Abstract:
The present study aimed to investigate the effect of chronic treatment with paracetamol on the production of pro-inflammatory cytokines IL-1α and TNF- α in the cerebral cortex. Male Wistar rats (250-300 g) were divided into 4 groups: the control, control with CSD activation, paracetamol, and paracetamol with CSD activation group (n=10, each). A single dose and daily paracetamol (200 mg/kg BW, intraperitonealy) treatment for a period of 0, 5, 15, and 30 days was injected into the rats of the paracetamol treated group whereas a vehicle was injected into those of the control group at the same volume. After completion of the treatment, all rats were humanely killed by injection of an excessive dose of sodium pentobarbital. The expression of pro-inflammatory cytokines (IL-1 α /TNF- α) was studied by immunohistochemistry and western blot analysis. Since the transcription factor of the nuclear factor kB (NF-kB) is an important signaling pathway involved in the inflammatory responses, the phosphorylation of NF-kB and IkB were studied by western blot analysis in all experimental groups as well. The results showed that short term exposure or acute paracetamol treatment at periods of 0 and 5 days had no effect on the expression of pro-inflammatory cytokines IL-1 α and TNF- α. The CSD activation without paracetamol treatment had no effect on the expression of both cytokines. However, long term exposure or chronic paracetamol treatment in both combination with and without CSD activation for 15 and 30 days induced an increase in the number of IL-1 α and TNF- α immunoreactive cells in the cerebral cortex more than those observed in the control group and correlated with the expression of these proteins level by western blot analysis. When compared between the chronic paracetamol with and without CSD activation, the expression of those cytokines in the paracetamol with CSD activation was higher. In addition, the expression of phospho-NF-kB and phospho-IkB in the rat with chronic paracetamol treatment (with and without CSD activation) for 15 and 30 days were significantly enhanced when compared with control group. The results of the present study suggest that chronic paracetamol treatment leads to an increase in the pro-inflammatory cytokines (both IL-1 α and TNF- α) production and the enhancement of those cytokines might mediate via the activation of the NF-kB signaling pathway.
