Message body

I click an object. The object sends a message to the brain object. The subject is “updateAmount” . The body uses the property amount… say… amt5 with a value of 5. So far so good.

Brain receives the message… looks for messages with “updateAmount” in the subject.
I dunno where to go from there.

Can we use the incoming messages “body”, which has the property… to update a “brains” property?
Can it be done using logic bricks? If not, thats ok, im just going in circles.

The body can only be read in python.