Maintaining the integrity of sperm DNA is vital to reproduction and male fertility. Sperm contain a number of molecules and pathways for the repair of base excision, base mismatches and DNA strand breaks. The presence of Poly (ADP-ribose) polymerase (PARP), a DNA repair enzyme, and its homologues has recently been shown in male germ cells, specifically during stage VII of spermatogenesis. High PARP expression has been reported in mature spermatozoa and in proven fertile men. Whenever there are strand breaks in sperm DNA due to oxidative stress, chromatin remodeling or cell death, PARP is activated. However, the cleavage of PARP by caspase-3 inactivates it and inhibits PARP's DNA-repairing abilities. Therefore, cleaved PARP (cPARP) may be considered a marker of apoptosis. The presence of higher levels of cPARP in sperm of infertile men adds a new proof for the correlation between apoptosis and male infertility. This review describes the possible biological significance of PARP in mammalian cells with the focus on male reproduction. The review elaborates on the role played by PARP during spermatogenesis, sperm maturation in ejaculated spermatozoa and the potential role of PARP as new marker of sperm damage. PARP could provide new strategies to preserve fertility in cancer patients subjected to genotoxic stresses and may be a key to better male reproductive health.

Throughout spermatogenesis, leptotene spermatocytes must traverse the blood-testis barrier (BTB) at stages VIII-XI to gain entry into the adluminal compartment for continued development. However, the mechanism underlying BTB restructuring remains somewhat elusive. In this study, interleukin 1 alpha (IL1A) was administered intratesticularly to adult rats in order to assess its effects on spermatogenesis. IL1A was shown to perturb Sertoli-germ cell adhesion, resulting in germ cell loss from approximately 50% of seminiferous tubules by 15 days posttreatment. Equally important, the functional integrity of the BTB was compromised when inulin-fluorescein isothiocyanate was detected in the adluminal compartment of the seminiferous epithelium following its administration via the jugular vein. Interestingly, IL1A did not affect the steady-state levels of proteins that confer BTB function, namely OCLN, CLDN1, F11R, TJP1, and CDH2. Instead, the localizations of OCLN, F11R, and TJP1 in the seminiferous epithelium were altered; these proteins appeared to move away from sites of cell-cell contact. Moreover, IL1A was shown to perturb the orderly arrangement of filamentous actin at the BTB and apical ectoplasmic specialization with distinct areas illustrating loss of actin filaments. Taken collectively, these results suggest that IL1A-induced BTB disruption is not mediated via the reduction of target protein levels. Instead, IL1A's primary cellular target appears to be the Sertoli cell actin cytoskeleton. It is possible that localized production of IL1A by Sertoli and/or germ cells in vivo results in BTB restructuring, and this may facilitate the movement of leptotene spermatocytes across the BTB.

Abstract-C-Atrial natriuretic peptide (ANP) 4-23 , a ring deleted analog of ANP that specifically interacts with natriuretic peptide receptor-C (NPR-C), has been shown to decrease the enhanced expression of Giα proteins implicated in the pathogenesis of hypertension. In the present study, we investigated whether in vivo treatment of spontaneously hypertensive rats (SHRs) with C-ANP 4-23 could attenuate the development of high blood pressure (BP) and explored the underlying mechanisms responsible for this response. Intraperitoneal injection of C-ANP 4-23 at the concentration of 2 or 10 nmol/kg body weight to prehypertensive SHRs attenuated the development of high BP, and at 8 weeks it was decreased by ≈20 and 50 mm Hg, respectively; however, this treatment did not affect BP in Wistar-Kyoto rats. C-ANP 4-23 treatment of adult SHRs for 2 weeks also attenuated high BP, heart rate, and restored the impaired vasorelaxation toward control levels. In addition, the enhanced levels of superoxide anion (O 2 − ), peroxynitrite, NADPH oxidase activity, and the enhanced expression of Giα proteins, NOX4, p47 phox , nitrotyrosine, and decreased levels of endothelial nitric oxide synthase (eNOS or NOS3) and NO in SHRs were attenuated by C-ANP 4-23 treatment; however, the altered levels of NPR-A/NPR-C were not affected by this treatment. In conclusion, these results indicate that NPR-C activation by C-ANP 4-23 attenuates the development of high BP in SHRs through the inhibition of enhanced levels of Giα proteins and nitroxidative stress and not through eNOS/ cGMP pathway and suggest that NPR-C ligand may have the potential to be used as therapeutic agent in the treatment of Li et al NPR-C and Blood Pressure Regulation 847injection of pertussis toxin in prehypertensive rats (2-week-old SHRs) has been reported to prevent the development of BP,22 suggesting the implication of enhanced expression of Gi proteins in the pathogenesis of hypertension. C-ANP 4-23 that specifically interacts with NPR-C has been reported to decrease the levels of Giα proteins in A10 vascular smooth muscle cell (VSMC) 23 and in VSMC from SHRs. 24 In addition, C-ANP 4-23 was also shown to attenuate the enhanced oxidative stress in VSMC from SHRs 24 that contributes to the enhanced expression of Giα proteins in SHRs.25 Taken together, it may be possible that C-ANP 4-23 treatment of SHRs could also attenuate the high BP in SHRs. The present study was undertaken to investigate the effect of in vivo administration of C-ANP 4-23 on the development of high BP in SHRs. We have provided the first evidence that the treatment of prehypertensive SHRs with C-ANP 4-23 , an activator of NPR-C, attenuates the development of high BP in SHRs through the inhibition of enhanced expression of Gi proteins and oxidative stress.We have provided the first evidence that NPR-C activation by C-ANP 4-23 attenuates high BP through decreasing the enhanced oxidative stress and the augmented levels of Giα proteins. From these results it may be suggested that C-ANP [4][5][6][7][8][9][10][...

Vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) exhibit decreased levels of nitric oxide (NO) that may be responsible for the overexpression of Giα proteins that has been shown as a contributing factor for the pathogenesis of hypertension in SHR. The present study was undertaken to investigate if increasing the intracellular levels of NO by NO donor S-Nitroso-N-acetyl-DL-penicillamine (SNAP) could attenuate the enhanced expression of Giα proteins in VSMC from SHR and explore the underlying mechanisms responsible for this response. The expression of Giα proteins and phosphorylation of ERK1/2, growth factor receptors and c-Src was determined by Western blotting using specific antibodies. Treatment of VSMC from SHR with SNAP for 24 hrs decreased the enhanced expression of Giα-2 and Giα-3 proteins and hyperproliferation that was not reversed by 1H (1, 2, 4) oxadiazole (4, 3-a) quinoxalin-1-one (ODQ), an inhibitor of soluble guanylyl cyclase, however, PD98059, a MEK inhibitor restored the SNAP-induced decreased expression of Giα proteins towards control levels. In addition, the increased production of superoxide anion, NAD(P)H oxidase activity, overexpression of AT1 receptor, Nox4, p22phox and p47phox proteins, enhanced levels of TBARS and protein carbonyl, increased phosphorylation of PDGF-R, EGF-R, c-Src and ERK1/2 in VSMC from SHR were all decreased to control levels by SNAP treatment. These results suggest that NO decreased the enhanced expression of Giα-2/3 proteins and hyperproliferation of VSMC from SHR by cGMP-independent mechanism and involves ROS and ROS-mediated transactivation of EGF-R/PDGF-R and MAP kinase signaling pathways.