[Sulforaphane regulates mitochondrial homeostasis through adenosine monophosphate-activated protein kinase signaling to treat acute carbon monoxide poisoning induced brain injury in rats].

Abstract

Objective: To explore the neuroprotective effect and molecular mechanism of sulforaphane (SFN) on acute carbon monoxide poisoning (ACOP) in rats.

Methods: A total of 135 healthy adult male Sprague-Dawley (SD) rats were randomly divided into normal control group, ACOP model group, and SFN intervention group, with 45 rats in each group. The ACOP animal model was reproduced using carbon monoxide (CO) inhalation in a hyperbaric oxygen chamber, while the normal control group was allowed to breathe fresh air freely. The rats in the SFN intervention group received intraperitoneal injection of SFN at a dose of 20 mg/kg once daily starting 2 hours after CO poisoning and continuing until euthanasia. The normal control group and the ACOP model group received equivalent volume of saline injection. Three rats from each group were sacrificed 1 day after intervention to observe the changes in the ultrastructure of neuronal mitochondria in brain tissues under transmission electron microscopy. Six rats from each group were evaluated for cognitive function using neurobehavioral test 7 days after intervention. Brain tissues of 6 rats in each group were collected 1, 3, and 7 days after intervention, and the expressions of phosphorylated-adenosine monophosphate-activated protein kinase (p-AMPK), mitofusin 2 (MFN2), and dynamin-related protein 1 (DRP1) were detected using immunohistochemistry staining and Western blotting. Linear regression analysis was performed to assess the correlations between the expression levels of above proteins.

Results: In the normal control group, the rats did not exhibit any abnormalities in cognitive function or the ultrastructure of neuronal mitochondria in brain tissues. ACOP induced cognitive impairment and ultrastructural injury to neuronal mitochondria in rats. However, SFN significantly improved cognitive function in poisoned rats and mitigated the extent of neuronal mitochondrial damage. Over poisoning time, the expression levels of p-AMPK and MFN2 in the brain tissues of ACOP rats were gradually decreased, while the expression level of DRP1 was gradually increased. Compared with the normal control group, the ACOP model group showed significant differences in the expressions of p-AMPK, MFN2, and DRP1. After SFN intervention, the expression levels of above proteins were significantly reversed. Compared with the ACOP model group, the SFN intervention group exhibited a marked increase in the expressions of p-AMPK and MFN2 [p-AMPK positive expression (A value): 0.226±0.003 vs. 0.177±0.033, p-AMPK protein (p-AMPK/GAPDH): 1.41±0.05 vs. 0.89±0.05, MFN2 positive expression (A value): 0.241±0.004 vs. 0.165±0.007, MFN2 protein (MFN2/GAPDH): 1.33±0.04 vs. 0.79±0.03, all P < 0.05], along with a significant decrease in DRP1 expression [DRP1 positive expression (A value): 0.103±0.002 vs. 0.214±0.011, DRP1 protein (DRP1/GAPDH): 1.00±0.03 vs. 1.50±0.03, both P < 0.05]. Linear regression analysis revealed a strong negative linear correlation between DRP1 protein expression and MFN2, p-AMPK protein expressions (R² values were 0.977 and 0.971, both P < 0.01), and a positive linear correlation between p-AMPK protein expression and MFN2 protein expression (R² = 0.985, P < 0.01).

Conclusions: SFN can help maintain neuronal mitochondrial homeostasis by activating the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway, thereby alleviating neuronal injury caused by ACOP.