Rats and Research

Along with mice and other rodents, rats make up more than 90 percent of animals used for medical research. Because humans and rats are both mammals, they share many similarities in structure and function. In addition, their small sizes, low cost, ease in handling, and ability to breed in captivity make rats ideal for laboratory experiments. What follows are examples of biomedical research using rats.

CANCER

Rats have been used in various cancer studies because certain strains can develop cancer spontaneously, as well as by viral and chemical induction.

  • Researchers can study how genetics affect the immune system when cancer is promoted by a virus.
  • Rats are used to study dietary components and environmental chemicals that may either prevent or cause cancers.1

PRODUCT SAFETY

Rats are the main subject in product safety tests. One is the repeated-dose chronic toxicity test, which is used to test a substance for effects of long-term exposure. Another is the developmental and reproductive toxicity test, which measures the likelihood of infertility or the effect on pregnancy of using a product.

Toxicological studies, which test whether certain products are harmful or poisonous, have relied on rats as their primary subjects for testing compounds for safety.

NEUROLOGY

Scientists believe research on rats may lead someday to development of a drug that can reduce or prevent permanent paralysis following a spinal cord injury. Researchers have discovered the protein that stimulates the regeneration of damaged nerves. Using rats with damaged spinal cord nerves, they have stimulated growth of new nerve cells. This may help in the treatment of trauma patients and gives hope to those suffering from paraplegia, strokes, Lou Gehrig’s disease and other diseases involving nerve damage.2

Researchers have duplicated the effect of human Alzheimer’s disease by injecting rats with a protein called beta amyloid, which is found in the brains of people with the disease. Scientist will us rats to explore ways of blocking beta amyloid’s toxic effects, possibly slowing or halting the effects of Alzheimer’s.3

HYPERTENSION/DIABETES

Certain strains of rats develop elevated blood pressure. These rats allow researchers to study the disease processes and possible treatments for obesity, diabetes and hypertension.4

DENTAL RESEARCH
Rats can be used to study cavities (dental caries). When a particular streptococcal bacteria is added to the normal bacteria in the rat’s mouth and the rats are fed a high sucrose diet, they develop dental caries similar to those in humans.

INFECTIOUS DISEASES

The study of natural infection of rats has allowed for the control of diseases, improving the health of laboratory colonies, thus providing more accurate research data.

Rats have been used as animal models for human infections like streptococcus and salmonella.5

REPRODUCTIVE BIOLOGY
Researchers have used rats to understand aspects of the reproductive cycle, including the effects that immunization of pregnant females could have on their offspring.6

NUTRITION
Rats are being used to study the relationship between nutrition and aging, in particular, exploring the possibility that restricted diets may increase life spans.

TRANSPLANTS

Work with rats as led to advances in understanding tissue rejection and transplant immunology. Scientists study rejection and genetics in transplants done with the pancreas, skin, heart, kidney, and bone marrow.

Rats have also been used in the development of microsurgery techniques.

BEHAVIOURAL SCIENCE

Since the late 19th century, researchers have used rats in behavioural studies and applied the data to humans. Experiment with mazes have provided a major research tool for the study of learning.7

  • Scientists are studying how genetics affects learning and reasoning functions.
  • Researcher have used rats to study the effects of psychological factors in susceptibility to disease.8

REFERENCES

1 Pour, PM; Groot, K; Kazakoff, K; Anderson, K; Schally, AV: Effects of high-fat diet on the patterns of prostatic cancer induced in rats by N-nitrosobis (2-oxopropyl) amine and testosterone. Cancer Res 1991 Sep 15;51(18): 4757-61.

2 Schnell, L; Schwag, ME: Axonal regeneration in the rat spinal cord produced by an antibody against myelin-associated neurite growth inhibitors. Nature 1990 Jan 18:343 (6255):269-72.

3 Kowall, NW; Beal, MF; Busciglio, J; Duffy, LK; Yankner, BA: An in vivo model for the neurodegenerative effects of bet amyloid and protection by substance P. Proc Natl Acad Sci USA 1991 Aug 15; 88(16):7247-51.

4 Bishop, SP: Cardiovascular Research. In: Baker, J.J., Lindsey, J.R. and Weisbroth, S.H. (eds.), The Laboratory Rat, Volume II, Research Applications. Academic press, NY, 1980.

5 Givner, LB: Human immuoglobulins for intravenous use: comparison of available preparations for group B streptococcal antibody levels, posonic activity, and efficacy in animal models. Pediatrics 1990 Dec; 86(6): 955-62.

6 Fox, RR, and Crary, DD: Gill, TJ III; Kunz, HW and Bernard, CF. Maternal-fetal interaction and immunological memory. Science 172:1346-1348, 1971.

7 Small, WS: An experimental study of the mental processes of the rat. Am. J. Psychol. 11-100, 1900.

8Adler, R: Psychological factors in comparative biomedical research. N: Animal Models for Biomedical Research. Washington, D.C.: Natl. Acad. Sci., 1970, vol. 3, p. 91-102.