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At least 19 recordsLinked to original sources
PubMed1999

Similarity in the qualities of individual odors among kin and species in Turkish (Mesocricetus brandti) and golden (Mesocricetus auratus) hamsters.

In this investigation, the authors used habituation techniques to explore similarities and differences in the qualities of individual odors from hamsters. In Experiment 1, male Turkish hamsters (Mesocricetus brandti) treated flank-gland odors of 2 males from 1 litter as similar compared with the odor of a male from another litter, whether the odor donors were familiar or unfamiliar. At the same time, the Turkish hamsters discriminated between the subtle differences in the individual odors of their familiar brothers. In Experiment 2, male Turkish and golden hamsters (Mesocricetus auratus) treated the flank-gland odors of 2 unfamiliar, unrelated conspecifics as similar compared with the flank odor of a heterospecific individual. The results suggest that similarities in individual odors are related to genetic similarity of the odor donors. These similarities could provide a basis for different types of social recognition, including kin and species recognition.

Animals↗
PubMed2005

New families of site-specific repetitive DNA sequences that comprise constitutive heterochromatin of the Syrian hamster (Mesocricetus auratus, Cricetinae, Rodentia).

We molecularly cloned new families of site-specific repetitive DNA sequences from BglII- and EcoRI-digested genomic DNA of the Syrian hamster (Mesocricetus auratus, Cricetrinae, Rodentia) and characterized them by chromosome in situ hybridization and filter hybridization. They were classified into six different types of repetitive DNA sequence families according to chromosomal distribution and genome organization. The hybridization patterns of the sequences were consistent with the distribution of C-positive bands and/or Hoechst-stained heterochromatin. The centromeric major satellite DNA and sex chromosome-specific and telomeric region-specific repetitive sequences were conserved in the same genus (Mesocricetus) but divergent in different genera. The chromosome-2-specific sequence was conserved in two genera, Mesocricetus and Cricetulus, and a low copy number of repetitive sequences on the heterochromatic chromosome arms were conserved in the subfamily Cricetinae but not in the subfamily Calomyscinae. By contrast, the other type of repetitive sequences on the heterochromatic chromosome arms, which had sequence similarities to a LINE sequence of rodents, was conserved through the three subfamilies, Cricetinae, Calomyscinae and Murinae. The nucleotide divergence of the repetitive sequences of heterochromatin was well correlated with the phylogenetic relationships of the Cricetinae species, and each sequence has been independently amplified and diverged in the same genome.

Animals↗
PubMed1976

Location of nucleolar organizing regions on the chromosomes of the Syrian hamster (Mesocricetus auratus) and the Djungarian hamster (Phodopus sungorus).

Terminal chromosome associations ("satellite associations") in ASG-banded preparations have been used to determine the number and location of staellites in the Syrian hamster (Mesocricetus auratus) and the Djungarian hamster (Phodopus sungorus). Five pairs of satellites are found in the former and four in the latter. Nucleolar organizing regions (NORs) were visualized with the Ag-AS silver precipitation technique, and their number and position corresponded exactly with the number and position of satellites in Phodopus, where positive chromosome identification can be made in the absence of banding. Numerical agreement is exact in Mesocricetus as well, and the morphology of the silver-tagged NOR-bearing chromosomes strongly suggests that corrrespondence also occurs in this species.

Animals↗
PubMed1982

Pineal is required for testicular maintenance in the turkish hamster (mesocricetus brandti).

The effect of pinealectomy on reproductive function was examined in the Turkish hamster, Mesocricetus brandti. Pinealectomy resulted in testicular regression in this species. This result was unexpected since pinealectomy prevents short day-induced regression of the gonads in the closely related Syrian hamster, Mesocricetus auratus. Decentralization of the superior cervical ganglia and exposure to continuous illumination also caused testicular regression in the Turkish hamster. These manipulations are believed to block pineal melatonin synthesis. In each case (i.e. pinealectomy, decentralization of the superior cervical ganglia, exposure to continuous illumination), the testes regressed after approximately 3--9 weeks and underwent recrudescence after approximately 16--28 weeks. This cycle of testicular regression and recrudescence was similar to that observed in Turkish hamsters exposed to a short day photoperiod. In further experiments, the effects of exogenous melatonin were studied in Turkish and Syrian hamsters. The results of these studies suggest that, in Turkish hamsters, pineal melatonin may be involved in both the maintenance of testis function during exposure to a long day photoperiod and also in the suppression of reproductive function in short days. This is in contrast to the Syrian hamster, in which melatonin appears to be important only for inhibition of gonadal function in short days.

