Zafer Sahin

Effects of letrozole on hippocampal and cortical catecholaminergic neurotransmitter levels, neural cell adhesion molecule expression and spatial learning and memory in female rats

We have investigated effects of letrozole, an aromatase inhibitor, on spatial learning and memory, expression of neural cell adhesion molecules (NCAM) and catecholaminergic neurotransmitters in the hippocampus and cortex of female rats. In the intact model, adult Sprague-Dawley rats were divided into four groups (n=8). Control received saline alone. Letrozole was administered to the animals in the second and third groups by daily oral gavage at 0.2 and 1 mg/kg doses, respectively, for 6 weeks. Another group of letrozole-treated rats was allowed to recover for 2 weeks. In the second model, 24 rats were ovariectomized (ovx) and the first group served as control. The second group received letrozole (1 mg/kg) for 6 weeks. Ovx rats in the third group were given letrozole (1 microg/kg) plus estradiol (E(2)) (10 microg/rat). At the end, all rats were tested in a spatial version of the Morris water maze. Then they were decapitated and the brains rapidly removed. Catecholamine concentrations were determined by high performance liquid chromatography with electrochemical detection. NCAM 180, 140 and 120 isoforms were detected by Western blotting. Uterine weights were significantly reduced by letrozole in a dose-dependent manner (P<0.01) which returned to control values following 2 weeks of recovery (P<0.05). Serum E(2) levels followed a similar course (P<0.01). Although improvement in spatial learning performance of letrozole-treated rats was not statistically significant, the high-dose letrozole-treated group remained significantly longer in the target quadrant compared with the control (P<0.05). Administration of letrozole to ovx animals significantly reduced the latency (P<0.001) and increased the probe trial performance compared with ovx controls (P<0.05). Letrozole increased expression of NCAM 180 and NCAM 140 in both hippocampus and cortex of intact rats. In the cortex samples of ovx animals, NCAM 180 was overall lower than the intact control values (P<0.05). Noradrenaline, dopamine and their metabolites were decreased in the hippocampus of the letrozole-treated group (P<0.01). Letrozole had differential effects on noradrenaline and dopamine content in the cortex. It appears that inhibition of estrogen synthesis in the brain may have beneficial effects on spatial memory. We suggest that structural changes such as NCAM expression and catecholaminergic neurotransmitters in the hippocampus and prefrontal cortex may be the neural basis for estrogen-dependent alterations in cognitive functions.

Kisspeptin antagonist prevents RF9-induced reproductive changes in female rats

The aim of this study was to determine the modulatory effects of peptide 234 (p234) (an antagonist of GPR54 receptors) on kisspeptin and RF9 (an RFamide-related peptide antagonist)-induced changes in reproductive functions and energy balance in female rats. Female Sprague-Dawley rats were weaned on postnatal day (pnd) 21. The animals were intracerebroventricularly cannulated under general anesthesia on pnd 23. Groups of female rats were injected with kisspeptin, RF9, p234, kisspeptin plus p234, or RF9 plus p234, daily. The experiments were ended on the day of first diestrus following pnd 60. Kisspeptin or RF9 alone advanced vaginal opening (VO), which was delayed by administration of kisspeptin antagonist alone. In the rats given kisspeptin plus p234 or RF9 plus p234, VO was not different from control rats. Kisspeptin and RF9 elicited significant elevations in circulating LH levels. Coadministrations of kisspeptin or RF9 with p234 decreased LH levels significantly. The use of p234 alone did not cause any significant change in LH secretion. Kisspeptin decreased both food intake and body weight while RF9 decreased only food intake without affecting body weight. The effects of kisspeptin on energy balance were also reversed by central administration of p234. In conclusion, kisspeptin antagonist, p234, modulates the effects of kisspeptin on reproductive functions and energy balance, whereas RF9 seems to exert only its effects on reproductive functions by means of GPR54 signaling in female rats.

Effects of Naringenin on Oxidative Stress and Histopathological Changes in the Liver of Lead Acetate Administered Rats

Lead has several adverse effects on the body due to one of the environmental pollutants. We aimed to determine the effects of naringenin on the oxidative stress and the hepatic damage against lead acetate treatment in the liver of male rats. Naringenin was administered by orogastric gavage (50 mg/kg) and lead acetate was given as daily 500 parts per million in drinking water for 4 weeks. Lead and antioxidant activities were measured, and histopathological evaluation was performed in the liver. Lead concentrations, malondialdehyde, and antioxidant activity were restored by the naringenin. The grade of necrosis, hydropic degeneration, and hepatic cord disorganization was decreased by the naringenin. However, there were no differences in the degree of sinusoidal congestion, hepatic steatosis, and capsular fibrosis between lead acetate and naringenin + lead acetate groups. We can suggest that naringenin has antioxidant and chelating effects in the liver. Nevertheless, this effect is not enough against the lead acetate induced hepatic injury.

