Developmental expression of Bcl-2 protein in human cortex

Apoptosis is essential for normal human neurodevelopment and is increasingl y recognized for its role in various neurodegenerative diseases such as Alz heimer's and Parkinson's diseases. Bcl-2 is a 26 kDa membrane-associated pr otein known to protect neurons against apoptosis. Interestingly, Bcl-2 prot ein levels are altered in certain neurodegenerative disorders that reveal i ncreased apoptosis. However, little is known about the normal expression of Bcl-2 protein in human brain. Bcl-2 protein levels were determined by ELIS A and semiquantitative Western Blotting in the frontal cortex of 20 human p ost-mortem brains, separated into three groups: six infants (age. 0.83 +/- 1.0 years, mean +/- S.D.), five adolescents (age: 17.4 +/- 1.7 years), and nine adults (age: 41.0 +/- 9.6 years). All subjects died of non-CNS related illness and had no history of psychiatric illness. Bcl-2 increased signifi cantly across the age groups in the ELISA (p = 0.0058) and the Western Blot (p = 0.002) experiments. The ELISA demonstrated significant differences in Bcl-2 levels between infant and adolescent cortex (p < 0.05), and between infant and adult cortex (p < 0.01) using a post-hoc Tukey's multiple compar ison test. The Western blots demonstrated a similar significant increase in Bcl-2 between infant and adult cortex (p < 0.01). A secondary analysis sho wed significant correlation between individual ages and Bcl-2 levels (r(2) = 0.4933, p = 0.0006). This study demonstrates that Bcl-2 protein expressio n in human cortex is developmentally regulated and supports the hypothesis that Bcl-2 is involved in normal aging. (C) 2000 Elsevier Science B.V. All rights reserved.