Suleyman Sandal

Kisspeptin-10 elicits triphasic cytosolic calcium responses in immortalized GT1-7 GnRH neurones.

Kisspeptins, which are alternatively called as metastin since they were originally identified as products of metastasis suppressor gene KiSS-1, are the natural ligands for the G protein-coupled receptor 54 (GPR54). Kisspeptins are the most potent activators of hypothalamic-pituitary-gonadal (HPG) axis reported to date. The pulsatile pattern of GnRH release, which results in the intermittent release of gonadotropic hormones from the pituitary, has a critical importance for reproductive function but the factors responsible from this release pattern are not known. Therefore, the pattern of kisspeptin-induced intracellular signaling and the role of PKC in the intracellular signaling cascade were investigated by fluorescence calcium imaging using the immortalized GnRH-secreting GT1-7 hypothalamic neurons. Kisspeptin-10 caused a triphasic change characterized by an initial small increase followed by a significant decrease and increase in intracellular free calcium concentrations ([Ca(2+)](i)). The changes in [Ca(2+)](i) were significantly attenuated by pre-treatment with protein kinase C inhibitor. The compatibility of appeared mirrored-patterns of kisspeptin-10-induced changes in [Ca(2+)](i) concentrations in these neurons and GnRH secretion confirm the importance of intracellular calcium flux downstream from GPR54 through PKC signaling pathway.

The effects of intracerebroventricular infusion of apelin-13 on reproductive function in male rats

Apelin is a novel bioactive peptide as the endogenous ligand for APJ. Apelin and APJ have also been identified in the testis, hypothalamic nuclei such as arcuate, supraoptic and paraventricular nuclei, implicating roles in the control of reproduction. Therefore, the present study was designed to investigate the effects of chronic central infusion of apelin-13 on LH, FSH and testosterone levels and testis morphology. 21 Wistar-Albino male rats received continuous intracerebroventricular infusion via Alzet osmotic mini pumps filled artificial cerebrospinal fluid (vehicle) or apelin-13 at concentrations of 1 or 10 nmol (10 μl/h) for seven days. At the last 90 min of the infusion period, the blood samples were collected at 15 min intervals (0-90 min) for LH and FSH analyses. At the last sampling point, the blood samples were analyzed for testosterone levels. Infusion of high dose apelin-13 significantly suppressed LH release compared with the vehicle values at 30, 60 and 75 min (p<0.05). However, FSH levels did not significantly differ among the groups. Serum testosterone levels in high dose apelin-13 group were statistically lower than the control group (p<0.05). In addition, histological examination showed that infusion of high dose apelin-13 significantly decreased the number of Leydig cells compared with the control and lower dose apelin-13 groups (p<0.05, p<0.01). Our results suggest that apelin-13 may play a role in the central regulation and decreases testosterone release by suppressing LH secretion. Thus, antagonists of the apelin receptor may, therefore, be useful for pharmaceuticals in the treatment of infertility.

Effects of central irisin administration on the uncoupling proteins in rat brain

Irisin is a thermogenic peptide that enables the development of brown adipose tissue from white adipose tissue by activating the UCP1. This study has been designed to determine the effects of the irisin on UCPs. Sprague Dawley female rats were used in the study. 1, 3 and 10μM concentrations of irisin were injected intracerebroventricularly to the rats, and the control group was received only vehicle. The animals were killed at the 16, 24, and 48h time intervals and their brains were taken out. The hypothalamus, pituitary gland, hippocampus, cerebellum, striatum and cortex areas were separated and the UCP2, UCP3, UCP4 and UCP5 mRNA levels were determined. Just before the animals were killed, their body temperatures were recorded. It was observed that after application of the high dose irisin, UCP5 mRNA level in the all brain areas increased (p<0.05); it was also observed that the three doses decreased the UCP4 expression in all brain areas (except the pituitary gland; p<0.05). The UCP2 and UCP3 mRNA expressions showed significantly increase in cerebellum and striatum (p<0.05). The UCP2 mRNA expression decreased in hypothalamus, pituitary gland, hippocampus and cortex areas (p<0.05). It was also observed that the body temperatures of the rats increased depending on the irisin injection and this increase was the most considerable at the 24h (p<0.05). The results of this study suggest that the UCP2-5 is expressed in different areas of the brain, and the irisin affects this expression, and may have effective roles in some brain functions.

