Abstract
BackgroundWhile it is well known that bradykinin B2 agonists increase plasma protein extravasation (PPE) in brain tumors, the bradykinin B1 agonists tested thus far are unable to produce this effect. Here we examine the effect of the selective B1 agonist bradykinin (BK) Sar-[D-Phe8]des-Arg9BK (SAR), a compound resistant to enzymatic degradation with prolonged activity on PPE in the blood circulation in the C6 rat glioma model.ResultsSAR administration significantly enhanced PPE in C6 rat brain glioma compared to saline or BK (p < 0.01). Pre-administration of the bradykinin B1 antagonist [Leu8]-des-Arg (100 nmol/Kg) blocked the SAR-induced PPE in the tumor area.ConclusionsOur data suggest that the B1 receptor modulates PPE in the blood tumor barrier of C6 glioma. A possible role for the use of SAR in the chemotherapy of gliomas deserves further study.
Highlights
While it is well known that bradykinin BK type-2 (B2) agonists increase plasma protein extravasation (PPE) in brain tumors, the bradykinin BK type1 (B1) agonists tested far are unable to produce this effect
It is well known that the blood-brain barrier (BBB) in brain tumor regions shows different plasma protein extravasation (PPE) characteristics when compared with the BBB of normal brain tissue and this effect is related to the increase of B2 receptors [5,6,7]
In order to test this hypothesis, we investigated the effect of SAR on PPE using the rat C6 glioma model [11]
Summary
While it is well known that bradykinin B2 agonists increase plasma protein extravasation (PPE) in brain tumors, the bradykinin B1 agonists tested far are unable to produce this effect. We examine the effect of the selective B1 agonist bradykinin (BK) Sar-[DPhe8]des-Arg9BK (SAR), a compound resistant to enzymatic degradation with prolonged activity on PPE in the blood circulation in the C6 rat glioma model. It is well known that the blood-brain barrier (BBB) in brain tumor regions ( called blood tumor barrier, or BTB) shows different plasma protein extravasation (PPE) characteristics when compared with the BBB of normal brain tissue and this effect is related to the increase of B2 receptors [5,6,7]. B1 receptor agonists with low metabolic resistance (MR) have already been unsuccessfully tested on PPE extravasation through the BTB in brain tumors [8,9]. In order to test this hypothesis, we investigated the effect of SAR on PPE using the rat C6 glioma model [11]
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