| 摘要: | Our previous study demonstrated that FSH-induced immediate
Ca2 influx in rat Sertoli cells (SCs) is mediated by the
Gh/phospholipase C-1 (PLC-1) signaling pathway. As to
which Ca2 channel is responsible for such Ca2 influx was
not understood. In this study, thapsigargin triggered an instore
calcium release and evoked a 1.5-fold elevation of intracellular
Ca2 in Ca2-free media, whereas FSH exhibited no
effect. The readdition of CaCl2 (2.5 mM) to FSH-pretreated or
thapsigargin-sensitized SCs in Ca2-free media immediately
elicited a rapid Ca2 influx or a 2-fold increase of second
intracellular Ca2 elevation, respectively. The addition of
Ca2 chelator EGTA (0.2 mM) reduced the FSH-induced elevation
of intracellular Ca2 in SCs incubated with CaCl2.However,
pretreatment with dantrolene (25 M), which inhibits
in-store calcium release, did not affect the FSH-induced elevation
of intracellular Ca2. NiCl2 (10 M), a T-type calcium
channel blocker, abolished the FSH-induced SC Ca2 influx.
Furthermore, mibefradil (10 and 100 M), another specific
blocker for T-type Ca2 channels, dose-dependently suppressed
the FSH-induced Ca2 influx. In contrast, nifedipine
(10 and 50 M) or -conotoxin GVIA (100 and 500 nM), blocker
of L- or N-type Ca2 channels, respectively, did not affect the
FSH-induced SC Ca2 influx. On the other hand, FSH-induced
Ca2 influx was significantly reduced by pretreatment of SCs
with myristoylated synthetic peptide (0.1 and 1 M) of PLC-1
fragment TIPWNSLKQGYRHVHLL but not affected by 2,5-
dideoxyadenosine (3 and 15 M), a selective inhibitor of adenylate
cyclase. In conclusion, the FSH-induced Gh/PLC-1
pathway-dependent Ca2 influx of rat SCs is mediated by Ttype
Ca2 channels and independent of in-store calcium
release. |
