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The Effects of Daily Melatonin Gavage on Reproductive Activity in the Male Syrian Hamsters

The Effects of Daily Melatonin Gavage on Reproductive Activity in the Male Syrian Hamsters

As SP presents longer period of darkness than LP, the period of elevated melatonin is relatively longer in SP, which is reflected by the length of melatonin secretion. Various modes of administration of melatonin into the animals, such as injections, implants, and infusions, have been applied whether they resulted in the testicular regression (Reiter 1980; Stetson & Tay, 1983; Stetson et al., 1983; Stetson & Watson-Whitmyre, 1984; Stetson & Watson-Whitmyre, 1986; Maywood et al., 1991; Grosse et al., 1993; Choi, 2001; Hiebert et al., 2006; Choi, 2013a; Choi, 2013b). Some plants also contain melatonin called phytomelatonin, structurally an identical molecule (Dubbels et al., 1995; Hattori et al., 1995; Paredes et al., 2009). The findings raised an interest in investigating the potential effects of plant phytomelatonin on the reproductive activity of small animals, among the diverse capacities reported so far, particularly through the edible plant diet (Choi, 2013b; Bonomini et al., 2018; Jiki et al., 2018). The amounts of phytomelatonin that plants contain differ widely (Ramakrishna et al., 2012; Choi et al., 2014; Oladi et al., 2014; Meng et al., 2017; Arnao & Hernández-Ruiz, 2018; Choi, 2019). The facts came across a possible action of phytomelatonin on the reproductive activity of male golden hamsters. The administration of an extract rich in phytometonin via gavage might induce testicular regression as the SP did. In order to measure a suitable dose of pure synthetic melatonin in inciting testicular involution, animals were subjected to pure melatonin by using gavage.
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Independence of circadian entrainment state and responses to melatonin in male Siberian hamsters

Independence of circadian entrainment state and responses to melatonin in male Siberian hamsters

The present experiments assess the specific dimensions of photoperiodic history that are necessary and sufficient to generate divergent responses to photoperiodic signals. In nearly all studies in this domain, two distinct factors have been confounded – namely, the duration of the prior melatonin exposure and the entrainment status of the cir- cadian system (i.e., whether it is in a LD or SD state). A critical role of melatonin history per se was suggested in the one study that specifically attempted to dissociate these two factors [13]. Male Syrian hamsters in 14L:10D were injected daily with melatonin or saline before lights off to generate two groups with presumably similar entrainment states but with melatonin histories corre- sponding to ~10L:14D (melatonin-injected) or 14L:10D (saline-injected). After 8 weeks, injections were discontin- ued and hamsters were moved to 12L:12D to assess whether melatonin injections had imparted a short-day photoperiodic history as would be indicated by a stimula- tory response to 12L:12D. Saline-injected hamsters under- went gonadal regression in 12L:12D, but gonadal growth was induced among males previously injected with mela- tonin. But because melatonin-injected hamsters trans- ferred to 8L:16D also exhibited gonadal growth, the response in 12L:12D may have reflected refractoriness to inhibitory photoperiods rather than reinterpretation of 12L:12D as a stimulatory photoperiod.
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Overcoming Diminished Motivation

Overcoming Diminished Motivation

To date, a majority of social recognition studies have focused on the ability of an adult rodent to recognize a juvenile or ovariectomized female of the same species (Le Moal et al., 1987; Ferguson et al., 2000; Ferguson et al., 2001; Winslow & Insel, 2004; Veenema et al., 2012). This approach was taken to investigate the social recognition of a relatively “neutral” social stimulus. Rats and mice fail to recognize a juvenile or an ovariectomized female within 2~3 hrs after an initial encounter in most behavioral tests (Ferguson et al., 2001; Winslow & Insel, 2004; Veenema et al., 2012), perhaps because of the neutral nature of the social stimulus. In the present study we investigated the duration of social recognition in adult male Syrian hamsters (Mesocricetus auratus) using odors obtained from flank glands as the social cue. Flank gland odor is a powerful social cue that serves to communicate a variety of different types of social information in hamsters including dominance status (Johnston & Lee, 1976; Ferris et al., 1984; Ferris et al., 1987). As such, investigating the recognition of flank gland odors in adult males provides a social recognition test with a high degree of relevance and validity for understanding of social memory.
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Understanding how ESOL Pre Services Teachers' Prior Experiences and Background Shape their Processes of becoming L2 (Reading) Teachers

