Narin Liman

Role of Thymus Oil in Burn Wound Healing

Thymus oil and its components are becoming increasingly popular as naturally occurring antimicrobial and antioxidant agents. The real importance of thymus on nitric oxide (NO) is unknown. NO is an important mediator in numerous physiologic and pathophysiologic events. Stasis and thrombosis in burn wound can progress as a result of the release of local mediators. The implication of NO in burn injury is not well studied. In this study, we tried to determine the role of burn-induced NO and whether thymus oil plays a protective role after a thermal injury. Rats were divided into five groups. We topically applied thymus oil, olive oil, and silverdin and sulfadiazine on the rats, respectively, during a period of 21 days after they were burned while under anesthesia. The burned control group and nonburned control group did not receive any treatment. The results of this study show that NO was overproduced by thermal injury and decreased during the days after burn injury. The decrease in rats treated with thymus and sulfadiazine was higher than the others. These data indicate that thymus oil may serve as a protective agent to the damaged tissues by decreasing the NO level. Histologic examination results show that the formation of new tissue in rats receiving thymus oil was more than other burned groups, and this finding supports our hypothesis.

The effects of ovariectomy on the mechanical properties of skin in rats

OBJECTIVE After menopause, observable changes occur in the physical characteristics of the human skin. These changes and their responses to various treatments can be assessed with non-invasive in-vivo mechanical tests. However, tests measuring breaking strength and tensile strengths can only be done ex-vivo, they require relatively higher quantities of skin and thus have generally been performed on animals. Mechanical changes in the skin of ovariectomized rats, an appropriate model for the study of postmenopausal period, have not been dealt with in the literature. In this study mechanical characteristics of the skin, such as breaking strength and tensile strength have been tested and studied histologically in ovariectomized rats. METHODS Sixteen rats were divided into two groups, one undergoing ovariectomy and one control group undergoing a sham operation. Three months later, the rats were sacrificed and tensile properties of their back skins were tested with a tensometer and evaluated histologically. RESULTS AND CONCLUSION Breaking strength, tensile strength and the Youngs modulus have increased and the thickness of the subcutis has decreased in ovariectomized rats. This study should be tested by others, because of existence of some conflicts between available knowledge and the results, relating to postmenopausal skin changes.

Effect of Low-Dose Doxycycline on Serum Oxidative Status, Gingival Antioxidant Levels, and Alveolar Bone Loss in Experimental Periodontitis in Rats

BACKGROUND Subantibiotic doses of doxycycline (low-dose doxycycline [LDD]) have been widely used in periodontal treatment for enzymatic inhibition and related anti-inflammatory properties. The aim of the present study is to verify the possible effects of LDD on oxidative stress in relation to periodontal attachment loss associated with ligature-induced experimental periodontal disease in rats. METHODS Thirty female Wistar albino rats were divided into three study groups as follows: 1) control (C) rats; 2) rats with experimental periodontitis (PED); and 3) rats with PED that were treated with doxycycline (PED + LDD). PED was induced by placing ligatures around the cervix of the maxillary second molars for 21 days. The PED + LDD group was treated orally with doxycycline (6 mg/kg) for 21 days after the ligature was placed. After 21 days, the rats were euthanized, and samples of the right maxilla were defleshed and used for histologic and morphometric analyses. The gingival tissue of the left maxilla was used for the analysis of lipid peroxidation (malondialdehyde [MDA]) and antioxidant enzymes (catalase, glutathione peroxidase, and superoxide dismutase). Levels of serum total antioxidant status (TAS)/total oxidant status (TOS) and oxidative stress index (OSI) were also analyzed. RESULTS Alveolar bone loss was significantly higher in the PED group compared with the PED + LDD and C groups (P <0.05). Doxycycline exhibited the most prominent inhibition on gingival tissue levels of MDA and antioxidant enzymes (P <0.05). Doxycycline also significantly reduced TOS and OSI levels (P <0.05) but increased the TAS level. CONCLUSION Doxycycline helps to prevent periodontal tissue breakdown by inhibiting local and systemic oxidative stress.

