Determining short-term effects on the activity of antioxidant enzymes in the rat uterus: the example of ibogaine

Abstract

The anti-addiction agent ibogaine interacts with different types of neural transmitter receptors, but also decrease cellular ATP level, followed by increased cellular respiration and production of reactive oxygen species, which change redox homeostasis. We wanted to investigate the effects of single dose of 1 or 20 mg/kg body weight of ibogaine (dose range commonly used for therapeutic purposes) on activity of antioxidant enzymes (SOD1 and SOD2, catalase - CAT, glutathione peroxidase - GSH-Px, glutathione reductase - GR and glutathione S transferase - GST) in rat uterus, 6 and 24 h after treatment. Three month-old virgin female rats were treated per os while in estrus phase of estrous cycle (determined by examination of vaginal smear). A problem in this experimental design was that activity of antioxidant enzymes changes during the estrous cycle (SOD2 activity is lower, GSH-Px and GR activities are higher in estrus compared to metestrus). Since estrus phase lasts 15–24 h, the female rats treated in estrus, after 6 h will still be in estrus, in most cases, but after 24 h they will be in metestrus. Therefore we used two approaches for 6 h treatment. First, females were treated immediately upon completion of vaginal smear, and sacrificed 6 h later (in the time of treatment they were in estrus phase). The others were treated with a delay of 18 h, and sacrificed 6 h later, so that in the time of sacrifice, they were in the same phase as the 24 h group (metestrus). The dose of 20 mg/kg has lowered CAT activity, but, in general, canonical discriminant analysis shows that the phase of the estrous cycle in the time of sacrifice has a greater impact than a dose of ibogaine. Thus, selection of the phase of the cycle, appropriate control groups and statistical model are of crucial importance in order to distinguish the effects of treatment from the effects of estrous cycle phase changes.