Understanding how ESOL Pre Services Teachers' Prior Experiences and Background Shape their Processes of becoming L2 (Reading) Teachers

iors. MA is densely interconnected with other ventral forebrain nuclei that receive chemosensory information and are sensitive to steroid hormones. Specifically, several lines of evidence suggest that MA may generate behavioral responses to socio-sexual odors via functional connections with the posterior bed nucleus of the stria terminalis (BNST) and medial preoptic area (MPOA). It is unknown, however, how these three nu- clei act as functional circuit to adaptively regulate appetitive and consummatory repro- ductive behaviors. Therefore, the overarching goal of this dissertation was to determine how BNST and MPOA function, both uniquely and as a circuit with MA, to generate at- traction to female odors and copulatory behaviors in male Syrian hamsters. We found that BNST is required for attraction to female odors, but not for copulation, in sexually- naïve males. In contrast, MPOA is required for both attraction to female odors and for copulation in sexually-naïve males. Surprisingly, prior sexual experience mitigated the requirement of BNST and MPOA for these behaviors. Next, we found that MA preferen- tially transmits female odor information to BNST and to MPOA, whereas BNST relays female and male odor information equivalently to MPOA. Finally, we found that the func- tional connections between MA and BNST are required for attraction to female odors but not for copulation, whereas the functional connections between MA and MPOA are required for copulation but not for attraction to female odors. Ultimately, these data may uncover a fundamental mechanism by which this ventral forebrain circuit regulates ap- petitive and consummatory reproductive behaviors across many species and modalities.
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Helicobacter mesocricetorum sp  nov , a Novel Helicobacter Isolated from the Feces of Syrian Hamsters

Helicobacter mesocricetorum sp nov , a Novel Helicobacter Isolated from the Feces of Syrian Hamsters

H. mesocricetorum lacks a flagellar sheath, an unusual char- acteristic that it shares with two other helicobacters with which it clusters: H. rodentium (21) and H. pullorum (23). The phy- logenetic significance of sheathed flagella is unknown, yet it is an unusual characteristic of most of the members of this sub- group. It is interesting that all of the known helicobacters that lack a flagellar sheath are nongastric, suggesting that the flagel- lar sheath may provide a means of protecting the flagellum in the acidic environment of the stomach. Histologic evaluation of the gastrointestinal tracts of H. mesocricetorum-infected Syr- ian hamsters did not reveal any unusual lesions; thus, this microbe is most likely a nonpathogenic enteric bacterium.
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Possible ameliorative effects of antioxidants on propionic acid / clindamycin - induced neurotoxicity in Syrian hamsters

Possible ameliorative effects of antioxidants on propionic acid / clindamycin - induced neurotoxicity in Syrian hamsters

A total of 54 young male golden Syrian hamsters weigh- ing about 80–100 grams were used in the present study. Animals were randomly into seven groups, each consist- ing of 6 animals. The groups studied included 1. Control group, which received phosphate buffered saline orally, 2. Propionic acid treated group which were given PA at a dose of 250 mg/Kg body weight/day for 3 days orally [18], 3. Clindamycin treated group which received a sin- gle dose of the antibiotic orogastrically at a dose of 30 mg/kg on the day of the experiment, 4. Carnosine- treated group were given carnosine at a dose of 10 mg/kg body weight/day orally for one week, 5. Carnitine treated group were given 50 mg/kg body weight/day carnitine or- ally daily for one week. The protected groups included Group 6. Carnosine followed by PA, Group 7. Carnitine followed by PA. The carnosine and carnitine protected group were given the same doses of the respective com- pounds for one week followed by PA for three days. All the groups were kept at controlled temperature (21 ± 1°C) with ad libtium access to food and water. The experiments were performed in accordance with national animal care
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Original Article Yellow Fever Virus Infection in Syrian Golden Hamsters: Relationship between Cytokine Expression and Pathologic Changes

