| Autor: |
Miyamoto N; Laboratory of Reproductive Biology, Division of Animal Science, Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Hyogo 657-8501, Japan., Ohya A; Laboratory of Reproductive Biology, Division of Animal Science, Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Hyogo 657-8501, Japan., Duritahala; Laboratory of Reproductive Biology, Division of Animal Science, Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Hyogo 657-8501, Japan., Sakase M; Hokubu Agricultural Technology Institute, Hyogo Prefectural Technology Center for Agriculture, Forestry and Fisheries, Hyogo 669-5255, Japan., Harayama H; Laboratory of Reproductive Biology, Division of Animal Science, Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Hyogo 657-8501, Japan.; Biosignal Research Center, Kobe University, Hyogo 657-8501, Japan. |
| Abstrakt: |
This study aimed to characterize calyculin A (CL-A)-induced and thimerosal-induced hyperactivation of cryopreserved bovine spermatozoa. Hyperactivation was effectively induced by treating with 10 nM CL-A for 60 min in the presence of cyclic AMP analogs, extracellular Ca 2+ , and albumin or with 12.5 µM thimerosal briefly in the absence of these capacitation-supporting factors. Majority of the spermatozoa exhibiting CL-A-induced hyperactivation were characterized by the 3-dimensional helical movement with head rotation, higher degree of flagellar curvature, and faster beating of the flagella than those exhibiting thimerosal-induced hyperactivation of the 2-dimensional planar movement without head rotation. The CL-A-induced hyperactivation was linked to the activation of cAMP/protein phosphorylation-dependent signaling cascades and to the decreased activity of glycogen synthase kinase-3α (GSK-3α). In contrast, the thimerosal-induced hyperactivation was suppressed by pretreatment with CL-A and cyclic AMP analogs in the absence of CaCl 2 to activate cAMP/protein phosphorylation-dependent signaling cascades. Additionally, the intracellular Ca 2+ level in live sperm flagella was significantly higher in the CL-A-treated samples than in the thimerosal-treated samples. These results indicate that CL-A-induced hyperactivation of cryopreserved bovine spermatozoa is an extracellular Ca 2+ -dependent type with the 3-dimensional helical movement, which can be regulated not only by the activation of cAMP/protein phosphorylation-dependent signaling cascades, leading to a large enhancement of the intracellular Ca 2+ level, but also by the reduction in GSK-3α activity. Considering the different characteristics of thimerosal-induced hyperactivation, our results suggest that the diversity of sperm hyperactivation arises from different combinations of flagellar bending and head rotation. |
