TIME COURSE OF CHANGES IN APOPTOTIC SIGNAL TRANSDUCTION FACTORS DURING AND AFTER EXPERIMENTAL STATUS EPILEPTICUS
Abstract number :
1.044
Submission category :
Year :
2002
Submission ID :
3025
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Mohamad A. Mikati, Alhan Shamseddine, Marwan Sabban, Ghassan Dbaibo, Rana Kurdi, Ralph Abi Habib, Nadine Bakkar. Departments of Pediatrics and Biochemistry, American University of Beirut, Beirut, Lebanon; Department of Physiology, American University of B
RATIONALE: Status epilepticus (SE) results in programmed cell death (PCD) and in activation of a number of related signal transduction factors including Bcl2, Bax, and caspase-3. Recent data from our laboratory suggest that ceramide may also be implicated in SE induced PCD. The exact time sequence of activation of those factors during, and following, SE is not known. The objective of this study is to determine the sequential changes in the above factors in an attempt to start understanding potential relationships that activation of those factors may have to each other.
METHODS: Adult Sprague Dawley rats (2-6/group) were injected intraperitoneally with 15mg/kg kainic acid (KA), underwent SE, were sacrificed at 1, 2, 3, 6, 12, 18, 24 and 30 hours after KA, and were compared to a group of 6 controls.The left hemisphere was cut into frozen sections for immunohistochemisty to detect Bax, Bcl-2 and CPP32/caspase-3 p20 activated fragment. The intenisity of each stain in the hippocampus was assessed blindly using an ordinal severity scale. The right hippocampus was used to assay the level of ceramide (nomalized to lipid phosphate levels) using the diacylglycerol method. Statistical analysis was performed using the Kruskal-Wallis and ANOVA tests.
RESULTS: Compared to baseline ceramide levels increased at 2 hours and remained increased at each of the subsequent time points. Bcl-2 increased at 2, 3, and 6 hours and went back to baseline after that. Bax increased at 12 hours. Caspase-3 activated fragment increased at 18 hours and remained increased after that (p[lt]0.05 in each of the above comparisons, data presented in Table).
CONCLUSIONS: SE induces early, and subsequently, sustained, increases in ceramide levels starting 2 hours after KA injection.This is accompanied by initial increases in the anti-apoptotic factor Bcl-2, and is subsequently followed by increases in the pro-apoptotic factors Bax and activated caspase-3. This suggests that Ceramide could, potentially, exert its effects upstream of these two pro-apoptotic factors.[table1]
[Supported by: DTS17988816700 and URB 17996074524]