Prepulse inhibition as affected by the acute use of caffeine intraperitoneallyRuiz, L., Gaviria, B., Tolve, T.

Department of Psychology and Neuroscience Program, Drew University, Madison, New Jersey 07940, USA. 614.20

Pre-pulse inhibition is the measure of reduction of

the startle response when a weak pre-pulse stimulus

is presented before a startling stimulus. This

phenomena reflects attention and sensorimotor

gating mechanisms. Typical levels of PPI are

influenced by factors, such as a white noise or pure

tone, for example.

Inhibitory impairment processes which are measured

by PPI are associated with a renown number of

psychiatric diseases. Schizophrenia is the most

common among these diseases. Individuals who

lack a certain gene known as 22q1DDS have shown

a greater chance of Schizophrenic behaviors. This

deletion reflects a diminished performance on

inhibitory information that measures pre-pulse

inhibition. Individuals with schizophrenia

demonstrate reduced PPI and is referred to as a

potential endophenotype for the disorder. The levels

of PPI increase with age, therefore that can

potentially be a confounding factor for individuals

with schizophrenia.

In this study, we are using caffeine to see its acute

effect on PPI and startle response. Caffeine is a

naturally occurring compound and it is the most

commonly used psychoactive drug in the world.

Caffeine can be found anywhere from coffee to colas

to cough syrups. Because caffeine acts as a

stimulant on the body, after the effect wears off,

individuals may experience withdrawal symptoms

such as anxiety. We hypothesized that the rats

would have a significantly weaker startle response

in PPI because they would be more attentive to the

pulses. We also hypothesized that these increased

levels of alertness would inhibit their overall startle

responses.The rats were administered 50mg/kg of

caffeine interperitonally. Interpertioneal injections are

most often used on animals and it involves an

injection through the peritneum, a serous membrane

that forms the lining of the abdomen.

Pre-pulse Inhibition was successful in the rats

before the administration of caffeine. In the noise burst

session subjects exhibited a stronger startle response relative to the

three different pre-pulse sessions. The three different sessions all

consisted of a 70 dB pulse, but with different frequencies ranging

from .04 kHz- .2 kHz. The startle responses decreased due to higher

attention and sensorimotor gating exhibited by the rats.

Pre-pulse inhibition was unaffected by the

administration of caffeine in the experimental

group. The prediction we had sought out was that caffeine was

going to have an impact on the startle responses of the subjects. The

data demonstrates that caffeine has no effect on the startle response

of rats as they were measured on the same dB and kHz levels in the

baseline sessions.

Pulse Intensity Differences and its Effect

on Startle

The administration of caffeine did not play a

mediating role on the effect of different pulse

intensities. The subjects in the experimental group received a

caffeine dosage of 50mg/kg intraperitoneally. This demonstrates that

the administration of caffeine has no effect on the startle response as

the intensity of the pulse is increased. The significant difference in the

90 dB session is most likely due to a poor assignment of the subjects.

When compared to the pre caffeine pulse intensity sessions, the

differences between the groups is similar. Although caffeine did not

have a significant effect on startle response, habituation was present in

both groups for the 80 and 90 dB sessions.

The subjects demonstrated an increase in startle

response as the acoustic pulse intensity increased.The baseline data shows that there is a linear relationship between

the dB increase and the increase of the startle response in the

subjects. The significant difference in the 90 dB session is most likely

due to a poor assignment of the subjects.

INTRODUCTION Pre-Pulse Inhibition CONCLUSION

● Rats showed an increase in acoustic

startle response as the frequency

intensities increased.

● Rats achieved pre-pulse inhibition

when presented with a 70 dB pre-

pulse with varying frequencies before

a 100 dB pulse.

● Habituation occurred across all post-

sessions.

● Caffeine had no significant effect on

pre-pulse inhibition.

● Caffeine had no significant effect on

startle response.

DISCUSSION

The outcome of our hypothesis replicates

that of Flaten & Elden (1999). Their results

demonstrated that caffeine had no

significant effect on the amplitude or latency

of the startle responses their human

subjects produced.Our study measured the

acute effects of caffeine use just as the

Flaten article, but with rats.

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McCabe et al. (2014). Pre-pulse inhibition and antisaccade

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inhibition in 22q11.2 deletion syndrome (22q11DS). Journal of

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