Neriman Colakoglu

A comprehensive immunohistochemical examination of the distribution of the fat-burning protein irisin in biological tissues.

Irisin was first identified in skeletal muscle cells, but its precise location has not yet been demonstrated, and there is limited information about irisin protein in other human and rat tissues. The present immunohistochemical study was undertaken to screen skeletal muscle and other tissues for irisin immunoreactivity. İrisin staining was found in the brain (neurons and neuroglia), cardiac and skeletal muscle (fibers) and skin (sebaceous glands) tissues in male rats. In both human adult and fetal skeletal muscle, the most intense immunohistochemical staining was in the perimysium and endomysium, in the peripheral nerve (epineurium) and axon and nerve sheaths spreading among the cells, in the sarcoplasma and subendomysium. Irisin was also demonstrated in the testis (seminiferous tubules, some spermatogenic cells in fetal and Leydig cells in fetal and adult testis, ductus epididymis in fetal human epididymis); pancreas (islets of Langerhans, serous acini cells, intralobular and intralobular ducts cells); liver (hepatocytes; Kupffer cells and sinusoidal endothelial cells); spleen (subcapsular region and periarterial lymphatic sheets); the stomach (gastric parietal cells, tunica muscularis cells). We conclude that the fat-burning protein irisin locally produced in peripheral and central tissues could act as a gatekeeper of metabolic energy regulation in those tissues, since this myokine converts white into brown adipose tissue, enhancing energy expenditure.

Dietary vitamin C and E modulates oxidative stress induced-kidney and lens injury in diabetic aged male rats through modulating glucose homeostasis and antioxidant systems.

Diabetes induces oxidative stress in aged human and rat, although daily supplementation of vitamins C and E (VCE) can be beneficial to aged diabetic rats by reducing free radical production. The aim of the present study was to evaluate whether dietary VCE supplementation relieves oxidative stress in streptozotocin (STZ)‐induced diabetic in aged rats. Thirty aged rats were randomly divided into three groups. The first group was used as a control. The second group was made diabetic using a single dose of intraperitoneal STZ. VCE‐supplemented feed was given to aged diabetic rats constituting the third group. On the 21st day of the experiment, blood, lens and kidney samples were taken from all animals. Glutathione peroxidase (GSH‐Px) activity in lens and kidney, reduced glutathione (GSH), vitamin E and β‐carotene concentrations in kidney were lower in the diabetic group than in the control whereas plasma glucose, urea and creatinine, and kidney and lens peroxidation (LP) levels were higher in the diabetic group than in the control. However, kidney and lens LP levels, and plasma glucose, urea and creatinine values were decreased by VCE supplementation. Lens and kidney GSH‐Px activity, kidney GSH, vitamin E and β‐carotene concentrations and erythrocyte counts were increased by VCE treatment. Kidney weights, vitamin A, haemoglobin, hematocrit, leukocyte and platelets values were not changed by diabetes and/or VCE supplementation. VCE ameliorated also diabetes‐induced histopathological changes in kidney. In conclusion, we observed that VCE supplementation is beneficial towards kidney and lens of aged diabetic rats by modulating oxidative and antioxidant systems. Copyright

Effects of pinealectomy and exogenous melatonin on ghrelin and peptide YY in gastrointestinal system and neuropeptide Y in hypothalamic arcuate nucleus: immunohistochemical studies in male rats.

