Effects of Nicotine on Human Luteal Cells In Vitro: RESULTS

RESULTS

We first investigated the effect of different doses of nicotine and M-nicotine (10—11 to 10—6 M) on progesterone release by human luteal cells cultured for 24 h. Both substances significantly reduced progesterone production compared to control. As shown in Figure 1, nicotine was able to significantly reduce progesterone production at all tested concentrations in a dose-dependent manner. A similar effect was seen when cells were treated with M-nicotine: The progesterone production was significantly reduced by this metabolite at all tested concentrations in a dose-dependent manner (Fig. 2). The negative effect exerted by both substances was in the same power range. However, neither nicotine nor M-nicotine at any tested concentration was able to affect the stimulatory effect of hCG (25 ng/ml) on luteal steroidogenesis (Fig. 3). The hCG treatment used (25 ng/ ml) represents the lowest concentration able to significantly stimulate progesterone production, as we have demonstrated previously.

The next step was to evaluate the effect of nicotine and its metabolite (10_11 to 10_6 M) on production of PGs. As shown in Figure 4, all tested doses of both substances were able to increase significantly PGF2a release by the cells; in particular, a steady-state level was reached with the lowest nicotine concentration (10_11 M), because no significant variation in PGF2a medium content was observed in the presence of higher nicotine doses. However, the effect of M-nicotine on the PG release was dose-related, and its stimulatory effect was slightly more potent than that of nicotine. canadian family pharmacy online

On the other hand, both alkaloids were able to decrease PGE2 release by luteal cells, following a trend similar to that previously described for PGF2a increase. In fact, nicotine significantly inhibited PGE2 release at all tested doses without a dose-dependent trend, whereas M-nicotine significantly inhibited PGE2 release in a dose-dependent manner (Fig. 5).

Finally, we tested the possibility for both substances to affect VEGF expression in cultured human luteal cells. As shown in Figure 6, nicotine was able to increase significantly the expression of VEGF in our cells. Interestingly, this effect was similar to that exerted by hCG, a powerful inducer of VEGF mRNA expression in this cell type. However, M-nicotine did not exert any effect.
Fig1Effects of Nicotine on Human-1
FIG. 1. Dose-dependent effect of nicotine on progesterone release by human luteal cells. Data are expressed as the mean percentage increase ± SEM of progesterone production with respect to control (CTR). Significance versus CTR: **P < 0.01, ***P < 0.001.

Fig2Effects of Nicotine on Human-4
FIG. 2. Dose-dependent effect of M-nicotine on progesterone release by human luteal cells. Data are expressed as the mean percentage increase ± SEM of progesterone production with respect to control (CTR). Significance versus CTR: **P < 0.01, ***P < 0.001.

Fig3Effects of Nicotine on Human-2
FIG. 3. Effects of nicotine and M-nicotine on hCG-induced progesterone release by human luteal cells. Data are expressed as the mean percentage increase ± SEM of progesterone production with respect to control (CTR). Significance versus CTR: *P < 0.05.

Fig4Effects of Nicotine on Human-3
FIG. 4. Effects of nicotine and M-nicotine on PGF2„ release by human luteal cells. Data are expressed as the mean ± SEM. Significance versus control (CTR): *P < 0.05, **P < 0.01, ***P < 0.001.

Fig5Effects of Nicotine on Human-5
FIG. 5. Effects of nicotine and M-nicotine on PGE2 release by human luteal cells. Data are expressed as the mean ± SEM. Significance versus control (CTR): **P < 0.01.

Fig6Effects of Nicotine on Human-6
FIG. 6. Effects of nicotine and M-nicotine on VEGF mRNA expression in human luteal cells. Data are expressed as percentage increase (mean ± SD) of VEGF/GAPD expression with respect to control (CTR). Significance versus CTR: *P < 0.05.


Category: Cell

Tags: cell, corpus luteum, progesterone