Gerbils Research Articles

Expression of Sonic hedgehog gene, interleukin-1β, tumor necrosis factor-α in gastric epithelium of mongolian gerbils afterH pyloriinoculation

目的：研究形态基因Sonic hedgehog（Shh）以及IL—1β和TNF-α在Hplori相关性胃炎中表达的相关性及作用． 方法：♂蒙古沙鼠50只给予悉尼菌株灌胃造成H pylori感染模型，另设50只6蒙古沙鼠作为对照．应用RT-PCR的方法对沙鼠胃黏膜组织中的Shh，IL—1β以及TNF-αmRNA表达水平进行检测；应用免疫组化的方法对于Shh蛋白进行细胞定位以及半定量分析其表达水平． 结果：Hpylori灌胃36和48wk后，ShhmRNA表达水平明显降低（0．28vs0．48，t=3．24，P〈0．05；0．18vs0．45，t=3．01，P〈0．05）．Shh mRNA表达水平与IL-1β，TNF-αmRNA表达之间以及与炎症分级之间呈显著负相关（r=-0．37，P〈0．01：r=-0．30，P〈0．05；r=-0．39，P〈0．001）．Shh蛋白主要表达于胃体壁细胞胞质中，H pylori灌胃36和46wk，表达Shh抗原的阳性细胞数明显减少（Z=4．84，P〈0．001：Z=4．57，P〈0．001）．Shh蛋白的表达与IL-1βmRNA，TNF-αmRNA的表达以及慢性炎症分级之间也呈显著负相关（r=-0．321，P〈0．05；r=-0．313，P〈0．05；r=-0．371，P〈0．001）． 结论：蒙古沙鼠胃黏膜感染H pylori后，IL-1β和TNF-α表达上调，并与炎症程度呈显著正相关；Shh表达下调，并与炎症分级及IL-1β和TNF-α表达呈显著负相关．

Inhibiting the inhibition

The precedence effect describes the phenomenon whereby echoes are spatially fused to the location of an initial sound by selectively suppressing the directional information of lagging sounds (echo suppression). Echo suppression is a prerequisite for faithful sound localization in natural environments but can break down depending on the behavioral context. To date, the neural mechanisms that suppress echo directional information without suppressing the perception of echoes themselves are not understood. We performed in vivo recordings in Mongolian gerbils of neurons of the dorsal nucleus of the lateral lemniscus (DNLL), a GABAergic brainstem nucleus that targets the auditory midbrain, and show that these DNLL neurons exhibit inhibition that persists tens of milliseconds beyond the stimulus offset, so-called persistent inhibition (PI). Using in vitro recordings, we demonstrate that PI stems from GABAergic projections from the opposite DNLL. Furthermore, these recordings show that PI is attributable to intrinsic features of this GABAergic innervation. Implementation of these physiological findings into a neuronal model of the auditory brainstem demonstrates that, on a circuit level, PI creates an enhancement of responsiveness to lagging sounds in auditory midbrain cells. Moreover, the model revealed that such response enhancement is a sufficient cue for an ideal observer to identify echoes and to exhibit echo suppression, which agrees closely with the percepts of human subjects.

Changes in otoacoustic emissions and auditory brain stem response after cis-platinum exposure in gerbils.

Ototoxicity associated with cis-platinum administration commonly presents as hearing loss and tinnitus. The hearing loss is usually an irreversible, high-frequency sensorineural loss. Histologic studies in humans and animals suggest that the outer hair cells (OHCs) are most susceptible to cis-platinum. Evoked otoacoustic emissions (EOAE), as a measure of outer hair cell function, are potentially useful in following ototoxic insults involving OHCs. Distortion-product otoacoustic emissions (DPOAE) test frequency-specific regions of the cochlea and therefore may be particularly well suited for monitoring ototoxic injuries. We measured distortion product otoacoustic emissions, at f2 = 2, 4, 6, 8, 10, and 12 kHz, in gerbils after a single large dose of cis-platinum. Animals treated with saline served as controls. The findings were compared to auditory brain stem evoked response (ABR) thresholds, using tone pips of the same frequencies. The DPOAE and ABR thresholds were measured before treatment and again 2, 5, and 14 days after drug administration. The changes in DPOAE were compared with the changes in ABR. No treatment effect was noted in the 2-day group. Animals treated with cis-platinum demonstrated significant elevation of DPOAE and ABR thresholds compared with control animals at 5 and 14 days. There was no significant difference between the threshold changes in the 5- and 14-day groups.

