Nature of tissue tolerance from opiate use

I have done some research to find out the biological cause of opiate addiction/withdrawl, and I would appreciate it if you would share your understanding with me.  I have read that the level of endogenous opiates (endorphins and such...) decreases with continued use of narcotic opiates, thus leaving you with "opiate receptor deficiency syndrome" from which you feel anxiety and joint pain and other symptoms.  This can be quickly reversed through a naloxone treatment in which all of your opiate receptors are blocked by the naloxone for a few hours thus jump-starting your body's endorphin producing centers.  Is all this correct?  And if so, how long does it take for someone's endorphin level to reach the levels at which they existed before addiction (i.e. how long until you no longer have joint pain and low energy)?  And, of what other biological basis for opiate addiction are you aware?    Thank you for your time!