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Golden Hamsters (golden + hamster)
Kinds of Golden Hamsters Selected AbstractsStructure of the Lining Epithelium of the Cauda Epididymis of the Golden HamsterANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 1 2009C. C. L. Beu Summary The ductus epididymis has roles in the maturation and storage of spermatozoa. The main function of the cauda epididymis is the storage of spermatozoa; however, this region exerts other morphophysiological roles. So, this study was aimed at investigating structural features of the cauda epididymis epithelium, which could indicate roles other than the storage. The relative percentages of the cell types in the epithelium were 74.9, 6.9, 12.5 and 5.6% of principal, clear, basal and halo cells respectively. Large intercellular spaces were seen among the lateral plasmatic membranes of adjacent principal cells or among these cells and others cell types. These spaces were found to be filled with multivesicular bodies, myelin figures, scrolls and debris of membranes or flocculent dense material. Clear cells had the cytoplasms filled with lysosomes (¾ of basal cytoplasm), and vacuoles and vesicles (¼ of apical cytoplasm). The observations allowed us to infer that clear cells could act in the process of endocytosis and also in water transfer from the lumen to the interstitium through the epithelium compartment. Moreover, transcytosis may occur at the cauda epididymis of Golden hamster. [source] Glucocorticoids and the Development of Agonistic Behaviour during Puberty in Male Golden HamstersJOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2005J. C. Wommack Abstract During puberty, the agonistic behaviour of male golden hamsters undergoes a transition from play fighting to adult aggression. Repeated exposure to social stress early in puberty accelerates this transition. The present study investigated the possible role of glucocorticoids on the maturation of agonistic behaviour. First, we compared serum cortisol levels following a 20-min restraint stress during early puberty, mid-puberty or adulthood. Across puberty, animals exhibited a two-fold increase in post-restraint cortisol levels. We also compared corticotrophin-releasing hormone (CRH) immunoreactive fibres projecting to the median eminence between animals in early puberty and adulthood. The CRH fibre density was two-fold greater in adults compared to juveniles. Furthermore, we investigated the effects of stress hormones on the maturation of agonistic behaviour. Male hamsters were injected daily with dexamethasone, a corticosteroid receptor type II agonist (0, 10 or 40 µg/100 g), early in puberty from postnatal day 31 (P-31) to P-36. When paired with a smaller and younger intruder on P-37, attack frequency did not differ between groups. However, dexamethasone-treated animals showed a dose-dependent decrease in the percentage of play-fighting attacks and an increase in the percentage of adult attacks. In summary, puberty can be described as a period of increasing hypothalamic-pituitary-adrenal activity in male golden hamsters. Moreover, increasing glucocorticoid levels influence the maturation of agonistic behaviour. These data shed new light on the neuroendocrine mechanisms that regulate the maturation of social behaviours during puberty. [source] Structure of the Lining Epithelium of the Cauda Epididymis of the Golden HamsterANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 1 2009C. C. L. Beu Summary The ductus epididymis has roles in the maturation and storage of spermatozoa. The main function of the cauda epididymis is the storage of spermatozoa; however, this region exerts other morphophysiological roles. So, this study was aimed at investigating structural features of the cauda epididymis epithelium, which could indicate roles other than the storage. The relative percentages of the cell types in the epithelium were 74.9, 6.9, 12.5 and 5.6% of principal, clear, basal and halo cells respectively. Large intercellular spaces were seen among the lateral plasmatic membranes of adjacent principal cells or among these cells and others cell types. These spaces were found to be filled with multivesicular bodies, myelin figures, scrolls and debris of membranes or flocculent dense material. Clear cells had the cytoplasms filled with lysosomes (¾ of basal cytoplasm), and vacuoles and vesicles (¼ of apical cytoplasm). The observations allowed us to infer that clear cells could act in the process of endocytosis and also in water transfer from the lumen to the interstitium through the epithelium compartment. Moreover, transcytosis may occur at the cauda epididymis of Golden hamster. [source] Photoperiod-induced apoptosis in the male genital tract epithelia of the golden hamsterINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2007Rosa Carballada Summary The aim of this study was to identify some details of the changes induced by a short-day light regime (8:16 light:dark) on the male genital tract and accessory sex glands of the golden hamster Mesocricetus