Laboratory rat
In 18th-century Europe, wild brown rats (Rattus norvegicus) ran rampant and this infestation fueled the industry of rat-catching.
Rat-baiting was a popular sport, which involved filling a pit with rats and timing how long it took for a terrier to kill them all.
Over time, breeding the rats for these contests may have produced variations in color, notably the albino and hooded varieties.
The reproductive function of rats was studied at the Institute for Experimental Biology at the University of California, Berkeley by Herbert McLean Evans and Joseph A.
[6] The genetics of rats was studied by William Ernest Castle at the Bussey Institute of Harvard University until it closed in 1994.
[2] Laboratory rats are frequently subject to dissection or microdialysis to study internal effects on organs and the brain, such as for cancer or pharmacological research.
of Rodentia) in many ways: they are calmer and significantly less likely to bite, they can tolerate greater crowding, they breed earlier and produce more offspring, and their brains, livers, kidneys, adrenal glands, and hearts are smaller.
There were even significant variations in the incidences of adrenal medulla tumors among rats from the same source raised in different laboratories.
The researchers found that the incidence of tumors in Sprague Dawleys from different suppliers varied as much from each other as from the other strains of rats.
"[10] During food rationing due to World War II, British biologists had eaten laboratory rats, creamed.
More than half of all laboratory rat strains are descended from the original colony established by physiologist Henry Herbert Donaldson, scientific administrator Milton J. Greenman, and genetic researcher/embryologist Helen Dean King.
[citation needed] The Sprague Dawley is an outbred, multipurpose breed of albino rat used extensively in medical and nutritional research.
However, since these rats are known to grow tumors at a high (and very variable) rate, the study was considered flawed in design and its findings unsubstantiated.
It has a naturally occurring genetic mutation that makes specimens unable to produce the hormone vasopressin, which helps control kidney function.
The rats were being raised for laboratory use by Henry Schroeder and technician Tim Vinton, who noticed that the litter of 17 drank and urinated excessively.
Hairless laboratory rats provide researchers with valuable data regarding compromised immune systems and genetic kidney diseases.
[38] The shaking rat Kawasaki (SRK) is an autosomal recessive mutant that has a short deletion in the RELN (reelin) gene.
[41][42][43] Obese Zucker rats have high levels of lipids and cholesterol in their bloodstream, are resistant to insulin without being hyperglycemic, and gain weight from an increase in both the size and number of fat cells.
[44] Obesity in Zucker rats is primarily linked to their hyperphagic nature and excessive hunger; however, food intake does not fully explain the hyperlipidemia or overall body composition.
Knockout rats can mimic human diseases, and are important tools for studying gene function and for drug discovery and development.