Animals↗
PubMed1988

Play-fighting in the Syrian golden hamster Mesocricetus auratus Waterhouse, and its relationship to serious fighting during postweaning development.

In the Syrian golden hamster Mesocricetus auratus, play-fighting precedes serious fighting during postweaning development, and so may be thought to be a developmental precursor to adult aggression. However, based on both the targets attacked--that is, the cheek pouches during play-fighting and the rump or flanks during serious fighting, and the behavior patterns employed to attack and defend these targets--these two forms of fighting are shown to remain distinct from each other throughout development, even during the ages where they overlap. The decline of play in post-sexually-mature animals is shown to result from an increasing intolerance to contact between animals, and hence greater difficulty in the maintenance of a "playful mood." Therefore, these data show that play-fighting does not grade into serious fighting, and thus does not serve as a developmental precursor to adult aggression.

Aggression↗
PubMed1980

Effects of the gene Wh on reproduction in the Syrian hamster, Mesocricetus auratus.

The gene Wh, causing anophthalmia in the Syrian hamster, Mesocricetus auratus, is a highly pleiotropic gene, which has profound effects upon eye development, pigmentation, and reproduction. Since male hamsters homozygous for this gene are usually sterile, the objective of this study was to determine whether the testes of mutant hamsters differed from the normal phenotype. Accordingly, the testicular tissue from ten normal, ten heterozygous, and ten homozygous mutant animals in the AN/As-Wh strain were compared at the gross, light, and electron microscopic level. Testicular tissue from several mutant animals approached the normal phenotype, due to variable expression of the gene. However, most testes from homozygous mutant hamsters were hypoplastic and aspermic. Abnormalities were observed in Leydig cells, Sertoli cells, and in the developing germ cells. Seminiferous tubules contained germinal epithelium arrested in the early spermatid stage of spermiogenesis, possibly due to premature failure of the Golgi apparatus and subsequent dysgenesis of the acrosome. Since the primary action of the gene is unknown, it was postulated that the gene either acts directly to alter pituitary function, or that the abnormalities in reproduction are due to a failure of eye development and subsequent lack of function of the visual pathway.

Animals↗
PubMed2000

Volitional ethanol consumption affects overall serotonin metabolism in Syrian golden hamsters (Mesocricetus auratus).

Methods were established for the determination of serotonin (5-HT)(1) metabolites 5-hydroxyindole-3-acetic acid (5-HIAA) and 5-hydroxytryptophol (5-HTOL) in the urine of Syrian golden hamsters (Mesocricetus auratus) and used to study the effect of volitional ethanol consumption on overall 5-HT metabolism in this ethanol-preferring rodent. The basal levels of 5-HIAA and 5-HTOL in 24-h urine of ethanol-naive hamsters were 300 +/- 101 and 4.96 +/- 1. 06 nmol (n = 8), respectively. Given free choice between water and a 15% ethanol solution, these hamsters chose to consume increasing amounts of ethanol. The increase was accompanied by a concomitant decrease in urine 5-HIAA and increase in urine 5-HTOL, indicating that volitional ethanol intake diverted part of the 5-HT metabolic flux from an oxidative into a reductive pathway. In a separate experiment, the amounts of ethanol consumed by and blood ethanol concentrations attained in ethanol-drinking golden hamsters were determined at 5 different time intervals between 6 PM and 7 AM when most feeding activities occurred. Except in the first hour after lights were turned off, ethanol was consumed at a relatively even pace throughout the night (2-3 g/kg/3 h) and blood ethanol levels were maintained at the low mM range which rarely exceeded 2 mM. These results suggest that the biochemical pathway that catalyzes 5-HT metabolism is extremely sensitive to ethanol and can play an important role in mediating the reported clinically beneficial action of a low concentration of ethanol during alcohol detoxification.

Animals↗
PubMed2001

Acute and chronic social defeat suppresses humoral immunity of male Syrian hamsters (Mesocricetus auratus).

