Syrian hamsters (Mesocricetus auratus) are one of several rodents used in animal testing. Syrian hamsters are used to model human medical conditions including various cancers, metabolic diseases, non-cancer respiratory diseases, cardiovascular diseases, infectious diseases, and general health concerns. [1] In 2014, Syrian hamsters accounted for 14.6% of the total animal research participants in the United States covered by the Animal Welfare Act. [2]
Since 1972 the use of hamsters in animal testing research has declined. [3] In 2014 in the United States, animal research used about 120,000 hamsters, which was 14.6% of the total research animal use (under the Animal Welfare Act which excludes mice, rats, and fish) for that year in that country. [3] [2] According to the Canadian Council for Animal Care, a total of 1,931 hamsters were used for research in 2013 in Canada, making them the sixth-most popular rodent after mice (1,233,196), rats (228,143), guinea pigs (20,687), squirrels (4,446) and voles (2,457). [4]
Humans get lung cancer from tobacco smoking. [5] Syrian hamsters are a model for researching non-small-cell lung carcinoma, which is one of the types of human lung cancer. [5] In research, when hamsters are injected with the carcinogen NNK several times over six months, they will develop that sort of cancer. [6] In both Syrian hamsters and humans, this cancer is associated with mutations to the KRAS gene. [7] For various reasons, collecting data on the way that Syrian hamsters develop this lung cancer provides insight on how humans develop it. [6]
Oral squamous-cell carcinoma is a common cancer in humans and difficult to treat. [8] Scientists studying this disease broadly accept Syrian hamsters as animal models for researching it. [8] In this research, the hamster is given anesthesia, has its mouth opened to expose the inside of its cheeks, and the researcher brushes the carcinogen DMBA on its cheeks. [8] The scientist can take cell samples from the mouth of the hamster to measure the development of the cancer. [8] This process has good reproducibility. [8] The cancer itself develops tumors in a predictable way starting with hyperkeratosis, then hyperplasia, then dysplasia, then carcinoma. [8] In humans with this cancer there is increased ErbB2 production of receptor tyrosine kinase and Syrian hamsters with this cancer also have increased levels of that kinase. [9] As the tumor develops in the hamster, they also have increased gene expression in p53 and c-myc which is similar to human cancer development. [10] Because hamsters develop this cancer so predictably, researchers are comfortable in using hamsters in research on prevention and treatment. [11]
There is scientific and social controversy about the virus SV40 causing cancers in human. [12] Leaving that controversy aside, Syrian hamsters injected with SV40 certainly will develop various cancers in predictable ways depending on how they are exposed to the virus. [13] The hamster has been used as a research model to clarify what SV40 does in humans. [14]
The golden hamster can contract contagious reticulum cell sarcoma [15] which can be transmitted from one golden hamster to another by means of the bite of the mosquito Aedes aegypti . [16]
Syrian hamsters are susceptible to many metabolic disorders which affect humans. [17] Because of this, hamsters are an excellent animal model for studying human metabolic disorder. [17]
Gallstones may be induced in Syrian hamsters by giving the hamster excess dietary cholesterol or sucrose. [18] Hamsters metabolize cholesterol in a way that is similar to humans. [19] Different sorts of fats are more or less likely to produce gallstones in hamsters. [20] The gender differences in gallstone formation in hamsters is significant. [20] Hamsters of different genetic strains have significant differences in susceptibility to forming gallstones. [20]
Diabetes mellitus is studied in various ways using Syrian hamsters. Hamsters which are feed fructose for 7 days get hyperinsulinemia and hyperlipidemia. [21] Such hamsters then have an increase in hepatic lipase and other measurable responses which are useful for understanding diabetes in humans. [21] Streptozotocin or alloxan may be administered to induce chronic diabetes in hamsters. [21]
Atherosclerosis may be studied with Syrian hamsters because both organisms have similar lipid metabolism. [22] Hamsters develop atherosclerosis as a result of dietary manipulation. [22] Hamsters develop atherosclerotic plaques as humans do. [22]
Smoke inhalation can be studied on Syrian hamsters by putting the hamster in a laboratory smoking machine. [23] Pregnant hamsters have been used to model the effects of smoking on pregnant humans. [24]
The emphysema component of COPD may be induced in hamsters by injecting pancreatic elastase into their tracheas. [25]
Pulmonary fibrosis may be induced in hamsters by injecting bleomycin into their tracheas. [26] [27]
Cardiomyopathy in hamsters is an inherited condition and there are genetic lines of hamsters which are bred to retain this gene so that they may be used to study the disease. [28]
Microcirculation may be studied in hamster cheek pouches. [29] The pouches of hamsters are thin, easy to examine without stopping bloodflow, and highly vascular. [29] When examined, the cheek pouch is pulled through the mouth while being grasped with forceps. [30] At this point the cheek is everted and can be pinned onto a mount for examination. [30]
Reperfusion injury may be studied with everted hamster pouches also. [31] To simulate reperfusion, one method is to tie a cuff around the pouch to restrict blood flow and cause ischemia. [32] Another method could be to compress the veins and arteries with microvascular clips which do not cause trauma. [33] In either case, after about an hour of restricting the blood, the pressure is removed to study how the pouch recovers. [31]
Several inbred strains of hamsters have been developed as animal models for human forms of dilated cardiomyopathy. The gene responsible for hamster cardiomyopathy in a widely studied inbred hamster strain, BIO14.6, has been identified as being delta-sarcoglycan. [34] Pet hamsters are also potentially prone to cardiomyopathy, which is a not infrequent cause of unexpected sudden death in adolescent or young adult hamsters.
