https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1939-4640.2002.tb02599.x

Sperm chromatin structure assay: its clinical use for detecting sperm DNA fragmentation in male infertility and comparisons with other techniques.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a 38-amino acid C-terminally alpha-amidated peptide that was first isolated 20 years ago from an ovine hypothalamic extract on the basis of its ability to stimulate cAMP formation in anterior pituitary cells (Miyata et al., 1989. PACAP belongs to the vasoactive intestinal polypeptide (VIP)-secretin-growth hormone-releasing hormone-glucagon superfamily. The sequence of PACAP has been remarkably well conserved during evolution from protochordates to mammals, suggesting that PACAP is involved in the regulation of important biological functions. PACAP is widely distributed in the brain and peripheral organs, notably in the endocrine pancreas, gonads, respiratory and urogenital tracts. Characterization of the PACAP precursor has revealed the existence of a PACAP-related peptide, the activity of which remains unknown. Two types of PACAP binding sites have been characterized: type I binding sites exhibit a high affinity for PACAP and a much lower affinity for VIP, whereas type II binding sites have similar affinity for PACAP and VIP. Molecular cloning of PACAP receptors has shown the existence of three distinct receptor subtypes: the PACAP-specific PAC1-R, which is coupled to several transduction systems, and the PACAP/VIP-indifferent VPAC1-R and VPAC2-R, which are primarily coupled to adenylyl cyclase. PAC1-Rs are particularly abundant in the brain, the pituitary and the adrenal gland, whereas VPAC receptors are expressed mainly in lung, liver, and testis. The development of transgenic animal models and specific PACAP receptor ligands has strongly contributed to deciphering the various actions of PACAP. Consistent with the wide distribution of PACAP and its receptors, the peptide has now been shown to exert a large array of pharmacological effects and biological functions. The present report reviews the current knowledge concerning the pleiotropic actions of PACAP and discusses its possible use for future therapeutic applications.

Pituitary Adenylate Cyclase-Activating Polypeptide and Its Receptors: 20 Years after the Discovery

Sperm DNA integrity is essential for the accurate transmission of genetic information. It has a highly compact and complex structure and is capable of decondensation-features that must be present in order for a spermatozoon to be considered fertile. Any form of sperm chromatin abnormalities or DNA damage may result in male infertility. In support of this conclusion, it was reported that in-vivo fecundity decreases progressively when > 30% of the spermatozoa are identified as having DNA damage. Several methods are used to assess sperm chromatin/DNA, which is considered an independent measure of sperm quality that may yield better diagnostic and prognostic approaches than standard sperm parameters (concentration, motility and morphology). The clinical significance of this assessment lies in its association not only with natural conception rates, but also with assisted reproduction success rates. Also, it has a serious impact on the offspring and is highly prognostic in the assessment of fertility in cancer patients. Therefore, screening for sperm DNA damage may provide useful information in cases of male idiopathic infertility and in those men pursuing assisted reproduction. Treatment should include methods for prevention of sperm DNA damage.

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Role of sperm chromatin abnormalities and DNA damage in male infertility

Recent advances in understanding of male infertility have implicated two major causative factors, oxidative stress and Y chromosome deletions. A major cause of oxidative stress appears to be the high rate of reactive oxygen species generation associated with the retention of excess residual cytoplasm in the sperm midpiece. Other possible causes include the redox cycling of xenobiotics, and antioxidant depletion or apoptosis. Oxidative stress induces peroxidative damage in the sperm plasma membrane and DNA damage in both the mitochondrial and nuclear genomes. Nuclear DNA damage in the germ line of the father may be associated with pathology in the offspring, including childhood cancer and infertility. Gene deletions on the non-recombining region of the Y chromosome account for the infertility observed in about 15% of patients with azoospermia and 5-10% of subjects with severe oligozoospermia. The Y chromosome is particularly susceptible to gene deletions because of the inability of the haploid genome to deploy recombination repair in retrieving lost genetic information. Aberrant recombination, defective chromatin packaging, abortive apoptosis and oxidative stress may all be involved in the aetiology of DNA damage in the germ line. The factors responsible for Y chromosome deletions in spermatozoa remain unresolved but may be one facet of a central reproductive problem: controlling the amount of oxidative stress experienced by germ cells during their differentiation and maturation in the male reproductive tract.

/pdf/oxidative-stress-dna-damage-and-the-y-chromosome-3dr9oq8vcx.pdf

Oxidative stress, DNA damage and the Y chromosome.

Male infertility accounts for up to half of the infertility cases and affects 13–15% couples worldwide. An optimal level of reactive oxygen species is crucial for maintaining spermatogenesis and sperm functions. However, excessive production of reactive oxygen species may cause oxidative stress. Oxidative stress has been identified as one of the major risk factors which affects the fertilizing potential of spermatozoa. Oxidative stress occurs due to excessive production of ROS and causes germ cell DNA damage, sperm fragility and defects in motility, culminating in infertility. Poor sperm quality and DNA damage may also result in pregnancy loss. This article highlights the significance of ROS in human male fertility and that of oxidative stress in infertility.

