RESUMO
Cerebrospinal fluid (CSF) was withdrawn from opiate-dependent rats following six hours of abstinence. It was infused into the third ventricle of opiate-dependent rats, precipitating immediate abstinence signs. The effect was similar to that of infusing the opiate antagonist naloxone, suggesting that opiate-dependent organisms may secrete an endogenous opiate antagonist substance. CSF withdrawn from non-dependent rats failed to precipitate an abstinence syndrome in morphine-dependent recipients. Conversely, CSF withdrawn from opiate-dependent rats following six hours of abstinence failed to precipitate an abstinence syndrome in non-dependent recipients. The active factor in the CSF is probably a peptide since it is filterable through a 10,000 MW filter and its activity is destroyed by three different proteolytic enzymes.
