Physiological and Behavioral Effects of Hyperinsulinism on Goldfish

Biology 231Supplement#4<strong>Physiological</strong> <strong>and</strong> <strong>Behavioral</strong> <strong>Effects</strong><strong>of</strong> <strong>Hyperinsulinism</strong> on GoldfishOBJECTIVES1. To observe the rapid, pronounced effect(s)that hormones can have on the body.2. To increase an underst<strong>and</strong>ing <strong>of</strong> the value<strong>and</strong> significance <strong>of</strong> the body’s homeostaticmechanisms.MATERIALSGoldfishBeakersInsulinGlucose solution (20% recommended)The endocrine system is the second majorcontrolling system <strong>of</strong> the body (the first is thenervous system). The role <strong>of</strong> the endocrinesystem is to alter the activity <strong>of</strong> body cellsprimarily through chemical changes inducedthrough the gl<strong>and</strong>s <strong>of</strong> the endocrine system.These chemical “messengers” are referred to ashormones, <strong>and</strong> are typically released into theblood for transport throughout the body.The origin <strong>of</strong> the word “hormone” is found in theGreek language with the meaning “to arouse”associated with the word. The body’s hormonesarouse the body’s tissues <strong>and</strong> cells by stimulatingchanges in their metabolic activity. Hormones arequite specific. A given hormone affects only thebiochemical activity <strong>of</strong> select organ or organsystems. Those tissues that respond to the effect<strong>of</strong> the hormone are referred to as the targettissues or organs.The most widely understood relationship <strong>of</strong> theendocrine system with animal behavior is in thearea <strong>of</strong> reproductive behaviors, <strong>and</strong> we will beexamining the role <strong>of</strong> the reproductive hormonesin a future lab. There are many otherrelationships that exist between the endocrinesystem <strong>and</strong> animal behavior. One easilyobserved interaction is seen in the study <strong>of</strong> thehormone insulin, <strong>and</strong> its effects on thehomeostatic maintenance <strong>of</strong> behaviors.Insulin, a hormone produced by the pancreas todecrease blood glucose levels, is found invirtually all vertebrates. When food is consumed<strong>and</strong> digested, glucose molecules enter thebloodstream <strong>and</strong> if enough food is eaten in asmall period <strong>of</strong> time, elevation <strong>of</strong> blood glucosecan occur. Without insulin, the levels <strong>of</strong> bloodglucose can reach such elevated levels that thereis great risk for cellular <strong>and</strong> tissue damage,especially within tissues <strong>of</strong> the nervous system.1

