Inhibition of Ferroptosis in the Subacute Phase of Ischemic Stroke Worsens Aversive Learning In Diabetic Rats: A Randomized Double-Blind Preclinical Trial

Abstract

Diabetes increases the risk of hemorrhagic transformation as well as post-stroke cognitive impairment (PCSI). We have shown that iron chelation in the subacute phase improves stroke cognitive outcomes in experimental models of diabetes. We hypothesized that inhibition of ferroptosis, iron-induced cell death, in the post-stroke period will prevent PSCI in diabetic animals. Methods: Male rats, housed in reverse light cycle, underwent sham or 60-min middle cerebral artery occlusion surgery 8 weeks after diabetes onset. After MRI, rats that met the preset inclusion criteria (adhesive removal time > 35 sec. and either a modified Bederson score <= 6 or weight loss > 10% on Day 3) were randomized to ferroptosis inhibitor UAMC-3 (2mg/kg) or vehicle treatment for 2 weeks (n=8-12). Sensorimotor and cognitive outcomes were monitored for 8 weeks in the dark (active) cycle. Results: As confirmed by MRI, inclusion criteria predicted successful stroke surgery in 95% of the animals. There were significant acute neurological deficits. Long-term weight gain and survival were better in this cohort as compared to our historical data collected in regular light cycle experiments. Blood glucose levels were comparable. In contrast to our previous data, there were no significant differences in indices measured by novel object recognition (NOR), Y-maze, and sucrose preference tests after stroke but there was a trend for a greater number of animals showing a cognitive decline in treated cohorts. Step-through latency in the passive avoidance test (PAT) was lower in the treated stroke group. Open field (OF) suggested anxiety-like behavior in RX group. Conclusions: Preset inclusion criteria were effective in controlling for stroke severity. Ferroptosis inhibition impaired aversive learning and appeared to worsen cognitive outcomes in some of the animals. Better post-stroke weight gain/maintenance and greater engagement of animals in behavioral tests conducted in the “dark” cycle may explain the lack of a progressive memory decline after stroke. While further studies are required to better understand whether ferroptosis and housing lighting impacts stroke recovery in diabetes, based on current findings, inhibition of ferroptosis with UAMC-3 is not desirable. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.