Original Article Yellow Fever Virus Infection in Syrian Golden Hamsters: Relationship between Cytokine Expression and Pathologic Changes

Previously published studies on yellow fever pathogenesis have mostly focused on the clinical manifestations and histological alterations in YFV infections [1, 21, 22], with limited description on the mechanisms of cell injury, or type of local immune responses. Knowledge of these mechanisms is important in developing better treatments for this disease. Studies of experimentally-induced disease in non-human primates and hamsters [10, 11] have shown that lymphoid tissues are one of the major targets of YFV. The depletion of lymphoid tissues seen in YFV-infected hamsters [11] is very similar to that of Ebola infection [23]. Rhesus and vervet monkeys infected intraperitoneally with Ebola virus develop an acute hemorrhagic fever with acute necrosis in the liver, spleen, lymph nodes, and
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Revealing the kinetics of Leishmania chagasi infection in the male genital system of hamsters

Revealing the kinetics of Leishmania chagasi infection in the male genital system of hamsters

5. Silva FL, Oliveira RG, Silva TMA, Xavier MN, Nascimento EF, Santos RL. Venereal transmission of canine visceral leishmaniasis. Vet Parasitol. 2009;160:55 – 9. Fig. 2 Proposed kinetic of L. chagasi infection in the genital system of male hamsters. Parasites reach testis through blood vessels (a). Upon the onset of a pro-inflammatory immune response, parasitism is controlled (b). The expression of testosterone and IL-4 may have favored the persistence of a low parasite load (c). Extracellular amastigotes migrate to the epididymis where they might be adhered to prismatic cells cilia or be released within sperm (d)
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Depletion of Alveolar Macrophages Does Not Prevent Hantavirus Disease Pathogenesis in Golden Syrian Hamsters

Depletion of Alveolar Macrophages Does Not Prevent Hantavirus Disease Pathogenesis in Golden Syrian Hamsters

How hamster AM ␪ respond to ANDV infection is not entirely clear. Alveolar macrophages, in general, need to walk a fine line between homeostasis and host defense to protect the host while preventing catastrophic inflammation. One way AM␪ contribute to lung protection is by phagocytizing most of the particulate mat- ter that enters the lungs. This suggests that they may also contrib- ute to the clearance of ANDV from the lungs of hamsters. Early after intranasal ANDV challenge, we saw a trend toward increased detection of viral genome in hamsters that were depleted of AM ␪ , although depletion of AM␪ does not significantly alter the amount of live virus or viral genome detected in lung tissue at late time points after infection (Fig. 3e and f). Hamsters devoid of AM␪ also developed disease faster than untreated or control-treated ANDV-infected hamsters. Interestingly, the highest number of surviving animals was found in control liposome-treated animals (Fig. 3d). Correspondingly, this group also had greater numbers of AM ␪ than liposomal clodronate-treated or untreated animals (Fig. 3a to c). Like other models, this could suggest that early after infection, AM ␪ help prevent the spread of infection by reducing infectious virus in the lung and by so doing may help control the rate at which disease pathogenesis progresses. At later times after infection, similar levels of viral genome and/or infectious virus were found in the lung of all hamsters, supporting the argument that AM␪ contribute more substantially to the immune response against ANDV early after infection but less so at later times once ANDV is primarily replicating in endothelial cells. This is also consistent with the reduced numbers of AM ␪ detected on day 17 compared to day 10.
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Reduced Ca2+ transport across sarcolemma but enhanced spontaneous activity in cardiomyocytes isolated from left atrium-pulmonary veins tissue of myopathic hamster

Reduced Ca2+ transport across sarcolemma but enhanced spontaneous activity in cardiomyocytes isolated from left atrium-pulmonary veins tissue of myopathic hamster

Background: Several lines of evidence point to a particularly important role of the left atrium (LA) in initiating and maintaining atrial fibrillation (AF). This role may be related to the location of pulmonary veins (PVs) in the LA. The aim of the present study was to investigate the action potential (AP) and ionic currents in LA-PV cardiomyocytes isolated from Bio14.6 myopathic Syrian hamsters (36-57 week-old) versus age-matched F1B healthy control hamsters.