Investigation of the effect of naringenin on oxidative stress‐related alterations in testis of hydrogen peroxide‐administered rats

Testis tissue is prone to oxidation because its plasma membrane contains many polyunsaturated fatty acids. Naringenin is a plant‐derived natural flavonoid. We investigated the possible ameliorative role of naringenin on the hydrogen peroxide (H2O2)‐induced testicular damage in Wistar rats. Animals received 12 mg/kg H2O2 by intraperitoneal injection, and 50 mg/kg naringenin via orogastric gavage for 4 weeks. In the H2O2 group, the testis malondialdehyde level increased, while the amount of reduced glutathione, glutathione transferase activities, and the testis weight decreased. There were severe testicular damages in the H2O2 group otherwise their grade were less in the naringenin + H2O2 group. However, the serum testosterone concentrations decreased in both the H2O2 and the naringenin + H2O2 groups. The testicular zinc and calcium levels reduced in the H2O2‐treated rats. In conclusion, the administration of H2O2 caused oxidative stress in the testes and naringenin supplementation decreased the H2O2‐induced effects, except for changes in testosterone levels.

Examination of Changes in Enzyme Activities of Erythrocyte Glucose 6-Phosphate Dehydrogenase and 6-Phosphogluconate Dehydrogenase in Rats Given Naringenin and Lead Acetate

In our study, controlled experimental groups were performed by giving substances Lead acetate, Naringenin and Naringenin + Lead acetate to rats in vivo conditions Changes in the glucose 6‐phosphate dehydrogenase (G6PD) and 6‐phosphogluconate dehydrogenase (6PGD) enzyme activities in erythrocytes of rats in these groups were compared to the Control group. An inhibition significant degree for G6PD enzyme activity was observed in all groups when compared to the Control group (p < 0.001). While inhibition significant degree for 6PGD enzyme activity was observed in Lead acetate groups (p < 0.001), no significant effect was observed in the Naringenin and Naringenin + Lead acetate groups (p > 0.05). In addition, lead levels in the groups of rats were determined using an inductively coupled plasma mass spectrometer (ICP‐MS) device. As a result of measurements by the ICP‐MS device, lead levels were found as an average of 42.9 ± 2.51, 36.71 ± 1.13, 172.16 ± 9.63, and 95.07 ± 5.87 ppm in the Control, Naringenin, Lead acetate and Naringenin + Lead acetate groups, respectively. Our results were shown that Naringenin has protective effects on the Lead acetate induced oxidative stress erythrocytes in rat.

Time-of-Day Dependent Neuronal Injury After Ischemic Stroke: Implication of Circadian Clock Transcriptional Factor Bmal1 and Survival Kinase AKT

Occurrence of stroke cases displays a time-of-day variation in human. However, the mechanism linking circadian rhythm to the internal response mechanisms against pathophysiological events after ischemic stroke remained largely unknown. To this end, temporal changes in the susceptibility to ischemia/reperfusion (I/R) injury were investigated in mice in which the ischemic stroke induced at four different Zeitgeber time points with 6-h intervals (ZT0, ZT6, ZT12, and ZT18). Besides infarct volume and brain swelling, neuronal survival, apoptosis, ischemia, and circadian rhythm related proteins were examined using immunohistochemistry, Western blot, planar surface immune assay, and liquid chromatography–mass spectrometry tools. Here, we present evidence that midnight (ZT18; 24:00) I/R injury in mice resulted in significantly improved infarct volume, brain swelling, neurological deficit score, neuronal survival, and decreased apoptotic cell death compared with ischemia induced at other time points, which were associated with increased expressions of circadian proteins Bmal1, PerI, and Clock proteins and survival kinases AKT and Erk-1/2. Moreover, ribosomal protein S6, mTOR, and Bad were also significantly increased, while the levels of PRAS40, negative regulator of AKT and mTOR, and phosphorylated p53 were decreased at this time point compared to ZT0 (06:00). Furthermore, detailed proteomic analysis revealed significantly decreased CSKP, HBB-1/2, and HBA levels, while increased GNAZ, NEGR1, IMPCT, and PDE1B at midnight as compared with early morning. Our results indicate that nighttime I/R injury results in less severe neuronal damage, with increased neuronal survival, increased levels of survival kinases and circadian clock proteins, and also alters the circadian-related proteins.

Role of geraniol against lead acetate-mediated hepatic damage and their interaction with liver carboxylesterase activity in rats.

Abstract In this study, the effect of geraniol (50 mg/kg for 30 d), a natural antioxidant and repellent/antifeedant monoterpene, in a rat model of lead acetate-induced (500 ppm for 30 d) liver damage was evaluated. Hepatic malondialdehyde increased in the lead acetate group. Reduced glutathione unchanged, but glutathione S-transferase, glutathione reductase, as well as carboxylesterase activities decreased in geraniol, lead acetate and geraniol + lead acetate groups. 8-OhDG immunoreactivity, mononuclear cell infiltrations and hepatic lead concentration were lower in the geraniol + lead acetate group than the lead acetate group. Serum aspartate aminotransferase and alanine aminotransferase activities increased in the Pb acetate group. In conclusion, lead acetate causes oxidative and toxic damage in the liver and this effect can reduce with geraniol treatment. However, we first observed that lead acetate, as well as geraniol, can affect liver carboxylesterase activity.