Stressors, both physical and psychological, can activate the hypothalamic-pituitary-adrenal (HPA) axis, leading to a wide range of physiological responses including increased glucocorticoid release and suppression of immune function. The majority of studies published to date have focused on the effects of physical stressors (e.g., cold exposure, electric shock) on immunity. The present study examined the role of a stressor, social defeat, on humoral immune function of Syrian hamsters (Mesocricetus auratus). Specifically, adult male Syrian hamsters experienced social defeat (i.e., exposure to a dominant animal in that animal's home cage) that was either acute (i.e., a single exposure) or chronic (i.e., daily exposures across 5 days). A control group of animals was placed in a resident's home cage without the resident animal present and did not experience defeat. After the last encounter, blood samples were drawn and animals were subsequently injected with keyhole limpet hemocyanin (KLH). Blood samples were again taken 5 and 10 days postimmunization and serum was analyzed to determine serum cortisol and anti-KLH immunoglobulin G (IgG) concentrations. Cortisol concentrations were elevated in both acutely and chronically defeated hamsters compared with control animals. In contrast, serum IgG concentrations were significantly reduced in both groups of defeated hamsters compared with control animals. Collectively, these results demonstrate that both acute social defeat and chronic social defeat lead to activation of the HPA axis and suppression of humoral immune function. These data suggest that social defeat is an important, ecologically relevant model with which to examine stress-induced immune suppression in rodents.

Acute Disease↗
PubMed2002

Short days and exogenous melatonin increase aggression of male Syrian hamsters (Mesocricetus auratus).

Many nontropical rodent species rely on photoperiod as a primary cue to coordinate seasonally appropriate changes in physiology and behavior. Among these changes, some species of rodents demonstrate increased aggression in short, "winter-like" compared with long "summer-like" day lengths. The precise neuroendocrine mechanisms mediating changes in aggression, however, remain largely unknown. The goal of the present study was to examine the effects of photoperiod and exogenous melatonin on resident-intruder aggression in male Syrian hamsters (Mesocricetus auratus). In Experiment 1, male Syrian hamsters were housed in long (LD 14:10) or short (LD 10:14) days for 10 weeks. In Experiment 2, hamsters were housed in long days and half of the animals were given daily subcutaneous melatonin injections (15 microg/day in 0.1 ml saline) 2 h before lights out for 10 consecutive days to simulate a short-day pattern of melatonin secretion, while the remaining animals received injections of the vehicle alone. Animals in both experiments were then tested using a resident-intruder model of aggression and the number of attacks, duration of attacks, and latency to initial attack were recorded. In Experiment 1, short-day hamsters underwent gonadal regression and displayed increased aggression compared with long-day animals. In Experiment 2, melatonin treatment also increased aggression compared with control hamsters without affecting circulating testosterone. Collectively, the results of the present study demonstrate that exposure to short days or short day-like patterns of melatonin increase aggression in male Syrian hamsters. In addition, these results suggest that photoperiodic changes in aggression provide an important, ecologically relevant model with which to study the neuroendocrine mechanisms underlying aggression in rodents.

Aggression↗
PubMed1998

The establishment of spermatogenesis in the seminiferous epithelium of the pubertal golden hamster (Mesocricetus auratus).

