[Effects of ketamine, imipramine, and their combination on depression-like behaviors in Wistar Kyoto rats].

Abstract The aim of the present study was to investigate the effects of ketamine, imipramine, and ketamine plus imipramine on chronic depression-like behaviors of Wistar Kyoto (WKY) rats and underlying mechanism. Six-week-old Wistar rats were used as normal control. WKY rats, depression model animal, were injected intraperitoneally with ketamine (1 week, replaced with saline in 2(nd) week), imipramine (2 weeks), or ketamine in combination with imipramine. The depression-like behaviors were assessed by sucrose preference and forced swimming tests. Protein expressions of β form of calcium/calmodulin-dependent protein kinase type II (βCaMKII) and membrane fraction of glutamate receptor 1 (GluR1) were measured in corresponding brain tissue with Western blot. The results showed that, compared with Wistar rats, WKY rats exhibited decreased sucrose preference and extended immobility time. Ketamine alone did not affect depression-like behaviors of WKY, whereas imipramine or its combination with ketamine could significantly decrease the immobility time. Compared with Wistar rats, WKY rats showed up-regulated levels of βCaMKII and membrane GluR1 protein expressions in habenula, and down-regulated level of membrane GluR1 protein expressions in the prefrontal cortex. Imipramine or its combination with ketamine could reverse these changes of protein expressions in WKY rats. There was no difference in reversing effect between imipramine and its combination with ketamine. Ketamine alone did not affect the βCaMKII and membrane GluR1 protein expressions in the habenula, but increased membrane GluR1 protein expression in the prefrontal cortex of WKY rats. These results suggest 2-week imipramine treatment significantly improves depressive behavior in WKY rats; however, the addition of ketamine in the first week fails to enhance the effect of imipramine. The underlying mechanisms of imipramine's anti-depressive effect may be associated with the down-regulation of βCaMKII and membrane GluR1 in the habenula, as well as the up-regulation of membrane GluR1 in the prefrontal cortex.