auratus. We principally examined the presence of apoptotic cells in the epithelium from different regions of the epididymis, seminal vesicles, prostate and coagulating gland. We detected an increase in the percentage of apoptotic cells in situ using the TUNEL technique in animals that were maintained for 6, 8 or 12 weeks in a short photoperiod. That those cells were indeed undergoing apoptosis was confirmed by the immunodetection of the active fragment of caspase-3. The apoptotic indices in the different tissues analysed were low, but were maintained for weeks, suggesting cell loss at a steady rate. We tried to correlate these changes with the testosterone levels in serum as well as with the oxidative stress in the tissue. On the other hand, the increase in size and number of lipofuscin granules indicated the possibility that a parallel increase in oxidative stress occurred in the tissues. The normalization in the number of apoptotic cells and lipofuscin granules in animals treated with testosterone suggests that both phenomena might be related to changes in the hormone levels. [source] Digital image analysis of the flagellar beat of activated and hyperactivated suncus spermatozoaMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 4 2007Takane Kaneko Abstract The flagellar beat of hyperactivated Suncus spermatozoa was analyzed by digital imaging and was compared to that of the nonhyperactivated (activated) spermatozoa in order to examine the function of the accessory fibers during the flagellar beat and the sliding filament mechanism inducing the motility of the hyperactivated spermatozoa. Unusual large and long characteristics of the accessory fibers were involved in generating the gently curved bends and a low beat frequency. Examination of the motility parameters of the flagellar beat of the activated and hyperactivated spermatozoa attached to a slide glass by their heads revealed that there were two beating modes: a frequency-curvature dependent mode in the activated flagellar beat and a nearly constant frequency mode in the hyperactivated flagellar beat. The hyperactivated flagellar beat was characterized by sharp bends in the proximal midpiece and a low beat frequency. The sharp bends in the proximal midpiece were induced by the increase in the total length of the microtubule sliding at the flagellar base. The rate of microtubule sliding (sliding velocity) in the axoneme remained almost constant in the flagellar beat of both the activated and hyperactivated spermatozoa. Comparison of the sliding velocity in Suncus, golden hamster, monkey, and sea urchin sperm flagella with their stiffness suggests that the sliding velocity is determined by the stiffness at the flagellar base and that the same sliding microtubule system functions in both mammalian and echinoderm spermatozoa. Mol. Reprod. Dev. 74: 478,485, 2007. © 2006 Wiley-Liss, Inc. [source] New local hyperthermia using dextran magnetite complex (DM) for oral cavity: experimental study in normal hamster tongueORAL DISEASES, Issue 3 2001S Wada The possibility of dextran magnetite complex (DM) as a new hyperthermic material was examined in this study. DM suspension of 56 mg ml ,1 iron concentration was locally injected into the normal tongue of golden hamster. DM injected tongues were heated by 500 kHz alternating current (AC) magnetic field and its serial changes in temperature were recorded at 30-s intervals. The temperature of DM injected tongue was maintained at about 43.0,45.0°C for 30 min by changing the AC magnetic field intensity. While temperature elevations of the contralateral tongue and the rectum were only of minor degree. In experiment on the extent of heating area, there was correlation between volume of black stain area and amount of the injected DM suspension (Y =,18.1 + 1.94X, r= 0.931, P < 0.0001, n= 9). Histological examination after heating revealed brown uniform DM accumulation in the connective tissue between fibers of the tongue muscle. Except for vascular dilatations, no tissue damage was seen in the heated tongue. Thus, DM which has the possibility of selective and uniform heating in local hyperthermia might be useful for oral cancer therapy. [source] Effects of different opportunities for social interaction on the play fighting behavior in male and female golden hamsters (Mesocricetus auratus)DEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2005Mauro Luís Vieira Abstract After social isolation, animals play significantly more than nonisolated animals. However, it is not always possible to affirm that the effect of the social isolation is due to the lack of play. Experimentally, selective privation has been used, such as allowing the animals to play during periods of the day. In the present study, two experiments were carried out to verify the possible differences in the play fighting behavior of golden hamsters that were allowed to have different daily periods of social interaction (10 min, 1 hr, or 2 hr). Through the statistical analysis, it was shown that males play more than females and that periods of up to 2 hr daily for interaction are insufficient to avoid the short-term effects of isolation. It is concluded that a period of daily social interaction greater than 2 hr is needed to offset the effects of social isolation in golden hamsters. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 47: 345,353, 2005. [source] Adolescent stress and neural plasticity in hamsters: a vasopressin-serotonin model of inappropriate aggressive behaviourEXPERIMENTAL PHYSIOLOGY, Issue 2000Craig F. Ferris Animal studies show that arginine vasopressin facilitates aggression, while serotonin (5-HT) inhibits aggression by blocking the activity of the vasopressin system. Clinical studies report that subjects with a history of ,fighting and assault' show a significant positive correlation between cerebrospinal fluid concentrations of vasopressin and aggression in the presence of a hyporeactive 5-HT system. Thus, in animals and humans, a hyporeactive 5-HT system may result in enhanced vasopressin activity and increased aggression. Can the stress of emotional and physical insult, i.e. threat and attack, during adolescence affect the development of the vasopressin and 5-HT systems and alter normal aggressive behaviour in early adulthood? Adolescent male golden hamsters were weaned at postnatal day 25, and stressed for 2 weeks by daily 1 h bouts of threat and attack by adult hamsters. Male littermates were run in a parallel stress study using daily 1 h trials of isolation in a novel environment. During early adulthood, on postnatal day 45, 3 days after the cessation of stress trials, animals were tested for aggression in a resident: intruder model. The results show a context-dependent change in aggression. Animals with a history of abuse show exaggerated attack behaviour toward smaller males compared to littermates with a history of isolation stress. Conversely, when confronted by males of equal size, animals with a history of abuse show diminished aggression and increased submission compared to controls. It was determined that the density of vasopressin fibres and neurones in the hypothalamus is lower in abused animals compared to controls. In contrast, the number of 5-HT terminals within the hypothalamus is higher in abused animals compared to controls. These results provide evidence in an animal model that stress in the form of threat and attack during adolescence can alter the balance between vasopressin and 5-HT in the brain, resulting in inappropriate aggressive behaviour in early adulthood. [source] Nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced pulmonary adenocarcinomas in Syrian golden hamsters contain beta 2-adrenergic receptor single-nucleotide polymorphismsGENES, CHROMOSOMES AND CANCER, Issue 2 2005Thomas Masi Cigarette smoking contributes to the development of lung cancer throughout the world, with cases of pulmonary adenocarcinoma (PAC) the most numerous. Nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), which is formed from nicotine, has been demonstrated to cause mutations in genes that affect cell regulation and proliferation. Moreover, NNK has been shown to interact directly with and stimulate beta adrenergic receptor (ADRB) signal transduction pathways. Our goal was to determine whether single-nucleotide polymorphisms (SNPs) in the Adrb2 from PAC tumors were induced in golden hamsters by the injection of NNK. Here we report the cloning and sequencing of Adrb2 clones from either dissected lung tumors from NNK-injected animals or whole-lung tissue from water-injected controls. Both sets of animals contained SNPs; however, we found significantly more SNPs in the Adrb2 from NNK-injected animals than in the controls. The majority of these SNPs were novel, nonsynonymous mutations found in regions of the Adrb2 known to be involved in ligand binding, G-protein coupling, and desensitization/down-regulation. Our data verified the mutagenic effects of NNK as well as demonstrated that this animal model provides an outstanding way of identifying mutations not only in the Adrb2, but also in other genes that may play essential roles in the regulation and growth of pulmonary adenocarcinomas. © 2005 Wiley-Liss, Inc. [source] Expression of inhibitors of apoptosis family protein in 7,12-dimethylbenz[a]anthracene-induced hamster buccal-pouch squamous-cell carcinogenesis is associated with mutant p53 accumulation and epigenetic changesINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 5 2008Shui-Sang Hsue Summary Fifty outbred Syrian golden hamsters were equally divided into three experimental groups and two control groups. The pouches of the experimental groups were painted bilaterally with a 0.5% 7,12-dimethylbenz[a]anthracene (DMBA) solution thrice a week for 3, 7 and 14 weeks. One of the control groups was applied with mineral oil while another control group remained untreated throughout the experiment. Neither survivin nor cIAP2 could be detected in any of the control tissues, whereas survivin and cIAP2 were found to be significantly increased in 3-, 7- and 14-week DMBA-treated