Formation of morphine tolerance in offspring of morphine-tolerant animals: neurochemical and neuroimmune correlates.

We carried out a complex physiological, neurochemical, and neuroimmunologic study of the formation of tolerance to analgetic effect of morphine and analyzed enkephalinase A activity in different brain structures and serotonin antibodies in the serum. More early development of morphine tolerance and a sharp increase in serum antibody titer was found in the offspring of morphine-tolerant rats. This points to an imbalance in the neurotransmitter system and can serve as a diagnostic marker of endogenous opioid system pathology.