Just because I know you're going to be a douche, here is a quote I found of him talking about it.
http://houseofbodybuilding.com/forum/index.php?topic=769.50
DP= Dave Palumbo
Dave Palumbo Q&A
QUESTION: It is my understanding that when on gear for a while your receptors clog up and if there are no more, you cannot absorb any gear you use. There for people take as much time OFF, as they have been ON.
Is this true? I have done a few cycles over the past few years, and I feel that my OFF time has been quite short. I recently took 6 weeks OFF, after quite a long cycle, and I'm curious as to the reality of all this receptor talk.
DP: Steroidal receptors are found in the nucleus of cells. When stimulated, they signal the cell to increase protein synthesis and increase the amount of muscle volume. A good analogy to help you visualize what's going on is to imagine that steroidal compounds are specific "keys" that fit into various nuclear receptors (the "keyholes'). Once this steroidal molecule unlocks the receptor, protein synthesis is stimulated. What happens when high amounts of anabolic steroids are utilized for long periods of time is that the NUMBER of receptors (keyholes) diminishes because the body is preventing itself from being overstimulated, and even though you still have lot of anabolic substance present (keys), they can't "work" to maximize protein synthesis because of the lack of these receptors. When you go OFF cycle, the body doesn't know that you're now lacking anabolic hormones. It thinks there aren't enough receptors present and thus it starts to upregulate (increase) the number of steroidal receptors.