It is reported that the pineal gland and its main hormone melatonin may have a role in the regulation of ghrelin synthesis in the brain. Stomach is the place where ghrelin is predominantly expressed and secreted. One aim of this study was to investigate possible effects of pinealectomy and melatonin treatment on gastric ghrelin amount. The studies on the effects of the pineal gland on leptin and ghrelin arises the question whether the pineal gland has also effects on the other energy-regulatory peptides such as peptide YY (PYY) and neuropeptide Y (NPY). Therefore, we also aimed to investigate the changes in the immunohistochemical staining of intestinal PYY and hypothalamic NPY following pinealectomy and melatonin treatment. Serum PYY levels were also investigated. Sprague-Dawley rats were divided into four groups as sham-operated (SHAM), sham-operated with melatonin treatment (SHAM-MT), pinealectomised (PNX) and melatonin-treated PNX (PNX-MT) groups. The cells immunostained for ghrelin were abundant throughout the gastric mucosa in all the groups. Neither pinealectomy nor exogenous melatonin affected significantly immunohistochemical staining of ghrelin in stomach. Pinealectomy resulted in a significant increase in immunohistochemical staining of PYY in ileum. The results of serum PYY measurement corresponded closely to the data obtained by immunohistochemical analysis of PYY in ileum, being significantly lower and higher in SHAM and PNX groups, respectively. Pinealectomy caused a decrease in NPY synthesis in ARC as understood from low immunohistochemical staining of NPY. Melatonin treatment increased NPY synthesis in SHAM rats and restored reduction in NPY synthesis caused by pinealectomy. In conclusion, the pineal gland and its main hormone melatonin can be suggested to have a role in the regulation of NPY synthesis in ARC and PYY in gastrointestinal system.

Effects of melatonin and vitamin C on cigarette smoke–induced damage in the kidney

This study was carried out to investigate smoke-induced structural and biochemical changes and protective effects of co-administered melatonin and vitamin C in the kidney. Twenty-four Wistar adult female rats were used in this study. Animals were divided into four groups. The first group rats were used as control. The second group of rats inhaled cigarette smoke. Smile smoke inhaling third and fourth group rats received melatonin and vitamin C, respectively. At the end of experimental study, kidney tissues and blood samples were taken under ether anesthesia. Tissues were prepared and examined by light microscopy. Malondialdehyde and glutathione levels and catalase activity were determined. By light microscopic observation, a decrease of Bowman space of some renal corpuscles, foamy-like tubules, dilatation and congestion of the peritubuler vessels, and atrophy of the some renal corpuscles were observed in group II. In groups III and IV melatonin and vitamin C relatively protected the kidney tissue against smoke intoxication. Biochemical examination showed that malondialdehyde and glutathione levels and catalase activity in group II were higher than in group I. Melatonin and vitamin C injection to group III and IV caused a decrease in malondialdehyde and glutathione levels. Catalase activity did not change in these groups. We have shown that cigarette smoke inhalation caused structural changes in the kidney. However, melatonin and vitamin C administration produced in some degree protection against smoke-induced damage.

Ameliorative effect of caffeic acid phenethyl ester on histopathological and biochemical changes induced by cigarette smoke in rat kidney

It was aimed to investigate the histopathological and biochemical changes in kidney tissues of rats exposed to cigarette smoke and possible protective effects of caffeic acid phenethyl ester (CAPE) on these changes. Twenty one male Wistar albino rats were divided into three equal groups. Animals in group I were used as control. Rats in group II were exposed to cigarette smoke and rats in group III were exposed to cigarette smoke and daily administration of CAPE. At the end of the 60-day experimental period, all the animals were sacrificed by decapitation. The serum samples obtained from the animals were studied for uric acid, creatinine and blood urine nitrogen (BUN) levels. Following routine histological procedures, kidney tissue specimens were examined under a light microscope. In addition, dismutase (SOD) and glutathione peroxidase (GSH-Px) enzyme activities and malondialdehyde (MDA) and nitric oxide (NO) contents were determined spectrophotometrically in tissue samples. It was found that serum uric acid and BUN levels of the rats exposed to cigarette smoke alone were elevated, although serum creatinine levels did not significantly change. Furthermore, renal SOD, GSH-Px, NO and MDA levels were significantly increased. These increases in serum BUN, and renal SOD, GSH-Px, NO and MDA levels were significantly inhibited by CAPE treatment. In light microscopic observations of tissues from rats exposed to smoke, mesangial cell proliferation in the renal corpuscles, dilatation and congestion in the peritubular capillaries and degenerative alterations in the proximal tubules were noted. There were also atrophic renal corpuscles. However, these histopathological changes were partially disappeared in the rats exposed to cigarette smoke plus CAPE. The present findings indicate that cigarette smoke causes impairment in renal structure and function, which can be prevented by CAPE administration.

