Discrimination of individuals by odor in male Mongolian gerbils, Meriones unguiculatus

The ability to discriminate among individuals plays a fundamental role in the establishment of social relationships in animals. We examined how Mongolian gerbils (Meriones unguiculatus) discriminate among individuals using odor. In the first experiment, the ability of male gerbils to discriminate among five odor sources from different individuals was investigated using a habituation-dishabituation paradigm. After male gerbils had been habituated to a scent from one individual, they were exposed to familiar and unfamiliar scents from different donors simultaneously. Where urine and ventral gland secretions were used, the subjects spent more time investigating novel odors than familiar ones, suggesting that they were able to discriminate individual differences in these odor sources. However, with the scents of feces and saliva, they could detect, but could not discriminate individual differences; with scent from inside the pinnae, they could not even detect. In the second experiment, we tested whether cross-habituation occurred between the scents of urine and ventral gland secretions. A male was exposed repeatedly to urine from one of two familiar donor males during four habituation trials, and was then exposed to the ventral gland secretions from two donors simultaneously. The subject males spent more time investigating scents of ventral gland secretions, but there was no difference in the investigation time between ventral gland scents from the two donors. These results suggest that male gerbils discriminate among individuals using odors from urine and ventral gland secretions and that cross-habituation may not occur between these scents during social-memory formation.     

Lysosomal enzymes in the rat harderian gland are altered by either bromocriptine treatment or hypophysectomy and hormone replacement therapy

Four groups of adult male hypophysectomized rats were injected subcutaneously twice daily between 0800-0900 hr and 1600-1700 hr with either saline diluent, 150 micrograms sheep prolactin and/or growth hormone (GH); intact rats received either saline or 150 micrograms bromocriptine twice daily. After 4 days of treatment, lysosomal enzyme assays revealed significant elevations in both acid phosphatase and alpha-mannosidase enzyme activities in the Harderian glands of saline-injected hypophysectomized rats compared to those in intact controls. beta-Glucuronidase levels were depressed and hexosaminidase activity unaffected by hypophysectomy treatment alone compared to intact controls. Lysosomal enzyme activities in hypophysectomized animals treated with prolactin were not different from the hypophysectomized control animals. However, treatment with GH alone or in combination with prolactin had a significant inhibitory effect on beta-glucuronidase, hexosaminidase, and alpha-mannosidase enzyme activities in the Harderian gland of hypophysectomized animals. Bromocriptine treatment in intact rats only elevated acid phosphatase activity. In summary, the patterns of responses did not reveal a role for prolactin in the control of Harderian gland lysosomal enzyme activities by the pituitary. However, some of the influence on this target system may be exerted by growth hormone.     

Gastric mucosal changes induced by long term infection with Helicobacter pylori in Mongolian gerbils: effects of bacteria eradication.

Helicobacter pylori infection has been reported to induce various mucosal changes, including gastric adenocarcinoma, in Mongolian gerbils 62 weeks after inoculation. Using Mongolian gerbils, this study examined whether or not eradication of the bacteria with drugs at specified times after infection prevents the development of mucosal changes. After orally inoculating with H. pylori (TN2GF4, vacA- and cagA-positive), the animals were killed 18 months later. Four or 8 months after H. pylori inoculation, eradication was performed by concurrent treatment with omeprazole+clarithromycin. Immediately after treatment ended, in both the 5 and 9 month groups, it was verified that H. pylori was completely eradicated. Autopsy performed 18 months after H. pylori inoculation revealed gastric hyperplastic polyps with erosive lesions and ulcers that were grossly visible in the non-treated control group. In addition, atrophic gastritis, intestinal metaplasia, carcinoids, and adenocarcinomas were histologically observed in the animals. In animals eradicated after 4 months and autopsied after 18 months, however, such mucosal changes were not observed. In contrast, intestinal metaplasia and mucosal atrophy was observed in animals eradicated after 8 months and autopsied after 18 months. It was concluded that early eradication of H. pylori infection with drug therapy can prevent severe gastric mucosal changes, to include adenocarcinomas, in Mongolian gerbils.     