Experimentally Induced Hyperthyroidism Disrupts Hippocampal Long-Term Potentiation in Adult Rats

Background: Manipulating thyroid hormones has been shown to influence learning and memory. Although a large body of literature is available on the effects of thyroid hormone deficiency on learning and memory functions during developmental or adult-onset hypothyroidism, electrophysiological findings are limited. This limitation is especially notable with respect to thyroxine administration in adult, normothyroid animals. Methods: Experiments were carried out on 12 adult male Wistar rats, each 9–10 months of age. Rats were randomly divided into hyperthyroid (0.2 mg/kg/day intraperitoneal thyroxine injection, for 21 days) and control groups (n = 6 animals in each group). Following spatial learning performance tests on hyperthyroid and control groups, rats were anesthetized with urethane and placed in a stereotaxic frame. A bipolar, tungsten electrode was used to stimulate the medial perforant path. A glass micropipette was inserted within the granule cell layer of the ipsilateral dentate gyrus to record field excitatory postsynaptic potentials (fEPSP). Following a 15-min baseline recording of fEPSPs, long-term potentiation (LTP) was induced by four sets of tetanic pulse trains. Results: Thyroxine-treated rats showed significantly worse performance in the spatial memory task and attenuated input-output relationships in the electrophysiological analyses. Treated rats also showed a lower efficacy of LTP induction when compared with controls. Conclusion: The present study provides clear in vivo evidence for the action of L-thyroxine in the impairment of synaptic plasticity and in inducing spatial memory task deficits in adult rats. These findings may explain the complaints of cognitive function reductions in hyperthyroid patients.

Experimental Hypothyroidism Delays Field Excitatory Post‐Synaptic Potentials and Disrupts Hippocampal Long‐term Potentiation in the Dentate Gyrus of Hippocampal Formation and Y‐Maze Performance in Adult Rats

Manipulations of thyroid hormones have been shown to influence learning and memory. Although a large body of literature is available on the effect of thyroid hormone deficiency on learning and memory functions during the developmental stage, electrophysiological and behavioural findings, particularly on propylthiouracil administration to adult normothyroid animals, are not satisfactory. The experiments in the present study were carried out on 12 adult male Wistar rats aged 6–7 months. Hypothyroidism was induced by administering 6‐n‐propyl‐2‐thiouracil in their drinking water for 21 days at a concentration of 0.05%. The spatial learning performance of hypothyroid and control rats was studied on a Y‐maze. The rats were then placed in a stereotaxic frame under urethane anaesthesia. A bipolar tungsten electrode was used to stimulate the medial perforant path. A glass micropipette was inserted into the granule cell layer of the ipsilateral dentate gyrus to record field excitatory post‐synaptic potentials. After a 15‐min baseline recording of field potentials, long‐term potentiation was induced by four sets of tetanic trains. The propylthiouracil‐treated rats showed a significantly attenuated input–output (I/O) relationship when population spike (PS) amplitudes and field excitatory post‐synaptic potentials (fEPSP) were compared. fEPSP and PS latencies were found to be longer in the hypothyroid group than in the control group. The PS amplitude and fEPSP slope potentiations in the hypothyroid rats were not statistically different from those in the control rats, except for the field EPSP slope measured in the post‐tetanic and maintenance phases. The hypothyroid rats also showed lower thyroxine levels and poor performance in the spatial memory task. The present study provides in vivo evidence for the action of propylthiouracil leading to impaired synaptic plasticity, which might explain deficit in spatial memory tasks in adult hypothyroid rats.

