Zoletil promotes apoptosis in BV-2 microglial cells via induction of oxidative stress and neural inflammation.

Zoletil® (ZOL) is a combination drug of tiletamine, a dissociative anesthetic and zolazepam, a minor tranquilize, which has been used to induce short-term anesthesia in various animals. Depending on the administered dose, the effects of ZOL can range from sedation to anesthesia. Here, we aimed to determine the neurotoxicity of ZOL and elucidate its mechanism of action using BV-2 microglial cells. The results of MTT reduction assay and TUNEL staining revealed that ZOL induced neuronal toxicity and apoptosis in BV-2 cells. ZOL caused apoptosis via phosphorylation of c-Jun N-terminal kinase, increased ratio of Bax to Bcl-2, disruption of mitochondrial membrane potential, activation of caspase-3, and cleavage of poly (ADP-ribose) polymerase. Furthermore, reactive oxygen species were involved in ZOL-induced neuronal cell death as assessed by 2',7'-dichlorofluorescein diacetate staining. Moreover, BV-2 cells treated with ZOL exhibited increased expression of inflammatory enzymes, such as inducible nitric oxide synthase and cyclooxygenase-2, along with subsequent production of nitric oxide and prostaglandin E2. ZOL upregulated the expression of interleukin-1β, a proinflammatory cytokine. With respect to its molecular mechanism, ZOL increased the nuclear translocation and DNA binding of redox-sensitive transcription factor NF-κB, which seemed to be mediated by activation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase. These findings suggest that ZOL leads to apoptosis in BV-2 cells by inducing oxidative stress and inflammatory responses.