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Effects of prepubertal manipulation with androgens on the development of sexual differences in the harderian glands of Syrian hamsters

Effects of prepubertal manipulation with androgens on the development of sexual differences in the harderian glands of Syrian hamsters

[nt I Ue\' BinI 35 133 138 (1991) 133 Shari ConlrilJl/liol1 Effects of prepubertal manipulation with androgens on the development of sexual differences in the Harderian glands of Syrian hamsters ARMAN[.]

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We summarize findings of SARS-CoV infections in several animal models each of which support viral replication in lungs accompanied by histopathological changes and/or clinical signs of illness to varying degrees. New findings are reported on SARS-CoV replication and associated pathology in two additional strains (C57BL/6 and 129S6) of aged mice. We also provide new comparative data on viral replication and associated pathology following infection of golden Syrian hamsters with various SARS-CoV strains and report the levels of neutralizing antibody titers following these infections and the cross-protective efficacy of infection with these strains in protecting against heterologous challenge. Finally, we summarize findings of a variety of vaccine approaches and discuss the available in vitro and in vivo data addressing the potential for disease enhancement following re-infection in animals previously vaccinated against or infected with SARS-CoV.
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Helicobacter aurati sp  nov , a Urease Positive Helicobacter Species Cultured from Gastrointestinal  Tissues of Syrian Hamsters

Helicobacter aurati sp nov , a Urease Positive Helicobacter Species Cultured from Gastrointestinal Tissues of Syrian Hamsters

Adult Syrian hamsters were submitted to our laboratory for diagnostic evaluation following a number of acute and sub- acute deaths in a research colony. A novel Helicobacter sp. was cultured from the inflamed stomachs and ceca of these ham- sters, and the same microorganism was found in Syrian ham- sters from several other facilities that were sampled. This pa- per describes the phenotypic characteristics and 16S rRNA analysis of the novel Helicobacter sp. with the proposed name Helicobacter aurati. In addition, repetitive sequence-based PCR was performed on the genomic DNA of the novel heli- cobacter isolates, as well as on related rodent helicobacters, in order to compare their DNA fingerprint patterns. Two other previously undescribed argyrophilic morphotypes were also isolated from the hamster gastrointestinal samples, but these bacteria are not addressed at length in the present report.
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Pharmacokinetic studies and human absorbed dose estimation of 68Ga-(4 {[(bis (phosphonomethyl)) carbamoyl] methyl}-7,10-bis(carboxymethy l) -1,4,7,10-tetraazacyclododec-1-yl) acetic acid

Pharmacokinetic studies and human absorbed dose estimation of 68Ga-(4 {[(bis (phosphonomethyl)) carbamoyl] methyl}-7,10-bis(carboxymethy l) -1,4,7,10-tetraazacyclododec-1-yl) acetic acid

agent, the absorbed dose of human organs after injection of this radiolabeled compound was estimated based on biositribution data in male Syrian ratsand according to the radiation absorbed dose assessment resource (RADAR) method.For this purpose, the accumulated activity of human organs was determined by extrapolating the accumulated activity of animal organs using the proposed method of Sparks et al. (15) .

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Endotoxin rapidly desensitizes the gonads to kisspeptin induced luteinizing hormone release in male Siberian hamsters (Phodopus sungorus)

Endotoxin rapidly desensitizes the gonads to kisspeptin induced luteinizing hormone release in male Siberian hamsters (Phodopus sungorus)

