Thymol-evoked Ca 2+ Mobilization and Ion Currents in Pituitary GH 3 Cells

• Published in: Natural product communications Vol. 4; no. 6
• Main Authors: Shen, Ai-Yu, Huang, Mei-Han, Wang, Trey-Shy, Wu, Hui-Ming, Kang, Ya-Fei, Chen, Chi-Lan
• Format: Journal Article
• Language: English
• Published: 01.06.2009
• ISSN: 1934-578X; 1555-9475
• DOI: 10.1177/1934578X0900400601

In this study, an attempt was made to elucidate the effects of thymol, a monocyclic phenolic compound, on Ca 2+ mobilization and ion currents in pituitary GH 3 cells with the aid of fura-2 fluorimetry and the whole-cell voltage-clamp technique. Thymol increased intracellular Ca 2+ concentrations ([Ca 2+ ] i ) in GH 3 cells loaded with Ca 2+ -sensitive dye fura-2. Removing extracellular Ca 2+ reduced the thymol-induced [Ca 2+ ] i rise. In Ca 2+ -free solution, thymol-evoked [Ca 2+ ] i rise was unchanged by depleting the Ca 2+ store with thapsigargin (1 μM), while the thapsigargin-induced [Ca 2+ ] i rise was reduced by pretreatment with thymol. These results imply that the Ca 2+ stores depleted by thymol comprise thapsigargin-sensitive and thapsigargin-insensitive pools. In addition, after depletion of the internal Ca 2+ store with 100 μM thymol in Ca 2+ -free solution, a subsequent application of Ca 2+ greatly induced a [Ca 2+ ] i increase. The results indicate that, similar to thapsigargin, 100 μM thymol may activate the capacitative calcium entry (CCE) channel. However, thymol (100 μM) had a slight depressant action in L-type calcium current ( I CaL ). The stimulatory actions of thymol on Ca 2+ signaling may partly be responsible for the underlying cellular mechanisms through which it affects neuroendocrine functions.