Low concentration of morphine protects against cell death, oxidative stress and calcium accumulation by nicotine in PC12 cells.

Nicotine causes cell death in many cell lines. Morphine at low concentrations has protective effects against cell death. We investigated the effects of low concentration of morphine on nicotine-induced cell death in PC12 cells. PC12 are cells that grow in DMEM culture medium. Cell viability was detected by MTT test and cells cytotoxicity was measured by LDH test. The activity of caspase-3 was diagnosed by the caspase activity colorimetric assay kit, and detection of mitochondrial membrane potential was confirmed by rhodamine 123 and TUNEL test was performed for DNA fragmentation detection. The fura-2 AM and also rhod 2-AM was used for measurement of intracellular calcium (Ca2+) ic and mitochondrial calcium (Ca2+) m and finally, measurement of antioxidant enzyme activities was assessed. The low concentration of morphine increased cell viability and suppressed cell cytotoxicity, cell death and the formation of mitochondrial membrane potential compared to nicotine treated cells.  It also reduced the intracellular calcium (Ca2+) ic and mitochondrial calcium (Ca2+)m concentration, respectively. Morphine as a pain reducer drug, in low concentrations, can protect PC12 cells from nicotine-induced cell death (Fig. 7, Ref. 59).