Apoptosis Pattern Elicited by Several Apoptogenic Agents on the Seminiferous Epithelium of the Adult Rat Testis

BLANCO‐RODRÍGUEZ, JOSEFA; MARTÍNEZ‐GARCÍA, CARMEN

doi:10.1002/j.1939-4640.1998.tb02043.x

Cited by 31 publications

References 60 publications

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Nickel‐Induced Oxidative Stress in Testis of Mice: Evidence of DNA Damage and Genotoxic Effects

Doreswamy

Balakrishna

Rajeshkumar

et al. 2004

Journal of Andrology

158

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Oxidative stress (OS) mechanisms are speculated to play a significant role in nickel-induced toxic effects and their carcinogenic potency. Although nickel-induced oxidative damage in somatic tissues is well demonstrated, evidence of the involvement of a similar mechanism(s) in nickel-induced testicular dysfunction and associated genotoxic effects is scarce. Hence, the present study aimed to investigate the nickel-induced OS response in testis and the associated genotoxic implications in vivo. Initially, the toxicity profile of nickel chloride was determined in adult albino mice (CFTSwiss) following administration (intraperitoneal) of single doses. Subsequently, multiple sublethal doses (1.25, 2.5, and 5.0 mol/100 g of body weight per day for 3 days) were used to characterize effects on testicular histoarchitecture, lipid peroxidation (LPO) in testis (homogenates, microsomal or mitochondrial fractions) and epididymal sperm, DNA damage, induction of apoptosis in testis, and incidence of sperm head abnormalities. Although short-term doses of nickel induced only a minimal LPO response, multiple doses elicited a moderate (15% to 30%) increase in LPO in whole homogenates and higher dose-related increases in both mitochondrial (20% to 50%) and microsomal fractions (25% to 60%). This was associated with a significant increase in DNA damage in the testis as evidenced by increased single-strand breaks (fluorimetric analysis of DNA unwinding assay). Further, at higher doses, nickel-induced apoptosis was demonstrable in the testis biochemically. Although caudal sperm counts determined at all sampling weeks showed no alterations, analysis for head abnormalities revealed a nearly 3-to 4-fold increase in the percentage of abnormal sperms among the nickel-treated males during the first 3 weeks. Furthermore, mating of nickel-treated (2.5 mol/100 g of body weight per day for 5 days) males sequentially for a period of 5 weeks with untreated females resulted in a significant increase in male-mediated dominant lethaltype mutations (the frequency of dead implantations) during the first 3 weeks, suggesting a stage-specific effect on postmeiotic germ cells. These findings suggest that testicular toxicity of nickel compounds may be related to enhanced production of reactive oxygen species, probably mediated through oxidative damage to macromolecules, including damage to DNA.

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Nickel‐Induced Oxidative Stress in Testis of Mice: Evidence of DNA Damage and Genotoxic Effects

Doreswamy

Balakrishna

Rajeshkumar

et al. 2004

Journal of Andrology

158

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Mouse spermatozoa contain a nuclease that is activated by pretreatment with EGTA and subsequent calcium incubation

Boaz

Dominguez

Shaman

et al. 2007

J of Cellular Biochemistry

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We demonstrated that mouse spermatozoa cleave their DNA into ~50 kb loop-sized fragments with topoisomerase IIB when treated with MnCl 2 and CaCl 2 in a process we term sperm chromatin fragmentation (SCF). SCF can be reversed by EDTA. A nuclease then further degrades the DNA in a process we term sperm DNA degradation (SDD). MnCl 2 alone could elicit this activity, but CaCl 2 had no effect. Here, we demonstrate the existence of a nuclease in the vas deferens that can be activated by EGTA to digest the sperm DNA by SDD. Spermatozoa were extracted with salt and dithiothreitol to remove protamines and then incubated with EGTA. Next, the EGTA was removed and divalent cations were added. We found that Mn +2 , Ca +2 , or Zn +2 could each activate SDD in spermatozoa but Mg +2 could not. When the reaction was slowed by incubation on ice, EGTA pretreatment followed by incubation in Ca +2 elicited the reversible fragmentation of sperm DNA evident in SCF. When the reactions were then incubated at 37°C they progressed to the more complete degradation of DNA by SDD. EDTA could also be used to activate the nuclease, but required a higher concentration than EGTA. This EGTA-activatable nuclease activity was found in each fraction of the vas deferens plasma: in the spermatozoa, in the surrounding fluid, and in the insoluble components in the fluid. These results suggest that this sperm nuclease is regulated by a mechanism that is sensitive to EGTA, possibly by removing inhibition of a calcium binding protein.

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γH2AX marks the main events of the spermatogenic process

Blanco‐Rodríguez¹

2009

Microscopy Res & Technique

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Recent findings reveal that chromatin reorganization requires formation and repair of DNA double strand breaks (DSBs). Therefore, dynamic changes in chromatin structure taking place along the mitotic and the meiotic processes should be accompanied by histone H2AX phosphorylation and formation of gamma H2AX, a prominent event occurring at DSB sites. Accordingly, gamma H2AX has been detected at multiple developmental steps in adult germ cells. Nevertheless, no comprehensive study focusing on the main biological events occurring in the seminiferous epithelium has been carried out in mammals. Here I analyze H2AX phosphorylation in immunostained testis sections comparing PAS/cresyl violet counterstained, noncounterstained, and immuno-fluorescence preparations and show several waves of H2AX phosphorylation/dephosphorylation coupled to various developmental phases of spermatogonia and spermatocytes as well as to spermatid differentiation. The combined detection of DNA replication or free 3'-OH DNA ends highlight the possible significance of gamma H2AX at these locations.

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Apoptosis Pattern Elicited by Several Apoptogenic Agents on the Seminiferous Epithelium of the Adult Rat Testis

Cited by 31 publications

References 60 publications

Nickel‐Induced Oxidative Stress in Testis of Mice: Evidence of DNA Damage and Genotoxic Effects

Nickel‐Induced Oxidative Stress in Testis of Mice: Evidence of DNA Damage and Genotoxic Effects

Mouse spermatozoa contain a nuclease that is activated by pretreatment with EGTA and subsequent calcium incubation

γH2AX marks the main events of the spermatogenic process

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