Syrian hamsters have been infected with a range of disease causing agents to study both the disease and the cause of the disease.
Hantavirus pulmonary syndrome is a medical condition in humans caused by any of the Hantavirus species. Syrian hamsters easily contract Hantavirus species, but they do not get the same symptoms as humans, and the same infection that is deadly in humans have effects ranging from nothing to flu to death in Syrian hamsters. [35] Because hamsters become easily infected, they are used to study the pathogenesis of Hantavirus. [36] Andes virus and Maporal viruses infect hamsters and cause pneumonia and edema. [37] [38] The Sin Nombre virus and Choclo virus will infect hamsters but not cause any disease. [35] [39]
SARS coronavirus causes severe acute respiratory syndrome in humans. Syrian hamsters may be infected with the virus, and like humans will have viral replication and lesions in the respiratory tract which can be examined with histopathological tests. [40] However, hamsters do not develop clinical symptoms of the disease. [41] Hamsters might be used to study the infection process. [42]
Leptospira viruses cause Leptospirosis in humans and similar symptoms in Syrian hamsters. [40] [43] Syrian hamsters are used to test drugs to treat the disease. [44]
Bacteria that have been studied by infection Syrian hamsters with them include Leptospira , Clostridioides difficile , Mycoplasma pneumoniae , and Treponema pallidum . [45]
Parasites which have been studied by infecting Syrian hamsters with them include Toxoplasma gondii , Babesia microti , Leishmania donovani , Trypanosoma cruzi , Opisthorchis viverrini , Taenia , Ancylostoma ceylanicum , and Schistosoma . [46]
Syrian hamsters are infected with scrapie so that they get transmissible spongiform encephalopathy. [47]
In March 2020, researchers from the University of Hong Kong have shown that Syrian hamsters could be a model organism for COVID-19 research. [48]
Scientists use male hamsters to study the effects of steroids on male behavior. [49] The behavior of castrated hamsters is compared to typical male hamsters. [49] Castrated hamsters are then given steroids and their behavior noted. [49] Some steroid treatments will cause castrated hamsters to do behaviors that typical male hamsters do. [49]
Poor nutrition may cause female infertility in mammals. [50] When hamsters do not have enough of the right food, they have fewer estrous cycles. [51] Studies in hamsters identify the nutritional needs for maintaining fertility. [52]
Syrian hamsters are used to study how NSAIDs can cause reactive gastropathy. [53] One way to study is to inject hamsters with indometacin, which causes an ulcer within 1–5 hours depending on the dose. [54] If repeatedly given doses, hamsters get severe lesions and die within 5 days from peptic ulcers in their pyloric antrum. [54] A model for creating a chronically ill hamster which will not die from the ulcers is to give naproxen by gavage. [55] When the hamster is chronically ill, it can be used to test anti-ulcer drugs. [55]
Syrian hamsters are also widely used in research into alcoholism, by virtue of their large livers, and ability to metabolise high doses. [56]
In captivity, golden hamsters follow well-defined daily routines of running in their hamster wheel, which has made them popular subjects in circadian rhythms research. For example, Martin Ralph, Michael Menaker, and colleagues used this behavior to provide definitive evidence that the suprachiasmatic nucleus in the brain is the source of mammalian circadian rhythms. [57]
Hamsters have a number of fixed action patterns that are readily observed, including scent-marking and body grooming, which is of interest in the study of animal behavior.