Systematics and evolution of the subfamily Gerbillinae (Mammalia, Rodentia, Muridae)

Although they represent a quarter of the mammalian species, the evolutionary relationships among as well as within, the main murid lineages are still controversial. The subfamily Gerbillinae is no exception as previous studies based on morphological, karyotypical, and allozyme characters are highly incongruent. Here, we present the first molecular phylogeny for gerbils based on cytochrome b and 12S rRNA mitochondrial genes. Results are largely congruent between the two genes as well as with the concatenated data set with most of the nodes being well-supported. Based on the topologies retrieved here, we (1) propose the identification of three main clades, (2) support the split of Tatera genus into an Asian and an African group, the latter including Gerbillurus species, and (3) provide some evidence towards the inaccuracy of subgeneric divisions within both Gerbillus and Meriones. In addition, the sharp contrast between the genetic characters and morphological data sets suggest high levels of convergence, probably as a result of strong environmental constraints imposed on these rodents adapted to arid and semi-arid regions. Finally, molecular datings for the various cladogenetic events are in good agreement with the known gerbilline fossil record and support an African origin with subsequent migrations to Asia.

In vivo assessment of diabetic lenses using dynamic light scattering.

One of the most threatening aspects of diabetes mellitus is the development of visual impairment. For example, cataracts are 1.6 times more common in people with diabetes than in those without diabetes. Cataract extraction is the only treatment. In many cases, diabetes-related ocular pathologies go undiagnosed until visual function is compromised. This paper compares and contrasts the ocular changes observed using dynamic light scattering (DLS) and conventional ophthalmic techniques during long-term maintenance of the sand rat (Psammomys obesus) on a high caloric diet. P. obesus is a wild rodent in the subfamily Gerbillinae that inhabits the desert areas of the Middle East and Africa. This animal is unique in that it develops mild to moderate obesity, hyperglycemia, pancreatic atrophy, impaired renal function, ketoacidosis, vision loss, and other diabetic complications when it consumes a high caloric diet. In this study, five animals were fed Purina sand rat chow and thus served as normal control animals. Five animals were fed a commercially prepared rodent diet (Purina 5002) consisting of only 4-5% fiber and a grain-based rabbit supplement (BioServe Rabbit Stix Appetite Stimulant) consisting of 50% carbohydrate to provide a high caloric (diabetogenic) diet and thus induce diabetes. Blood samples for the biochemical analyses, DLS, and other optical examinations were obtained on alternate weeks. Our preliminary results have demonstrated subtle changes in the lens of the diabetic sand rats as early as 2 months on a diabetogenic diet. This is an ongoing joint project with Food and Drug Administration and the National Aeronautics and Space Administration. This technique is proving to be a practical, sensitive, noninvasive diagnostic tool useful for the early detection of ocular pathologies and understanding the mechanism of cataract formation.

Spatial distribution of Psammomys obesus (Rodentia, Gerbillinae) in relation to vegetation in the Negev desert of Israel

Dans le desert du Negev, Psammomys obesus creuse des terriers dans le lit des oueds densement couverts de grands buissons d'Atriplex halimus, et sur la premiere terrasse fluviale qui est couverte de buissons disperses et bas d'Anabasis articulata. Nous pensons que la repartition de P. obesus depend de l'intensite et de l'allure asynchronique de la vegetation de ces deux Chenopodiacees. Pour tester cela, nous avons etudie la repartition spatio-temporelle de P. obesus en rapport avec le couvert vegetal de ces deux habitats. Le pourcentage de buissons de A. halimus en vegetation s'est accru fortement de 1999 a 2001, tandis que les buissons de A. articulata ont ete beaucoup plus verdoyants en 1999 et 2001 que en 2000. En general, l'importance de la vegetation de A. articulata varie plus selon les annees que celle de A. halimus. En 1999 et 2001 les terriers frequentes par P. obesus ont ete repartis presque egalement entre les habitats, tandis qu'en 2000 il y avait beaucoup plus de terriers inhabites dans l'oued, specialement ceux de femelles qui etaient confinees dans cet habitat. Le nombre de terriers inhabites sur la terrasse varie fortement selon les annees, alors que la variation du nombre des terriers inhabites dans le lit de l'oued etait beaucoup moins importante. Les habitats Oued et Terrasse sont consideres respectivement comme des quais et des habitats temporaires.

The epidemiology of ocular toxocariasis.

