title: Effects of raloxifene on voltage-dependent T-type Ca2+ channels in mouse spermatogenic cells.
abstract: Voltage-dependent T-type Ca(2+) channels have eminent roles in sperm function. In the present study, we investigated the effects of raloxifene, a selective estrogen receptor modulator, on T-type Ca(2+) channels in mouse spermatogenic cells by using both electrophysiological and molecular techniques. We found that T-type calcium currents (I(T-Ca)) were inhibited by raloxifene in a concentration-dependent manner with an IC(50) of 2.97 μM, as assessed with the patch clamp technique. Application of raloxifene at 2 μM inhibited I(T-Ca) by 54.9 ± 2.1% at -20 mV (n = 10, p < 0.05). Furthermore, raloxifene-induced inhibition of I(T-Ca) was associated with a negative shift of both the activation and the steady-state inactivation properties. The time constants of activation and inactivation were decreased, the time constant of deactivation was increased, but the time constant of recovery was not affected. In addition, the inhibitory effects of raloxifene and 17β-estradiol on I(T-Ca) were unaffected by the estrogen receptor antagonist ICI 182,780. We also found that raloxifene treatment decreased the mRNA expression of Ca(V)3.2 and Ca(V)3.3, but not Ca(V)3.1 in GC-2spd (ts) cells (mouse spermatocyte cell line), as assessed by real-time RT-PCR. Taken together, these data indicate that in mouse spermatogenic cells, raloxifene decreases I(T-Ca) independent of classical estrogen, and the mRNA expression of T-type calcium channels and therefore may affect male reproductive function.
authors.affiliation: Department of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, PR China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Liang
authors.initials: L
authors.lastname: Lu
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Gao
authors.forename: Changsong
authors.initials: C
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Cheng
authors.forename: Rong
authors.initials: R
authors.lastname: Gao
authors.forename: Hang
authors.initials: H
authors.lastname: Xiao
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020747:Calcium Channels, T-Type / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000378:metabolism; D020849:Raloxifene Hydrochloride / Q000494:pharmacology*; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology*; D013090:Spermatocytes / Q000187:drug effects* / Q000378:metabolism
chemical_list: C504883:Cacna1h protein, mouse; C534770:Cacna1i protein, mouse; D002121:Calcium Channel Blockers; D020747:Calcium Channels, T-Type; D004965:Estrogen Antagonists; D004968:Estrogens, Non-Steroidal; D012333:RNA, Messenger; D020845:Selective Estrogen Receptor Modulators; D020849:Raloxifene Hydrochloride; D004958:Estradiol