Electroencephalography in the diagnosis of hydrocephalus in golden hamsters (Mesocricetus auratus).

The golden hamster (Mesocricetus auratus) is a popular laboratory animal and is used in a multitude of behavioural studies. However, it has been shown that it suffers from different forms of hereditary hydrocephalus, which may result in behavioural changes. This prospective study was designed to look into the usefulness of electroencephalography (EEG) measurements in the diagnosis of hydrocephalus in hamsters.

Golden hamsters are nocturnal in captivity but diurnal in nature.

Daily activity rhythms are nearly universal among animals and their specific pattern is an adaptation of each species to its ecological niche. Owing to the extremely consistent nocturnal patterns of activity shown by golden hamsters (Mesocricetus auratus) in the laboratory, this species is a prime model for studying the mechanisms controlling circadian rhythms. In contrast to laboratory data, we discovered that female hamsters in the wild were almost exclusively diurnal.

Photic and non-photic effects on the daily activity pattern of Mongolian gerbils.

The paper analyses the daily activity pattern of Mongolian gerbils with and without access to a running wheel. To evaluate the synchronizing and the masking effects of light, experiments were performed under different photoperiods (L:D=14:10 h and 10:14 h), and light and dark pulses were applied at different phases of the day-night cycle. In order to get a more direct estimate of the central pacemaker of the circadian system, the body temperature rhythm was investigated via implanted transmitters.

Molecular phylogeny of the Cricetinae subfamily based on the mitochondrial cytochrome b and 12S rRNA genes and the nuclear vWF gene.

Despite some popularity of hamsters as pets and laboratory animals there is no reliable phylogeny of the subfamily Cricetinae available so far. Contradicting views exist not only about the actual number of species but also concerning the validity of several genera. We used partial DNA sequences of two mitochondrial (cytochrome b, 12S rRNA) and one partial nuclear gene (von Willebrand Factor exon 28) to provide a first gene tree of the Cricetinae based on 15 taxa comprising six genera.

Male expulsion in cooperative Mongolian gerbils (Meriones unguiculatus).

Mongolian gerbils are territorial rodents of steppes and semideserts of Mongolia and Northern China. At least under laboratory conditions, the family life is characterized by long-term harmonious and short-term aggressive periods in which some members are expelled. The purpose of this study was to clarify which features of male offspring promote their expulsion.

Indicators for post-surgery recovery in Mongolian gerbils (Meriones unguiculatus).

Telemetric investigations of various parameters are widely used to estimate an animal's state. However, the implantation of the transmitters includes anaesthesia and surgery and has short and longer lasting impacts on the studied object. The aim of the present paper was to evaluate these effects in Mongolian gerbils, namely the hypothermia caused by the anaesthetic and the enduring disturbance of daily rhythmicity until complete recovery.

Genetic spatial structure of European common hamsters (Cricetus cricetus)--a result of repeated range expansion and demographic bottlenecks.

The spatial genetic structure of common hamsters (Cricetus cricetus) was investigated using three partial mitochondrial (mt) genes and 11 nuclear microsatellite loci. All marker systems revealed significant population differentiation across Europe. Hamsters in central and western Europe belong largely to two allopatric mitochondrial lineages south and northwest of the Carpathian and Sudetes.

Running-wheel activity and body composition in golden hamsters (Mesocricetus auratus).

Running wheels are frequently used in behavioural and physiological experiments. The function of wheel-running activity in laboratory animals is controversial. In the present long-term study, the influence of this activity was evaluated in male golden hamsters over a period of 52 weeks.

Social categories in families of Mongolian gerbils.

Mongolian gerbils are a species of rodent in Asia living in families, although aggression occurs within these social units. The aim of this study was to determine the causes for the surge of intrafamily aggression and to characterize different types of animals. Due to behavioral measures, animals were assigned to distinct social categories and the consequences of social stress were analyzed on an individual level.

Comparative studies of body mass, body measurements and organ weights of wild-derived and laboratory golden hamsters (Mesocricetus auratus).

All laboratory golden hamsters originate from a sibling pairing back in 1930. To investigate possible differences between domesticated and wild conspecifics, descendants of both strains were maintained under standardized laboratory conditions individually and in unisexual groups. Body mass and food consumption were monitored from birth to 22 weeks of age.

Asynchrony in the estrous cycles of golden hamsters (Mesocricetus auratus).

The golden hamster has been described as exhibiting estrous cycle synchrony caused by social dominance. This has recently been reexamined by J. C.

