[Effects of GnRH analogues on MAPK pathway in rat Leydig cells].
OBJECTIVE
To investigate the effects of GnRH analogues GnRHa and GnRHant on the MAPK pathway in rat Leydig cells.


METHODS
Rat Leydig cells were primarily cultured for 24 hours in vitro and serum-starved for 2 hours, followed by treatment with GnRHa (10(-7) mol/L) or GnRHant (10(-6) mol/L) for 0, 5, 15, 30, 60 and 90 minutes, with the 0 min group as the control. Then the protein levels of phosphorylated ERK (p-ERK) and phosphorylated p38 (p-p38) were detected by Western blot, and that of p-ERK determined by the same means after co-incubation of GnRHa or GnRHant with the PKC inhibitor GF109203X at 1, 5, 10 and 20 micromol/L.


RESULTS
After stimulation of the Leydig cells with GnRHa or GnRHant for different times, the protein level of p-p38 showed no significant difference from that of the control group (P > 0.05). Then the Leydig cells were treated with GF109203X at different concentrations for 20 minutes and with addition of GnRHa for another 10 minutes. The level of p-ERK was significantly decreased (P < 0.05) by GF109203X at 10 and 20 micromol/L. Compared with the control, the p-ERK expression was increased by 65% at 15 minutes (P < 0.05) in the GnRHant stimulation group, by 81% (to the peak) at 30 minutes (P < 0.05), began to fall at 60 minutes, and returned to the base level at 90 minutes. The p-ERK level exhibited no significant difference from that of the control (P > 0.05) after treatment of the Leydig cells with different concentrations of GF109203X for 20 minutes and then with GnRHant for 30 minutes.


CONCLUSIONS
The ERK MAPK activation induced by GnRHa depends on the PKC pathway, but not that induced by GnRHant. The p-38 MAPK pathway may not be involved in the effect of GnRH analogues on rat Leydig cells.
Liu
Hai-yan
HY
PLA Research Institute of Clinical Laboratory Medicine, Nanjing General Hospital of Nanjing Military Region, Nanjing, Jiangsu 210002, China. qzhaiyan@126.com
Wang
Da-yong
DY
Shi
Shan-shan
SS
Tao
Xiao-qian
XQ
Han
Xue-feng
XF
Lin
Chai-ying
CY
Yao
Bing
B
D000818:Animals; D002478:Cells, Cultured; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
D007987:Gonadotropin-Releasing Hormone