The effects of intracerebroventricular infusion of irisin on feeding behaviour in rats

Irisin, a novel exercise-induced myokine, has attracted attention with its effects on energy metabolism. This study was conducted to determine the possible effects of irisin on nutritional behaviour. In this study, 40 male Wistar Albino rats were separated into 4 groups (n=10 for each group). Osmotic mini-pumps were connected to metal cannulas implanted to lateral ventricle; and artificial cerebrospinal fluid (vehicle), and 10 and 100nM of irisin was infused for 7days. The daily food and water consumptions and body weights of rats were followed up. After the infusion, the animals were killed, and the hypothalamus and blood samples were collected. NPY, POMC, and UCP2 mRNA levels in the hypothalamus were examined by RT-PCR. In serum, leptin and ghrelin levels as well as the levels of metabolic parameters were measured by using ELISA. It was determined that irisin administration increased the daily food consumption (p<0.05), without causing significant changes in water consumption and body weight. Irisin also caused increases in ghrelin level in circulation and NPY and UCP2 mRNA levels in the hypothalamus, whereas it decreased the leptin level in circulation and POMC mRNA levels in the hypothalamus (p<0.05). Otherwise, irisin caused decrease in LDL, triglycerides and cholesterol levels, while increasing HDL and glucose levels (p<0.05). Results indicates that long-term irisin treatment increases food intake without increasing body weight associated with increased ghrelin, NPY and UCP2 mRNAs, and decreased leptin and POMC mRNA in the hypothalamus.

Pro-oxidant and antiproliferative effects of the 1,3,4-thiadiazole–based Schiff base and its metal complexes

Adverse biological activities of Schiff base (SB) derivatives are well known. In this study, the ligand and its metal complexes have been synthesized and characterized by IR, 1H-NMR spectra, elemental analyses, magnetic susceptibility, UV-Vis spectra, and thermogravimetry/differential thermal analysis. From the elemental analyses data, the complexes were proposed to have the general formula [Mn(L)2(H2O)2], [Co(L)2(H2O)2], and [Ni2(L)(H2O)4(Cl)3]. From the magnetic moment and UV-Vis spectra data, it was found that the geometrical structures of these complexes are octahedral. In the in vivo experiment, adult male rats were injected subcutaneously with a new SB (L) and its [Mn(L)2(H2O)2], [Co(L)2(H2O)2], and [Ni2(L)(H2O)4(Cl)3] complexes (25 mg/kg body weight) and were then sacrificed 16 days later. Effects of these compounds on serum antioxidant vitamins (i.e., vitamins A, E, and C) and malondialdehyde (MDA) levels were measured in blood serum, liver, and kidney tissues. In an in vitro experiment, antiproliferative effects of these compounds were assessed on the human breast carcinoma MCF-7 and murine leukemia L1210 cell lines. Serum MDA and vitamins A, E, and C levels did not change by the treatments. However, in the kidney and liver tissues, MDA levels were higher, whereas vitamin levels were lower in treatment groups, compared to the control group. All compounds inhibited cell proliferation of MCF-7 and L1210 cancer cell lines in a dose- and time-dependent manner. In conclusion, SB derivatives tested in the current study induced oxidative stress in vivo and exhibited anti-proliferative effects in an in vitro culture system.

Correlation of spermiogram profiles with DNA damage in sperm cells of infertile men: a comet assay study.

We have investigated a relationship between DNA damage in sperm and spermiogram profiles in the infertile men. Twenty-one non-smoking infertile men <40 years of age with no systemic or genetic disease were randomly selected from the pool of infertile couples applied to our clinic. Sperm samples were collected and evaluated according to WHO guidelines. DNA damage of sperm cells was assessed using neutral comet assay. Fifty cells per slide and two slides per sample were scored to evaluate DNA damage. The cells were visually classified into four categories based on DNA migration such as undamaged (UD), little damage (LD), moderate damage (MD) and significant damage (SD). Total comet scores (TCS) were calculated as: 1×UD + 2×LD + 3×MD + 4×SD. There was a negative correlation between the percentage of slow- and in situ-motion sperm cells in spermiograms and TCS (p < 0.001 and p < 0.05, respectively). The relationship between the percentage of non-motile sperm cells and TCS was negative (p < 0.001). This study provides new evidence that DNA damage in spermatozoa and sperm motility parameters are negatively correlated. We suggest that evaluation of sperm DNA by the neutral comet assay may be valuable to use in fertility research.

Effects of apelin on reproductive functions: relationship with feeding behavior and energy metabolism

Abstract Apelin is an adipose tissue derived peptidergic hormone. In this study, 40 male Sprague–Dawley rats were used (four groups; n = 10). Apelin-13 at three different dosages (1, 5 and 50 μg/kg) was given intraperitoneally while the control group received vehicle the same route for a period of 14 days. In results, apelin-13 caused significant decreases in serum testosterone, luteinizing hormone and follicle-stimulating hormone levels (p < 0.05). Administration of apelin-13 significantly increased body weights, food intake, serum low-density lipoprotein and total cholesterol levels (p < 0.05), but caused significant decreases in high-density lipoprotein levels (p < 0.05). Serum glucose and triglyceride levels were not significantly altered by apelin-13 administration. Significant decreases in both uncoupling protein (UCP)-1 levels in the white and brown adipose tissues and UCP-3 levels in the biceps muscle (p < 0.05) were noted. The findings of the study suggest that apelin-13 may not only lead to obesity by increasing body weight but also cause infertility by suppressing reproductive hormones.

