Effects Of Acute Exercise To Exhaustion On Liver Injury And Apoptosis In Rat

Many studies have proven liver cells undergo apoptosis under a broad range of physiological and pathological conditions, such as development, homeostasis, disease and exercise. However, the mechanism of this phenomenon is not clear. This study, through the influence of different exhaustive exercises on hepatic apoptosis and injury as well as the role oxygen free radicals and mitochondria uptaking calcium play in hepatic injury and apoptosis, attempts to seek the correlation between hepatic injury and apoptosis and exhaustive exercise.Methods: Thirty male adult Sprague-Dawley rats are randomly divided into three groups: control (C, n=10), middle intensity exercise (ME, n=10) and high intensity exercise(HE, r.=10). The rats of ME and HE group run on the treadmill to exhaustion at the speed of 19. 3 m . min^-1 (76% Vo₂max) and 26.8 m .min^-1 (92. 3%Vo₂max) respectively. The rats in control group and in exhaustive groups are killed by decapitation respectively in quiet status and immediately after exercise, and 3ml of blood reeds to be taken to be made into serum. Some hepatic tissue are removed to made into paraffin wax sample, electron microscopy sample, tissue homogenate and mitochondria homogenate. Then the SOD activity and MDA , GSH content in serum, tissue homogenate and the mitochondrial Ca2+ content are measured. Paraffin wax sections labeled by TUNEL, the apoptotic liver nuclei are detected under optical microscope and the change of liver nuclear ultra-structure examined under electronic microscope.Results (1) Fewer liver nuclei TUNEL positive are detected in liver cells_of the control group. In HE group and in ME group,there are many detectable apoptotic hepatic_cells, AI is 33.40 ± 8. 38% and 13. 50 ± 3. 81%(p<0. 05) respectively , ^$hieh—are-significant compared with that in the control group. What is more , the difference of apoptotic cells between two exercise groups is also significant(p<0. 05).(2) Apoptotic liver cell displays an irregular shape and a highly condensed chromatin along the inner surface of the nuclear envelope under the electron microscope. In both exercise group mitochondrion bulges and cell membrane shrinks somewhat like ripple.(3) In the HE stain, liver cell bulges in exercise group, sinus hepaticus narrows or dies away, nucleus diminishes and is deep dyed; outline of liver lobule changes.(4) The SOD activities in exercise groups decrease and their difference between control and exercise group are significant (p<0.05). The SOD activities of serum decreases in both exercise groups, which , compared with that in control group , are apparently significant (p<0. 01) , although there is no significant difference between exercise groups.(5) After exhaustion in both exercises, MDA content in the liver is increased significantly, MDA content of serum is decreased obviously, which are significant compared with that in the control group (p<0. 05) , although the differences between the two exercise groups are not significant.(6) In ME group, GSH content of the liver cell, which decreases about 53%, is significant compared with that in control group (p<0. 05). The GSH content in HE group also decreases,_but its difference between this group and control group is of no significance. GSH content of serum decreases obviously in the exercise groups, which , compared with that in the control group, is significant (p<0.05), although the difference between the two exercise groups is not significant.