حاصل از تجويز مرفين در موش هاي سوري TOLERANCE بررسي اثر استرس شنا بر

In the present study, the effect of swim stress on morphine-induced tolerance was investigated in mice using formalin test. In this respect, intraperitoneal administration of different doses of morphine (3, 6, and 9 mg/kg) induced a dose-dependent antinociception in both acute and chronic phases of the formalin test. In addition, an exposure to swim stress 2 or 3 times for 3 consecutive days was performed in order to induce tolerance. This exercise decreased morphine-induced antinociception. Meanwhile, morphine administration (25 mg/kg) for 3 days in the presence of swim stress (for two to three times) potentiated tolerance induced by morphine in both phases of the formalin test. Administration of a higher dose of morphine (50 mg/kg) for 3 days in the presence of swim stress did not alter morphine-induced tolerance in both phases of the test. On the other hand, administration of the latter dose of morphine for 3 days in the absence of swim stress decreased morphine-induced antinociception in both phases of the formalin test. It can be concluded that there may be a cross interaction between morphine-induced antinociception and swim stress.