Likewise, too much insulin in the body will causeglucose levels to plummet below normal levels. Ifthe drop in insulin levels is not too severe, theorganism will experience mild symptoms <strong>of</strong>fatigue, anxiety, tremors, <strong>and</strong> hunger. However, ifthe drop in glucose through very high levels <strong>of</strong>insulin grows more extreme, the organism canexperience insulin shock. Insulin shock occurswhen the blood glucose levels drop to such lowlevels that the brain is no longer sufficientlyprovided with glucose <strong>and</strong> begins to malfunction.Symptoms <strong>of</strong> insulin shock include disorientation,convulsions, unconsciousness, <strong>and</strong> if leftuntreated will result in death. Fortunately, weshall see that insulin shock is easily reversed byproviding a rapidly metabolized form <strong>of</strong> glucoseto those affected.Many people with diabetes mellitus needinjections <strong>of</strong> insulin to maintain blood glucosehomeostasis. Therefore it is easy for us to use thisavailable source <strong>of</strong> injectable insulin in behavioralexperiments in our laboratory. We shall usegoldfish to demonstrate the effects <strong>of</strong>hyperinsulinism on goldfish behavior. Since theaction <strong>of</strong> insulin is similar in all vertebrates, wecan make some generalized conclusions about ourresults with many other species.There are three very distinct behavior patterns thatcan be observed in goldfish. One, mouth gapingbehavior, is an indication <strong>of</strong> the fishes’metabolism. As the metabolism <strong>of</strong> the fishincreases, the mouth gaping behavior increases ingoldfish. To observe mouth gaping behavior,researchers simply count the number <strong>of</strong> times afish opens its mouth in a set time frame. Asecond behavior, operculum movement, is abehavior that signifies oxygen consumption in theanimal. As the number <strong>of</strong> operculum movementsincreases in a given unit <strong>of</strong> time, it is associatedwith decreased overall oxygen within the body.The operculum movements are an attempt by thefish to increase the flow <strong>of</strong> water through the gillsto increase oxygen absorption. The third behavioreasily viewed in the goldfish is pectoral finmovement behavior. The movement <strong>of</strong> thesefins, the “arms” <strong>of</strong> the fish, are vital for balance,directional movements, <strong>and</strong> maintenance <strong>of</strong>position in the fish. The number <strong>and</strong> quality <strong>of</strong>the fin movement signifies the overall physicalstate <strong>of</strong> the fish.Experimental Materialsgoldfishinsulinsyringes <strong>and</strong> needlesicebeakerswhite papertimersglucose solutionExperimental Procedure —Normal Behaviors in theGoldfishWhat is the normal behavior pattern in goldfish?1. Obtain a beaker <strong>and</strong> fill it with 1–1.5 cm <strong>of</strong>water.2. Place one goldfish in the beaker. Allow itto acclimate for 5 minutes.3. Begin observing the behavioral patterns <strong>of</strong>the fish in the following order: mouthgaping, operculum movements, pectoral finmovements. Observe each behavior for aperiod <strong>of</strong> two minutes. Have each member<strong>of</strong> your group record these behaviors (thiscan be simultaneous or consecutive viewing... you as a group must decide <strong>and</strong> remain2

consistent) <strong>and</strong> take an average <strong>of</strong> each set <strong>of</strong>data collected by individuals in your group.This average for a given behavior willrepresent the normal rate <strong>of</strong> each <strong>of</strong> thesebehaviors in the goldfish.3. Record the temperature <strong>of</strong> the water inwhich the fish is residing.4. Repeat the above steps for two other fish.Experimental Procedure —Behaviors in the GoldfishExposed to InsulinWhat effect will high insulin levels have on thegoldfish <strong>and</strong> its behaviors?1. Into the beaker <strong>of</strong> fish you examined in theexperiment above, inject 1 ml <strong>of</strong> insulin intothe water surrounding the fish.2. Repeat steps 3 & 4 above (in experiment 1)<strong>and</strong> record the behaviors <strong>of</strong> the fish.3. Pour into the beaker, 50 ml <strong>of</strong> sucrosesolution. After waiting 2 minutes, againrecord the behaviors <strong>of</strong> the fish.Experimental Procedure —Behaviors in the GoldfishExposed to Insulin <strong>and</strong> ColdWhat effect will high insulin levels have on thegoldfish <strong>and</strong> its behaviors if the fish are in a coldenvironment? How will this compare to the roomtemperature environment?1. Recreate the situation outlined in the firstexperiment in steps 1 & 2. However, thistime, place the beaker in a bowl containing aquantity <strong>of</strong> ice.2. Repeat the steps outlined in experiment two(steps 1–3) for insulin exposure.3

QUESTIONS1. Why is it important to have multiple observations <strong>of</strong> the same fish that you average?2. What conclusions can you draw from your results about the action that insulin has on each <strong>of</strong> thebehaviors recorded in the fish?3. To generalize, what can you say about the overall behavior <strong>of</strong> the fish in each <strong>of</strong> the threeexperiments? How can you compare <strong>and</strong> contrast them?4

4. How has cold altered the effect <strong>of</strong> insulin on the fish? How has cold altered the effect <strong>of</strong> recoveryin the fish?5. Create one additional study you feel would be a beneficial addition to this laboratory exercise.5