Characteristics of microbial association in secretions of various mammalian sebaceous glands

The following secretions of mammalian skin glands were subjected to a microbiological survey: the middle-abdominal glands of great and Mongolian gerbils, the preputial gland of musk deer, the perineal organ of African civet cat, the interdigital skin regions and interdigital glands of bison, European bison, European roe deer, and musk deer. All the secretions were found to contain microbial associations. The composition of bacterial species in the secretions and the quantity of microorganisms varied among different animal species, during the ontogenesis of an animal, and depended on the topography of a gland on an animal body as well as on its functional state in different seasons or upon hormonal changes. The secretions of certain glands contain factors which determine the composition of microbial species in a particular ecological niche and the stability of such a cenosis.     

Spontaneous lesions and parasites of the Mongolian gerbil, Meriones unguiculatus.

Four-hundred-eighty Mongolian gerbils, Meriones unguiculatus [Uclp:(MON)], most of which were experimentally infected with filarial worms, were examined for spontaneous lesions. Previously unrecognized lesions included cutaneous squamous cell carcinoma, duodenal adenocarcinoma, malignant blue nevus, hepatic choleangiocarcinoma, malignant hemangiopericytoma of the uterus, ovarian teratoma, chronic interstitial nephritis, renal cortical retention cysts, splenic hemangiomas, and various histologic abnormalities of the lung. Previously reported lesions also seen in the present study were a malignant melanoma, adrenal cortical adenoma or carcinoma, uterine leiomyoma, sebaceous gland adenoma, hepatic lymphangioma, and renal hemangioma. Hymenolepis diminuta (Cestoda) and Tyrophagus castellani (Acarina) were accidentally recovered from experimental animals. Tritichomonas caviae and a species of Entamoeba were the most common intestinal protozoa. Tyzzer's disease, however, was clearly the most significant infectious disease of gerbils in the UCLA School of Public Health colony.     

周龄和激素水平对长爪沙鼠超数排卵效果的影响

目的探讨不同周龄和激素水平对长爪沙鼠超数排卵效果的影响,以期确定长爪沙鼠最佳超排周龄和激素使用剂量。方法腹腔注射10 IU PMSG/HCG对4～18周龄8个年龄段的雌性长爪沙鼠进行超数排卵,末次注射16～17 h内对各组动物卵母细胞计数,确定最佳超排周龄后,对该年龄动物以5、10、15 IU3个剂量水平腹腔注射PMSG/HCG,观察各组动物的卵母细胞计数差异。结果与其它周龄组相比,6周龄组长爪沙鼠超数排卵后的卵母细胞数最多,各组间有统计学意义（P〈0.05）,而5、10、15IU等3个剂量组的超排效果也有一定的差异,10 IU组数量最高。结论对长爪沙鼠而言,采用10 IU激素注射和6周龄的动物进行超数排卵,获得的卵母细胞数量最多而且超排效果稳定性。     

Distribution of Helicobacter pylori in a Mongolian gerbil gastric ulcer model

BACKGROUND AND PURPOSE: To the authors' knowledge, histopathologic changes associated with early H. pylori infection and ulceration have not been established. We examined presence of H. pylori infection in an acetic acid-induced gastric ulcer (AAU) model in Mongolian gerbils. METHODS: Sixty Mongolian gerbils were used as an AAU model, and another 60 gerbils were studied as a control (non-AAU) group. All animals were orally administered H. pylori, then were evaluated by use of histologic and bacteriologic examinations. RESULTS: Helicobacter pylori were scattered on the surface mucous gel layer and in the pyloric gland gastric were pits; inflammation seen at the early stages later extended to the mucosa of the fundic gland area. The organisms were predominantly observed in the AAU model, but findings were comparable to those in controls at 1, 3, 7, 14, 28, or 56 days. Evaluation with regard to viable bacterial numbers reflected the histologic aspects, that the pyloric gland area had more viable counts than did the fundic gland area. Carbohydrate composition of mucin differed between pyloric and fundic gland areas. These findings shed light on L-fucose related to the H. pylori adhesive factor abundant in mucin of the pyloric gland area. CONCLUSIONS: Findings for this ulcer model of Helicobacter pylori infection make it useful for the study of onset of infection and screening of anti-ulcer agents.     

Rhythms in immunoreactive melatonin in the retina and harderian gland of rats: Persistence after pinealectomy

Immunoreactive melatonin levels were measured in the retina and Harderian gland of adult male rats throughout a 24 hour period. The animals were maintained under a light:dark cycle of 14:10 (lights on at 0600h). In intact animals, immunoreactive melatonin values in both organs exhibited a 24h rhythm with peak levels being measured at 0800h, 2 hours after lights on. Pinealectomy significantly increased peak levels at 0800h in both the retina and the Harderian gland. Gonadectomy abolished the peak retinal melatonin levels at 0800h. Likewise, continual light exposure for 1 week depressed the melatonin peak in the retina but not in the Harderian gland.     