Immunohistochemical localization of beta defensins in the endometrium of rat uterus during the postpartum involution period

Abstractβ-Defensins are small cationic molecules that have antimicrobial actions against bacteria, fungi and viruses and contribute to mucosal immune responses at epithelial sites. The female reproductive tract is an important site of defensin production. This study was conducted to determine the possible changes in proportions and localization of β-defensin 1-4 in the rat uterus at the 1st, 3th, 5th, 10th and 15th days of postpartum and at the period of diestrus using immunohistochemical techniques. In the present study, it was determined that β-defensin 1-4 were generally found in all structural components of the endometrium (luminal and glandular epithelium, stromal cells and blood vessels) in both the nucleus and the cytoplasm of cells during the involution period and diestrus. Suprisingly, immunoreaction of β-defensin 2 was also observed in the lateral membrane of the luminal and glandular epithelial cells on the 10th day of involution and immunostaining of β-defensin 4 was also localized in the apical membrane of the luminal and glandular epithelial cells. The current study demonstrated β-defensin 1-4 immunoreactivities in the endothelium of blood vessels were stronger throughout the involution period. Although β-defensins 2 and 3 were localized in both the nuclei and the cytoplasm of endothelial cells, β-defensins 1 and 4 were present in only cytoplasm. These results show that the most component of rat endometrium expresses human β-defensin 1-4 in a involution-dependent manner. Therefore it may be asserted that these molecules constitute a organised protection to prevent uterus from probable infections during the involution process.

The differences between the localizations of MUC1, MUC5AC, MUC6 and osteopontin in quail proventriculus and gizzard may be a reflection of functional differences of stomach parts

Mucins are high molecular weight glycoproteins which constitute the major component of the mucus layer and are produce by many epithelial tissues in vertebrates. Osteopontin (OPN) is an adhesive phosphorylated glycoprotein that is expressed by a broad range of tissues and cells. Although gastric mucins MUC1, MUC5AC, MUC6 and OPN have been widely used in histological studies and in diagnostic pathology in order to diagnose gastric carcinomas, their localizations in the stomach of quail have not yet been studied. In this study, the localizations of MUC1, MUC5AC, MUC6 and OPN in the proventriculus and gizzard of Japanese quail during the post‐hatching period were compared at light microscope levels by applying immunohistochemical methods. In all ages studied, the immunoreactivity of MUC5AC was present in the lining epithelium of both folds and superficial proventricular glands in the proventriculus, whereas MUC1, MUC6 and OPN reactivity was found in the oxynticopeptic cells of profound proventricular glands. In addition, some cells in the fold epithelium of the proventriculus showed a positive reaction to OPN. The immunoreactivity of MUC1 in gizzard was different from that of MUC5AC. Although MUC5AC was expressed in the cells of both the surface epithelium and profound glands of the gizzard, MUC1 was only localized in the profound glands of the gizzard. However, MUC6 and OPN immunoreactivity was absent in the gizzard. The results indicated that the differences between the localizations of MUC1, MUC5AC, MUC6 and OPN in quail proventriculus and gizzard may be a reflection of functional differences of stomach parts. Although the biological significances of the expressions of MUC1, MUC5AC, MUC6 and OPN in the quail stomach remains unknown, these notable glycoproteins may be associated with barrier function, host defence, and/or secretion.

Immunolocalization of vascular endothelial growth factor, its receptors (flt1/fms, flk1/KDR, flt4) and vascular endothelial growth inhibitor in the bitch uterus during the sexual cycle