Ocular toxocariasis damages vision and may cause blindness. It is a relatively 'new' disease, the histological changes having been described in 1950 and the causative organism identified in 1956. Many aspects of the epidemiology of toxocariasis are unclear. It is generally accepted that the usual route of entry to the eye is via the blood stream. Once the eye is invaded characteristic changes are produced with comparative sparing of the anterior segment. Species differences in susceptibility can be very marked. In Mongolian gerbils 55% of infected animals exhibit ocular lesions. Humans are fortunate in that they are far less susceptible to ocular infection. While it has been established that ocular toxocariasis is caused by Toxocara canis, the role of T. cati in this condition is still unclear. It is perhaps surprising that the prevalence of such a disease in humans should remain in doubt. However, the wide variation in the few estimates of prevalence may well be a reflection of the wide variation in exposure as evidenced by the wide variation in seroprevalence. A further factor mitigating against an identification of prevalence rates is the fact that the condition is usually unilateral. Most surveys of blindness stipulate a vision of 6/60 or less in the better eye and so toxocariasis cases go unrecorded. There is a need for surveys which identify the level of vision in both eyes.

Animal models in ocular toxocariasis.

Ocular toxocariasis is a clearly defined disease. However, much remains to be learned concerning the migratory route, ocular changes, diagnosis and treatment. Studies in paratenic hosts have contributed to our understanding and will yield more information. Various experimental animals have been used, such as mice, rabbits, guinea pigs, primates, hamsters and gerbils. Of these, the last appear to be the most appropriate model due to their high susceptibility to ocular infection. Results obtained from different animal models are often not comparable due to the fact that dose and routes of inoculation are diverse. Early stages in the pathogenesis of ocular toxocariasis are manifested by haemorrhages in the anterior chamber and iris, replaced in time by accumulations of white cells. Ocular migration produces an early cell reaction, formed by an infiltration of neutrophils accompanied by vasculitis and retinal microinfarcts. Over a period of time, an increase of macrophages and the distribution of the infiltrates is observed. Later, granulomatous lesions are formed. These do not necessarily contain a larva and their appearance varies in different animal models. Local production of IgE and the presence of specific IgG have been described.

Effect of Melatonin on the Changes of Hippocampal Polyamine Content and Neuronal Damage Following Transient Global Ischemia in Mongolian Gerbil: a Study of the Differences of Pre- and Post-ischemic Treatment

Background: We designed this study to examine whether melatonin has a neuroprotective effect against hippocampal neuronal damage following transient global ischemia in a gerbil. Because polyamine is known to participate in the process of ischemic neuronal damage, we examined the influence of melatonin on the polyamine level as well as histology. In particular, we examined the difference between preand post-ischemic treatments of melatonin by using the above mentioned parameters. Methods: Male Mongolian gerbils (60-80 g) were used in this study. Transient global ischemia was induced by occlusion of the bilateral common carotid arteries for 3 min with microclips. Melatonin was administered 1 h before or 1 h after occlusion. The animals were dissected 4 days after the occlusion for polyamine measurement by a high performance liquid chromatography (HPLC) and histological evaluation (hematoxylin and eosin staining). A histological examination was performed by a blinded investigator. Results: The hippocampal putrescine (PU) level increased compared to sham-operated animals and the increase of PU was attenuated by melatonin administration (preor post-ischemic treatment). Spermidine (SD) and spermine (SM) levels didn't show significant changes after ischemia. Hippocampal neuronal damage in the CA1 region was markedly observed in vehicle-treated animals compared to shamoperated animals. Both preand post-ischemic melatonin administration significantly inhibited hippocampal CA1 neuronal damage compared to corresponding vehicle-treated animals (P < 0.01, respectively). Conclusions: Melatonin attenuates the polyamine response following transient global ischemia and may have putative neuroprotective effects against global ischemia-induced neuronal damage. There is no difference in neuroprotective effects of melatonin between pre& post-ischemic treatments. (Korean J Anesthesiol 2001; 40: 664∼670) ꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏ

Microglia Proliferate in Striatum and Cortex but not Hippocampus Following Brief Periods of Ischemia that do not Kill Neurons

61 Because ischemia induced tolerance induces the birth of new neurons following global ischemia, this study determined whether 2.5 minutes of global ischemia and ischemia-induced tolerance would induce the birth of glia in the brain.Following 0, 2.5, or 5 minutes of global ischemia, adult male gerbils were injected with BrdU (50mg/kg) and dividing cells detected using immunocytochemistry. At four days following 2.5 minutes of global ischemia, when cell proliferation was maximal, BrdU labeled cells were detected in striatum and in neocortex, but not in hippocampus. The majority of the BrdU labeled cells were double-labeled with iso-lectin B4, showing that these dividing cells were mainly microglia. Similarly, BrdU labeled microglia were found in striatum and cortex but not in hippocampus of most animals four days following ischemia-induced tolerance (2.5 minutes of global ischemia followed three days later by 5 minutes of global ischemia). Some of the animals subjected to 2.5 minutes of ischemia showed decreased myelin associated glycoprotein (MAG) immunostaining and increased numbers of APC stained oligodendrocytes in the lateral striatum without apparent neuronal loss. Though the CA1 pyramidal and hilar interneurons of hippocampus are the most vulnerable neurons to ischemia, this data suggests that non-neuronal elements in the striatum may be more sensitive to ischemia than the neurons. In some animals proliferation of microglia in striatum following brief global ischemia may occur in response to injury to white matter and oligodendrocytes.