Scientific studies of animal welfare concerning captive golden hamsters have shown they prefer to use running wheels of large diameters (35 cm diameter was preferred over 23 cm, [58] and 23 cm over 17.5 cm, [59] ), and that they prefer bedding material which allows them to build nests, if nesting material is not already available. [60] They prefer lived-in bedding (up to two weeks old – longer durations were not tested) over new bedding, suggesting they may prefer bedding changes at two-week intervals rather than weekly or daily. [61] They also prefer opaque tubes closed at one end, 7.6 cm in diameter, to use as shelter in which to nest and sleep. [62]
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Model organisms are widely used to research human disease when human experimentation would be unfeasible or unethical. This strategy is made possible by the common descent of all living organisms, and the conservation of metabolic and developmental pathways and genetic material over the course of evolution.
Ribavirin, also known as tribavirin, is an antiviral medication used to treat RSV infection, hepatitis C and some viral hemorrhagic fevers. For hepatitis C, it is used in combination with other medications such as simeprevir, sofosbuvir, peginterferon alfa-2b or peginterferon alfa-2a. It can also be used for viral hemorrhagic fevers, specifically for Lassa fever, Crimean–Congo hemorrhagic fever, and Hantavirus infection with exceptions for Ebola or Marburg infections. Ribavirin is usually taken orally or inhaled. Despite widespread usage, it has faced scrutiny in 2010 because of lack of efficacy in treating viral infections as it has historically been prescribed for.
The golden hamster or Syrian hamster is a rodent belonging to the hamster subfamily, Cricetinae. Their natural geographical range is in an arid region of northern Syria and southern Turkey. Their numbers have been declining in the wild due to a loss of habitat from agriculture and deliberate elimination by humans. Thus, wild golden hamsters are now considered endangered by the International Union for Conservation of Nature. However, captive breeding programs are well established, and captive-bred golden hamsters are often kept as small house pets. They are also used as scientific research animals.
SV40 is an abbreviation for simian vacuolating virus 40 or simian virus 40, a polyomavirus that is found in both monkeys and humans. Like other polyomaviruses, SV40 is a DNA virus that sometimes causes tumors in animals, but most often persists as a latent infection. SV40 has been widely studied as a model eukaryotic virus, leading to many early discoveries in eukaryotic DNA replication and transcription.
Cell culture or tissue culture is the process by which cells are grown under controlled conditions, generally outside of their natural environment. After cells of interest have been isolated from living tissue, they can subsequently be maintained under carefully controlled conditions. They need to be kept at body temperature (37 °C) in an incubator. These conditions vary for each cell type, but generally consist of a suitable vessel with a substrate or rich medium that supplies the essential nutrients (amino acids, carbohydrates, vitamins, minerals), growth factors, hormones, and gases (CO2, O2), and regulates the physio-chemical environment (pH buffer, osmotic pressure, temperature). Most cells require a surface or an artificial substrate to form an adherent culture as a monolayer (one single-cell thick), whereas others can be grown free floating in a medium as a suspension culture. This is typically facilitated via use of a liquid, semi-solid, or solid growth medium, such as broth or agar. Tissue culture commonly refers to the culture of animal cells and tissues, with the more specific term plant tissue culture being used for plants. The lifespan of most cells is genetically determined, but some cell-culturing cells have been 'transformed' into immortal cells which will reproduce indefinitely if the optimal conditions are provided.
An oncovirus or oncogenic virus is a virus that can cause cancer. This term originated from studies of acutely transforming retroviruses in the 1950–60s, when the term oncornaviruses was used to denote their RNA virus origin. With the letters RNA removed, it now refers to any virus with a DNA or RNA genome causing cancer and is synonymous with tumor virus or cancer virus. The vast majority of human and animal viruses do not cause cancer, probably because of longstanding co-evolution between the virus and its host. Oncoviruses have been important not only in epidemiology, but also in investigations of cell cycle control mechanisms such as the retinoblastoma protein.
Campbell's dwarf hamster is a species of hamster in the genus Phodopus. It was given its common name by Oldfield Thomas in honor of Charles William Campbell, who collected the first specimen in Mongolia on July 1, 1902. It is distinguished from the closely related Djungarian hamster as it has smaller ears and no dark fur on its crown. Campbell's dwarf hamster typically has a narrow dorsal stripe compared to the Djungarian hamster and brown or gray fur on the stomach. This hamster may be raised in captivity and kept as a small pet.
