Can programmed cell death be induced in post-ejaculatory bull and stallion spermatozoa?
Abstract: Apoptosis is common during spermatogenesis. Here, it was tested whether apoptosis could be induced in sperm after ejaculation. There were several lines of evidence to indicate that sperm are resistant to induction of apoptosis. First, incubation of bull sperm at temperatures characteristic of normothermia (38.5 degrees C) or heat shock (40 and 41 degrees C) for 4h did not increase the proportion of sperm positive for the TUNEL reaction. There was also no reduction in mitochondrial polarity caused by exposure to 40 or 41 degrees C. Incubation at 38.5 degrees C (least-squares mean+/-SEM=4.0+/-1.4%), 40 degrees C (6.2+/-1.4%), and 41 degrees C (7.0+/-1.4%) for 24h did increase the proportion of sperm that were TUNEL positive slightly as compared to non-incubated control sperm (1.0+/-1.4%). However, the increase in TUNEL labeling was not affected by incubation temperature and occurred even in the presence of the group II caspase inhibitor, z-DEVD-fmk. In addition, exposure of bull sperm to carbonyl cyanide 3-chlorophenylhydrazone (CCCP), which depolarizes mitochondrial membranes, did not increase TUNEL labeling. Stallion sperm were also resistant to increased TUNEL labeling in response to incubation at 41 degrees C for 4h or exposure to CCCP. Western blotting was performed to determine whether failure of induction of apoptosis was due to aberrant caspase activation. Procaspase-9 was detected in bull sperm, but cleavage to caspase-9 was not induced by short-term aging at 38.5, 40, or 41 degrees C, or exposure to CCCP. Procaspase-3 was not detected in bull spermatozoa. In conclusion, post-ejaculatory bull and stallion sperm were resistant to induction of apoptosis; this resistance, at least in bulls, was due to refractoriness of mitochondria to heat shock-induced depolarization, lack of activation of procaspase-9, and an absence of procaspase-3.
Publication Date: 2009-01-25 PubMed ID: 19171374DOI: 10.1016/j.theriogenology.2008.12.006Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- Non-P.H.S.
Summary
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The research article looks into the ability to induce apoptosis, or programmed cell death, in sperm of bulls and stallions after ejaculation. It concludes that these sperm types are resistant to this process, potentially explained by the refractoriness of mitochondrial behavior, lack of activation of a specific enzyme, procaspase-9, and the absence of another enzyme, procaspase-3.
Methodology of the Research
The researchers conducted several tests on bull and stallion sperm, including:
- Incubation of bull sperm at typical body and high temperatures (38.5, 40 and 41 degree Celsius) for four hours.
- Detection of the sperm’s reaction (TUNEL reaction) to these conditions and any subsequent temperature-induced reduction in mitochondrial polarity.
- Comparing increments in TUNEL labels or tags on bull and stallion sperm exposed to carbonyl cyanide 3-chlorophenylhydrazone (CCCP), a compound that depolarizes mitochondrial membranes.
- Examination of the presence and activation of specific enzymes (procaspase-9 and procaspase-3) in bull sperm, considered markers of apoptosis, under the different conditions.
Key Findings of the Research
Based on the tests conducted, the researchers found that:
- There was no significant increase in apoptosis evidenced by TUNEL reactions after exposure to normothermia and heat shock conditions of 38.5, 40 and 41 degree Celsius.
- There was no decrease in mitochondrial polarity when exposed to 40 and 41 degrees Celsius.
- Long term incubation for 24 hours at various temperatures did increase TUNEL labeling, though only slightly and not affected by the temperature.
- Increased TUNEL labeling also occurred despite the presence of a group II caspase inhibitor, z-DEVD-fmk, indicating resistance to apoptosis.
- Exposure to CCCP, did not significantly increase TUNEL labels for both bull and stallion sperm.
- Procapsase-9 was detected in bull sperm but did not show any signs of activation by the conditions.
- Procaspase-3 was not detected in bull sperm at all.
Concluding Insights
In summary, the study concludes that post-ejaculatory bull and stallion sperm are resistant to programmed cell death, or apoptosis. This resistance is attributed to resistance of mitochondria to heat shock-induced depolarization, lack of activation of procaspase-9, and absence of procaspase-3. These insights may impact future studies into sperm viability and the effect of environmental conditions on sperm survival and function.
Cite This Article
APA
Hendricks KE, Hansen PJ.
(2009).
Can programmed cell death be induced in post-ejaculatory bull and stallion spermatozoa?
Theriogenology, 71(7), 1138-1146.
https://doi.org/10.1016/j.theriogenology.2008.12.006 Publication
Researcher Affiliations
- Department of Animal Sciences, University of Florida, Gainesville, FL 32611-0910, USA.
MeSH Terms
- Animals
- Apoptosis / physiology
- Biomarkers, Tumor
- Blotting, Western
- Caspase 3 / metabolism
- Caspase 9 / metabolism
- Cattle / physiology
- Horses / physiology
- In Situ Nick-End Labeling
- Male
- Membrane Potential, Mitochondrial / physiology
- Spermatozoa / cytology
- Spermatozoa / physiology
- Time Factors
Citations
This article has been cited 4 times.- Takeda K, Uchiyama K, Kinukawa M, Tagami T, Kaneda M, Watanabe S. Evaluation of sperm DNA damage in bulls by TUNEL assay as a parameter of semen quality.. J Reprod Dev 2015;61(3):185-90.
- Dogan S, Mason MC, Govindaraju A, Belser L, Kaya A, Stokes J, Rowe D, Memili E. Interrelationships between apoptosis and fertility in bull sperm.. J Reprod Dev 2013;59(1):18-26.
- García Vazquez S, Aragón Martínez A, Flores-Alonso JC. Confocal microscopy and image analysis indicates a region-specific relation between active caspases and cytoplasm in ejaculated and epididymal sperm.. PLoS One 2012;7(4):e35477.
- Hansen PJ. Effects of heat stress on mammalian reproduction.. Philos Trans R Soc Lond B Biol Sci 2009 Nov 27;364(1534):3341-50.
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