The Protection Of Ketamine On Spinal Cord Dorsal Horn Astrocytes Of Wistar Rats

Objective To observe the effect of ketamine on the apoptosis and changes of the intracellular calcium concentration([Ca²+]i), Bcl-2 and Bax, interleukin-1 peptide(IL-l β ), tumor necrosis factor- α (TNF α ) and interleukin-10( IL-10), malondialdehyde(MDA) and superoxide dismutase(SOD) in rat cultured spinal cord dorsal horn astrocytes under N-methyl-D-asparate(NMDA) receptor over activation-induced conditioned to discuss the protective mechanism of ketamine anti-injury on the cells.Methods Astrocytes were derived from T₁1-L₆ spinal cord dorsal horn of 2-3 day old Wister rat. After cultured for two weeks, they were treated with following six conditions: (1) sham wash with Hanks solution (control group-C); (2) 100 μM of NMDA (NMDA group-N); (3) 100 μM of ketamine (ketamine group-K); (4-6) 100 μM of NMDA was added and 10 min later, ketamine at 10, 50 or 100μM was superposed respectively (group NK1-NK3). After 24 hrs or 30 min treatments, the concentrations of IL-1β ,TNFα and IL-10 in culture medium and the contents of MDA and activity of SOD intracellular were measured. The expression of Bcl-2 and Bax were detected with immunostaining, the apoptosis and [Ca²+]i were analyzed with flow cytometer.Results Apoptotic cell death was significantly increased in Group N compared with Group C (25+/-6 vs 6 +/- 2, p < 0.01).The [Ca²+]i and concentrations of IL-1β and TNFα were significantly increased, but the IL-10 remained low , the content of MDA was significantly increased and the activity of SOD was marketly attenuated in Group N compared with those in Group C; The Bax expression was positive but the expression of Bcl-2 was negative in Group N. The apoptotic astrocytes, the [Ca²+]i and concentrations of IL-1β and TNFα were significantly lower,but the IL-10 was greatly higher , the contents of MDA were significantly lower and the activity of SOD significantly increased in the NK3 group than in Group N; The expression of Bcl-2 was significantlypositive and the Bax expression was negative in the NK3 group compared with Group N. No effect of ketamine itself at lOOuM was found.Conclusions Overactivated NMDA receptors can lead to the intracellular Ca2+overload and induce cellular apoptosis or injury in rat cultured spinal cord dorsal horn astrocytes. Ketamine at 100 \iM inhibits such apoptosis cell death and the activation. Its anti-injury mechanisms may be explained by the intracellular Ca2+overload inhibited, Bcl-2 expression increase meanwhile Bax expression decrease, the synthesis and release of DL-10 increase as well as IL-1J5 and TNFa decrease, and oxygen free radcial attenuation and reinforcement activity of SOD.