Murine respirovirus, formerly Sendai virus (SeV) and previously also known as murine parainfluenza virus type 1 or hemagglutinating virus of Japan (HVJ), is an enveloped, 150-200 nm–diameter, negative sense, single-stranded RNA virus of the family Paramyxoviridae. It typically infects rodents and it is not pathogenic for humans or domestic animals.
Seoul orthohantavirus (SEOV) is a member of the genus Orthohantavirus of rodent-borne viruses, and is one of the four hantaviruses that are known to cause Hantavirus hemorrhagic fever with renal syndrome (HFRS). It is an Old World hantavirus; a negative sense, single-stranded, tri-segmented RNA virus.
Andes orthohantavirus (ANDV), a species of Orthohantavirus, is a major causative agent of hantavirus cardiopulmonary syndrome (HCPS) and hantavirus pulmonary syndrome (HPS) in South America. It is named for the Andes mountains of Chile and Argentina, where it was first discovered. Originating in the reservoir of rodents, Andes orthohantavirus is easily transmitted to humans who come into contact with infected rodents or their fecal droppings. However, infected rodents do not appear ill, so there is no readily apparent indicator to determine whether the rodent is infected or not. Additionally, Andes orthohantavirus, specifically, is the only hantavirus that can be spread by human to human contact via bodily fluids or long-term contact from one infected individual to a healthy person.
A transmissible cancer is a cancer cell or cluster of cancer cells that can be transferred between individuals without the involvement of an infectious agent, such as an oncovirus. The evolution of transmissible cancer has occurred naturally in other animal species, but human cancer transmission is rare. This transfer is typically between members of the same species or closely related species.
Rodents are commonly used in animal testing, particularly mice and rats, but also guinea pigs, hamsters, gerbils and others. Mice are the most commonly used vertebrate species, due to their availability, size, low cost, ease of handling, and fast reproduction rate.
Free fatty acid receptor 2 (FFAR2), also known as G-protein coupled receptor 43 (GPR43), is a rhodopsin-like G-protein coupled receptor (GPCR) encoded by the FFAR2 gene. In humans, the FFAR2 gene is located on the long arm of chromosome 19 at position 13.12 (19q13.12).
A humanized mouse is a genetically modified mouse that has functioning human genes, cells, tissues and/or organs. Humanized mice are commonly used as small animal models in biological and medical research for human therapeutics.
Marburg virus (MARV) is a hemorrhagic fever virus of the Filoviridae family of viruses and a member of the species Marburg marburgvirus, genus Marburgvirus. It causes Marburg virus disease in primates, a form of viral hemorrhagic fever. The World Health Organization (WHO) rates it as a Risk Group 4 Pathogen. In the United States, the National Institute of Allergy and Infectious Diseases ranks it as a Category A Priority Pathogen and the Centers for Disease Control and Prevention lists it as a Category A Bioterrorism Agent. It is also listed as a biological agent for export control by the Australia Group.
Choclo orthohantavirus (CHOV) is a single-stranded, negative-sense RNA zoonotic New World hantavirus. It was first isolated in 1999 in western Panama. The finding marked the first time Hantavirus pulmonary syndrome (HPS) was found in Central America.
Favipiravir, sold under the brand name Avigan among others, is an antiviral medication used to treat influenza in Japan. It is also being studied to treat a number of other viral infections, including SARS-CoV-2. Like the experimental antiviral drugs T-1105 and T-1106, it is a pyrazinecarboxamide derivative.
Nova virus is a single-stranded, negative-sense, enveloped RNA virus with a trisegmented genome. It belongs to one of the most divergent lineages of the hantavirus group, which consists of zoonotic viruses belonging to the family Bunyaviridae. As of now, no human cases of infection have been reported.
Galidesivir is an antiviral drug, an adenosine analog. It was developed by BioCryst Pharmaceuticals with funding from NIAID, originally intended as a treatment for hepatitis C, but subsequently developed as a potential treatment for deadly filovirus infections such as Ebola virus disease and Marburg virus disease, as well as Zika virus. Currently, galidesivir is under phase 1 human trial in Brazil for coronavirus.
Janet S Butel is the Chairman and Distinguished Service Professor in the molecular virology and microbiology department at Baylor College of Medicine. Her area of expertise is on polyomavirus pathogenesis of infections and disease. She has more than 120 publications on PubMed. She also has 6 publications in Nature, which is considered one of the most prestigious science journals. She is a member of 9 different organizations and has 13 honors and awards.