pouches compared with the control pouches. Expression of XIAP, cIAP1 and NAIP were noted for both the control and 3-, 7- and 14-week DMBA-treated pouches, but levels were found to be significantly elevated in the experimental groups compared with the control pouches. p53 was not detected in any control tissues, but was significantly increased in 3-, 7- and 14-week DMBA-treated pouches. Direct sequencing revealed a point mutation (C,G) of p53 for pouch tissues treated with DMBA for 3 and 7 weeks, and there was a wide variation in the p53 sequence of the 14-week DMBA-treated pouch tissues, as compared with the control tissues. The control tissues had a survivin - and cIAP2 -methylated allele, whereas the DMBA-treated tissues showed no evidence of survivin - and cIAP2 -methylation. Neither the control nor DMBA-treated pouches showed evidence of XIAP -, cIAP1 - or NAIP -methylation. Our results suggest that the expression of inhibitors of apoptosis family in DMBA-induced hamster buccal-pouch squamous-cell carcinogenesis may be modulated by both genetic (mutant p53) and epigenetic mechanisms. [source] Glucocorticoids and the Development of Agonistic Behaviour during Puberty in Male Golden HamstersJOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2005J. C. Wommack Abstract During puberty, the agonistic behaviour of male golden hamsters undergoes a transition from play fighting to adult aggression. Repeated exposure to social stress early in puberty accelerates this transition. The present study investigated the possible role of glucocorticoids on the maturation of agonistic behaviour. First, we compared serum cortisol levels following a 20-min restraint stress during early puberty, mid-puberty or adulthood. Across puberty, animals exhibited a two-fold increase in post-restraint cortisol levels. We also compared corticotrophin-releasing hormone (CRH) immunoreactive fibres projecting to the median eminence between animals in early puberty and adulthood. The CRH fibre density was two-fold greater in adults compared to juveniles. Furthermore, we investigated the effects of stress hormones on the maturation of agonistic behaviour. Male hamsters were injected daily with dexamethasone, a corticosteroid receptor type II agonist (0, 10 or 40 µg/100 g), early in puberty from postnatal day 31 (P-31) to P-36. When paired with a smaller and younger intruder on P-37, attack frequency did not differ between groups. However, dexamethasone-treated animals showed a dose-dependent decrease in the percentage of play-fighting attacks and an increase in the percentage of adult attacks. In summary, puberty can be described as a period of increasing hypothalamic-pituitary-adrenal activity in male golden hamsters. Moreover, increasing glucocorticoid levels influence the maturation of agonistic behaviour. These data shed new light on the neuroendocrine mechanisms that regulate the maturation of social behaviours during puberty. [source] In vivo behaviour of long-circulating liposomes in blood vessels in hamster inflammation and septic shock models,use of intravital fluorescence microscopyLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2001Jean-Marie Devoisselle Abstract This study aimed to observe liposome uptake by leukocytes in vivo. The study was performed on skin by using a dorsal skin-fold chamber implanted in golden hamsters using intravital microscopy. 5 and 6-CF-encapsulated polyethylene glycolated liposomes were injected intravenously. The skin microcirculation was observed with an intravital Eclipse E800 Nikon microscope (using ×40, ×80 magnification) fitted with a Xenon light source and an epifluorescence assembly (excitation, 470,nm, FWHM 40,nm; emission, 540,nm, FWHM 40,nm). An ultra-high sensitivity videocamera mounted on the microscope projected the image onto a monitor, and the images (720,×,576 pixels) were recorded for playback analysis with a digital video cassette recorder. An acute inflammatory response was obtained by removing one complete layer of skin and the underlying fascia and avascular tissue on the opposing side of the flap corresponding to an area equivalent to the window aperture. Using this model and set-up, leukocyte rolling and adhesion were easily observed and the entry of PEGylated liposomes into hamster blood leukocytes was studied for a period of 6,h. PEGylated liposomes were clearly identified alone inside the blood flow and inside the leukocytes as soon as the inflammatory reaction appeared. This study shows for the first time that blood leukocytes in their natural milieu of whole blood are capable of interacting with, and taking up, liposomes. This observation is in accordance with previous in vitro studies. Copyright © 2001 John Wiley & Sons, Ltd. [source] Reduced expression of the Rassf1a gene and its aberrant DNA methylation in pancreatic duct adenocarcinomas induced by N-nitrosobis(2-oxopropyl)amine in hamstersMOLECULAR CARCINOGENESIS, Issue 2 2008Kyoko Shimizu Abstract Alterations of the Rassf1a gene were investigated in pancreatic duct adenocarcinomas (PDAs) induced