Changes of brain gangliosides in rats transient global cerebral ischemia/reperfusion models after hyperbaric oxygen treatment

Yanguo TAN; Rui CHEN; Yanzhi HOU; Lin SUN; Peilan YU; Hua LIU

ABSTRACT

BACKGROUND:

Ganglioside (Gls) is a kind of N-acetylneuraminatecontaining glycosphingolipid, which is abundant in neural tissues and exerts neuroprotective roles, and has been found its changes in content and composition pattern after cerebral ischemia or hypoxia diseases.

OBJECTIVE:

To investigate the effect of hyperbaric oxygen on brain gangliosides after cerebral ischemia/reperfusion and explore the possible mechanism of hyperbaric oxygen treatment to ameliorate cerebral ischemia/reperfusion damage.

DESIGN:

Randomized-control observation.

SETTING:

Department of Hyperbaric Oxygen, Chaoyang Hospital Affiliated to Capital University of Medical Sciences and Department of Biochemistry and Molecular Biology, Basic College, Capital University of Medical Sciences.MATERIALS Animal models were established at Department of Hyperbaric Oxygen, Chaoyang Hospital Affiliated to Capital University of Medical Sciences (Key Laboratory of Beijing) from March to April 2002. All indexes were determined at the Department of Biochemistry and Molecular Biology, Basic College, Capital University of Medical Sciences. A total of 54 SD male rats were selected and randomly divided into 9 groups shamoperated group; ischemia/reperfusion 6, 24, 48 and 96 hours group; and hyperbaric oxygen 6, 24, 48 and 96 hours group with 6 rats in each group.

METHODS:

Animal models with cerebral ischemic/reperfusion were established in the other 8 groups, except the sham-operation group. Global cerebral ischemia was induced by a four-vessel occlusion and reperfusion allowed after 20-minute ischemia. The rats in sham-operation group were operated in the same way except of arterial occlusion. The rats in the HBO group were placed in experimental animal chamber. After 5-minute wash by pure oxygen, the pressure of oxygen cabins was increased to 0.1 MPa in 5 minutes and kept stable for 45 minutes, then decreased to ambient level within 10 minutes. The rats in the HBO groups were treated once by hyperbaric oxygen at reperfusion 3, 24, 48 and 96 hours respectively; while the rats in the ischemia/reperfusion group and sham-operation group were placed in normal atmospheric environment. The rats of HBO and ischemia/reperfusion groups were killed by decapitation at the 6th, 24th, 48th and 96th hours respectively, and the brains removed quickly. Gls and its percentage content in each group were detected with high performance thin-layer chromatography plate.MAIN OUTCOME

MEASURES:

Total content of gangliosde in the whole brain tissue of rats and its percentage content.

RESULTS:

Totally 54 rats were involved in the result analysis without drop out. ①The contents of Gangliosides in HBO groups at 24 and 48 hours was significantly higher than those in sham-operation group and ischemia/reperfusion group at corresponding time phase (F=12.730,122.246,P ＜ 0.01), but there was no significant difference between ischemia/reperfusion and sham-operation groups (P ＞ 0.05). ② N-acetylneuraminosylgalactosyl-N-acetylgalactosaminyl- (N-acetylneuraminosylα2→8- N-acetylneuraminosyl) -galactosylglucosylceramide (GT1b) proportion in the ischemia/reperfusion 24 hours group was lower markedly than that in the S-O (F=13.575,P ＜ 0.01); Both galactosyl-N-acetylgalactosaminyl- (N-acetylneuraminosyl- α2→8-N-acetylneuraminosyl) - galactosylglucosylceramide (GD1b) and galactosyl- N-acetylgalactosaminyl-(N-acetylneuraminosyl)galactosylglucosylceramide (GM1) in the reperfusion 48 hours group were lower than those in the sham-operation group (F= 4.015,3.979,P ＜ 0.05); (N-acetylneuraminosyl)galactosylglucosylceramide (GM3)in ischemia/reperfusion 24 hours group was much higher than that in sham-operation and any other ischemia/reperfusion groups (F=21.450,P＜ 0.01 ); An unknown increase of GM3 was found again at the 96th hour;③GM1and GM3 proportion in the hyperbaric oxygen group was higher than that of sham-operation group at the 24th hour (F=3.970,21.450,P＜ 0.05, ＜ 0.01), and all of GD1a, GD1b and GT1b were lower than that in the sham-operation group at the same times (F= 13.575,5.745,8.783, P＜ 0.05-0.01), but GT1b was remarkably higher than that in ischemia/reperfusion group (F=8.783 ,P ＜ 0.05).

CONCLUSION:

The pattern of brain gangliosides changed after transient whole cerebral ischemia/reperfusion. The new mechanism of neuron damage after transient whole cerebral ischemia/reperfusion might be the decreasing of GT1b, GD1b and GM1 with increasing of GM3 proportion. The hyperbaric oxygen treatment could ameliorate cerebral ischemia/reperfusion damage by increasing total gangliosides content and GM1 proportion and accelerating GT1b restoration to normal level. It is unknown that the effect of percentage content of GD1a and GD1b decreased.