The present study deals with initial spermatogenesis in the pubertal golden hamster (Mesocricetus auratus), in the course of which both the complex process of germ cell proliferation and differentiation and the cyclic pattern of organization of spermatogenesis are established. Germ cells pass through the complete sequence of spermatogenic differentiation from the A-spermatogonium up to the mature spermatid between days 12 and 38. During this period, germ cell development is already based on the pattern of organization and synchronization characteristic of adult spermatogenesis: 1. Judged by the germ cell types present, each of the successively appearing germ cell associations conforms to one of the adult stages of the seminiferous epithelium (stage conformity of the developmental steps of the pubertal seminiferous epithelium). 2. The overall intratesticular variance of the developmental levels reached in different tubular segments each covers almost exactly one cycle length of spermatogenesis. 3. There is a regular, continuous succession of developmental steps along the longitudinal course of the tubules which, in every single tubule, comprises the interval of one spermatogenic cycle ("wave" of the pubertal seminiferous epithelium). 4. Taken together, the latter two results indicate that the tubules of one given testis are equal to one another with respect to their developmental level, i.e., they develop synchronously. Germ cell propagation follows the clonal mode of proliferation. In quantitative terms, stage-related S-phase indices largely parallel the values of adult spermatogenesis. Both the frequently found germ cell apoptosis and degenerating intrameiotic spermatocytes correspond to degenerative phenomena in the adult seminiferous epithelium with respect to degenerative mode and stage-related occurrence. Germ cell development is closely related to the maturation of both Sertoli cells and Leydig cells. At two developmental phases, localized disturbances of germ cell differentiation occur which are specific to the pubertal period and which correlate with a maturational delay of Sertoli cells and Leydig cells, respectively: 1. Completion of Sertoli cell barrier formation may temporarily follow the initial onset of meiosis in the neighboring germ cells. As a result, mitotically dividing germ cells fall under the influence of a (hitherto hypothetic) "meiotic milieu" and characteristically degenerate (arrested germ cell mitoses). This relationship emphasizes the functional significance of the separation of the two seminiferous compartments and, in addition, heightens the understanding of the necessity of normal termination of Sertoli cell proliferation before germ cells initially enter meiosis. 2. The Leydig cell enzyme 11 beta-HSD, which is known to promote testosterone output, is established several days after the leading spermatids initially reach step 6 of spermiogenesis (which is immediately prior to the particularly testosterone-dependent start of elongation). The resulting selective developmental arrest of round spermatids of steps 6-6/7 between days 26 and 30 leads to a localized, partial desynchronization of the seminiferous epithelium, which can be traced for several days after the above-mentioned maturational delay of Leydig cells has been overcome and which is accompanied by an extensive degenerative disposition of the spermatids involved. The present investigation documents an organizational and synchronizational level of initial spermatogenesis that is similar to the situation in the adult animal. The analysis of temporarily occurring perturbations in the process of establishing the pubertal seminiferous epithelium emphasizes and specifies the close structural and functional relationships between the maturational state of somatic cells and germ cell differentiation.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1985

Differential permeability of pineal capillaries to lanthanum ion in the rat (Rattus norvegicus), gerbil (Meriones unguiculatus) and golden hamster (Mesocricetus auratus).

Capillaries in the pineal gland of the rat (Rattus norvegicus), gerbil (Meriones unguiculatus) and golden hamster (Mesocricetus auratus) were investigated by means of electron-microscopical tracer studies using lanthanum. The tracer was administered together with the fixative solution by perfusion via the left cardiac ventricle. In the rat, endothelial junctions of fenestrated capillaries are permeable to lanthanum. In the gerbil the tracer does not leave the capillaries, which are of the non-fenestrated type throughout the organ. In the golden hamster the two portions of the pineal system have different types of capillaries. While in the superficial pineal fenestrated capillaries permeable to lanthanum predominate, the deep pineal possesses capillaries that are, without exception, devoid of fenestrations and impermeable to the tracer. It is suggested that differences in the structure of the capillaries are related to differences in the extent of a specialized contact of the pineal gland to the third ventricle.

Animals↗
PubMed1979

Synaptic ribbons during postnatal development of the pineal gland in the golden hamster (Mesocricetus auratus).

Synaptic ribbons, functionally enigmatic structures of mammalian pinealocytes, were studied during the postnatal development of the pineal gland in the golden hamster (Mesocricetus auratus). On day 4 post partum, synaptic ribbons appear in cells that have already started to differentiate into pinealocytes. Between days 4 and 9, an increase in the number of synaptic ribbons occurs, concomitant with the continuing differentiation of the pineal tissue. Between days 9 and 16, when differentiation of this tissue is almost completed, the number of synaptic ribbons decreases and approaches that characteristic of the adult pineal gland. During development, the synaptic ribbons increase in length, and dense core vesicles are frequently found in the vicinity of these structures. It is assumed that a functional relationship exists between dense core vesicles and the synaptic ribbons, which are considered to be engaged in a certain form of secretory activity of the mammalian pineal gland.

Animals↗
PubMed1993

Diurnal variation in thermal and metabolic parameters of the golden hamster (Mesocricetus auratus).

The purpose of this study is to examine diurnal variation in several thermal and metabolic parameters of the golden hamster, Mesocricetus auratus. Metabolic rate, core temperature, and evaporative water loss were measured during night and day at several ambient temperatures. Wet minimal thermal conductance, dry minimal thermal conductance, basal metabolic rate, minimal net heat production and the lower critical temperature difference were estimated from these measurements. Wet and dry minimal thermal conductance, evaporative water loss, core temperature, basal metabolic rate, and lower critical temperature difference were greater during the active phase than during the resting phase. The diurnal variation in wet minimal thermal conductance was much smaller than that predicted from published allometric equations. The diurnal variation in wet minimal thermal conductance was 9% of the 24-h mean. The diurnal variation in dry minimal thermal conductance was 26% of the 24-h mean. The higher active-phase core temperature and basal metabolic rate may function to enhance peak metabolic performance during the active phase. The lower resting phase metabolism and core temperature may reduce energetic costs. The greater active-phase lower critical temperature difference may be a result of the greater active-phase basal metabolic rate. Diurnal variation in minimal thermal conductance may be caused by changes in peripheral circulation.

