The Effects of Ginkgo biloba on Memory in Jack Dempsey Cichlid Fish
Principle Investigator: Sarah Mook
Affiliation: Wofford College
Budget Request -- $105.31
March 19, 2002
Project Summary
Ginkgo biloba will be administered every other day by dissolving a specific amount, increasing weekly, into the tank of an experimental group of Jack Dempsey (Cichlasoma octofasciatum) fishes, a species in the Cichlid
family (4). The control group will receive an equivalent volume of an isotonic saline solution. A memory test will
be given to each of the fish by introducing a decoy food source and timing the duration of interest shown to the decoy. It is anticipated that both the control and experimental groups will show a decline in interest over time; however, the experimental group is expected to show disinterest sooner than the control group if Ginkgo biloba enhances
memory.
Justification
This experiment is expected to clarify the ambiguous results of previous tests on memory using Ginkgo biloba. The majority of the studies in humans agree that the improvement of memory is inversely proportional to the
severity of memory loss at the beginning of testing; however, some studies showed that Ginkgo biloba has no affect
on memory (6). This study will enhance the knowledge of the memory enhancing effects of Ginkgo biloba. The
Jack Dempsey fish was chosen because it is small, can live with other fish of its species, and eats live fish. The eating of live fish is crucial with the memory test being conducted.
Background
Coming from the Ginkgo tree, Ginkgo biloba has been used for many centuries by the Chinese for medicinal purposes. The ingredients of Ginkgo biloba are not all known. Two components are flavinoids and terpenoids.
These two ingredients are antioxidants that bind to “free radicals that have been implicated as the mediators of the
cellular damage observed in Alzheimer’s disease.” It is assumed that after the antioxidants have bound to the free
radicals, the free radicals will not be able to cause the damage to the cells, preventing further progression of Alzheimer’s. The terpenoid antioxidant acts like aspirin in that it “interfer[es] with platelet aggregation and slowing
blood clotting (6).” It has been found that unless the patient has moderate to severe memory loss, Ginkgo biloba
will not improve the memory of that person (6).
In a non-peer reviewed study, the memory of largemouth bass was tested using a technique that employed a
decoy minnow. This minnow was presented to the bass and the number of times the bass attempted to consume the
minnow before ignoring it was recorded. Once the bass determined that the minnow was inedible, they ignored the
decoy minnow (5). This is an example of habituation, the simplest form of learning (2). The bass learned that attempting to consume the decoy would be an expanse on their energy supply, leading to the ignoring of the decoy (2).
Even after placing another decoy that was physically different, the bass still ignored it. This learned memory lasted
for the full three months of the experiment (5). This method of testing will be used with the carnivorous Jack
Dempsey to determine memory capabilities and the effects of Ginkgo biloba on their memory.
Jack Dempsey fish are a species of the Cichlid family. They can be either herbivorous or carnivorous, depending on their environment. It has been this adaptability that has allowed them to survive for so long (1). These
tropical fish are able to live with other cichlid species, while only consuming fish of other families (10).
Methods
The Jack Dempsey fish will be divided into two groups of five each, the control and the experimental. The
experimental group will be given Ginkgo biloba, while the control will receive an equal volume of an isotonic saline
solution. Each fish will be housed individually, to ensure that there are no overlaps in the testing and administration
of the Ginkgo biloba. These fish require a constant temperature of 24 to 27 degrees Celsius (10); therefore they will
need a heater in the aquatic lab to maintain this temperature.
The Ginkgo biloba will be administered by dissolving the dosage, beginning at 10mg/kg (8), in a small
amount of water and dispersing it into the experimental tanks. The initial dosage was chosen because doses of
600mg in humans (with an average weight range of 50 - 100 kg) are effective. This equates to be 6 - 12 mg/kg; this
study will take the middle of the range, beginning at 10 mg/kg (8). The fish will each be weighed, by displacement,
to obtain the correct dosage. There may be some complications with knowing how much Ginkgo biloba each fish
consumed using this technique, however the alternate routes of administration were either too dangerous (injections)
or posed the same problem of not knowing the amount ingested (syringe feeding) (Dr. David Kusher, personal
communication).