Activation of the immune system induces rapid reductions in hypothalamic-pituitary – gonadal (HPG) axis activity, which in turn decreases secretion of sex steroids. This response is likely adaptive for survival by temporarily inhibiting reproduction to conserve energy; however, the physiological mechanisms controlling this response remain unclear. The neuropeptide kisspeptin is a candidate to mediate the decrease in sex hormones seen during sickness through its key regulation of the HPG axis. In this study, the effects of acute immune activation on the response to kisspeptin were assessed in male Siberian hamsters (Phodopus sungorus). Specifically, an immune response was induced in animals by a single treatment of lipopolysaccharide (LPS), and reproductive hormone concentrations were determined in response to subsequent injections of exogenous kisspeptin. Saline-treated controls showed a robust increase in circulating testosterone in response to kisspeptin; however, this response was blocked in LPS-treated animals. Circulating luteinizing hormone (LH) levels were elevated in response to kisspeptin in both LPS- and saline-treated groups and, thus, were unaffected by LPS treatment, suggesting gonad-level inhibition of testosterone release despite central HPG activation. In addition, blockade of glucocorticoid receptors by mifepristone did not attenuate the LPS-induced inhibition of testosterone release, suggesting that circulating glucocorticoids do not mediate this phenomenon. Collectively, these findings reveal that acute endotoxin exposure rapidly renders the gonads less sensitive to HPG stimulation, thus effectively inhibiting sex hormone release. More broadly, these results shed light on the effects of immune activation on the HPG axis and help elucidate the mechanisms controlling energy allocation and reproduction.
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Endotoxin and cytokines increase hepatic messenger RNA levels and serum concentrations of apolipoprotein J (clusterin) in Syrian hamsters

Endotoxin and cytokines increase hepatic messenger RNA levels and serum concentrations of apolipoprotein J (clusterin) in Syrian hamsters

concentrations of the acute phase proteins. Our results show that apolipoprotein (apo) J is a positive acute phase protein. Endotoxin (LPS), tumor necrosis factor (TNF), and interleukin (IL)-1 increased hepatic mRNA and serum protein levels of apo J in Syrian hamsters. Hepatic apo J mRNA levels increased 10- to 15-fold with doses of LPS from 0.1 to 100 micrograms/100 g body weight within 4 h and were elevated for > or = 24 h. Serum apo J concentrations were significantly increased by 16 h and further elevated to 3.3 times that of control, 24 h after LPS administration. Serum apo J was associated with high density lipoprotein and increased fivefold in this fraction, after LPS administration. Hepatic apo J mRNA levels increased 3.5- and 4.6-fold, with TNF and IL-1, respectively, and 8.2-fold with a combination of TNF and IL-1. Serum apo J concentrations were increased 2.3-fold by TNF, 79% by IL-1, and 2.9-fold with a combination of TNF and IL-1. These results demonstrate that apo J is a positive acute phase protein.
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Identification of urinary isoflavone excretion phenotypes related to the cholesterol lowering ability of soy protein in Golden Syrian hamsters

Identification of urinary isoflavone excretion phenotypes related to the cholesterol lowering ability of soy protein in Golden Syrian hamsters

had the potential to affect the progression of atherosclerotic disease by modifying coagulation responses. In this study, they did not establish its effect on experimental vascular lesion formation to assess the potential of genistein as a therapeutic for vascular disease. However, Raines et al. (1995) indicated that the increased levels of isoflavonoids, in particular genistein, which are associated with consumption of soy-based diets, inhibited cell adhesion, altered growth factor activity and inhibited cell proliferation involved in lesion formation. Furthermore, Adams et al. (2005) determined the effects of the long-term (31 mo) consumption of commercially available soy protein containing 2 concentrations of isoflavones on the development of atherosclerotic plaques and vascular reactivity in coronary arteries of adult male monkeys. The monkeys were fed atherogenic diets that differed only in the source of protein: Control (n = 30), casein and lactalbumin; low-isoflavone soy (n = 30), a mixture of unmodified soy protein isolate and isoflavone-depleted soy protein isolate containing 0.94 mg of isoflavones/g protein; and high-isoflavone soy (n = 31), unmodified soy protein isolate containing 1.88 mg of isoflavone/g protein. Although there were no effects of dietary soy on endothelium-dependent or -independent reactivity of coronary arteries, atherosclerosis (mean plaque size in the coronary arteries) was reduced by 34% in both groups fed soy protein. Plasma LDL cholesterol was reduced, whereas HDL cholesterol and apolipoprotein A-1 were increased in both groups that consumed soy protein.
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Effect of Preexisting Immunity on Oncolytic Adenovirus Vector INGN 007 Antitumor Efficacy in Immunocompetent and Immunosuppressed Syrian Hamsters

