Suspected case of hyperadrenocorticism in a golden hamster (Mesocricetus auratus).

Dermatologic disease is a common problem in pet rodents. This article describes the case of a pet golden hamster (Mesocricetus auratus) with dermatologic and other clinical signs (polyuria, polydypsia) similar to those found in other mammalian species with hyperadrenocorticism. Among other diagnostic tests, the urine cortisol/creatinine ratio was measured and was found to be increased, which appeared to support the diagnosis. Treatment with ketoconazole was initiated, without apparent success.     

Hereditary hydrocephalus in laboratory-reared golden hamsters (Mesocricetus auratus)

A colony of golden hamsters had an ongoing problem with hydrocephalus. In an attempt to clear the colony of the problem, new breeders from another supplier had been purchased. At termination of a behavioral study, the brain was collected from 35 animals (four of which had died with hydrocephalus during the study) and was examined macroscopically and by light microscopy. Although no animals manifested obvious behavioral changes, 31 of 35 (88.6%, 13/15 males and 18/20 females in control and manipulated groups) had hydrocephalus. Twenty-five animals had macroscopically identifiable hydrocephalus, and six had hydrocephalus identified microscopically. Neither teratogenic concentrations of metals nor mycotoxins were detected in tissues or food, and sera from breeders tested negative for antibodies to Sendai virus, reovirus 3, and lymphocytic choriomeningitis virus. Trial matings of breeders expected to produce hydrocephalic offspring resulted in affected offspring, and mating of breeders expected to produce normal offspring resulted in normal or less-affected offspring. Hydrocephalus was confirmed retrospectively in some breeders. Hereditary hydrocephalus appears to be widespread in hamster stocks in Central Europe. Affected animals do not manifest signs of disease and usually die without obvious premonitory signs. Despite severe hydrocephalus, the animals can breed, and animal handlers do not identify motor deficits or abnormal behavioral activity. This entity is unlike the previously described, hereditary hydrocephalus of hamsters that is phenotypically identifiable and usually is lethal before they attain breeding age.     

Hamster polyomavirus infection in a pet Syrian hamster (Mesocricetus auratus)

An approximately 8-week-old pet Syrian hamster (Mesocricetus auratus) with a 1-week history of dyspnea, hyporexia, and ataxia was submitted for necropsy. On gross examination, the hamster had multiple abdominal adhesions and enlargement of the mesenteric lymph node. Histologic evaluation revealed multicentric lymphoma of the liver, jejunum, mesenteric lymph node, testicular fat pad, and epididymis. Based on the hamster's age and the type and distribution of the lymphoma, a presumptive diagnosis of hamster polyomavirus-induced lymphoma was made. A specific polymerase chain reaction (PCR) was developed, which confirmed the diagnosis. An in situ PCR demonstrated hamster polyomavirus DNA within lymphocytes of the multicentric lymphoma and renal tubular epithelial cells and within clusters of enterocytes in the jejunum. These data are consistent with environmental dissemination of hamster polyomavirus virions through the renal tubular epithelium and into the urine and with fecal shedding of hamster polyomavirus virions; however, additional studies will be needed to confirm these observations.     

Spontaneous uterine leiomyosarcoma in a golden hamster (Mesocrietus auratus)

Uterine leiomyosarcoma occurring spontaneously in a domestic golden hamster was examined histologically and immunohistochemically. The histological findings for this tumour were similar to those for leiomyosarcomas described in other species. Immunohistochemical examination demonstrated the positivity of neoplastic cells with alpha-smooth muscle actin and desmin. From the results mentioned above, the tumour of this case was revealed to be of smooth muscle origin. To our knowledge, this is the first report of a uterine leiomyosarcoma in domestic golden hamsters.     

Inhibin secretion in the golden hamster (Mesocricetus auratus) testis during active and inactive states of spermatogenesis induced by the restriction of photoperiod

Gonadal function in the male golden hamster (Mesocricetus auratus) was investigated during exposure to a short photoperiod condition. Within 3 weeks of exposure to the short photoperiod condition, FSH and testosterone in the plasma significantly decreased, and subsequently immunoreactive (ir)-inhibin significantly decreased. Testicular contents of ir-inhibin and testosterone, and pituitary contents of LH and FSH also significantly decreased by 3 weeks with regression of weight of testes, epididymis and seminal vesicles and sperm head count. Circulating LH varied but not significantly. Thereafter, all reproductive parameters and secretion of LH, FSH, ir-inhibin and testosterone gradually recovered after 17 weeks of exposure even though animals continued to be subjected to the short photoperiod condition. Plasma concentrations of inhibin B and inhibin pro-alphaC were detectable and were significantly decreased after 15 weeks of exposure to the short photoperiod, but their levels were still detectable. Immunopositive reaction of inhibin alpha and betaB subunits was found in Sertoli cells and Leydig cells in the regressed testes of animals subjected to short photoperiod as was also seen in animals before exposure to the short photoperiod. Although the spermatogenic cycle was suppressed like prepubertal animals, the present study showed that the testicular recovery, so-called refractoriness, is functionally different from the developing stage of immature animals, especially with regard to inhibin secretion. The present results showed that changes in FSH preceded changes in inhibin during the regression and recovery phases, indicating that FSH is a major regulatory factor of inhibin secretion in male golden hamsters. The present study also demonstrated that regressed testes still secrete a small amount of bioactive inhibin during exposure to a short-photoperiod condition.     