Room F, 10/16/2000 9: 00 AM - 11: 00 AM (PS) Induction of Inducible Nitric Oxide Synthase in the Gerbil Hippocampus Following Transient Forebrain Ischemia

<b>Room F, 10/16/2000 9: 00 AM - 11: 00 AM (PS) Induction of Inducible Nitric Oxide Synthase in the Gerbil Hippocampus Following Transient Forebrain Ischemia</b>

The cerebral microcirculation in focal ischemia and reperfusion

P111 The role of the microcirculation and of the inflammatory response in secondary brain damage from cerebral ischemia is hardly understood. Objective of the study was to assess leukocyte-endothelium interactions (LEI), functional capillary density (FCD), and the microvascular patency in the reperfusion period after an acute ischemic insult. Focal ischemia was induced in gerbils by transient (2 h) ligation of the left CCA. Only animals with a reduction of rCBF to -1 to 7 ± 5 cm -1 (p

Induction of gastritis and gastric ulcer in Mongolian gerbils infected with Helicobacter pylori.

To induce the model of Mongolian gerbil infected by Helicobacter pylori (HP) and to observe the changes of the infiltration and the proliferation of inflammatory cells before and after the bactericidal treatment. The animal model of HP infection was induced by inoculating the HP strain (American Type Culture Collection) to male Mongolian gerbil MGS/Sea (SPF). Half a month, 1 month and 3 months after inoculation, kill the animals and make HE staining and immunohistochemistry staining of the stomach to observe the pathological changes. The infiltration of a great number of inflammatory cells was observed with the center of the mucosa of pylorus at the second week of HP infection. At the 3rd month of infection, ulcer appeared near the lesser curvature side of the pylorus. On the early stage of infection, the lesion was acute inflammation characterized by the neutrophilic infiltration, and then transformed into the chronic inflammation characterized by the lymphatic infiltration and the wide formation of lymphatic follicles. Mongolian gerbil is an ideal and standard animal model of HP infection.

Reproductive biology of the South Indian gerbil (Tatera indica cuvieri) under laboratory conditions

Les auteurs ont etudie la biologie de la reproduction du rongeur tropical Tatera indica cuvieri. La duree du cycle œstral a ete de 4,5 jours: la secretion vaginale est plus fiable que l'apparence externe du vagin pour determiner les stades de l'œstrus. Pres de 50 % des mâles ont ete sexuellement inactifs: ils avaient des organes reproducteurs plus petits que les mâles sexuellement actifs. La duree de gestation a ete de 21.0 jours. Les femelles ont atteint leur maturite sexuelle plus tot que les mâles. Au laboratoire la sex-ratio des portees montre un exces de mâles.

Sequence divergence within the sperm-specific polypeptide TCTE1 is correlated with species-specific differences in sperm binding to zona-intact eggs.

The T-complex-associated testes-expressed (TCTE1) gene encodes a novel sperm cell-specific polypeptide (TCTE1) that is conserved across vertebrate species. TCTE1 is absolutely required for fertilization and is expressed in earlier stages of spermatogenesis. When the amino acid sequence of the TCTE1 gene product is compared among various mammalian species, a large, highly conserved domain is observed, along with a divergent domain encoding the 56-58 residues at the N terminus. In this study, the N-terminal regions of the TCTE1 polypeptide from three rodent species--mouse, gerbil, and rat--were compared. The results show that while the gerbil and mouse species are most distant in evolutionary terms, their TCTE1 homologs have not undergone significant divergence. In contrast, the N-terminal region of the rat TCTE1 homolog has evolved rapidly, a finding that indicates positive Darwinian selection. We have tested the correlation between TCTE1 divergence and heterospecific sperm-egg binding ability in the three species under study. Gerbil sperm bind to mouse eggs, while no significant binding is observed between rat sperm and mouse eggs. The results obtained support the hypothesis that the sperm-specific polypeptide TCTE1 may facilitate species-specific divergence of sperm function.

