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September 6, 2026International Journal of Medical SciencesOpen Access

Immobilization-induced frailty reduces post-anesthesia Y-maze alternation ratio by ~55% versus controls.

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Why the study?

Because frailty is associated with postoperative adverse events in older surgical patients, this study evaluated the effect of frailty on postoperative cognitive dysfunction in aged rats undergoing general anaesthesia.

Does frailty increase vulnerability to postoperative cognitive dysfunction in aged rats undergoing general anesthesia?

Population

Twenty male Sprague-Dawley rats aged 18 months

Comparison

Frailty induced by hind limb immobilisation vs control

Design

Animal experimental study

Follow-up

Two days after general anaesthesia

Key result

Frailty induced by hind limb immobilization significantly reduced the alternation ratio in the Y-maze test two days after general anesthesia compared to controls (29% vs 65%, p=0.01).

Authors

ECEun-Hwa ChoTKTae-Hoon KimSHSeungwan Hong

Discussion

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Overview

May heighten POCD risk awareness in frail elderly; hypothesis-generating in aged rats and leaves open human translation.

Key Points

  • To evaluate the effect of physical frailty on postoperative cognitive dysfunction following general anesthesia in an aged rat model.
  • Allocated 20 18-month-old male Sprague-Dawley rats evenly into a control group and a frailty group induced by hind limb immobilization using aluminum splints (N=20).
  • Evaluated cognitive function before and two days after general anesthesia using the Y-maze test.
  • Assessed frailty and muscle atrophy by measuring quadriceps weight, glutathione peroxidase 4 (GPX4) levels, and threonine concentrations.
  • Two days after general anesthesia, the Y-maze alternation ratio was significantly lower in the Frailty group (29% ± 28%) compared to the Control group (65% ± 37%, p = 0.01), with no baseline differences.
  • Quadriceps weight was significantly lower in the Frailty group [2.0 (1.7–2.3) g vs. 2.4 (2.3–2.6) g, p = 0.0001], despite similar total body weights across groups.
  • Levels of GPX4 and threonine in quadriceps tissue were significantly reduced in the Frailty group compared to controls.

Structured PICO

Does frailty increase vulnerability to postoperative cognitive dysfunction in aged rats undergoing general anesthesia?

P
Population
20 male Sprague-Dawley rats aged 18 months were randomized to a frailty induction or control group to evaluate vulnerability to postoperative cognitive dysfunction following general anesthesia.
I
Intervention
Frailty induced by hind limb immobilization using aluminum splints for 7 days prior to general anesthesia (isoflurane 1.5 vol% for 2 hours)
C
Comparator
Control group without hind limb immobilization, undergoing the same general anesthesia protocol
O
Outcome
Alternation ratio in the Y-maze test on day 2 after general anesthesiasurrogate

Main Result

Absolute Event Rate: 29% vs 65%

p-value: p=0.01

In an aged rat model, frailty induced by hind limb immobilization significantly increased vulnerability to postoperative cognitive dysfunction and neuroinflammation following general anesthesia.

Limitations

  • Possibility that forelimb muscle strength increased as a compensatory mechanism in the Frailty group.
  • The procedure used to establish frailty was performed under anesthesia, which may have influenced the results.
  • Cognitive function was assessed using the Y-maze test alone.
  • Possibility of forelimb muscle strength increase as a compensatory mechanism
  • Procedure to establish frailty was performed under anesthesia, which may have influenced results
  • Cognitive function was assessed using the Y-maze test alone

Cite This Study

Cho et al. (2026) studied Postoperative cognitive dysfunction (POCD) (n=20). Hind limb immobilization (Frailty model) vs. No immobilization (Control) was evaluated on Alternation ratio in the Y-maze test on day 2 after general anesthesia (p=0.01). Frailty induced by hind limb immobilization significantly reduced the alternation ratio in the Y-maze test two days after general anesthesia compared to controls (29% vs 65%, p=0.01).

synapsesocial.com/papers/6a9d1df228139818eab20bb5https://doi.org/10.7150/ijms.139225
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