Extramedullary plasmacytoma of the salivary gland in two Syrian hamsters (Mesocricetus auratus)

Two Syrian hamsters developed marked swelling of the ventral neck. Histologic examination of both masses revealed that the submaxillary salivary glands were effaced by large numbers of neoplastic plasma cells. In one hamster, neoplastic cells had infiltrated the adjacent lymph node. The neoplastic cells expressed CD79a antigen and were negative for CD3, lambda, and kappa light chains. Ultrastructural features of neoplastic cells in the salivary gland of one hamster included abundant cytoplasmic rough endoplasmic reticulum profiles, and peripherally displaced nuclei that contained marginated heterochromatin, consistent with plasma cells. Salivary gland plasmacytomas are extremely rare in humans and have not previously been reported in nonhuman species. The occurrence of such neoplasms in two hamsters suggests that this species may be predisposed to developing tumors of this type.     

Hematological findings and antibody responses in Syrian hamster (Mesocricetus auratus) infected with Babesia microti

Hematological findings during the course of infection and the antibody response in Syrian hamsters infected with Babesia microti were examined. A macrocytic hypochromic anemia with an increase of the reticulocyte count was detected as a rise in the parasitized erythrocyte rate. White blood cell counts also remarkedly increased with the increases of both neutrophils and active-shaped monocytes, and thus they particularly play an important role in eliminating the parasite. In Western blotting with the sera from the hamsters infected with B. microti, a 38 kDa protozoan antigen reacted to the early-term sera, and additionally 28, 32, and 34 kDa antigens also reacted to the medium- and latter-term, and convalescent sera. These antigens were immunodominant and the antibodies against these antigens had also important roles for inhibition of this parasite.     

Lactating females Syrian hamster (Mesocricetus auratus) show protection against experimental Leishmania infantum infection

The Syrian hamster (Mesocricetus auratus) is the best animal model for human leishmaniosis, an emergent disease that causes 400,000 new cases every year. The main objective of this assay was to prove the relationship between female lactation, which implies hyperprolactinaemia (IFN-gamma, IL-12, IL-2 and TNF-alpha elevated), and leishmaniosis (IFN-gamma, IL-12, IL-2 and TNF-alpha diminished). The results demonstrate the clear implication of lactation in immune response. The infected lactating females did not show any symptoms of sickness, a 24 g mean increase was noticed, throughout the assay they were negative in the indirect diagnosis test (Direct Agglutination Test (DAT)), and in the direct diagnosis tests (N-N-N isolation, tissue impressions).     

Effects of hypothyroidism on gonadal function after transition of short day photoperiod in male golden hamsters (Mesocricetus auratus)

Thyroid hormones permit the annual reproductive transition of seasonal breeders. Although, precise function of thyroid hormones in seasonal breeding is not well understood. In the present study, we examined effects of hypothyroidism on the hypothalamus-pituitary-gonadal axis in adult male golden hamsters after transition of the short-day photoperiod (SD; 8 h light: 16 h dark) condition. We confirmed that hypothyroid, which had been induced by administration of thiouracil in drinking water for 4 weeks, did not have direct effects on testes in male hamsters under the long-day photoperiod. Plasma concentrations of free T3 and T4 decreased 15 weeks after transition of SD condition. Plasma concentrations of testosterone in the hypothyroid group decreased earlier than in the control group after the transition from LD to SD. In animals treated with testosterone after castration, plasma concentrations of LH in the hypothyroid group decreased earlier than in the control group after the transition of SD. On the other hand, pituitary response to GnRH for LH release did not change in castrated hamsters as a result of hypothyroidism. These results suggest that thyroid hormones act the hypothalamus and might be required to maintain GnRH secretion in male golden hamsters.     

Rudimentary Coronary Artery in Syrian Hamsters (Mesocricetus auratus)

Congenital underdevelopment of one or more main branches of the coronary arteries has been reported in man, but not in non-human mammals. In man, this defective coronary artery arrangement may cause myocardial ischaemia and even sudden death . The main goal of this study was to describe the coronary artery distribution patterns associated with the presence of a markedly underdeveloped (rudimentary) coronary artery in Syrian hamsters. Moreover, an attempt was made to explain the morphogenesis of these patterns, according to current knowledge on coronary artery development. Eleven affected hamsters belonging to a laboratory inbred family were examined by means of internal casts of the heart, great arterial trunks and coronary arteries. The aortic valve was tricuspid (normal) in seven hamsters and bicuspid in the other four. A rudimentary coronary artery arose from the right side of the aortic valve in four specimens, from the left side of the aortic valve in a further three, and from the dorsal aortic sinus in the remaining four. In all cases, a second, well-developed coronary artery provided for all the coronary blood flow. Except for the existence of a rudimentary coronary artery, the present anomalous coronary artery distribution patterns are similar to coronary artery patterns reported in Syrian hamsters, dogs and humans in association with a solitary coronary ostium in aorta. We suggest that an unusual prolonged time interval in the development of the embryonic coronary stems might be a key factor in the formation of coronary arteries displaying significantly dissimilar developmental degrees.     