Oxidative stress and male infertility

Background. The objective of this study was to determine the incidence of spermatozoa with DNA strand breaks in four clinically different groups of infertile couples, and to correlate DNA damage with other semen analysis parameters, as well as fertilization rates and IVF outcome. Methods. One group consisted of 75 men where the female partners had a tubal obstruction, Group A . Fifty sperm samples were collected from men in unexplained infertile couples, Group B . Fifty men with oligozoospermia and IVF made up Group C . Finally, 61 men with oligozoospermia and where ICSI was performed made up Group D . Sperm samples were assessed according to the WHO manual and for the presence of DNA strand breaks in spermatozoa. The study was blinded for the technician involved in the assessment of DNA strand breaks. IVF was carried out according to a long down regulation protocol using GnRH, FSH and hCG. Embryos were transferred on day 2 after fertilization with a maximum of three embryos. Results. This study demonstra...

The role of DNA strand breaks in human spermatozoa used for IVF and ICSI.

Apoptosis in human cumulus cells in relation to zona pellucida thickness variation, maturation stage, and cleavage of the corresponding oocyte after intracytoplasmic sperm injection.

Background. The purpose of this study was to examine the correlation between DNA strand breaks in human spermatozoa and semen quality, fertilization rate and IVF outcome. Methods. A total of 50 men suffering from unexplained infertility and 50 men with oligozoospermia undergoing IVF treatment entered a prospective study. Sperm samples were assessed according to the WHO manual and for the presence of DNA strand breaks in spermatozoa. The study was blinded for the technician involved in assessment of DNA strand breaks. IVF was carried out according to a long down regulation protocol using GnRH, FSH and hCG. The ova were inseminated with 200,000 spermatozoa/ml. Embryos were transferred on day 2 after fertilization with a maximum of three embryos. Results. This study demonstrates a negative correlation between the proportion of spermatozoa having DNA strand breaks and the proportion of oocytes fertilized after IVF. Conclusion. The number of human spermatozoa with DNA strand breaks is a good predictor for fert...

https://obgyn.onlinelibrary.wiley.com/doi/pdf/10.1034/j.1600-0412.2000.079003189.x

DNA strand breaks in human spermatozoa: Correlation with fertilization in vitro in oligozoospermic men and in men with unexplained infertility

Background The aim of this report was to compare the degree of DNA strand breaks in known normal fertile men to those with oligozoospermia, and evaluate the presence of DNA strand breaks in normal raw sperm, after Percoll and swim-up and following conventional cryopreservation, as all these preparation methods might differ in selection of healthy sperm cells. Methods Sperm samples from proven fertile sperm donors (n=20) and infertile men with oligozoospermia (n=33) were tested for the presence of DNA strand breaks in the spermatozoa, by direct immunoperoxidase detection of digoxigenin-labeled genomic DNA. A correlation to other sperm parameters, sperm counts, motility and Kruger's strict criteria was performed. Results DNA strand breaks were found significantly more often in sperm samples from men with oligozoospermia compared to sperm samples of normal fertile men. The degree of spermatozoa with DNA strand breaks was correlated proportional with the degree of morphological pathological sperm cells judged by Kruger's strict criteria. The percentage of spermatozoa with DNA strand breaks in the samples was not influenced by procedures such as the swim-up technique, Percoll gradients or cryopreservation and thawing. Conclusion DNA strand breaks were found significantly more often in men with oligozoospermia compared to normospermic men. The DNA strand breaks might play an important role for the maturation process of the spermatozoa in the same way as apoptosis is controlling the number of early meiotic germ cells in the testis, and hereby play an important role in advanced fertility treatments (ICSI).

https://obgyn.onlinelibrary.wiley.com/doi/pdf/10.1034/j.1600-0412.1999.780412.x

DNA strand breaks in human sperm cells: a comparison between men with normal and oligozoospermic sperm samples.

Background. The purpose of this study was to determine the incidence of apoptosis in cumulus cells, and correlate these findings with the maturation stage, fertilization rate and embryo score of the corresponding oocyte, in couples undergoing ICSI due to a male factor.Methods. The study group consisted of 21 couples where ICSI was performed. The total number of oocyte-cumulus complexes retrieved was 164. Sperm samples were assessed according to the WHO manual, morphology according to the strict criteria and for the presence of apoptosis. The degree of apoptotic DNA fragmentation was determined using the free 3'OH DNA termini in situ with chemically labeled and unlabeled nucleotides. The study was blinded for the technician involved in the assessments of apoptosis in the cumulus cells, apoptosis and morphology in spermatozoa. Ovarian hyperstimulation was carried out according to a long down regulation protocol using GnRH, recFSH and hCG. A maximum of 3 embryos were transferred on day 2 after ICSI.Results. ...

https://obgyn.onlinelibrary.wiley.com/doi/pdf/10.1034/j.1600-0412.2000.079011936.x

Erik Høst

Papers

The role of DNA strand breaks in human spermatozoa used for IVF and ICSI.

Apoptosis in human cumulus cells in relation to zona pellucida thickness variation, maturation stage, and cleavage of the corresponding oocyte after intracytoplasmic sperm injection.

DNA strand breaks in human spermatozoa: Correlation with fertilization in vitro in oligozoospermic men and in men with unexplained infertility

DNA strand breaks in human sperm cells: a comparison between men with normal and oligozoospermic sperm samples.

Apoptosis in human cumulus cells in relation to maturation stage and cleavage of the corresponding oocyte.