by N-nitrosobis(2-oxopropyl)amine (BOP) in hamsters. Female Syrian golden hamsters received 70 mg/kg BOP, followed by repeated exposures to an augmentation pressure regimen consisting of a choline-deficient diet combined with a sequential course of DL -ethionine, L -methionine, and 20 mg/kg BOP. A total of 15 PDAs were obtained, and total RNAs were assessed by real-time quantitative reverse transcription (RT)-polymerase chain reaction (PCR). Expression of the Rassf1a was significantly reduced in PDAs (P,<,0.005) compared with normal pancreatic tissues. For analysis of methylation status, bisulfite sequencing was performed. Normal tissues were all unmethylated in the 5, upstream region of Rassf1a. In contrast, four PDAs were highly methylated, correlating with reduced expression of the Rassf1a gene. Using reverse transcription (RT)-polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis, mutations were detected in 3 out of 15 PDAs (20%). These results suggested that alterations of the Rassf1a gene may be involved in development of PDAs induced by BOP in hamsters. © 2007 Wiley-Liss, Inc. [source] Immunohistochemical demonstration of p63 in DMBA-induced hamster buccal pouch squamous cell carcinogenesisORAL DISEASES, Issue 5 2003YK Chen Objectives: Abnormalities in the p53 gene are regarded as the most consistent genetic abnormalities detected in head and neck squamous cell carcinogenesis. Two new members of the p53 gene family, p73 at the 1p36 region and p63 at the 3q27-29 region, have recently been identified. They share considerable sequence homology with p53 in the transactivation, DNA binding, and oligomerization domains, indicating possible involvement in carcinogenesis. To our knowledge, however, p63 expression in experimental oral carcinogenesis has not been studied. Materials and methods: Immunohistochemical analysis of p63 protein expression was performed in 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch squamous cell carcinogenesis. Fifty outbred, young (6 weeks), male, Syrian golden hamsters (Mesocricatus auratus) were randomly divided into three experimental groups (each consisting of 10 3-, 9- and 15-week DMBA treated animals), and two control groups (with 10 animals in each). The pouches of the three experimental groups were painted bilaterally with a 0.5% DMBA solution three times a week. The treatment protocol for animals in one of the control groups was identical with only mineral oil applied, while the other control group remained untreated throughout the experiment. Results: In all of the untreated and mineral oil-treated pouch mucosa, nuclear positivity for p63 was mainly observed in the basal/parabasal cell layers. The p63 nuclear positivity extended from the basal/parabasal layers to the whole epithelial layers in the 3- and 9-week DMBA-treated pouch mucosa. Furthermore, the positive nuclear-stain cells were randomly distributed throughout the entire epithelial layers in the 3- and 9-week DMBA-treated pouch-mucosa specimens. In carcinomas from 15-week DMBA-treated pouch specimens, p63 staining was more uniform and homogeneous for the less-differentiated tumor areas. By contrast, p63 expression was noted mainly in the peripheral cells of tumor nests in the well-differentiated tumor areas. Conclusions: The results of this study are consistent with those from previous analyses of p63 expression in human oral mucosa, suggesting that p63 may be associated with the regulation of epithelial differentiation and proliferation in DMBA-induced hamster buccal pouch squamous cell carcinogenesis. Further study is required to investigate which p63 isoform(s) is/are involved in hamster buccal pouch carcinogenesis. [source] Inhibitory effect of esculin on oxidative DNA damage and carcinogenesis induced by N-nitrosobis(2-oxopropyl)amine in hamster pancreasBIOFACTORS, Issue 1-4 2004Takao Kaneko Abstract The effects of esculin, a natural coumarin compound, on the formation of 8-ox O2,,-deoxyguanosine (8-oxodG) and carcinogenesis induced by a chemical carcinogen, N-nitrosobis(2-oxopropyl)amine (BOP), were examined in the pancreas of female Syrian golden hamsters. Animals were given a diet containing esculin for 7 days, and killed 4h after BOP treatment, and the contents of 8-oxodG were measured in the nuclear DNA of the pancreas. Esculin suppressed significantly the increase in the 8-oxodG content of hamster pancreas induced by BOP. Furthermore, the effect of esculin on the rapid production model experiment for pancreatic carcinogenesis using BOP was investigated. Esculin was given ad libitum as a 0.05% aqueous solution during either the initiation or promotion phases. The incidence of invasive tumors in animals given esculin during the initiation phase was significantly lower than in the control group, while the incidence in animals given esculin during the promotion phase showed no significant change. These results suggest that the intake of esculin has an inhibitory effect on BOP-induced oxidative DNA damage and carcinogenesis in hamster pancreas. [source] | |||||||||||||