Gastric mucosal changes induced by long term infection with Helicobacter pylori in Mongolian gerbils: effects of bacteria eradication

Helicobacter pylori infection has been reported to induce various mucosal changes, including gastric adenocarcinoma, in Mongolian gerbils 62 weeks after inoculation. Using Mongolian gerbils, this study examined whether or not eradication of the bacteria with drugs at specified times after infection prevents the development of mucosal changes. After orally inoculating with H. pylori (TN2GF4, vacA- and cagA-positive), the animals were killed 18 months later. Four or 8 months after H. pylori inoculation, eradication was performed by concurrent treatment with omeprazole+clarithromycin. Immediately after treatment ended, in both the 5 and 9 month groups, it was verified that H. pylori was completely eradicated. Autopsy performed 18 months after H. pylori inoculation revealed gastric hyperplastic polyps with erosive lesions and ulcers that were grossly visible in the non-treated control group. In addition, atrophic gastritis, intestinal metaplasia, carcinoids, and adenocarcinomas were histologically observed in the animals. In animals eradicated after 4 months and autopsied after 18 months, however, such mucosal changes were not observed. In contrast, intestinal metaplasia and mucosal atrophy was observed in animals eradicated after 8 months and autopsied after 18 months. It was concluded that early eradication of H. pylori infection with drug therapy can prevent severe gastric mucosal changes, to include adenocarcinomas, in Mongolian gerbils.     

Age-related changes on marking, marking-like behavior and the scent gland in adult Mongolian gerbils (Meriones unguiculatus).

Marking behavior, marking-like behavior [3], and changes of the scent glands were observed in aged Mongolian gerbils. In Experiment 1, changes in the marking and marking-like behavior with aging were evaluated in adult male and female Mongolian gerbils of an inbred strain aged 6 to 36 months. The frequency of marking behavior in males was significantly higher than females throughout the observation period except at 36 months of age. On the other hand, frequency of marking-like behavior in males, but not in females decreased with aging, significantly. In Experiment 2, changes of the scent gland in adult males and females aged 6 to 36 months were morphologically evaluated. Macroscopic examination revealed an increase in the size length and width of the glands of males aged 12 months and females aged 6 months. Histologically the glands of all the males and females aged 6 months developed moderately or well. Some of the 12-month-old males and females showed acinar atrophy of the glands, and all the females aged 18 months or more had highly atrophied scent glands. From these results, we concluded that there is no relationship between the changes of marking behavior and those of the scent glands in aged male Mongolian gerbils, and assume that marking behavior in aged animals does not have an important meaning as marking. In Experiment 3, marking and marking-like behavior in castrated adult Mongolian gerbils aged 16 weeks were observed. The result showed that marking behavior, not marking-like behavior was inhibited after castration. From these findings, we consider that generally marking behavior in Mongolian gerbils consists of androgen-dependent marking behavior and androgen-independent marking behavior (marking-like behavior).     

The androgenic effect on the fine structure of the harderian gland in the male hamster

Summary A sexual dimorphism of the hamster Harderian gland at the ultrastructural level has been reported. The effect of testosterone on the fine structure of the gland from castrated male golden hamsters is reported here. Harderian glands from the following three groups of animals were examined at regular intervals up to 60 days after castration: (1) castrated; (2) castratedsham-injected, receiving 0.1 ml sesame oil per day; (3) castrated-testosterone injected, receiving 2mg testosterone propionate in 0.1 ml sesame oil per day. In groups 1 and 2, clusters of cylindrical tubules, typical of the male gland, decreased in number and disappeared almost completely 2 weeks after castration. Membranous structures, typical of the female gland, prevailed in these two groups throughout the remaining period of experiment. On the other hand, these changes were prevented in the group of castrated animals maintained on testosterone propionate. It is concluded that castration modified the ultrastructure of the male hamster Harderian gland toward the female type and that daily administration of testosterone propionate prevented this change.     

