Distinct Expression Of Bax,Bcl-2 And Caspase-3 In Spinal Dorsal Horn Of Different Age Rats With Pain Irritation

Bcl-2, Bax and Caspase-3 are proteins which are related with apoptosis.Bax can promote apoptosis and Bcl-2 can prevent apoptosis.The ratio of this two proteins decide that the cell apoptosis or not. Caspase-3,a factor in downstream of several apoptotic pathways, is one of the most important protease in apoptotic process. This study is to detect the expression of the apoptosis proteins in spinal cord and the expression change of the proteins in different age rats after pain irritation. The time of rats shrinking legs and lapping claws was recorded in every 5 minutes and reaction of every group was observed in 1 hour after pain initation. Immunohistochemical method is used to detect the expression of Caspase-3 in spinal dorsal horn of every group, comparing the side of pain irritation(SPI) with the side of no pain irritation(SNPI). Western blotting was used to detect the expression of Bax and Bcl-2 in spinal dorsal horn of every group, and count the ratio of Bax and Bcl-2. The results showed as follows: 1. Ethology detection revealed that the time of shriking legs and lapping claws was significant different in different groups with pain irritation (P < 0.05). The time of the same behaviors in young group was the longest, but the time in old group was the shortest. 2. Immunohistochemical method revealed that in both SNPI and SPI, the mean value of optic density of Caspase-3 in old group was significantly higher than those of other two groups, but the value was the lowest in young age rat. In SPI of three groups, the expression of Caspase-3 was significant higher than that of SNPI. The ratio of SPI/SNPI in young age rats was significantly higher than those of other two groups, but no significant difference of this ratio was found between middle and old age rats. 3.Western blotting reavealed that the expression of Caspase-3 is basically coincident with the result of immunohistochemistry.In SNPI, the ratio of Bax/Bcl2 in old and middle-age rats were significant higher than that of young group( P < 0.05), but there was no significant difference between middle-age and old group ( P >0.05). In SPI, the ratio of Bax/Bcl-2 in old group and middle-age group was significantly higher than that of young group( P < 0.05), but there was no significant difference between them.The ratio of Bax/Bcl-2 in SPI was siginificant higher than that in the SNPI, But is was significantly increased in young group.According to above results, we make following conclusions:(1) In both SNPI and SPI, the expression of apoptosis related protein(Caspase-3,Bax/Bcl-2)show significant change with age.The expression of apoptosis related protein in old group and middle-age group are more than that of young group.(2) Pain irritation can induce spinal dorsal horn neuron apoptosis.(3) Pain irritation may affect young individuals more than middle-age and old ones in the aspects of spinal dorsal horn neuron apoptosis.