Gokhan Akkoyunlu

The effect of testosterone on gastrocnemius muscle fibres in growing and adult male and female rats: a histochemical, morphometric and ultrastructural study.

In this study, the effect of testosterone on gastrocnemius muscle fibres in growing and adult rats (male and female) was examined using histochemical, morphometric and ultrastructural techniques.

The effects of docosahexaenoic acid on glial derived neurotrophic factor and neurturin in bilateral rat model of Parkinson's disease.

Parkinsons disease (PD) is the second most common neurodegenerative disorder marked by cell death in the Substantia nigra (SN). Docosahexaenoic acid (DHA) is the major polyunsaturated fatty acid (PUFA) in the phospholipid fraction of the brain and is required for normal cellular function. Glial cell line derived neurotrophic factor (GDNF) and neurturin (NTN) are very potent trophic factors for PD. The aim of the study was to evaluate the neuroprotective effects of GDNF and NTN by investigating their immunostaining levels after administration of DHA in a model of PD. For this reason we hypothesized that DHA administration of PD might alter GDNF, NTN expression in SN. MPTP neurotoxin that induces dopaminergic neurodegeneration was used to create the experimental Parkinsonism model. Rats were divided into; control, DHA-treated (DHA), MPTP-induced (MPTP), MPTP-induced+DHA-treated (MPTP+DHA) groups. Dopaminergic neuron numbers were clearly decreased in MPTP, but showed an increase in MPTP+DHA group. As a result of this, DHA administration protected dopaminergic neurons as shown by tyrosine hydroxylase immunohistochemistry. In the MPTP+DHA group, GDNF, NTN immunoreactions in dopaminergic neurons were higher than that of the MPTP group. In conclusion, the characterization of GDNF and NTN will certainly help elucidate the mechanism of DHA action, and lead to better strategies for the use of DHA to treat neurodegenerative diseases.

Immunohistochemical and ultrastructural changes in the renal cortex of cadmium-treated rats

The aim of this study was to determine the cadmium-induced immunohistochemical and morphological changes in the renal cortex of adult male rats exposed to high doses of cadmium for 30 d. Animals used as controls received a standard diet and water ad libitum. The animals used for this study received 15 ppm CdCl2 in their drinking water for 1 mo. The mean arterial pressure (MAP), the mean blood Cd level, and the mean tissue Cd content were significantly higher when compared to controls (p < 0.01). Immunohistochemical studies demonstrated a weak labeling to type IV collagen and laminin, but a strong labeling to fibronectin in the renal cortex of the Cd-treated animals when compared to controls. The ultrastructural alterations found in Cd-treated rats were a diminution in the amount of filtration slits, increased fusion of foot processes in epithelial cells of the glomeruli, increase of lysosomal structures and pinocytic vesicles as well as large mitochondria in proximal tubule cells, and degenerated cells in distal tubules. Additionally, the glomerular basement membrane was slightly thickened. In conclusion, cadmium toxicity results in alterations in the renal extracellular matrix and tubular or glomerular cells, which could play an important role in renal dysfunction.

Recurrence of keratoconus in two corneal grafts after penetrating keratoplasty.

Purpose: To report the recurrence of postkeratoplasty keratoconus in 2 corneal grafts harvested from the same donor. Design: Interventional case reports. Methods: A 21-year-old-man with advanced keratoconus in his right eye and a 28-year-old-woman with corneal leucoma in her right eye underwent penetrating keratoplasty with 2 grafts coming from the same donor. Approximately 1.5 years after grafting, corneal irregularity and astigmatism caused visual acuities of the patients to decrease to counting fingers. Clinical findings and corneal topography suggested the recurrence of keratoconus. A repeat keratoplasty was performed in both patients. Results: Histopathology of the excised corneal grafts was consistent with keratoconus and confirmed the preoperative diagnosis. Conclusions: Recurrence of keratoconus in a patient who had no preexisting keratoconus and in 2 corneal grafts coming from the same donor suggested transmission of the disorder from the donor instead of true recurrence.

The role of Wnt signaling members in the uterus and embryo during pre-implantation and implantation

Wnt family members are best known for their roles in cell fate determination, differentiation, proliferation and apoptosis during embryonic development. Wnt signaling becomes effective during these cellular processes through the proper interaction between its ligands, receptors, effectors and inhibitors. Here we review Wnt signaling in terms of embryonic development to the blastocyst stage implantation with emphasis on endometrial changes that are critical for receptivity in the uterus. The relationship between Wnt signaling and implantation clearly reveals that, Wnt family members are critical for both early embryonic development and changing of the endometrium before implantation. Specific Wnt signaling pathway members are demonstrated to be critical for endometrial events such as decidualization and endometrial gland formation in addition to cyclic changes in the endometrium controlled by reproductive hormones. In conclusion, specific roles of Wnt members and associated factors for both uterine function and embryonic development should be further investigated with respect to the efficiency of human ARTs.

Expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and peroxiredoxin 6 (Prdx6) proteins in healthy and pathologic placentas of human and rat

A relationship has been shown between preeclampsia (PE) and intrauterine growth restriction (IUGR) and oxidative stress (OS). Since such pregnancies experience OS, we aimed to detect the distribution pattern and expression levels of a transcription factor, Nuclear factor erythroid 2-related factor-2 (Nrf2) that has a role in the regulation of antioxidant enzymes, and peroxiredoxin 6 (Prdx6) an antioxidant enzyme, in human healthy, IUGR, PE and in groups of rat healthy and IUGR placentas using immunohistochemistry and Western blotting. Both Nrf2 and Prdx6 immunoreactivities were weaker in human and rat IUGR group placentas compared to human and rat control group placentas, respectively. Nrf2 and Prdx6 were immunostained in labyrinth trophoblasts, decidua, giant, glycogen and fetal vessel endothelial cells in rat control and IUGR group placentas. Nrf2 and Prdx6 immunoreactivities were seen in the decidua, syncytiotrophoblasts, villous stromal cells, and vascular endothelium in human control, IUGR and PE group placentas. Results of Nrf2 and Prdx6 Western blotting applied for rat and human placentas were compatible with the results of Nrf2 and Prdx6 immunohistochemical observations with regard to rat and human placentas. Down-regulation of Nrf2 and Prdx6 proteins in human and rat IUGR group placentas may have led to the formation of OS which may have impaired proliferation and invasion of cytotrophoblasts.

Distribution patterns of leucocyte subpopulations expressing different cell markers in the cumulus–oocyte complexes of pregnant and pseudopregnant mice

The nature of leucocyte subpopulations expressing different cell markers around the cumulus-oocyte complex (COC) of pregnant and pseudopregnant mice was investigated in the present study. Immunolabelling for CD4, CD8, CD14, CD45 and CD163 and transmission electron microscopy were used to determine whether leucocytes differ between pregnant and pseudopregnant mice. Sexually mature female BALB/c mice (n = 36; 18 pregnant, 18 pseudopregnant) were stimulated to superovulate with pregnant mares serum gonadotropin and human chorionic gonadotrophin, then mated with either fertile or vasectomised males. Postovulatory oocytes were collected after mating. The cumulus cell masses of the pregnant group contained spermatozoa between cells and were more variable than COCs of the pseudopregnant group. Streptavidin-biotin-peroxidase immunohistochemical labelling of the cell markers CD4, CD8, CD14, CD45 and CD163 showed that there were fewer leucocytes in the COCs of the pseudopregnant group compared with the pregnant group. Transmission electron microscopy revealed that often there were macrophage-like cells containing spermiophagic bodies between the cumulus cells. These observations suggest that, together with other cumulus cells and oviducal cells, these macrophage-like cells may be involved in removing unsuitable or excess spermatozoa and, therefore, in maintaining a suitable microenvironment for normal fertilisation.

The zonal distributions of alkaline phosphatase, adenosine triphosphatase, laminin, fibronectin and chondroitin 4-sulphate in growing rat humerus proximal epiphyseal cartilage: a histochemical and an immunohistochemical study.

Although there are many studies about epiphyseal cartilage extracellular matrix (ECM) macromolecules in bone formation, studies of their distribution and role in the mineralization of these components in growing rat humerus proximal epiphyseal cartilage have not been sufficiently detailed. The aim of this study was to determine the distributions of alkaline phosphatase (ALP), adenosine triphosphatase (ATPase), laminin, fibronectin and chondroitin 4‐sulphate in growing rat humerus proximal epiphyseal cartilage. The rats were killed by cervical dislocation, and the humeri were removed, sectioned (6 and 10 μm) on a cryotome or paraffin microtome, and stained using histochemical and immunohistochemical methods. ALP and ATPase were markedly observed in the hypertrophy and calcifying cartilage. In addition, ATPase was found to be very strongly positive in the tangential zone of articular cartilage. Results of immunohistochemical staining for laminin, fibronectin and chondroitin 4‐sulphate showed that the immunostaining was the heaviest in the tangential zone of articular cartilage. In growing epiphyseal plates, there were differences in the density of these macromolecules of chondrocytes as a function of the maturation process. In conclusion, these ECM macromolecules of epiphyseal cartilage may regulate the cell–cell and cell–matrix interactions as well as the matrix calcification during the ossification of epiphyseal cartilage.

