With the creation of new animal protecting
laws, the number of animals used in experiments has certainly decreased, however
this total is still insignificant compared to the ratio of the immense increase
in animals being brought in for experimentation. In an effort to further reduce
experimental animal subjects, various alternatives have been constituted aimed
at substituting animal models in drug, chemical and other forms of
experimentation (1).


Over the past decade, the processing capacity
and technology of computers have improved exponentially and are able to handle
more intensive software and programming. Computers are considered to be an
integral part in experimental laboratories to store large quantities of data
and process them into an easily understandable form. Another great use of
computers for researchers is the ability to generate various simulations to
mimic and predict the effects of chemicals and drugs without the usage of
animal models. The Structure Activity Relationship (SARs) computer programs
have the ability to estimate the properties and biological activity of a
selected chemical substance based on its molecular structure. The predicted
activities include the carcinogenicity and mutagenicity of the tested chemical.

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(2). Another popular computer software is the Computer Aided Drug Design (CADD)
program which has the power to determine the receptor binding site for a
selected drug molecule. The identification of the binding site enables
researchers to establish which substances have no biological activity, hence
avoiding using them which in turn saves a lot of time. Furthermore, using this
program will enable the production of new drugs for specific binding sites, and
finally animal testing is done to confirm the validity of the drugs (3). The
two computer software (SARs and CADD) are cost-efficient, fast, and most
importantly reduces the number of experimental animals being used, therefore
the principals of the 3Rs by Russel and Burche are achieved.


Additionally, computers may be used to power
intricate machinery like computed tomography (CT) scans and magnetic resonance
imaging (MRI). These devices enable high imaging techniques which would give
researchers information like the progression of a disease without any invasive
surgery to the animals subjects. Normally, a few animals are required to be
dissected or sacrificed in order to obtain the same results. Therefore, these
modern machinery will decrease the animals used in experimentation dramatically
as well as being able to uphold the Refinement principal by minimalizing the
animal suffering while still obtaining the intended results (10).


The use of in
vitro cell and tissue cultures provides an alternative to animal  experimentation. Rather than using
conventional in vivo studies which
involves using the animal as a whole, this method takes advantage of the cells
and tissues harvested from the skin, brain, kidney, and liver from an animal.

The extracts would then be cultured and grown into fully functional test models
which give similar cellular responses as animal models (4). An example of an
application of this method would be in a Draize test where the irritancy and
effects of chemicals were tested on the eyes of animals, commonly using rabbits
as test subjects. This test is extremely painful and each animal only can be
used once.  Ke ping Xu and her colleagues
cleverly cultured the bovine corneal organ and analyzed the toxicological
effects of chemical irritancy in vitro,
instead of using animal models (5). This culture method highlights the
Reduction principal from the 3Rs as it manages to use an animal to its fullest
potential in producing lots of experimental models. Therefore, wastage is
prevented and less animals are used in the experimentation.


Instead of using animal cultures, the use of
human cells gives a complementary alternative to animal experimentation, for
disease and toxicology testing purposes. The genes of selected diseases are
planted into embryonic stem cells which are later induced to transform into different
human diseases tissues, and the tissues will be used for drug screening. The
human tissues that are grown in the laboratory will provide a more accurate and
similar impact profile to an actual human being during toxicological tests
compared to the use of animals. Recently, scientists have managed to use the
genes from a Parkinson’s patient to create an embryonic stem cell line which is
used to study the degenerative symptoms of Parkinson’s disease (6). Animals are
not the best model for reflecting a drug’s toxicity on the heart and liver. The
human stem cell culture method not only provides more reliable results, but
also eliminates the usage of any animals, as well as being cost-effective (7).


While humans can be used for their stem cells,
they can also participate in a relatively new technique known as microdosing.

Low doses of selected drugs are administered into a human subject and the
metabolism data is obtained to study the effects of the drugs. The dose of the
drugs is low enough to prevent any whole-body effects whilst high enough for
the detection of cellular response (8). The ability of microdosing to screen
out drugs that will likely fail is extremely accurate, fast and cheaper than
conventional animal experimentation methods. It costs £0.25
million per drug tested and a period of 4-6 months for microdosing to take
place (9)


The new legislations for animal experimentation have placed a tight
restriction upon the methods used, in the best interest of the welfare of
higher vertebrates like dogs, pigs, rats and cats. Many of these animals are
known to exhibit a change in their behaviour and physiology like eating less
food or the release of stress hormones in their bloodstream, when exposed to
activities that are believed to cause pain (11). Also, the legislations in most
countries only cater for live vertebrates and not for organisms from the lower
phylogenetic orders (12). With all of this, it has been proposed that
alternative organisms are to replace conventional experimental animals in
experiments whenever possible.


Lower vertebrates are often considered to be an alternative as they share
close genetic material to higher vertebrates like mammals. One example would be
the use of the zebra fish (Danio Rerio).

This fish is small, around 2-4cm in length so it can be stored easily. The main
reason why this species is chosen from a whole range of fish is the transparent
body is possess hence making it easier to observe the pheonotypc traits