Human interferon-α increases immobility in the forced swimming test in rats

Abstract 

Objectives: We examined the immobility of the forced swimming test induced in an animal model by human interferon (IFN), which has often been reported to induce depression in clinical use. Methods: In the present study, we examined the effects of human IFNs on results of the forced swimming test in rats. Results: Single intravenous (IV) administration of human IFN-α (6×10⁴ IU/kg), but not of human IFN-β or -γ, significantly increased immobility time in the forced swimming test in rats. Repeated administration of human IFN-α (6×10³ IU/kg) also significantly increased the immobility time. On the other hand, none of the rat IFNs (rat IFN-α, -β and -γ, 6×10⁴ IU/kg, IV) changed the immobility time. Neither human IFNs nor rat IFNs changed the locomotor activity of rats. Conclusions: These findings suggest that human IFN-α has a greater potential for inducing increase of the immobility in the rat forced swimming test than human IFN-β and -γ, and that the effect of human IFN-α might not be mediated through IFN-α/β receptors.