Anesthesia/stereotaxic surgery exposure affects cognitive impairment and hippocampal synaptic plasticity dysfunction in male rats

Abstract

Postoperative cognitive dysfunction (POCD) is a frequent complication after major surgery and anesthesia exposure, particularly in advanced aging. However, the effects of anesthesia/stereotaxic surgery (A/SS) on cognitive function in rats remain inadequately understood. This study aims to elucidate the effects of A/SS on cognitive function in male Sprague Dawley rats and explore potential alterations in hippocampal synaptic plasticity. Male Sprague Dawley rats, aged 6 months, were subjected to anesthesia (A) or A/SS, involving anesthesia with ketamine/xylazine (50/10 mg/kg, ip) and stereotaxic surgery to create a burr hole above the lateral ventricle. Anxiety-like behavior and locomotor activity were assessed using the open-field test one week post-surgery. Spatial memory and learning were evaluated through the Y-Maze test and novel object recognition test (NORT). Moreover, to determine hippocampal synaptic plasticity, we evaluated hippocampal long-term potentiation (LTP) at perforant pathway-dentate gyrus synapses. No statistically significant differences in anxiety and motor activity were observed between groups. Compared to the no-treatment group, the A/SS group rats exhibited a significantly (p<0.05) lower exploration of a novel arm and novel object in the Y-Maze and NORT, respectively. Furthermore, on postoperative day 7, LTP induced by high-frequency stimulation in the dentate gyrus region was attenuated (p<0.05) in the A/SS group compared to the no-treatment group. These findings indicated that A/SS induced cognitive decline and functional synaptic plasticity dysfunction. The results of the present study may be useful for future studies examining cognitive functions in experimental models involving such procedures.

Keywords

• Stereotaxic surgery
• Anesthesia
• Postoperative cognitive dysfunction

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