Tianeptine's effects on spontaneous and Ca2+-induced uterine smooth muscle contraction.

Tianeptine is a novel anti-depressant with an efficacy equivalent to that of classical anti-depressants. Additional beneficial effects include neuroprotection, anti-stress and anti-ulcer properties whose molecular mechanisms are still not completely understood but may involve changes in the anti-oxidant defence system. Herein, we have studied the effects of tianeptine on both contractile activity of isolated rat uteri and components of the endogenous anti-oxidative defence system. Tianeptine-induced dose-dependent inhibition of both spontaneous and Ca2+-induced contraction of uterine smooth muscle. The effect was more pronounced in the latter. Tianeptine treatment increased glutathione peroxidase (GSH-Px) and catalase (CAT) activities in spontaneous and Ca2+-stimulated uteri. A significant decrease in glutathione-reductase (GR) activity in both spontaneous and Ca2+-induced uterine contractions after tianeptine treatment indicated a reduction in reduced glutathione and consequently a shift toward a more oxidised state in the treated uteri. In spontaneously contracting uteri, tianeptine caused a decrease in copper-zinc SOD (CuZnSOD) activity. Tianeptine's anti-depressant effects may be accomplished by triggering a cascade of cellular adaptations including inhibition of smooth muscle contractility and an adequate anti-oxidative protection response.

Hydrogen peroxide affects contractile activity and anti-oxidant enzymes in rat uterus.

BACKGROUND AND PURPOSE: The effects of hydrogen peroxide (H(2)O(2)) on uterine smooth muscle are not well studied. We have investigated the effect and the mechanism of action of exogenous hydrogen peroxide on rat uteri contractile activity [spontaneous and calcium ion (Ca(2+))-induced] and the effect of such treatment on anti-oxidative enzyme activities. EXPERIMENTAL APPROACH: Uteri were isolated from virgin Wistar rats and suspended in an organ bath. Uteri were allowed to contract spontaneously or in the presence of Ca(2+) (6 mM) and treated with H(2)O(2) (2 microM-3 mM) over 2 h. Anti-oxidative enzyme activities (manganese superoxide dismutase-MnSOD, copper-zinc superoxide dismutase-CuZnSOD, catalase-CAT, glutathione peroxidase-GSHPx and glutathione reductase-GR) in H(2)O(2)-treated uteri were compared with those in uteri immediately frozen after isolation or undergoing spontaneous or Ca(2+)-induced contractions, without treatment with H(2)O(2). The effect of inhibitors (propranolol, methylene blue, L-NAME, tetraethylamonium, glibenclamide and 4-aminopyridine) on H(2)O(2)-mediated relaxation was explored. KEY RESULTS: H(2)O(2) caused concentration-dependent relaxation of both spontaneous and Ca(2+)-induced uterine contractions. After H(2)O(2) treatment, GSHPx and MnSOD activities were increased, while CuZnSOD and GR (In Ca(2+)-induced rat uteri) were decreased. N(omega)-nitro-L-arginine methyl ester antagonized the effect of H(2)O(2) on Ca(2+)-induced contractions. H(2)O(2)-induced relaxation was not affected by propranolol, potentiated by methylene blue and antagonized by tetraethylamonium, 4-aminopyridine and glibenclamide, with the last compound being the least effective. CONCLUSIONS AND IMPLICATIONS: H(2)O(2) induced dose-dependent relaxation of isolated rat uteri mainly via changes in voltage-dependent potassium channels. Decreasing generation of reactive oxygen species by stimulation of anti-oxidative pathways may lead to new approaches to the management of dysfunctional uteri.

The anti-oxidative defence system in the isolated rat uterus during spontaneous rhythmic activity.

Possible interactions between nitric oxide donors, reactive oxygen species and anti-oxidative defence enzymes led us to determine the activities of anti-oxidative defence enzymes in isolated uterine smooth muscle before and after spontaneous rhythmic activity ex vivo. For our experiments we used isolated uteri from female Wistar rats. Our results showed an increase in total superoxide dismutase (SOD) and Mn SOD activities in uterine smooth muscle after spontaneous contractions when compared with nonexercised uterine smooth muscle. The activity of catalase (CAT) and glutathione preoxidase (GSH-Px) were also increased. No statistically significant changes in the activities of glutathione reductase (GR) and CuZn SOD were found. It is known that an organism's anti-oxidative defence system (guarding against excessive reactive oxygen species generation) requires balanced increments in its individual anti-oxidative enzyme activities rather than increases in the activity of only some enzymes without increases in others. Thus, we may conclude that some adaptive responses are found in exercised uterine smooth muscle but are not complete. Therefore, our results indicate that changes in anti-oxidative enzyme activities may influence the results of the examination of substances ex vivo.