Animals↗
PubMed1984

Seasonal variations in the cerebrospinal fluid-contacting area of the pineal gland in the golden hamster (Mesocricetus auratus).

The cerebrospinal fluid-contacting area in the pineal recess of the golden hamster (Mesocricetus auratus) has been investigated light and electron microscopically. The results reveal that in this area the ventricular surface is composed of glial cell processes and protruding pinealocytes. The relative extent of these two components varies considerably and seems to be related to the season of the year: Morphometric analysis shows that in June, the mean size of the total cerebrospinal fluid-contracting area and, in addition, the relative extent of the area occupied by protruding pinealocytes is significantly larger than in November. The physiological significance of this finding remains to be determined.

Animals↗
PubMed1982

Occurrence of preantral intra-ovarian oocyte release in the rat and the Syrian hamster (Mesocricetus auratus).

Serial sections of 62 rat ovaries and 66 ovaries from Syrian hamsters (Mesocricetus auratus) have been examined by light microscopy. The relative and absolute percentage of preantral intra-ovarian oocyte release (PIOR) was recorded. PIOR was incomplete when the rupture of the basal membrane was not followed by the release of the oocyte from its preantral follicle into the ovarian stroma; conversely, a PIOR was regarded to be complete if the oocyte was released from the preantral follicle into the adjacent stroma. PIOR occurred in 23% of rat ovaries and in 32% of hamster ovaries; meiosis was not resumed. In rat ovaries the frequency of complete PIOR was 71%; the oocyte disappeared quickly after its release and herniated granulosa cells could invade capillaries. By contrast, incomplete PIOR was prevalent in hamster ovaries (67%); oocytes survived in the interstitial cortical tissue after the disappearance of their granulosa and theca cells ("free oocytes"). It is concluded that PIOR reflects the onset of follicular atresia and that different local factors are probably responsible for species differences.

Animals↗
PubMed1978

A liquor contacting area in the pineal recess of the golden hamster (Mesocricetus auratus).

The wall of the third ventricle in the pineal recess of the golden hamster (Mesocricetus auratus) has been investigated by light and electron microscopy. Deep in the pineal recess, where the ependymal lining is thin and non-ciliated, clusters of pinealocytes protrude into the ventricular lumen. They force the ependyma apart so that their surface is directly exposed to the CSF, while basal processes extend towards the hypependymal pineal tissue. It is assumed that these cells may secrete melatonin into the CSF which is known to contain varying amounts of this hormone.

Animals↗
PubMed1995

The effect of dexamethasone on the course of Echinostoma caproni and E. trivolvis infections in the golden hamster (Mesocricetus auratus).

Golden hamsters (Mesocricetus auratus) were given intramuscular injections of dexamethasone and infected with Echinostoma caproni or E. trivolvis. All animals were necropsied on day 14 postinfection. Dexamethasone treatment at high doses resulted in increased parasite recovery. Decreased total white blood cell counts and decreased relative splenic weights were observed in corticosteroid-treated hamsters. Dexamethasone-treated animals also demonstrated significantly lower mean parasite dry weights for E. caproni. Specific serum IgG against the parasites was not detected in corticosteroid-treated hamsters on day 14 postinfection.

Animals↗
PubMed1989

The influence of negative ionization of the air on motor activity in Syrian hamsters (Mesocricetus auratus Waterhouse) in light conditions.

The motor activity of Syrian hamsters (Mesocricetus auratus Waterhouse) under the influence of negative ionization of the atmosphere applied for 10, 20 or 30 min per day was investigated. An ionizer with output of 14,000 light negative ions per 1 cm3 of air was used. Studies carried out in the light phase of a 12:12 h light/dark regime revealed a relation between the reaction of the animal and the time of day at which ionization was applied. Ionization for 20 or 30 min in the light phase decreased motor activity, while 10 min of ionization increased it compared to control animals. Ionization in the dark phase gave a more distinct rise in activity than that applied in the light phase for all three durations of ionization.

Air Ionization↗