EFFECTS OF MORPHINE ON MUSCARINIC RECEPTO RS IN LIMBIC SYSTEM IN ACUTE ADJUVANT-INDUCED ARTHRITIC RATS

To induce arthritis, the adjuvant with heat-killed Mycobacterium tuber culosis was injected into the ankle joint in rats. Local redness, swel ling, hotness, pain, and motor dysfunction of the inflammed joint (as well as mental dullness) were observed 48 h after inoculation. At this time, the maximal binding capacity (B(max)) of muscarinic receptors i n limbic system was increased, while the dissociation constant (K(d)) was unchanged. Injection of morphine (5 mg.kg-1) 3 times within 48 h a fter the inoculation resulted in a decrease of B(max) and an increase of K(d) of M-receptors, together with diminution of pain and disappear ance of dullness.