Effect of leptin on growth hormone secretion and apoptosis of GH3 cells / 生理学报

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.

Three subtypes expressions of leptin receptor in the rat anterior pituitary and influence of leptin on intracellular free Ca2+ of the rat growth hormone cell / 中国应用生理学杂志

<p><b>AIM</b>To observe the expression of Leptin receptors (OB-R) in male rat anterior pituitary, and study the influence of Leptin on the level of intracellular free Ca2+ ([Ca2+]i) in the cultured growth hormone (GH) cell of male rat pituitary.</p><p><b>METHODS</b>RT-PCR method was used to observe the expression of Leptin receptors (OB-R) in male rat anterior pituitary. We used grade centrifuging method to get growth hormone (GH) cell, and [Ca2+]i in GH cell was examined by laser scanning confocal system.</p><p><b>RESULTS</b>OB-R mRNA were expressed in male rat anterior pituitary, including OB-R (common form), OB-Ra (short form) and OB-Rb (long form). There were about 70% or 80% GH cell by grade centrifuging. Leptin at 10(-8)mol/L could decrease the level intracellular free Ca2+ ([Ca2+]i) in cultured GH cell.</p><p><b>CONCLUSION</b>There are three subtypes of Leptin receptors expressions in male rat anterior pituitary, and Leptin could reduce intracellular free Ca2+ level of GH cell markedly.</p>

Expression of estrogen receptors alpha and beta in human tongue squamous cancer cell and influence of beta-estradiol on the proliferation of tongue cancer cell / 中国应用生理学杂志

<p><b>AIM</b>To observe the expression of estrogen receptors alpha and beta in human tongue squamous cancer line Tca8113 cell, and to study the influence of beta-estradiol (beta-E2) on the proliferation and cell cycle of cultured Tca8113 cell.</p><p><b>METHODS</b>Immunocytochemistry and RT-PCR methods were used to observe the expression of estrogen receptors (ER) in human tongue squamous carcinoma line Tca8113 cell. 3H-TdR incorporation and cell cycle analysis were used to examine the change of proliferation and DNA synthesis of Tca8113 cell.</p><p><b>RESULTS</b>ER-alpha and ER-beta mRNA were expressed in human tongue squamous cancer cell, and the expression of ER-beta was weaker than that of ER-alpha. beta-Estradiol at 10(-8) mol/L - 10(-6) mol/L could increase the proliferation of human tongue squamous carcinoma cell in a dose dependent manner (P < 0.01). beta-E2 (10(-6) mol/L) could increase the proportion of cells in S phase and G2 phase from 23.5% up to 37.7%. The effect of estradiol on the proliferation of cultured human tongue squamous cancer line Tca8113 cell could be inhibited by Tamoxifen.</p><p><b>CONCLUSION</b>There are ER-alpha and ER-beta expression in human tongue squamous cancer line Tca8113 cell, and beta-estradiol promotes the proliferation and cell cycle of cultured human Tca8113 cell.</p>

Influence of ACh on the level of protein kinase C, intracellular free Ca(2+) and cyclic AMP/cyclic GMP of cultured human pituitary adenoma cells / 生理学报

We found previously that ACh can significantly inhibit the proliferation of cultured human pituitary adenoma cells. In order to make a further investigation of the mechanism of the inhibitory effect of ACh on the proliferation of pituitary adenoma cells, we observed the levels of protein kinase C (PKC), [Ca(2+)](i) and cAMP/cGMP in cultured pituitary adenoma cells after treatment with ACh. The results demonstrate that (1) compared with control, PMA, a PKC activator, increased the activity of cytoplasm, membrane and total PKC in human pituitary adenoma cells. However, after a 15-min treatment with ACh (10 micromol/L), a significant reduction of the activity of cytoplasm, membrane and total PKC in human pituitary adenoma cells was observed, and the reduction effect could be blocked by atropine. (2) The level of [Ca(2+)](i) of single adenoma cells was found to decrease immediately on the addition of ACh (10 micromol/L), which could also be blocked by atropine. (3) ACh increased the amount of cAMP in the cytoplasm of human pituitary adenoma cells, but had no effect on that of cGMP. These data provide an important clue to explore the molecular mechanisms of the inhibitory effect of ACh on the proliferation of pituitary adenoma cells, and suggest that the modulating effect of ACh on the proliferation of pituitary adenoma cells results from the interactions of several cellular signaling pathways.

The effect of acetylcholine on the proliferation and apoptosis of three kinds of cultured human pituitary adenoma cells / 生理学报

In order to elucidate the effect of acetylcholine (ACh) on the occurrence and development of human pituitary adenoma, it was firstly observed whether there exists choline acetyl transferase (ChAT) which is necessary for the synthesis of acetylcholine in the cells of human pituitary adenoma, and then MTT method, (3)H TdR incorporation, cell cycle analysis and TUNEL were employed to estimate the influence of ACh on the proliferation, DNA synthesis and apoptosis of three kinds of human pituitary adenoma (human prolactinoma, somatotropinoma and non-functional tumor) cells cultured in vitro. The results showed that (1) the positive staining of ChAT was obviously observed in the cells of the three kinds of human pituitary adenoma, however, it was lower than that in normal human pituitary gland; (2) ACh had a similar effect on the proliferation of the three kinds of human pituitary adenoma cells. ACh at 0.1-10 micromol/L decreased the (3)H TdR incorporation and the MTT A value in a dose-dependent manner. At the same time, ACh decreased the ratio of S or G(2) phase pituitary adenoma cells significantly, but increased the ratio of G(1) phase pituitary tumour cells markedly; (3) the effect of acetylcholine on the proliferation of human pituitary adenoma cells was inhibited by atropine, but not by tubocurarine; (4) ACh had no effect on the apoptosis of human pituitary adenoma cells cultured in vitro. These data suggest that ACh may have a significant modulating effect on the proliferation of pituitary adenoma cells by means of paracrine or autocrine, and the effect is mediated by muscarinic receptor.