Underfeeding and exposure to short photoperiod alters rat pineal and Harderian gland lysosomal enzyme activities

Harderian gland (HG) weight and lysosomal enzyme activity were evaluated after 21-day-old female rats were singly caged in a long (LP; 14:10 LD) or short (SP; 8:16 LD) photoperiod and fed on one of two dietary regimens (fed ad libitum or 50% underfed) for 50 days; an additional fed and an underfed group of animals in LP were injected every afternoon with 100 micrograms melatonin. Absolute HG weights were significantly lower in all underfed groups compared to their respective fed controls or to the LP fed control group. Absolute HG weights of underfed rats in SP were significantly lower than the underfed rats in LP. Relative HG weights (mg/100 g body wt) were significantly higher in the underfed saline or melatonin-treated groups compared to their respective fed controls; however, HG of the underfed SP group were not different from SP-fed controls. No significant differences in HG acid phosphatase, hexosaminidase, and beta-glucuronidase activities were observed in any of the treatment groups maintained in LP. Acid phosphatase, hexosaminidase, and beta-glucuronidase activities were significantly elevated in HG of underfed animals maintained in SP compared to their respective fed controls or to the LP-underfed group. Both the underfed control and the underfed-melatonin treated groups had lower pineal protein values than their respective fed groups; underfed animals in 8:16 LD had similar pineal protein values compared to those of the fed control group in SP. Significant effects of photoperiod and underfeeding with no interaction between these variables were observed on pineal acid phosphatase. The fed group maintained in 8:16 LD had significantly higher acid phosphatase activity than the fed group kept in 14:10 LD. In conclusion, underfeeding resulted in severely reduced body weights and absolute Harderian gland weights. Increased activity in certain lysosomal enzymes occurred in both the pineal and Harderian gland and in some instances this was dependent upon the light cycle and dietary regimen to which the animals were exposed.     

Further observations on spontaneous neoplasms in the Mongolian gerbil, Meriones unguiculatus.

One hundred sixty Mongolian gerbils, Meriones unguiculatus, were examined for the presence of naturally occurring lesions. The first recognized cases of cecal adenocarcinoma, testicular teratoma, and sebaceous gland pad carcinoma were found. Neoplasms previously reported from the gerbil and also seen in the present study included ovarian theca lutein and granulosa lutein cell tumors, sebaceous gland pad adenoma, cutaneous squamous cell carcinoma, malignant melanoma, and renal and splenic hemangiomas. Calcinosis cutis was also observed in two male gerbils.     

Acute ethanol administration and transient ischemia: a behavioral and neuropathological study

A pressing clinical question is how acute ethanol exposure might alter the outcome of a simultaneous transient ischemic attack (TIA), since ethanol is known to dysregulate key intermediary metabolites post-ischemia. Mongolian gerbils were administered ethanol (1 or 4 g/kg, s.c.) 1 hour before induction of transient ischemia, via bilateral carotid occlusions of 5 minutes duration. A control group was administered isotonic saline and rendered ischemic. All animals were maintained normothermic during the ischemic procedure. Subjects underwent behavioral assay of acquisition to the water maze 7 days after recovery from the surgery, and neuropathological examination 1-month after the ischemic brain insult. There were no behavioral or neuropathological between-group differences suggesting that mechanisms other than adverse ethanol-induced perturbations of ischemic processes predominate in mediating epidemiological findings of elevated stroke morbidity with high ethanol consumption.     

The Harderian gland of the Cheesman's gerbil (Gerbillus cheesmani ) of the Kuwaiti desert

The Harderian gland is a large orbital structure. Several functions have been ascribed to the gland such as lubrication of the eye, a source of pheromones, thermoregulartory lipids and photoprotective secretions and a part of the retinal-pineal axis. In the present study, the Harderian gland of the Cheesman's gerbil, Gerbillus cheesmani, is described for the first time. The gland is located around the posterior portion of the eyeball. The gland is compound tubular, surrounded by a thin connective tissue capsule. Only one secretory epithelial cell type was recognized, characterized by the presence of lipid vacuoles and cytoplasmic slashes in high numbers; the former being more concentrated towards the apical part while the latter being more concentrated towards the central and basal parts. Some of the cytoplasmic slashes contained electron dense filamentous structures. Similar structures were observed in the lipid vacuoles. Thus, a functional relationship between the cytoplasmic slashes and the lipid vacuoles is suggested. A unique structure was observed, termed dome-like cells, located between the epithelial cells and the basement membrane. These cells were characterized by the extensive presence of pleomorphic mitochondria and compact lamellae of granular endoplasmic reticulum (GER) in the form of finger prints. The gland was found to be actively secreting porphyrins as well as lipids. Cellular debris was also seen in the tubular lumina. Myoepithelial cells with their spindle shape and elongated nuclei were evident between the basement membrane and the secretory epithelium. Sparse interstitial tissue was observed in-between the gland tubules of both male and female gerbils. Macrophages, dendritic melanocytes and lymphocytes are the most represented cellular components of the interstitium. Further studies are required to investigate the function of the dome-like cells as well as the role of lymphocytes in the rodents Harderian gland.     