Physiological adaptation to aridity in the bushveld gerbil, Tatera leucogaster

Oxygen consumption, rectal temperature, thermal conductance, and evaporative water loss (EWL) were determined in resting captive Tatera leucogaster at ambient temperatures of between 14 and 38 °C. Basal metabolic rate (BMR) was 0.86 ml O2. min−1 (S.D.=0.15, n= 6), 45% of that expected for a rodent of the same body mass (106.2 g). Minimum wet thermal conductance was 0.21 ml O2. min−1, °C−1 (S.D. = 0.01, n= 6), 113% of that expected for a mammal of the same body mass. Wet thermal conductance increased exponentially at temperatures greater than 32 °C. Mean rectal temperature was 35.3 °C below 35 °C (S.D. = 0.5, n= 6) and 39.3 (S.D. = 0.6, n= 5) at 38 °C. Mean resting EWL was 1.43 mg. min−1 (S.D. = 0.14, n= 6) between 15 and 32 °C and increased dramatically at temperatures above 32 °C. Combining our data with data from the literature suggests that gerbils (Family Muridae; subfamily Gerbillinae) have, on average, low BMR and average minimum wet thermal conductance when compared to other rodents and other mammals, respectively, of the same body mass. Similarly, rodents (including gerbils) from arid habitats have, on average, lower rates of EWL when at rest below thermoneutrality than do other rodents of the same body mass from mesic habitats.

Pre- and postmating isolation in two allopatric gerbil species, Tatera afra and T. brantsii

Chez deux especes de Gerbillides dont le caryotype est identique, Tatera afra et T. brantsii, on a etudie l'isolement reproductif pre- et postcopulatoire. Ces especes sont allopatriques et morphologiquement distinctes. On n'en connait pas d'hybrides naturels. On n'a pas pu mettre en evidence de preuve concluante d'une discrimination precopulatoire entre individus conspecifiques ou heterospecifiques. Toutefois on a pu observer des tendances plus marquees au flairement nasal et anogenital, et moins marquees au frottement perineal chez des couples conspecifiques que chez les heterospecifiques, mais les differences n'ont ete statistiquement significatives que dans quelques couples. Six sur 16 couples heterospecifiques ont produit des portees hybrides. Mais 50 % des hybrides sont morts avant l'âge de 5 mois, les hybrides mâles etant plus vulnerables que les femelles. Aucun couple d'hybrides n'a eu de jeunes, mais l'un des 3 couples de croisements en retour entre femelles hybrides et mâles de souche pure a produit une portee normale. En depit de l'absence de divergence chromosomique, souvent associee a la speciation chez les rongeurs, l'isolement reproductif postcopulatoire agit en desavantageant l'hybride et probablement en favorisant la sterilite mâle. Les mecanismes d'isolement precopulatoire semblent tres peu developpes.

Cyclic Transmission of Sarcocystis gerbilliechis n. sp. by the Arabian Saw-Scaled Viper, Echis coloratus, to Rodents of the Subfamily Gerbillinae

Cyclic Transmission of Sarcocystis gerbilliechis n. sp. by the Arabian Saw-Scaled Viper, Echis coloratus, to Rodents of the Subfamily Gerbillinae

Attempted induction of blood brain barrier in vitro by co-culture of gerbil brain microvessel endothelial cells and glial cells

Attempted induction of blood brain barrier in vitro by co-culture of gerbil brain microvessel endothelial cells and glial cells

Effects of Substrate on Foraging Decisions by a Namib Desert Gerbil

We investigated the role of foraging and escape substrates on foraging decisions of a Namib Desert gerbil, Gerbillurus tytonis (Rodentia), in the field. We used the giving-up density technique, which uses artificial seed trays to assess foraging decisions. We tested whether the foraging decisions made in the trays were an artifact of prior knowledge of a food source by comparing giving-up densities in trays that were randomly placed in different parts each night with that in trays that remained in fixed position throughout the experiment. There was no significant difference in giving-up densities between these two treatments, which suggests that prior knowledge of food location does not affect foraging decisions. We examined the preferences of gerbils for the different substrates using seed trays. The gerbils showed significant differences among habitats in the amount of seed taken and between new-moon and full-moon nights. They removed more seeds where the difference between the size of the seeds and the size of the sand substrate was large. This finding is congruent with the hypothesis that tactile discriminatory ability affects the foraging behavior of these rodents. Although these rodents alter their foraging behavior in response to predation risk, there was no significant difference in the amount of seeds taken in habitats differing only in the degree of compaction of escape substrates.