Angiogenesis is regulated by proangiogenic and antiangiogenic factors. Vascular endothelial growth factor (VEGF) is a prime proangiogenic regulator, whereas vascular endothelial growth inhibitor (VEGI) is a specific antiangiogenic cytokine. To clarify temporal changes in the localization of pro-angiogenic and anti-angiogenic factors in the uterus of normal bitches during the proestrus, estrus, diestrus and anestrus phases of the estrous cycle, the expressions of VEGF and its receptors (flt1/fms, flk1/KDR and flt4) and their correlation with VEGI were analyzed using immunohistochemistry. Uteruses were collected after ovariohysterectomy. Immunohistochemical staining was evaluated semi-quantitatively by an immunohistochemical total score consisting of the sum of the intensity and proportional scores. The results in the bitch uterus demonstrated that positive immunohistochemical staining was found exclusively in the cytoplasm and apical membrane of luminal and glandular epithelial, stromal and smooth muscle cells and nuclear staining was observed in the flt1/fms, flk4 and VEGI during proestrous and estrous. Semi-quantitative analyses revealed that the total score for VEGF in the glandular epithelial cells was significantly higher than that of luminal, endometrial stromal and myometrial smooth muscle cells during proestrous (p<0.05). The total score for flk1/KDR and flt4 in the glandular epithelium was also significantly higher than that of endometrial stromal cells during proestrous, whilst the total score for flt1/fms in the glandular epithelium was significantly higher than that of endometrial stromal cells during anestrus (p<0.05). We conclude that, in the bitch uterus, cyclic changes may be precisely regulated by the combined functions of VEGF family members, angiogenic VEGF and VEGF receptors, and the angiogenesis inhibitor VEGI.

The expression of epidermal growth factor receptors and their ligands (epidermal growth factor, neuregulin, amphiregulin) in the bitch uterus during the estrus cycle

In order to study the possible role of EGFR receptors in the bitch reproductive process, we have analyzed the expression pattern and localization of EGFR receptors and some of their ligands epidermal growth factor (EGF), neuregulin (NRG), amphiregulin (AREG), in the uterus during the estrus cycle using immunohistochemistry. The immunostaining for receptors and ligands of EGFR/ligand system was confined to membrane and cytoplasm of the target cells. Variations were observed, not only at the different stages of the estrous cycle, but also in the different tissue compartments of the uterus. However, it was detected that the immunostainings for NRG and AREG in the different cells do not show important differences at stages of the estrus cycle. In the luminal epithelium, strong immunostaining for ErbB1/HER1, ErbB2/HER2, ErbB4/HER4 and EGF was found at estrus. In the glandular epithelium, strong immunostaining for ErbB4/HER4 was observed at diestrus, while strong immunostaining for EGF was detected in both of estrus and diestrus. ErbB3/HER3 immunoreactivity in the stromal cells was higher at diestrus and anestrus, while ErbB4/HER4 immunoreactivity was lower at anestrus. In the myometrium, the highest levels of immunoreactivity of ErbB2/HER2 were found at estrus, while ErbB3/HER3 immunoreactivity was higher at anestrus. EGF immunoreactivity was lower at anestrus compared to other stage of cycle. Altered EGFR/ligand system expression during the estrus cycle suggests this growth factor system is a potent regulator of proliferation and differentiation events during preparation for implantation of bitch uterus.

Adult-onset hyperthyroidism impairs spatial learning: possible involvement of mitogen-activated protein kinase signaling pathways.

Given evidence that mitogen-activated protein kinase (MAPK) activation is part of the nongenomic actions of thyroid hormones, we investigated the possible consequences of hyperthyroidism for the cognitive functioning of adult rats. Young adult rats were treated with L-thyroxine or saline. Twenty rats in each group were exposed to Morris water maze testing, measuring their performance in a hidden-platform spatial task. In a separate set of rats not exposed to Morris water maze testing (untrained rats), the expression and phosphorylated levels of p38-MAPK and of its two downstream effectors, Elk-1 and cAMP response element-binding protein, were evaluated using quantitative reverse transcriptase-PCR and western blotting. Rats with hyperthyroidism showed delayed acquisition of learning compared with their wild-type counterparts, as shown by increased escape latencies and distance moved on the last two trials of daily training in the water maze. The hyperthyroid rats, however, showed no difference during probe trials. Western blot analyses of the hippocampus showed that hyperthyroidism increased phosphorylated p38-MAPK levels in untrained rats. Although our study is correlative in nature and does not exclude the contribution of other molecular targets, our findings suggest that the observed impairments in acquisition during actual learning in rats with hyperthyroidism may result from the increased phosphorylation of p38-MAPK.