Activity rhythms of wild and laboratory golden hamsters (Mesocricetus auratus) under entrained and free-running conditions.

The golden hamster (Mesocricetus auratus) is one of the most frequently used laboratory animals, particularly in chronobiological studies. One reason is its very robust and predictable rhythms, although the question arises whether this is an inbreeding effect or rather is typical for the species. We compared the daily (circadian) activity rhythms of wild and laboratory golden hamsters.

Low microsatellite variation in laboratory gerbrils.

The Mongolian gerbil has become a model organism of increasing importance for the understanding of aging, epilepsy, the process of domestication or sociobiological questions. We report the development and characterization of the first nine polymorphic dinucleotide repeat loci in this species. Average observed heterozygosity and allele number of laboratory animals measured 0.

Housing conditions affect susceptibility to mercury in the golden hamster.

Individually-housed and group-housed golden hamsters (Mesocricetus auratus), aged 8 weeks, were studied with regard to their susceptibility to a single gavage of mercuric chloride (10 mg/kg body weight). Body weight and food consumption were measured for 10 days (day -9 to day 0) in a pre-application period and for 13 days (day 1 to day 13) in a post-application period. Mercuric chloride administration significantly reduced body weight gain in both isolated and grouped hamsters at day 1 compared to vehicle controls.

Effects of social stress on behavior and corpus luteum in female golden hamsters (Mesocricetus auratus).

The consequences of group-keeping as a social stressor on the solitary-living golden hamster were studied. Two females at the same stage of the estrous cycle were kept together for 5 weeks. Behavioral observations showed that the dominance structures within groups were unstable.

Circadian activity rhythms and sensitivity to noise in the Mongolian gerbil (Meriones unguiculatus).

Since consistent data on endogenous circadian rhythms of Mongolian gerbils are not available, the main aim of our study was to identify suitable conditions to receive stable and reproducible free-running rhythms of activity under different light intensities. Another objective was to determine the role of social cues as an exogenous zeitgeber in the absence of a light-dark (LD) cycle. We performed two long-term sets of experiments with adult male gerbils kept in climatic chambers under various photoperiods of at least 30 days each.

Beta-adrenoceptor blockade and open-field behavior in male golden hamsters.

Open-field behavior was compared between untreated, saline-treated, and butoxamine (a beta-2-adrenoceptor antagonist) treated (15 and 5 mg/kg body weight) male golden hamsters (Mesocricetus auratus). Butoxamine-treated males spent significantly more time self-grooming than saline-treated and untreated males. Especially, untreated males and very similar saline control males showed a clear time sequential structure of behavior with two axes: a grooming-grooming sequence and a highly organized flankmark followed by scrape axis.

Behavioral alterations in male golden hamsters exposed to chlorodibromomethane.

A number of behavioral parameters in male golden hamsters (Mesocricetus auratus) exposed to chlorodibromomethane (CDBM) were registered over a 10-day (day -9 to day 0) pretest period and a 14-day (day 1 to day 14) test period beginning at 8 weeks of age. Whereas the subchronically treated group (5 mg/kg body weight) only showed significantly increased water bottle contacts on days 4-7 compared with vehicle controls, the acutely treated group (50 mg/kg body weight) exhibited significantly increased locomotor activity on days 3-6 and decreased wheel running at day 6 until day 9. In the open field, the acutely exposed males displayed significantly more flank-mark movements at days 4 and 7 than did the vehicle control animals.

Time of day and stress response to different stressors in experimental animals. Part I: Golden hamster (Mesocricetus auratus Waterhouse, 1839).

The present paper describes the effects of animal house routine stressors on adult golden hamsters during activity time (2 hrs after lights off) and rest time (2 hrs after lights on). In addition, for determination of norm values, the circadian rhythms of the stress indicators heart rate, core body temperature and general activity of unstressed animals were telemetrically registered via implanted transmitters. The three circadian patterns of the nocturnal golden hamster under L:D = 12:12 were unimodal with a main peak after lights off.

Measurement of physiological parameters and activity in a Mongolian gerbil during gravidity and lactation with an implanted transmitter.

This communication reports the first use of a transmitter implanted into the abdominal cavity of a small pregnant rodent to simultaneously measure the heart rate, core body temperature and general locomotory activity with no apparent side effects to the animals. Using this method the heart rate of one female Mongolian gerbil (Meriones unguiculatus) decreased from a mean of 303 +/- 6 (SE) (beats per minute) during gravidity to a level of 248 +/- 3 (SE) (beats per minute) during lactation. At the same time, the core body temperature increased from 37.