Geraniol attenuates hydrogen peroxide-induced liver fatty acid alterations in male rats -

Background: Hydrogen peroxide (H2O2) is an oxidant agent and this molecule naturally occurs in the body as a product of aerobic metabolism. Geraniol is a plant-derived natural antioxidant. The aim of this study was to determine the role of geraniol on hepatic fatty acids alterations following H2O2-induced oxidative stress in male rats. Methods: After randomization, male Wistar rats were divided into four groups (n = 7 each group). Geraniol (50 mg/kg, dissolved in corn oil) and H2O2 (16 mg/kg, dissolved in distilled water) were administered by an intraperitoneal injection. Administrations were performed during 30 days with 1-day interval. Results: Administration of H2O2 resulted with a significant increase in malondialdehyde (MDA) and a significant decrease in glutathione (GSH) peroxidase glutathione level; geraniol restored its effects on liver. However, hepatic catalase (CAT) activities were significantly higher in H2O2, geraniol, and geraniol+H2O2 groups than control group. The ratio of hepatic total saturated fatty acids increased in H2O2-treated animals compared with control. In addition, hepatic total unsaturated fatty acids reduced in H2O2 group compared with control. The percentages of both hepatic total saturated and unsaturated fatty acids were not different between geraniol+H2O2 and control groups. Conclusions: H2O2-induced oxidative stress may affect fatty acid composition in liver and body. Geraniol can partly restore oxidative hepatic damage because it cannot completely reverse the H2O2-induced increase in hepatic CAT activities. Moreover, this natural compound can regulate hepatic total saturated and unsaturated fatty acids percentages against H2O2-induced alterations.

Studies on the reproductive effects of chronic treatment with agomelatine in the rat.

Agomelatine is an antidepressant with a novel mechanism of action. It is a melatonergic agonist for MT1 and MT2 receptors and a serotonin (5-HT2C) receptor antagonist. Agomelatine has been suggested not to have adverse effects on sexual functions. However, the effects of chronic agomelatine administration on reproductive functions have not been sufficiently studied in animal models. We mainly aimed to explore the effects of agomelatine on reproductive functions in the male and female rats. For the experimental studies, Sprague Dawley rats were used. The animals started to receive daily oral agomelatine (10mg/kg) on post-natal day 21. Agomelatine advanced vaginal opening in the female rats whereas it delayed puberty onset in the male rats. Agomelatine treatment significantly decreased intromission frequencies, which indicates a facilitator role of this antidepressant on male sexual behavior. In the forced swimming test (FST) used for assessing antidepressant efficacy, agomelatine induced a significant decrease in duration of immobility, and an increase in the swimming time, respectively, which confirms the antidepressant-like activity of agomelatine. The present findings suggest that agomelatine shows a strong antidepressant effect in the male rats without any adverse influences on sexual behavior, and its effects on pubertal maturation seem to show sex-dependent differences.

Investigation of the role of α-lipoic acid on fatty acids profile, some minerals (zinc, copper, iron) and antioxidant activity against aluminum-induced oxidative stress in the liver of male rats

Abstract Background: We have investigated the effects of α-lipoic acid (LA), a powerful antioxidant, on the fatty acid (FA) profiles, aluminum accumulation, antioxidant activity and some minerals such as zinc, copper and iron against aluminum chloride (AlCl3)-induced oxidative stress in rat liver. Methods: Twenty-eight male Wistar rats were divided into four groups as control, LA, AlCl3 and LA+AlCl3. For 30 days, LA was intraperitoneally administrated (50 mg/kg) and AlCl3 was given via orogastric gavage (1600 ppm) every other day. Results: AlCl3-treated animals exhibited higher hepatic malondialdehyde concentration and lower glutathione peroxidase and catalase activity, whereas these alterations were restored by the LA supplementation. Total saturated FA of the AlCl3-treated group was higher than the LA supplementation groups. Moreover, total unsaturated FA level of the LA+AlCl3 group was higher than the AlCl3-treated group. Hepatic zinc level of the AlCl3-treated group was lower than the control group, whereas it was higher in the LA and the LA+AlCl3 groups. Hepatic copper levels did not significantly change in the experimental groups. Iron level was lower in the LA and LA+AlCl3 groups compared with the AlCl3-treated group. Moreover, the liver Al concentration was found to be lower in the LA and LA+AlCl3 groups compared to the AlCl3 group. Conclusions: These results indicate that AlCl3 treatment can induce oxidative stress in the liver. LA supplementation has a beneficial effect on the AlCl3-induced alterations such as high lipid peroxidation, Al accumulation, FA profile ratios and mineral concentrations.