Colonization of Helicobacter pylori in the gastric mucosa of Mongolian gerbils

Helicobacter pylori was orally inoculated into Mongolian gerbils. The organisms were able to colonize in the gastro-mucosal layer of the gerbils, especially in those gerbils which had mucosal lesions caused by indomethacin treatment. The pathological changes developed by H. pylori infection were restricted to the stomachs, and only slightly inflammatory cells were observed.     

Ethinylestradiol and its effects on the macrophages in the prostate of adult and senile gerbils

Prenatal and neonatal exposure to estrogenic compounds, such as ethinylestradiol (EE), promotes a variety of developmental disorders, including malformations and alterations in the morphology of glands, such as the prostate gland. Therefore, the aim of this study was to evaluate the morphological effects of neonatal exposure to EE on prostatic tissue and on the identification and quantification of gerbil gland macrophages in adult and senile Mongolian gerbils. The animals were exposed to EE (10 μg/kg/day) and to the vehicle, mineral oil (100 μL) (control group) during the first 10 days of postnatal life (lactation period). Adult gerbils were euthanized at 120 days and senile gerbils at 12 months of age. Our findings permitted verification of the presence of areas with proliferative foci in the prostate glandular portions in the adult and senile animals exposed to EE. There was also an increase in macrophages in the prostate tissue of adult and senile gerbils; these cell types alter the stromal microenvironment and possibly modify the interactions between the epithelium and stroma. Neonatal exposure to EE changes the pattern of prostatic development, leading to alterations in the arrangement of cells, including macrophages, and may be related to the onset of proliferative disorders in the prostate of adult gerbils and during aging.     

Marking behavior is innate and not learned in the Mongolian gerbil.

We studied whether marking behavior in Mongolian gerbils would be innate or learned behavior. The marking behavior was defined as "animals rubbing their abdominal scent glands on small protruding objects". Between 21 and 90 days of age, Mongolian gerbils, which were kept under such conditions that they would be unable to learn this behavior, were observed at intervals of 5-15 days to find out if there were signs of the behavior or not. Six male and four female Mongolian gerbils were used for observing. Neonate Mongolian gerbils during the age of 3 to 28 days were fostered by ICR mother mice. Weaning Mongolian gerbils were then individually kept away from the others. Marking behavior was observed in 2 out of 6 males at 50 days of age and 2 of 4 females at 60 days and the mean frequency of the marking behavior for 10 min was 3.5 in the males and 5.0 in the females. These results suggest that marking behavior was innate and not learned behavior in Mongolian gerbils.     

Enterohepatitis in Mongolian gerbils (Meriones unguiculatus) inoculated perorally with Tyzzer's organism (Bacillus piliformis)

Enterohepatitis was produced in Mongolian gerbils by intragastric inoculation with Tyzzer's organism from natural infection of a gerbil. Death occurred in 50 to 60% animals 5 to 7 days postinoculation (p.i.). On day 3 p.i., when a few necrotic foci appeared in the liver, a large amount of bacterial antigen was present within ileocecal enterocytes and reticuloendothelial cells of the Peyer's patches. Neutrophil and monocyte infiltration was found in the lamina propria. On day 5 or 6 p.i. there was severe necrotizing and hemorrhagic ileotyphlocolitis. Bacterial antigen was abundant within not only enterocytes, but also smooth muscle cells of the ileum and jejunum as well as reticular cells of the mesenteric lymph nodes. On day 7 p.i. the intestinal lesions subsided in the presence of fewer bacteria, while necrotizing hepatitis became well developed. The results indicated that Mongolian gerbils were highly susceptible to the oral route of infection with the Tyzzer's organism.