Effects of pinealectomy and exogenous melatonin on immunohistochemical ghrelin staining of arcuate nucleus and serum ghrelin leves in the rat

Although the main source of circulating ghrelin is the stomach, it is also present in physiologically relevant amounts in the hypothalamus. It is reported that pharmacological doses of melatonin decrease blood levels of ghrelin. Thus, melatonin (MT) may be a candidate for the regulation of ghrelin synthesis in the brain. This study was therefore undertaken to investigate possible effects of pinealectomy and exogenous melatonin on hypothalamic ghrelin amount. Serum ghrelin levels following pinealectomy and administration of melatonin were also sought. Adult male Sprague-Dawley rats were divided into four groups as sham-operated (SHAM), sham-operated with melatonin treatment (SHAM-MT), pinealectomised (PNX) and melatonin-treated PNX (PNX-MT) groups. Ghrelin staining in the hypothalamus was determined by immunohistochemistry. Hypothalamic ghrelin was not observed in PNX rats. Much higher staining was detected in SHAM-MT rats compared to SHAM group. Lack of effect of melatonin on hypothalamic ghrelin in PNX rats implicates that exogenous melatonin requires an intact pineal to exert its effects. Although there were remarkable changes in the immunohistochemical activity of ghrelin in the hypothalamic arcuate nucleus, neither pinealectomy nor exogenous melatonin significantly changed serum levels of ghrelin. We have demonstrated for the first time that the pineal gland may play a role in ghrelin amount in the hypothalamus.

Teratogenicity of retinoic acid and its effects on TGF-β2 expression in the developing cerebral cortex of the rat

Vitamin A metabolites are potent teratogens in a wide variety of species, including man. Transforming growth factor betas (TGF-βs) are involved in several mammalian prenatal developmental processes. The aim of this study was to determine the effects of exogenous and excessive all-trans retinoic acid on TGFβ2 expression in the developing cerebral cortex of the rat. Many of the malformations including exencephaly, exophtalmus, abdominal wall defects, extremity reduction defects observed in this study were dependent on the time of administration of retinoic acid. TGF-β2 was diversely expressed, as revealed immunohistochemically, in the cerebral cortex and plexus choroideus. The diversity depended on the gestational day and the was affected by the administration of retinoic acid. In the 15-day-old fetus from mothers who had been fed by gavage a single dose of 60 mg/kg body weight of all-trans retinoic acid on the 8th day of gestation, TGF-β2 immunoreactivity in the brain was decreased. However, by the 18th day of gestation, TGF-β2 expression increased. The expression of TGF-β2 in fetuses whose mothers had been given all-trans retinoic acid after the neurulation period (on day 12 of gestation) was generally similar to that in a control group. We conclude that all-trans retinoic acid leads to severe congenital malformations if administered before neurulation whereas if given after neurulation, it is not so teratogenic. Further, retinoic acid has a variable effect on the expression of TGF-β2.

Evaluation of the effect of methylprednisolone and N-acetylcystein on anastomotic degeneration and regeneraton of the facial nerve

