FIGURE 4.

Morphine induces the release of HSP70 in vivo and in vitro. Representative western blot images were shown in this figure. (A) Morphine induced the efflux of HSP70 into extracellular environment in SH-SY5Y cells. Supernatants were collected 12 h after morphine (200 μM) administration and measured by western blot (n = 3). (B) Morphine decreased the intracellular protein level of HSP70 in SH-SY5Y cells. Cell extracts were collected 12 h after morphine (200 μM) treatment and analyzed by western blot (n = 3). (C) Rats were subcutaneously injected with morphine (7.5 mg/kg) twice daily for 6 consecutive days. Consecutive administration of morphine induced the release of HSP70 in CSF. CSF was collected from rats 1 h after the last administration and determined by western blot (n = 6). Transferrin is used as a loading control. (D) Consecutive administration of morphine (5 mg/kg) twice daily for 7 days in mice induced the release of HSP70 in the spinal cord. The spinal samples were collected 1 h after the last morphine treated and determined by western blot (n = 4). (A–D) data were analyzed by Student’s t test (*P < 0.05, **P < 0.01, ***P < 0.001 vs. control).