Effect of Preexisting Immunity on Oncolytic Adenovirus Vector INGN 007 Antitumor Efficacy in Immunocompetent and Immunosuppressed Syrian Hamsters

Role of preexisting immunity in vector spread to other or- gans. We showed previously that when INGN 007 is injected into tumors, it replicates inside the tumors and spreads to other organs, such as the liver and lungs, where it also repli- cates (30). This spread might lead to hepatotoxicity and healthy tissue damage, which might limit the use of such vec- tors in humans. As mentioned before, much of the human population has preexisting immunity to Ad5. The experiments described for Fig. 2, 3, 5, and 6 addressed the role of preex- isting immunity in vector efficacy, but an equally interesting question is the role of immunity in vector spread from the site of injection. Therefore, using some of the same hamsters from the two large experiments described for Fig. 2, 3, 5, and 6, we asked whether preexisting immunity to Ad5 can prevent vector spread and toxicity to other organs. Following injection of the tumors in preimmunized and nonimmunized immunocompe- tent hamsters with INGN 007 (six consecutive injections), as described for Fig. 2 and 3, the liver and lungs were collected 7 and 13 days after the first i.t. injection. When the liver and lung extracts were examined by TCID 50 assay, all of the samples
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The impact of hydroxycitric acid on the lipid metabolism profile under experimental insulin resistance syndrome of Syrian hamsters

The impact of hydroxycitric acid on the lipid metabolism profile under experimental insulin resistance syndrome of Syrian hamsters

The syndrome of insulin resistance (Ir) is one of the leading reasons for the increased risk of cardiovascular diseases and their complications. Among the key components of Ir are obesity and dyslipidemia. hydroxycitric acid (hCA), an inhibitor of a key enzyme of lipogenesis ATp citrate lyase (ACLy) is a promising obesity treatment agent. The aim of this work was to investigate the effect of hCA on lipid and lipoproteins content in the blood serum, as well as lipid content and activity of some lipid metabolism enzymes in the liver of hamsters with Ir. Ir was modeled by keeping animals on high-fat diet with addition of fructose. Lipid content was determined by using standard reagent kits, the level of lipoproteins, the activity of glucose 6-phosphate dehydrogenase and ACLY – spectrophotometrically, lysosomal lipase activity – fluorimetrically. Development of hyperlipidemia and atherogenic dyslipidemia, lipid accumulation in the liver, activation of lysosomal lipase and ACLy and reduction of glucose 6-phosphate dehydrogenase activity were shown under Ir. The treatment by hCA reduces the manifestations of hyperlipidemia, but enhances the lipid accumulation in the liver.
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A Lethal Disease Model for Hantavirus Pulmonary Syndrome in Immunosuppressed Syrian Hamsters Infected with Sin Nombre Virus

A Lethal Disease Model for Hantavirus Pulmonary Syndrome in Immunosuppressed Syrian Hamsters Infected with Sin Nombre Virus

and humoral response. Not surprisingly, the four surviving ham- sters in the cyclophosphamide-treated group were unable to mount a robust immune response and had ELISA titers that were either at or below the level of detection for the assay (P ⬍ 0.0001). Immunosuppression of SNV-infected hamsters allows de- tection of viremia. We have previously reported that SNV-in- fected hamsters had undetectable levels of infectious virus in both the serum and whole blood and viral genome was not detectable in peripheral blood mononuclear cells (PBMCs) (12). In the current study, serum and lung tissue were collected from hamsters 10 days postinfection and evaluated for the presence of viral genome and infectious virus (Fig. 3). Increased levels of viral genome were detectable in the serum of immunosuppressed hamsters com- pared to those in the serum of immunocompetent hamsters (P ⫽ 0.0867) (Fig. 3A), and levels were highest, by approximately 2-fold, in hamsters treated with both dexamethasone and cyclo- phosphamide. Similarly, approximately 4-fold more infectious vi- rus was detected in the serum of cyclophosphamide- and dexa- methasone/cyclophosphamide-treated hamsters than in that of hamsters treated with dexamethasone and untreated hamsters
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