Carvacrol alleviates the proconvulsive effects of lipopolysaccharide (LPS) and reduces the gene expression of proinflammatory cytokines interleukin-1 and tumor necrosis factor-α.

Objective: Carvacrol has anti-inflammatory effects. According to the links between inflammatory processes and seizures, this study was designed to investigate the potential effect of carvacrol in reducing seizure severity and involvement of hippocampal pro- and anti-inflammatory cytokines.

Materials and methods: This research was conducted on 42 adult male Wistar rats. Animals were randomly divided into seven groups (n=6). Seizures were induced by PTZ (Pentylenetetrazol) injection (80 mg/kg). LPS (lippolysaccharide) was injected (400 μg/kg) 4 hr before PTZ. Carvacrol (100 mg/kg) was injected immediately after LPS. All injections were intraperitoneal (i.p.). Experimental groups were as follows: 1. Control (Cnt) 2. Carvacrol (Cav); 3. LPS; 4. PTZ, 5. PTZ+LPS; 6. PTZ+Cav; 7. PTZ+LPS+Cav. Seizures were observed for 30 min after the PTZ injection and the occurrence of behavioral stages of seizures was recorded. Following the behavioral study, hippocampal samples were collected for gene expression evaluation using the Real Time-PCR technique to assess IL (interleukin)-1, IL-6, IL-4 and TNF (tumor necrosis factor)-α gene expression.

Results: The current study showed that receiving LPS exacerbated seizures in the studied groups. Carvacrol reduced the severity of seizures in the LPS-receiving groups. In the gene expression study, receiving LPS increased the expression of cytokines TNF-α and IL-1 in the hippocampal tissue. Carvacrol significantly decreased gene expression of TNF-α and IL-1.No significant changes were detected for IL-6, IL-4 gene expression.

Conclusion: There could be a relationship between carvacrol ability to modulate the proconvulsive effects of LPS and its ability to decrease the gene expression of inflammatory cytokines.