Central irisin administration suppresses thyroid hormone production but increases energy consumption in rats

Irisin, which is secreted from the skeletal muscle in response to physical exercise and defined as a thermogenic peptide, may play an important role in energy metabolism. Thyroid hormones, which are one of the other influential factors on the metabolic status, increase heat production and are the main regulators of energy metabolism. This study was conducted to determine the possible effects of irisin administration on thyroid hormones. Forty adult male Wistar albino rats were used in the study. The rats were equally divided into 4 groups (n = 10). The brain infusion kit was implanted in the groups, and irisin (or solvent as control) was centrally administered to the rats via osmotic mini pumps for 7 days. During the experiment, food consumption, body weights, and body temperatures of the animals were recorded. Food intake was significantly increased in the groups treated with irisin (p < 0.05), but their body weights were not changed. Hypothalamic TRH gene expression, serum TSH, fT3, and fT4 levels were significantly lower in the groups treated with irisin as compared to the naive and control groups (p < 0.05). In addition, irisin increased UCP1 mRNA expression in white and brown adipose tissue and UCP3 mRNA expression in muscle tissue in rats and also raised their body temperature (p < 0.05). Consequently, although central irisin administration has inhibitory effects on the hypothalamic-pituitary-thyroid axis, it seems to be an important agent in the regulation of food intake and energy metabolism.

Synthesis, structural and thermal characterizations and in vitro cytotoxic activities of new cyclotriphosphazene derivatives

GRAPHICAL ABSTRACT ABSTRACT We investigated the cytotoxic effects of the newly synthesized cyclotriphosphazene derivatives on A2780 (ovarian), PC-3 and LNCaP (prostate) cancer cell lines. 4′-hydroxy-substituted-chalcone compounds (2–8) were reacted with diphenyl-cyclotriphosphazene (DPP) in the presence of acetone/K2CO3 in order to obtain novel cyclotriphosphazene compounds (DPP 2–8). The structures of DPP 2–8 were characterized by MALDI-TOF mass spectrometry, FT-IR, elemental analysis, 1H, 13C-APT, and 31P NMR measurements. The thermal properties of all phosphazene compounds have been studied after synthesis and characterization procedure. The cytotoxic effects of DPP 2–8 were examined primarily by applying the MTT method based on the measurement of mitochondrial activity. In this regard, several phosphazene compounds have shown high chemotherapeutic effect at low dose (p < 0.05). When the cytotoxic effects of DPP 2–8 at doses of 1, 5, 25, 50 and 100 µM on A2780 cells were examined, it was observed that DPP-3, DPP-4, DPP-5 and DPP-7 were more effective than other derivatives suggested by their high Log IC50 values (p < 0.05). The compounds DPP 2–8 possess cytotoxic activity against PC-3 and LNCaP cells (especially compounds DPP-4 and DPP-5, p < 0.05).

Synthesis, structural and thermal characterizations, dielectric properties and in vitro cytotoxic activities of new 2,2,4,4-tetra(4′- oxy-substituted-chalcone)-6,6-diphenylcyclotriphosphazene derivatives

In this study, we aimed to investigate the relationship between the cytotoxic and dielectric properties of newly synthesized 2,2,4,4-tetra(4′-oxy-substituted-chalcone)-6,6-diphenylcyclotriphosphazene derivatives (3–10). Firstly, 2,2,4,4-tetrachloro-6,6-diphenyl cyclotriphosphazene (2) was obtained through Friedel Crafts alkylation in the presence of hexachlorocyclotriphosphazene, benzene and triethylamine and anhydrous AlCl3. The compounds 3–10 were synthesized from the reaction of the hydroxychalcone compounds (1a–h) with 2 in the presence of K2CO3 and within the acetone solvent for the first time and their dielectric constant, dielectric loss factor and ac conductivity of compounds 3–10 were examined through the impedance analyzer as a function of frequency. The in vitro cytotoxic activities of compounds 3–10 in five different concentrations (1, 5, 25, 50, and 100 µM) were analyzed by colorimetric MTT assay which is based on reduction of MTT salt by mitochondria of alive cells over the human ovarian cancer (A2780) and human prostate cancer (PC-3 and LNCaP) cell lines. The LogIC50 values of 3–10 were calculated by using a Graphpad prism 6 programs on a computer. The obtained results suggests that the compounds have a powerful cytotoxic activity (especially A2780, p < 0.05).