG of aged rats were significant reduced 1d and 3d post-surgery (p<0.001, respectively), however this didn’t happen at cingulate cortex (P>0.05); (3) In young adult rats, surgery didn’t affect the activation of microglia and levels of TNF-α and IL-1β at hippocampus (P>0.05), but significantly activated microglia and increased levels of TNF-α and IL-1β at hippocampus of aged rats (P<0.05). Our data suggest that (1) partial hepatectomy-induced POCD mainly involves hippocampus impairments, and (2) differential loss of neuronal dendritic spines and neuroinflammation at hippocampus are most likely the mechanism for the formation of POCD in aged rats.

Highlights

Postoperative cognitive dysfunction (POCD) is usually detected among aged patients after surgery, especially after critical illness [1,2,3]
Animal studies of POCD mainly focused on the changes of structures and functions of hippocampus induced by surgery, neglecting the fact of POCD that multiple brain regions and multiple brain functions are affected in patients
Hepatectomy differentially impaired the memory of young adult and aged rats The effects of surgery on the memory of rats were detected by Morris water maze

Summary

Introduction

Postoperative cognitive dysfunction (POCD) is usually detected among aged patients after surgery, especially after critical illness [1,2,3]. Risk factors of POCD include preoperative factors (such as age, cognitive function level, mental illness), perioperative factors (such as surgery type, duration of surgery, anesthesia type, intraoperative hypotension), and postoperative factors (such as postoperative infection, respiratory complications) [6,7,8,9]. Animal studies of POCD mainly focused on the changes of structures and functions of hippocampus induced by surgery, neglecting the fact of POCD that multiple brain regions and multiple brain functions are affected in patients It remains unclear (1) whether POCD in animals involves other brain areas besides hippocampus; (2) how age influences POCD of young adult and aged animals

Objectives

Methods

Results

Conclusion