EFFECT OF CHRONIC PARACETAMOL TREATMENT ON THE CORTICAL SPREADING DEPRESSION INDUCED THE ALTERATION OF BLOOD BRAIN BARRIER INTEGRITY

Abstract

Paracetamol (APAP) has long been used as a drug for treatment of pain and headache including migraine. Recently, a number of non-beneficial effects of chronic treatment with APAP have been reported in several systems, including the circulatory system. Since APAP can easily cross the blood brain barrier (BBB), the effect of chronic treatment of this drug on the BBB integrity can be expected. In order to prove this hypothesis, the effect of acute (1 hour) and chronic (15 and 30 days) APAP treatments on the alteration of cerebral microvessels and CGRP expression were studied in a cortical spreading depression (CSD) migraine animal model. Wistar rats were divided into the control, CSD, and APAP treatment and APAP treatment with CSD group. APAP (200 mg/kg body weight) was i.p. injected as a single or once-daily dose for the acute and chronic APAP treated groups, respectively. CSD was induced by KCl application on the cortical surface. The results demonstrated that the induction of CSD caused alterations of the BBB integrity, as indicated by increases in ultrastructural alteration of the endothelial cell and expression of cell adhesion molecules (ICAM-1, VCAM-1). Tight junction proteins (ZO-1occludin, claudin-5) were decreased while the IgG extravasation was increased in the CSD group. Acute APAP treatment attenuated those alterations induced by CSD. However, chronic APAP treatment resulted in an enhancement of the abnormalities of BBB integrity induced by CSD. Interestingly, the rats that received chronic (2 weeks) APAP treatment alone also induced alterations in the BBB integrity as compared with the control group. Moreover, the CGRP immunohistochemistry demonstrated that CSD activation could increase the CGRP expression in TG as compared with the control group. Acute APAP treatment significantly reduced the CGRP expression in TG. In contrast, chronic APAP treatment alone (15 and 30 days) significantly enhanced CGRP expression, especially in the combination with CSD activation. In order to confirm the effect of chronic APAP treatment and the involvement of CGRP on the alteration of the brain endothelial cell, in vitro study using cultured mouse brain endothelial (bEnd.3) cells was performed as well. The results revealed that acute APAP treatment could attenuate the CGRP-induced alteration of the tight junction protein in bEnd.3 cells, whereas the chronic treatment demonstrated the opposite effect showing the significantly lower the level of tight junction proteins (ZO-1, occludin, and claudin-5) than those observed in control. Furthermore, chronic treatment with APAP (more than 2 weeks) either alone or in combination with CGRP could significantly enhance the CYP2E1 activity, cell adhesion molecules (ICAM-1 and VCAM-1), and phospho-NF-κB in cultured bEnd.3 cells. The expression of phosphorylated-PKA was also increased in the CGRP treated bEnd.3 cells with or without APAP treatment groups. These data suggested that chronic APAP treatment alone induces the alterations of BBB integrity. Additionally, the severity of those alterations is more prominent when combined with either CSD or CGRP activation. In summary, the results obtained from both in vivo and in vitro studies demonstrate that the short-term treatment of APAP has a protective effect on cerebral microvessels against CSD activation. However, long-term treatment with this drug can induce the damage to these vessels. With CSD activation, the damage to cerebral microvessels induced by long-term APAP treatment is more severe. The increment of the CGRP expression in TG due to the chronic APAP treatment is at least one mechanism involved in those alterations. Thus, long-term treatment with APAP for patients with CSD-related disorders, particularly migraine headaches, might need to be carefully monitored.