OBJECTIVES This study was aimed to determine the effects of methylprednisolone and N-acetylcystein on nerve healing in facial nerve anastomosis. METHODS Thirty rabbits were randomly divided into 3 groups: Group I: control group received no medication; Group II: 50mg/kg/day N-acetylcystein administered group; Group III, 1mg/kg/day Methylprednisolone administered group. All rabbits underwent the same standard surgical procedure. A 1mm segment was resected from the facial nerve and the free ends were anastomosed. The drugs were administered for two months twice a day. At the end of the second month, the anastomosed regions were dissected and examined under electron and light microscopy. RESULTS Best nerve regeneration was observed in the N-acetylcystein and the control groups, respectively, whereas the weakest regeneration was determined in the methylprednisolone group. In the N-acetylcystein group, due to Schwann cell and glial cell proliferation, the increased regeneration rate was significantly higher compared to that of the methylprednisolone group. In the methylprednisolone group, no significant regeneration was observed despite the presence of degenerative signs of significant axonal withdrawal and an increase in the number of myelin debris. CONCLUSION In the present study, we demonstrated that methylprednisolone had no beneficial effect in nerve regeneration after facial nerve anastomosis. It further caused increased degeneration. On the contrary, N-acetylcystein administration significantly increased the extent of regeneration, whereas it decreased the extent of degeneration compared to the control and the methylprednisolone groups.

Effects of high dose retinoic acid on adult rat liver: electron microscopic and immunohistochemical study

Abstract The aim of the present study was to determine the effects of all-trans retinoic acid, a vitamin A metabolite, on liver structure. Twelve adult male rats were used and they were divided into three groups. The first group of rats was fed by gavage 20 mg/kg/day all-trans retinoic acid, whereas second group of rats received 40 mg/kg/day all-trans retinoic acid by gavage for 15 days. The rats in the 3 rd group were used as control. At the end of the study liver tissue samples were taken under ether anesthesia and fixed in Bouins and 2.5% glutaraldehyde solution for immunohistochemical and electron microscopic investigations. On light and electron microscopic investigations, we observed sinusoidal dilatation, periportal cellular infiltration, increase of lipid droplets in the Ito cells that correlated to the increase in the amount of all-trans retinoic acid. By immunohistochemical staining, diminished TGF-β2 immune reaction in the hepatocytes of experimental groups and increased immune reaction in the sinusoidal space. However expression of TGF-β2 was significantly increased in hepatocytes of which the infiltrating cells were abundant. As a result we observed that high dose of all-trans retinoic acid disturbed the normal liver structure. Thus, we concluded that structural changes occurred after RA administration was related to the increased dose of the agent and to the interrelation between RA and TGF-β2 level.

Effects of Systemic Octreotide, Local Mytomycine-C and Local Corticosteroids on Wound-Healing Reaction after Glaucoma Surgery

Purpose: To determine and compare the effectiveness of octreotide,mitomycine-C and corticosteroids on wound-healing reaction after glaucomasurgery. Methods: A full thickness scleral trephination was carriedout by the same surgeon on tour groups of six rabbits. A sponge soaked inmytomicine-C was applied subconjunctivally in group 1 before trephination.Group 2 received corticosteroid drops tid topically for 14 days. Group 3 received subcutaneous octreotide injections tid for 14 days. The controlgroup (group 4) was not given any drug that may interfere with wound healing.All groups received gentamycine drops tid for seven days. The rabbits wereSacrificed on the fourteenth day and the trephination area with overlyingconjunctiva was excised. The samples were prefixed with glutaraldehyde,dehydrated and embedded in Araldite Cy 212. Ten semithin sections stainedwith toluidin blue were analysed for each group. Fibroblast and macrophagecounts were performed on the surgical site and subconjunctival area.Results: Intensive fibroblastic activity, increased number of vessels andactive macrophages were observed only in group 4. The fibroblast and macrophagedensities in this group were significantly higher than the other three groups inwhich wound healing was modulated (p < 0.001). Mean number of fibroblasts ingroup 1 was also significantly less than the ones of groups 2 and 3(p < 0.01). Macrophage densities were similar in groups 1, 2 and 3. No statistical significance was found between groups 2 and 3 by means offibroblast and macrophage densities. Conclusion: Octreotide reducedwound-healing reaction in a similar fashion to corticosteroids ormitomycine-C. These initial results seem promising.