Influence of alginic sodium diester on intraneuronal Ca2+ content and nerve cell apoptosis before and after reperfusion in experimental ischemic rats

Yong YOU; Hongju XIE; Qidong YANG; Yuefeng ZHANG; Zunjing LIU

ABSTRACT

BACKGROUND:

Alginic sodium diester (ASD) possesses neuroprotective function because of its selective calcium antagonist effects.

OBJECTIVE:

To compare the influences of ASD on intraneuronal Ca2+content and nerve cell apoptosis before and after reperfusion in focal cerebral ischemic rats.

DESIGN:

Randomized controlled observation.

SETTING:

Neurological Department of Xiangya Hospital Affiliated to South China University; Laser Orthopedic Surgery of the First Hospital Affiliated to Southern China University.MATERIALS This experiment was carried out between November 2003and April 2004 at the Neurological Department of Xiangya Hospital Affiliated to South China University. A total of 65 male SD rats were recruited and randomized into 6 groups; 17 got lost during the experiment, and the other 48 rats completed the experiment with 8 rats in each group.

METHODS:

In sham operation group, an incision was made on rats' cervical skin and sutured. Right cerebral middle artery was occluded in rats of ischemic group, ASD 5 mg/kg preischemic group, ASD 5 mg/kg postischemic group, ASD 10 mg/kg preischemic group, and ASD 10 mg/kg postischemic group. After that, rats in all but ischemic group were subjected to intraperitoneal injection of various dosage of ASD or excipient 30minutes before reperfusion and 5 hours after reperfusion. FCM was used to determine intraneuronal Ca2+ content and rate of nerve cell apoptosis;meanwhile, neurological dysfunction was scored.MAIN OUTCOME

MEASURES:

[1] Influence of ASD on the score for neurological dysfunction, intraneuronal Ca2+ fluorescence intensity, and neuronal apoptosis in rats with right cerebral middle artery ischemia. [2]Correlation of behavioral obstacle score with intraneuronal Ca2+ fluorescence intensity and neuronal apoptosis in rats with right cerebral middle artery ischemia.

RESULTS:

Totally 65 rats were enrolled in this study, 17 of which got lost and the other 48 rats entered the result analysis. [1] Influence of ASD on the score for neurological dysfunction, intraneuronal Ca2+ fluorescence intensity, and neuronal apoptosis in rats with right cerebral middle artery ischemia The score was obviously reduced in ASD 5 mg/kg preischemic group, ASD 5 mg/kg postischemic group, ASD 10 mg/kg preischemic group and ASD 10 mg/kg postischemic group as compared with ischemic group (1.80±0.21, 2.20±0.23, 1.20±0.11, 2.00±0.22, 3.40±0.65); moreover,functional improvement was more obvious due to pre-reperfusional administration than post-reperfusional administration. Intraneuronal Ca2+ concentration was reduced after ASD administration at different degrees and lower than that of ischemic group. Decrement of intraneuronal Ca2+ concentration was found most obvious due to 10 mg/kg ASD administration 30 minutes before reperfusion, approximately reduced by 70%; moreover, neuronal apoptosis rate on the ischemic side was obviously suppressed by ASD administration, displaying time-dependent manner, with apoptotic suppression effect more obvious in pre-reperfusional group than in post-reperfusional group (5.68%, 10.03%; 4.00%, 9.91%). [2] Correlation of behavioral obstacle score of right cerebral middle artery ischemic rats with intraneuronal Ca2+ fluorescence intensity and membrane associated protein/propidium iodide apoptosis Obvious positive correlation was found between behavioral obstacle score and intraneuronal Ca2+ fluorescence intensity and detection rate of membrane associated protein/propidium iodide apoptosis (r=0.51,0.62, P ＜ 0.05); intraneuronal Ca2+ fluorescence intensity was also positively correlated with the detection rate of membrane associated protein/propidium iodide apoptosis (r=0.84, P ＜ 0.05).

CONCLUSION:

[1] ASD can exert anti-apoptosis effect by suppressing the increment of intraneuronal Ca2+ concentration, thus having neuroprotective function and ultimately improving neurological dysfunction. [2] Its effect displays time-dependent manner, and neurological functional improvement is more obvious by pre-reperfusional administration than by post-operational administration.