Objective To explore how and where ski expresses under lipopolysaccharide (LPS) in rats' astrocytes. Methods Astrocytes were obtained from cerebral cortex of a newborn (within 3 days) Sprague-Dawley rat and cultured in vitro. Astrocytes were cultured with LPS in concentration of 0μg/ml, 0.001μg/ml, 0.01μg/ml, 0.1μg/ml, 1μg/ml, 10μg/ml and 100μg/ml for six hours;and cultured with LPS in concentration of 0.1μg/ml for 0 day, 2 days, 4 days, 6 days and 8 days. The level of ski was determined with Western blotting, and the lo-cation of ski was detected with indirect immunofluorescent staining. Results The expression of ski was induced by LPS, especially in the concentration of 0.1μg/ml. The expression of ski induced with 0.1μg/ml LPS peaked at 4 days of inducement and then decreased. Ski was mainly observed in nuclear in the normal astrocytes and the astrocytes induced with 0.1μg/ml LPS for 6 days. However, it was observed in cytoplasm 2 and 4 days of inducement. Conclusion LPS could induce the expression of ski in rats' astrocytes, which may participate in in-flammation.

Spinal edema is a very important pathophysiological basis for secondary spinal cord injury,which affects the repair and prognosis of spinal cord injury.Aquaporin-4 is widely distributed in various organs of the body,and is highly expressed in the brain and spinal cord.Inward rectifying potassium channel 4.1 is a protein found in astrocytes of central nervous system.It interacts with aquaporins in function.Aquaporin-4 and inward rectifying potassium channel 4.1 play an important role in the formation and elimination of spinal cord edema,inhibition of glial scar formation and promotion of excitotoxic agents exclusion.The distribution and function of aquaporin-4 and inward rectifying potassium channel 4.1 in the central nervous system and their expression after spinal cord injury have multiple effects on spinal edema.Studies of aquaporin-4 and inward rectifying potassium channel 4.1 in the spinal cord may provide new ideas for the elimination and treatment of spinal edema.

Objective To investigate the effect of Ski on the secretion of inflammatory cytokines from activated astrocytes. Methods Astrocytes were obtained from cerebral cortex of a three-day old Sprague-Dawley rat and cultured in vitro. They were divided into blank group, control group and siRNA group. The Ski gene was silenced in siRNA group. The expression of Ski was tested with Western blotting and immunofluorescence 48 hours later. Then the astrocytes were stimulated with lipopolysaccharide for 24 hours. The secretion of tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) in activated astrocytes was detected with ELISA. Results The expression of Ski protein reduced in the siRNA group (P<0.001), as well as the secretion of TNF-α and IL-1β (P<0.001). Conclusion Ski may play a role in inflammatory response of astrocyte.

Objective To explore the expression and the changes of microtubule, aquaporin-4 (AQP4) and potassium ion channel 4.1 (Kir4.1) after spinal cord injury in rats.Methods Ninety female adult Sprague-Dawley rats were randomly divided into sham operation group (n=30) and injury group (n=60). The injury group was divided into six hours, one day, three days, five days and seven days subgroups, with twelve rats in each subgroup. Spinal cord injury at T10 was established with modified Allen's method (20 g×25 mm) in the injury group. The water content of spinal cord was measured at each time point after injury. Then, the pathology was observed with HE staining, the expression of α-Tubulin, AQP4 and Kir4.1 was detected and analyzed with immunohistochemical staining and Western blotting.Results The water content of the spinal cord was higher in the injured group than in the sham operation group (P<0.05), and was highest on the fifth day. HE staining showed that the gray matter hemorrhage at six hours after injury; one day after injury, the gray matter bled seriously, and neuron swelling was aggravated; three days after injury, the area of gray matter necrosis increased, and the edema phenomenon was obvious; five days and seven days after injury, the gray matter necrosis and the edema phenomenon were more serious. Western blotting and immunohistochemistry showed that the expression of AQP4 gradually increased after injury, and raised at peak on the fifth day; the expression of α-Tubulin and Kir4.1 was similar, and the expression gradually decreased after injury, especially on the fifth day.Conclusion The expression of α-Tubulin and Kir4.1 is similar after spinal cord injury, and is contrary to the expression of AQP4. α-Tubulin, AQP4 and Kir4.1 may be related after injury and may participate in the formation of spinal cord edema.