Freshwater fish, like the Jack Dempsey, do not take in water unless they are feeding. This de-
creases excess water from accumulating (7). Chloride cells in the secondary lamellae of the gills create a concentra-
tion gradient that allows sodium and chloride to enter the body (9). It is anticipated that along with Na+ and Cl-,
Ginkgo biloba will also be taken up into the gills. The Ginkgo biloba will be administered every other day because
too much Ginkgo biloba could be detrimental to memory formation. The experimental group will receive a dosage
of 10mg/kg, which is a 600mg dose in an average 60kg human (8). This dose will be increased by 10mg every
week. The control group will receive the same volumes of an isotonic saline solution being poured into their tank.
By slowly acclimating the fish to Ginkgo biloba, the toxic effects of the supplement, if any, can be avoided. This
will also show at which point the Ginkgo biloba affects memory. Both the Ginkgo biloba and the food will be administered at the same times every day to ensure stability and consistency.
On the days the experimental fish are not receiving the Ginkgo biloba, all of their water will be changed
with dechlorinated water. The water is dechlorinated via an air pump. This not only keeps the tanks clean, it also
ensures that the Ginkgo biloba is not accumulating in the water and that the fish is not ingesting more than the administered amount of Ginkgo biloba.
Acclimating the Jack Dempsey fish to the live food could be a problem. Not knowing which food it prefers
and if they will eat live food are complications. These can be remedied by trying different live food as well as flake
food. According to Zurlo (4), however, all types of cichlid fish prefer live food to flakes and should be given both to
maintain a balanced diet. A vegetarian diet is also acceptable if it is balanced. If these fish are not accepting live
food, another means of testing their memory will have to be found, since the memory test being used will only work
if live food is eaten.
The decoy will be made to look like the live food the Jack Dempsey fish will eat, Guppies. The fish in this
project are small and require a proportionally small feeder fish(Guppies). The decoy will be made using the tips of
plastic micropipettes, painted iridescent silver with black eyes. To be as lifelike as possible, the decoys will be kept
in the tank with the Guppies to have the same scent in addition to the same appearance. There may be a problem
with the movement of the decoy, however preliminary observations have shown that the Guppies “play dead.” The
Guppies “play dead” by sinking to the bottom of the tank and lie still, so movement may not pose that great of a
problem.
After an observer records the duration of interest in the decoy over a period of four weeks, a graph will be
constructed to analyze the data, plotting the duration of interest on the y-axis and the time in weeks along the x-axis.
The observer will observe two fish a day, each fish being randomly selected to prevent habituation. The time of day
the fish are fed and observed will remain constant. Live food in the morning, 11am, and pellets every other evening
at 9pm. The observations will be made at 11 each morning, not lasting more than thirty minutes because preliminary observations showed that the Jack Dempseys ate the Guppies in less than twenty minutes. The observer collecting the data will not know which fish received the Ginkgo biloba and which did not.
Goals
The goal of this experiment is to determine to what effect Ginkgo biloba has on memory in the Jack Dempsey fish. Assuming the Ginkgo biloba improves memory, the information collected may then be applied to humans
to determine the dosage needed to improve memory of humans.
Budget
10 Jack Dempsey fish @ $2.95
35/wk @ 4 weeks guppies @ $0.10
1 cans of fish food @ $3.25
2 heaters @ $10.95
1 bottle of Ginkgo biloba @ $5.99
2 thermometers @ $1.95
1 space heater (shared cost with another principal investigator) @ $50/2
All other equipment is being supplied by Wofford College.
Total Budget = $100.29
Tax + Budget = $105.31
Bibliography
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March 17.
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