I don't think levels of B-tubulin changes in different brain regions since it is a house keeping gene. I am however not sure as to what happens to the levels in pathological condition. Did you check if your transfer was 100% accurate and also using x-ray film has its own limitations.

i am using ECL for developing. So have you ever faced this problem?

There are only two chances a) your bradford was not accurate b) your western is not accurate. (Frankly speaking both of them are not accurate). How different are the band sizes of your tubulin control? if it is a lot, you can run another gel by normalising for the tubulin signals by approximation.

I am trying that.thanks

Let me know how it goes. Cheers.