Expression of nerve growth factor (NGF), and its receptors trkA and p75 in ovaries of the cyclic golden hamster (Mesocricetus auratus) and the regulation of their production by luteinizing hormone

In the present study, changes in localization of nerve growth factor (NGF) and its receptors, trkA and p75 in the ovary were investigated during the estrous cycle of the golden hamster. The effect of LH surge on changes in localization of NGF, trkA and p75 in the ovary was also investigated. NGF and its receptors trkA and p75 were localized in oocytes, granulosa cells and theca cells of various stages of follicles throughout the estrous cycle. NGF and its two receptors were also present in numerous interstitial cells and luteal cells. The number of interstitial cells staining positively for NGF and its two receptors was greater in ovaries of day 1 (day 1=day of ovulation) than the other days during the estrous cycle. Treatment with the antiserum against luteinizing hormone releasing hormone (LHRH-AS) at 1100 h on day 4 completely blocked ovulation. There were few positive reactions for NGF and its two receptors in interstitial cells 24 hr after LHRH-AS injection. The effect of LHRH-AS treatment was blocked by a single injection of 10 IU human chorionic gonadotropin. The distinct widespread distribution of NGF and its two receptors in the ovary of golden hamsters suggest that NGF may be an important growth factor for regulation of ovarian function. Furthermore, the LH surge may be an important factor for inducing production of NGF and its two receptors in interstitial cells of the cyclic golden hamster.     

Molecular cloning and sequences of interleukin-10 in the Djungarian (Phodopus sungorus), Chinese (Cricetulus griseus), and Syrian (Mesocricetus auratus) hamster

Interleukin 10 (IL-10) genes of Djungarian, Chinese, and Syrian hamsters were cloned. The clones of IL-10 consisted of 537 bp nucleotides and 178 amino acids in full length, and the nucleotide and amino acid sequences exhibited a high degree of homology with those of the mouse and human. Since the number and position of signal sequences, N-glycosylations and cysteine sites in the IL-10 amino acid sequences of the hamsters were the same as those of the mouse, we suggest that the IL-10 molecular structures of the hamster are closer to that of the mouse than human.     

Effect of host age in the distribution of adult Trichinella zimbabwensis in the small intestines of golden hamsters (Mesocricetus auratus) and Balb C mice

Golden hamsters (Mesocricetus auratus) and Balb C mice were experimentally infected with Trichinella zimbabwensis to determine the effect of host age in the distribution of adult stages in the small intestines. The hamsters and mice were divided into two groups of young and old animals. Hamsters aged 90 days were designated as young and those aged 360 days were designated as old while mice of 30 days of age were designated as young and those aged 90 days as old. To recover the adult parasites of T. zimbabwensis, the small intestines of each animal were separated and divided into four equal parts and each part was slit open longitudinally. The contents were incubated in 0.85% saline for 4 h at 37 degrees C before the adult worms were recovered from the saline. They were fixed in 70% alcohol and counted under a dissecting microscope. In both young and old hamsters and mice, T. zimbabwensis adult worm counts were significantly higher (P < 0.05) in the second segment of the intestines thus invariably reflecting a significantly high count (P < 0.05) in the first (anterior) half of the small intestines. From this study it was demonstrated that host-age had no effect on the distribution of T. zimbabwensis adult worms in the different segments of the small intestines of golden hamsters and Balb C mice.     

Turkey respiratory tract adenoviruses: oncogenic potential in neonatal hamsters (Mesocricetus auratus)

The tumorigenic properties of 3 turkey adenoviruses (CUA, NC-K, and MST) isolated from turkeys with respiratory tract disease and injected into neonatal hamsters (Mesocricetus auratus) have been determined. One of 30 adenovirus isolates (CUA) induced tumors at the site of inoculation (subcutaneously or intracranially) in neonatal hamsters. The tumors were identified as fibrosarcomas and undifferentiated sarcomas. The tumors were found to be free of infective virus, but hamsters which had tumors produced antibody to the virus-specific tumor antigen detectable by the complement-fixation test. The antibody titers for the tumor antigen were from 1:8 to 1:16. Abnormalities were not observed in the major organs collected from hamsters inoculated with the virus. Inoculations of hamster embryo cells and of adult and baby hamster kidney cells with the 3 turkey adenoviruses at a high multiplicity of infection did not produce transformed cells in monolayers. Hamster cells were permissive for CUA virus, since cytopathic effect was observed in 3 to 5 days after inoculation.