Effect of Lithium on Swim Stress-Induced Antinociception in Naïve Mice and Mice with Subchronic Administration of Morphine or Swim Stress in Formalin Test

Background: Lithium has been shown to relieve mania and induce antinociception. In the present study, swim stress at 8°C induced antinociception in both phases of the formalin test. Intraperitoneal administration of lithium chloride (LiCl) (0.05, 0.25, and 0.5 mg/kg) also induced antinociception in both phases of the formalin test. Methods: Antinociception was assessed by the formalin test method. Swim stress was achieved in the 8°C water in a container 5 cm in diameter and 20 cm tall filled with water do a depth of 11 cm. Results: The drug (0.5 and 5 mg/kg) potentiated swim stress-induced antinociception in the second phase of the test. Repeated exposure to water swimming stress with a period of 40 sec, once daily for three days, in combination with lithium chloride did not alter stress-induced antinociception in either phases of the formalin test, when swim stress-induced antinociception was tested on the fourth day. Subchronic treatment with morphine (25 mg/kg), once daily for three days, in the presence or absence of lithium chloride (5 mg/kg) did not alter swim stress-induced antinociception, either, when swim stress-induced antinociception was tested on the fourth day. Conclusion: It may be concluded that lithium chloride potentiates swim stress-induced antinociception, but the drug has no influence on the response of subchronic administration swim stress or morphine.