[Effect of leptin on growth hormone secretion and apoptosis of GH3 cells]

In order to investigate the effect of leptin on the secretion of rat pituitary adenoma GH3 cell and its mechanisms, we observed the effect of leptin on the growth hormone secretion, proliferation and apoptosis of GH3 cells. The results indicated that leptin at 1, 10, and 100 nmol/L could inhibit the basal growth hormone secretion of GH3 cells in a dose dependent manner (P<0.05). Short-term treatment of leptin (10 nmol/L) for 30 min, 1 and 3 h did not affect basal GH secretion. However, treatment of the GH3 cells with leptin (10 nmol/L) for 1 d or longer resulted in an inhibition of GH secretion (P<0.05). We used MTT method and flow cytometery (FCM) to study the effect of leptin on the proliferation and apoptosis of GH3 cells. We found that leptin inhibited proliferation of GH3 cells with a dose-dependent manner. And leptin reduced the proportion of cells in S phase, increased the proportion of cells in G1, and increased the proportion of GH3 cells in 2 and 4 phase. These results demonstrate that leptin inhibits the basal GH secretion of GH3 cells, which may be due to the inhibition of DNA synthesis and advanced apoptosis of GH3 cells.