Investigation of Contrast-Induced Neurotoxicity and the Effects of Sildenafil and N-Acetylcysteine on HIF-1α Levels in Wistar Rats.

BACKGROUND

Contrast-induced encephalopathy (CIE) is an uncommon yet clinically significant complication associated with iodinated contrast media, with its mechanisms remaining unclear.

OBJECTIVE

The aims of this study are to examine the neurotoxic effects of contrast media and assess the neuroprotective roles of N-Acetylcysteine (NAC) and sildenafil with regard to HIF-1α expression.

METHODS

Thirty-six female Wistar albino rats (n = 36) were allocated into four experimental groups (n = 9 each): control, contrast media + saline (CMA + Saline), contrast media + NAC (CMA + NAC), and contrast media + sildenafil (CMA + Sildenafil). NAC (150 mg/kg) and sildenafil (50 mg/kg/day) were administered intragastrically for 48 h before exposure to contrast media. Biochemical, histopathological, and immunohistochemical evaluations were conducted 48 h post-contrast administration.

RESULTS

Exposure to contrast media resulted in neuronal death, vascular obstruction, and increased hypoxia-inducible factor-1 alpha (HIF-1α) immunoreactivity. The primary outcome measure, tissue HIF-1α concentration by ELISA, did not differ significantly among groups (p = 0.119). Semi-quantitative immunohistochemical analysis revealed significant group differences in HIF-1α immunoreactivity (p < 0.001), with all injury/treatment groups differing significantly from control. The difference between the contrast media group and the sildenafil-treated group approached but did not reach statistical significance after correction for multiple comparisons (Dunn's test, p = 0.050).

CONCLUSIONS

The primary biochemical endpoint did not demonstrate significant group differences. Secondary IHC analysis suggests a potential attenuation of HIF-1α immunoreactivity by sildenafil, though this did not reach statistical significance and requires confirmation in adequately powered studies. HIF-1α immunoreactivity warrants further investigation as a potential biomarker for contrast-induced neural injury.