Propofol-induced age-different hypocampal long-term potentiation is associated with F-actin polymerization in rats

Elderly patients may experience a decline in cognition after a surgery performed under anesthesia. Propofol (2,6-diisopropylphenol), a common intravenous anesthetic agent, has been reported to mediate the long-term potentiation (LTP), a major form of synaptic plasticity. The present study was conducted to investigate the underlying mechanisms in young (3-month-old) and elderly (20-month-old) male rats. A decline of theta-burst stimulation (TBS)-induced LTP in the hippocampal CA1 area was found in the young rats at 72 h post-anesthesia, and this alteration almost disappeared after 2-week-recovery as compared with their age-matched control rats. On the other hand, the propofol-induced CA1 LTP reduction was persistent in the aged rats during the whole experimental process. Moreover, TBS-induced increases in CA 1 filamentous-actin (F-actin) polymerization and phospho-cofilin expression were enhanced at 72 h post-anesthesia in young rats, and this change was significantly attenuated after 2 weeks. However, in anesthetic elderly rats, the alterations in F-actin and phospho-cofilin of the CA1 region were still presented at the end of the experiments. Taken together, our results indicate that the discrepant responses between young and aged rats to propofol anesthesia may be associated with the differential polymerization of F-actin.

General anesthetic and the risk of dementia in elderly patients: current insights

In this review, we aim to provide clinical insights into the relationship between surgery, general anesthesia (GA), and dementia, particularly Alzheimer’s disease (AD). The pathogenesis of AD is complex, involving specific disease-linked proteins (amyloid-beta [Aβ] and tau), inflammation, and neurotransmitter dysregulation. Many points in this complex pathogenesis can potentially be influenced by both surgery and anesthetics. It has been demonstrated in some in vitro, animal, and human studies that some anesthetics are associated with increased aggregation and oligomerization of Aβ peptide and enhanced accumulation and hyperphosphorylation of tau protein. Two neurocognitive syndromes that have been studied in relation to surgery and anesthesia are postoperative delirium and postoperative cognitive dysfunction, both of which occur more commonly in older adults after surgery and anesthesia. Neither the route of anesthesia nor the type of anesthetic appears to be significantly associated with the development of postoperative delirium or postoperative cognitive dysfunction. A meta-analysis of case-control studies found no association between prior exposure to surgery utilizing GA and incident AD (pooled odds ratio =1.05, P=0.43). The few cohort studies on this topic have shown varying associations between surgery, GA, and AD, with one showing an increased risk, and another demonstrating a decreased risk. A recent randomized trial has shown that patients who received sevoflurane during spinal surgery were more likely to have progression of preexisting mild cognitive impairment compared to controls and to patients who received propofol or epidural anesthesia. Given the inconsistent evidence on the association between surgery, anesthetic type, and AD, well-designed and adequately powered studies with longer follow-up periods are required to establish a clear causal association between surgery, GA, and AD.