Blocking T-type calcium channels disrupts spermatogenesis in vivo and adversely affects spermatocytes in vitro by
Xiuling Zhao1, Lei Wang1, Shiqin Huang1
1Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, Jiangsu 226019, China.
Abstract:
T-type calcium channels are pivotal in spermatogenesis. To evaluate the molecular mechanisms by which T-type calcium channels regulate spermatogenesis, we constructed animal and cellular models using T-type calcium channel inhibitor flunarizine (FNZ). Intraperitoneal administration of FNZ (30 mg/kg) significantly impaired sperm motility, inhibited testicular germ cell proliferation, and disrupted sperm mitochondrial function in male mice. FNZ, at concentrations of 7.5 μM, 15 μM, and 30 μM, significantly inhibited mouse spermatocyte (GC-2) cells proliferation. The detrimental effects of FNZ were mediated through the disruption of calcium homeostasis, mitochondrial dysfunction, and the induction of apoptosis. Moreover, FNZ exposure resulted in the accumulation of autophagosomes and an upregulation of P62 protein, which is implicated in autophagic degradation. Notably, the autophagy activator Rapamycin (Rapa) was found to mitigate FNZ-induced cellular damage in GC-2 cells by enhancing autophagy process. Conversely, chloroquine (CQ), an autophagy inhibitor that disrupts lysosomal degradation, corroborated the role of FNZ in autophagy modulation. Our results indicate that FNZ induces mitochondrial damage, impairs sperm motility and spermatocyte proliferation, and is accompanied by obstacles to autophagic flux.
Insights
Flunarizine impairs male fertility by damaging sperm and inhibiting germ cell proliferation. This drug disrupts calcium balance and autophagy, crucial processes for sperm development and function.
Area of Science:
- Reproductive Biology
- Cell Biology
- Pharmacology
Background:
- T-type calcium channels are essential for spermatogenesis.
- Understanding their regulation is key to male reproductive health.
Purpose of the Study:
- To investigate the molecular mechanisms of T-type calcium channels in spermatogenesis.
- To evaluate the effects of the T-type calcium channel inhibitor flunarizine (FNZ) on male reproductive function.
Main Methods:
- Animal models (male mice) and cellular models (GC-2 spermatocyte cells) were used.
- Flunarizine (FNZ) was administered to mice and cells at various concentrations.
- Effects on sperm motility, germ cell proliferation, mitochondrial function, calcium homeostasis, apoptosis, and autophagy were assessed.
- Autophagy modulators Rapamycin (Rapa) and chloroquine (CQ) were employed.
Main Results:
- FNZ administration significantly impaired sperm motility, testicular germ cell proliferation, and mitochondrial function in mice.
- FNZ inhibited GC-2 cell proliferation in a dose-dependent manner.
- FNZ disrupted calcium homeostasis, induced mitochondrial dysfunction, apoptosis, and accumulation of autophagosomes.
- FNZ upregulated P62 protein, indicating impaired autophagic flux.
- Rapamycin mitigated FNZ-induced damage, while chloroquine confirmed FNZ's role in autophagy modulation.
Conclusions:
- Flunarizine negatively impacts male reproductive parameters by damaging sperm and inhibiting spermatocyte proliferation.
- FNZ-induced cellular damage is linked to disrupted calcium homeostasis, mitochondrial dysfunction, and impaired autophagy.
- Targeting autophagy may offer therapeutic strategies for conditions involving T-type calcium channel dysfunction in spermatogenesis.
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