The Potential Role of Advanced Glycation End Product and iNOS in Chronic Renal Failure-Related Testicular Dysfunction

Objectives: To investigate the impact of advanced glycation end products (AGEs) and inducible nitric oxide synthase (iNOS) in chronic renal failure (CRF)-associated testicular dysfunction in an experimental model. In additionally, we examined whether different peritoneal dialysis (PD) fluids could contribute to the elevation in AGE level and iNOS expression in the testes. Methods: Adult male Wistar rats, 10 and 12 weeks of age and weighing 200–330 g, were divided into 5 groups. Group 1 served as the control group. In group 2, CRF was induced and a peritoneal catheter was implanted, but the dialysis procedure was not performed until the end of the study. In group 3, CRF was induced and PD was performed with dialysis fluids containing 1.36% glucose and icodextrin. In group 4, CRF rats received dialysis fluids containing 3.86% glucose and icodextrin. Finally, an indwelling catheter was implanted and the dialysis procedure was performed using dialysis fluids containing 3.86% glucose and icodextrin (group 5). Chronic PD began 4 weeks after insertion of the catheter. Each morning, this fluid was drained and 20 ml dialysis fluid, containing either 1.36 or 3.86% glucose, was given intraperitoneally for 4 h in unanesthetized animals. Each evening, 20 ml icodextrin was given for 10 h. The dialysis procedure was performed for 8 weeks. The AGE level was determined from the 5-hydroxymethyl-2-furaldehyde (5-HMF) content of penis samples and iNOS expression was assessed by immunohistochemistry. Results: The elevation of 5-HMF was significant in the testes from groups 2, 3, 4, and 5 when compared with group 1. Furthermore, the differences between groups 2 and 4, 3 and 4, and 4 and 5 were also significant (p < 0.05). Immunohistochemical analysis revealed the presence of iNOS predominantly in the Leydig cells. While iNOS staining was significantly lower in group 1 than in other groups, there were also significant differences between groups 2 and 3, 2 and 4, 2 and 5, 3 and 5, and 4 and 5 (p < 0.05). Finally, a significant statistical correlation was found between the 5-HMF and iNOS levels (r = 0.698, p = 0.001). Conclusions: The present study identifies, for the first time, a potential role of AGE and iNOS in experimental CRF-associated testicular dysfunction. In addition, we found that PD fluids containing glucose contribute to this effect. These results may lead to a better understanding of the pathophysiological pathway in CRF-related testicular dysfunction.

2100-MHz electromagnetic fields have different effects on visual evoked potentials and oxidant/antioxidant status depending on exposure duration.

The purpose of the present study was to investigate the duration effects of 2100-MHz electromagnetic field (EMF) on visual evoked potentials (VEPs) and to assess lipid peroxidation (LPO), nitric oxide (NO) production and antioxidant status of EMF exposed rats. Rats were randomized to following groups: Sham rats (S1 and S10) and rats exposed to 2100-MHz EMF (E1 and E10) for 2h/day for 1 or 10 weeks, respectively. At the end of experimental periods, VEPs were recorded under anesthesia. Brain thiobarbituric acid reactive substances (TBARS) and 4-hydroxy-2-nonenal (4-HNE) levels were significantly decreased in the E1 whereas increased in the E10 compared with their control groups. While brain catalase (CAT), glutathione peroxidase (GSH-Px) activities and NO and glutathione (GSH) levels were significantly increased in the E1, reduction of superoxide dismutase (SOD) activity was detected in the same group compared with the S1. Conversely, decreased CAT, GSH-Px activities and NO levels were observed in the E10 compared with the S10. Latencies of all VEP components were shortened in the E1 compared with the S1, whereas latencies of all VEP components, except P1, were prolonged in the E10 compared with the S10. There was a positive correlation between all VEP latencies and brain TBARS and 4-HNE values. Consequently, it could be concluded that different effects of EMFs on VEPs depend on exposure duration. In addition, our results indicated that short-term EMF could provide protective effects, while long-term EMF could have an adverse effect on VEPs and oxidant/antioxidant status.