Effect of minocycline on expression of Bcl-2, Bax and Bcl-xl in rats with spinal cord injury

Gang CHEN; Qun LIANG; Anmin CHEN; Fengjin GUO; Jianglin LI; Weiguo XU; Hongbo YOU

ABSTRACT

BACKGROUND:

Neuronal apoptosis produced a main effect in secondary injury after injury of central nervous system. Recently, minocycline has been reported to protect neurologic function evidently by decreasing apoptosis.

OBJECTIVE:

To study the effect of minocycline on apoptosis and expression of related factor, and protective effect of minocycline on neurologic function of injured spine after spinal cord injury (SCI) in rats.

DESIGN:

A randomized controlled animal study.

SETTING:

Tongji Hospital Affiliated to Tongji Medical College,Huazhong University of Science and Technology.MATERIALS The experiment was performed at the Tongji Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology between November 2003 and December 2004. A total of 36male SD rats were divided into four groups ①Blank control group (group A) with 6 rats, ②injured group (group B) with 10 rats, ③minocycline treatment group (group C) with 10 rats, and ④methylprednisolone treatment group (group D) with 10 rats.

METHODS:

The animal SCI model was established. Spinal cords of rats in the group A were exposed without injury. Spines of rats in the group B were injured without treatment. Rats of group C was treated with minocycline (50 mg/kg) by intraperitoneal injection at 1 hour after injury, and 24 hours later another 50 mg/kg was given, and then another 25 mg/kg was injected for 5 days. Methylprednisolone (100 mg/kg) was intraperitoneally injected 1 hour after injury in the group D. The rats in the group A and the group B were treated with saline, and the method of administration was the same with that of the group C.MAIN OUTCOME

MEASURES:

①Neurofunction evaluation of rats in each group. ②Expressions of Bcl-2 family members (Bcl-2, Bcl-xl, and Bax) were tested with immunocytochemical method. ③Apoptosis index of spinal tissue of rats of each group.

RESULTS:

A total of 36 rats were involved in the result analysis. ①Neurofunction of rats in the group C increased as compared with the group B (P ＜ 0.05), and there was insignificant difference between group C and the group D (P ＞ 0.05). ②Bcl-2 positive expressive cells in the group C was more than that in the group B, and showed obvious difference between the two groups [(62.53±7.76)%, (35.14±3.70)%,P ＜ 0.05]. There was insignificant difference between expressions of Bcl-xl and Bax in group C as compared with the group B (P ＞ 0.05). ③The number of apoptosis positive cells in the group B was more than that in the group C and D [(44.63± 5.90)%, (32.71± 5.26)%, (34.31± 6.84)%,P ＜ 0.05].

CONCLUSION:

Minocycline can up-regulate the expression of Bcl-2, and raise the ratio of Bcl-2/Bax, so as to inhibit the neural apoptosis of spine,which have protective effect on neurologic function of injured spine.