Neuroprotective effect of dauricine after transient middle cerebral artery occlusion in rats: involvement of Bcl-2 family proteins.

Previous studies have shown that the bisbenzyl isoquinoline alkaloid dauricine can protect the brain against ischemic damage. We investigated here whether dauricine could inhibit neuronal apoptosis and modulate Bcl-2 family protein levels in a rat model of transient focal cerebral ischemia. Male Sprague-Dawley rats underwent a 60 min temporary occlusion of the middle cerebral artery (MCAO). Two doses of dauricine (5 and 10 mg/kg as low and high dose respectively) were administered intraperitoneally at 1 hour after MCAO. After neurological deficits were assessed at 3 hours and 24 hours of reperfusion, rats were killed and brain samples were collected. Apoptotic changes were evaluated by TUNEL method. The immunohistochemistry and Western blot were used to assess the protein expressions of Bcl-2 and Bax. RT-PCR was used to determine Bcl-2 and Bax mRNA expressions. Dauricine (5 and 10 mg/kg) treatment improved neurological deficits, diminished DNA fragmentation, increased Bcl-2 expression and reduced Bax expression in the penumbra. The infarct-reducing effects of dauricine may be due, in part, to the inhibition of apoptotic cell death via modulation Bcl-2 family protein in the penumbra.

Daurisoline suppressed early afterdepolarizations and inhibited L-type calcium current.

Our previous studies have shown that daurisoline (DS) exerted antiarrhythmic effects on various experimental arrhythmias. In this study, the effects of DS on early afterdepolarizations (EADs) and its possible mechanisms have been investigated. Cardiac hypertrophy was induced in rabbits by coarctating the abdominal aorta. The effects of DS on action potential duration (APD) and the incidences of EADs were studied in hypertrophied papillary muscles of rabbits in the conditions of low external K(+) concentration ([K(+)]o) and dofetilide (dof) by using standard microelectrode technique. The whole-cell patch clamp was used to record the L-type calcium current (I(Ca-L)) in isolated left ventricular cells of rabbits. The results showed that in hypertrophied papillary muscles of rabbits with low [K(+)]o ([K(+)]o = 2.7 mM), 1 microM dof prolonged APD(50) and APD(90) markedly and the incidence of EADs was 66.7% (4/6, p < 0.01); when 15 microM DS was applied, the incidence of EADs was 0% (0/4, p < 0.01) and the prolonged APD was shortened (p < 0.01). In a single myocyte, DS could also inhibit EADs induced by dof, low [K(+)]o and low external Mg(2+) concentration ([Mg(2+)]o) ([Mg(2+)](o) = 0.5 mM). DS could decrease the triangulation. In a single myocyte, DS could make the I-V curve upward, shift the steady-state activation curves to the right and the steady-state inactivation curves to the left and prolong the tau value of recovery curve obviously. These results suggested that DS could inhibit EADs which may be associated with its blockade effects on I(Ca-L).

Inhibitory effect of dauricine on inflammatory process following focal cerebral ischemia/reperfusion in rats.

Our previous experimental studies showed that dauricine could protect the brain from ischemic damage, but the underlying mechanisms were unknown. In this study, we investigated the effect of dauricine on the changes of the inflammation process induced by ischemia/reperfusion (I/R). After I/R, the enzyme activity of MPO, the expression of ICAM-1 and the transcription of IL-1beta and TNF-alpha mRNA were all significantly increased (p < 0.01). And after treatment with dauricine, they were all significantly reduced compared to the vehicle-treated I/R group (p < 0.05 or p < 0.01). These results suggest that dauricin attenuates the inflammation process induced by I/R. The neuroprotective effect of dauricine may partly due to the inhibition acute inflammation induced by I/R.