Animal research in science

The controlled and regulated use of laboratory animals in medical research has helped to extend our understanding of the healthy and diseased lifecourse, as well as the development of novel and effective therapeutic interventions.

Introduction

Historically, animal research has led to many scientific breakthroughs, including elucidating the actions of our hormones. These discoveries were possible because the major hormone systems of most biological organisms are highly conserved and essential to healthy life.

The discovery of insulin

A pivotal moment in hormone research occurred in October 1920 when Fredrick Banting, a scientist working in Toronto, wrote these words in his note book: “Ligate pancreatic ducts of dog....Try to isolate the internal secretion of these to try to relieve glycosuria”.  This note refers to identifying a substance produced by the pancreas - which we now know as insulin - for the treatment of diabetes mellitus.

Other scientists had already suggested that the cause of diabetes mellitus was the loss of secretion of a hormone (insulin, from the Latin for ‘island’) by the islets of langerhans cells in the pancreas. Theories suggested insulin controlled sugar metabolism, and consequently its loss led to a build-up of blood sugar and an excess of sugar in the urine. Scientists attempted to give insulin to diabetic patients by feeding them fresh pancreatic extracts, but this did not work as the insulin was broken down by digestive enzymes in the extracts before it was even given to patients. Therefore, the problem was to develop a way to extract insulin from the pancreas before it had been destroyed.

The original source of insulin was animal pancreases obtained from abattoirs. This picture shows the first stage of the extraction process (grinding the animal material) at the Indianapolis plant of the America pharmaceuticals company Eli Lilly in 1923.

The original source of insulin was animal pancreases obtained from abattoirs. This picture shows the first stage of the extraction process (grinding the animal material) at the Indianapolis plant of the America pharmaceuticals company Eli Lilly in 1923.

Fredrick Banting, along with his medical student assistant Charles Best, used dogs to test whether his method of extracting insulin, as described in his note book, would lower blood sugar levels in these experimental animals. It worked, and within a few weeks and with help from a chemist, James Collip, who managed to purify the insulin even further, they treated a 14-year old diabetic boy and saved his life. Later, working with calves, they refined this insulin extraction method and proceeded to save millions of lives and win a Nobel Prize.  Without his laboratory animals, which were key components in the breakthrough, Banting would have failed, making the collection of insulin and the subsequent treatment of diabetes impossible.

Charles Best (left) and Frederick Banting (right), Canadian physiologists and co- discoverers of the hormone insulin, standing with the first dog kept alive by insulin injections following the removal of its pancreas.

Charles Best (left) and Frederick Banting (right), Canadian physiologists and co- discoverers of the hormone insulin, standing with the first dog kept alive by insulin injections following the removal of its pancreas.

Banting’s work demonstrates the importance of using laboratory animals in scientific research. Those against using animals in research say that because animals look and act differently to us, they cannot possibly represent the human body or mimic human diseases. But in fact animals are very similar in the genes that they carry and the hormones they produce and when we look at life at the cellular level in these animals, it seems remarkably similar. For example, we possess almost all the same hormones that a dog and a calf possess. The insulin that Banting extracted from the pancreas of his dogs and calves, when given to diabetic patients, was only effective as a treatment because the insulin molecule is so similar across species. 

It is not just our understanding of hormone-related disorders, such as diabetes, that have benefited from the use of animals. Rabbits helped Louis Pasteur to cure rabies; rhesus monkeys provided Jonas Salk with the polio vaccine; Albert Starr pioneered heart valve replacement surgery through his research on dogs; armadillos harbouringthe leprosy bacteria led to the synthesis of leprosy antibiotics; and macaques were used in the process of developing effective drugs against the AIDS virus. At the cellular and molecular level, humans are similar to other animals and this makes those animals good models to use in order to understand human biology and find new treatments for disease. 

But one might ask why not just experiment on cells grown in a test tube or on a culture plate? The answer is that huge numbers of experiments are carried out on cells that do not involve animals but these cells act in isolation and are not wholly representative of cells, organs and tissues that all act in concert within a living body. So in the end one has to transfer that knowledge gained from isolated cells into a whole living animal.   

The importance of knockout mouse models

Since Banting’s work, animal models have continued to play a vital role in scientific research; in particular, the dawn of ‘transgenic animals’ that carry a foreign or over-expressed gene and ‘knockout mouse models’ in which the expression of a particular gene is removed. These models have led to a number of scientific breakthroughs and have allowed us to find out how different hormones, coded by a particular gene, can work in different parts of the body. For example, we now understand the role of leptin, secreted by fat, in controlling obesity and all the other problems associated with obesity including diabetes; the role of glucocorticoids in foetal programming; the importance of oestrogen in bone growth and the important role of the newly discovered hormone, kisspeptin, in controlling puberty and fertility.

Various knockout mouse models have also led to the discovery of unexpected physical traits in the animal which has then sparked the search for the (rare) human equivalents and in doing so opened up new areas of understanding of endocrine diseases with more general applications to the population. 

Alternatives to animals

Animal models can’t always accurately predict the effects of a new drug in humans, but they often do. This is not to say that alternatives to animals should not be thoroughly investigated. In fact significant money, primarily provided by the National Centre for the 3 R’s - NC3R is invested for the replacement, refinement and reduction of animals in science. Furthermore, regulations and the ethical management of animal research are regularly re-assessed and refined, with the UK having very tough laws on these issues. Most scientific societies, including the Society for Endocrinology, highlight their importance and scientists constantly have to justify their requirements for the use of animals in their work.

Encouragingly, the UK public’s perception of animal research is generally supportive. Nine out of ten people conditionally accept the idea of animal research and testing to some degree, with three in five accepting the idea unconditionally. About three quarters accept animal studies as long as they are for medical research purposes. Sometimes, however, small, vocal anti-vivisectionist groups dominate the media limelight to suggest these facts are otherwise. Recently, scientists have begun to fight back as they recognise the importance of greater public transparency of their work. Supporters of the need for animals in research have rallied under the Pro-Test banner and march annually in Oxford. Furthermore, there are various web-sites (Understanding Animal Research, Speaking of Research and The Ark Hive) that highlight how critical animal research is for furthering the biological goals of understanding life and curing disease.

It is now over 90 years since Fredrick Banting’s historic hormonal studies. Since then, by aiding the development of a plethora of vaccines, surgery techniques, antibiotics, and drugs, animal research has saved countless lives. Alternatives are in development, but animals seem likely to be necessary to further scientific understanding and combat disease for the foreseeable future.

 

 


Last reviewed: Dec 2016