Behavioral and Side Effects of Caffeine

Behavioral and Side Effects of Caffeine

Caffeine is the most consumed psychoactive drug in the world

(Solinas et al, 2002). Caffeine has been known to have many

side effects on hour external behavior and our internal

physiological behavior. We use caffeine in our lives to

sometimes stay awake to study or just get through the day.

Caffeine decreases the blood flow to the brain by

constricting the blood vessels but can also increase blood flow

after continuous intake that may cause headaches (Kalat, 2004).

Caffeine has a tendency to block adenosine (A1-, A2A-, A2B-,

A3), which increases throughout the day to allow us to sleep and

then decreases as we sleep which allows us to wake. Thus, if

caffeine blocks adenosine we are unable to sleep when feeling

the urge or wanting to sleep, which may cause us to decrease our

caffeine intake.

Caffeine acts to antagonize adenosine receptors, which then

affects cell populations because it counteracts many adenosine

effects. The caffeine mainly has an effect on the A2a adenosine

receptors which then elevates the energy metabolism in the brain

and also causes a decrease in cerebral blood flow

(Cameron,et.al, 1990; Ghelardini, et.al, 1997; Nehliget.al,1992;

Neuhauser-Berthold et.al, 1997). Along with caffeine affecting

the adenosine it also has an effect on GABA receptors and the

release of dopamine (Nehlig et.al, 1992).

Caffeine not only blockades adenosine it also releases

intracellular calcium, inhibits phosphodiesterases and blockade

or regulatory sites of GABAa-receptors (Gupta and Gupta, 1999).

Withdrawal symptoms of caffeine are headache, drowsiness,

fatigue and lethargy (Gupta and Gupta, 1999).

Dopamine and glutamate neurotransmission is modulated by

adenosine in the striatum. Adenosine A1 in the nerve terminals

inhibits dopamine and glutamate from being released. Caffeine

has an effect in this system by antagonizing of adenosine, which

can then stimulate neurotransmitters to release dopamine and

stimulate dopamine receptors (Solinas et al, 2002). A study

done on rats showed that caffeine increased extracelluar

concentrations of dopamine and glutamate in the shell of the

nucleus accumbens (Solinas et al, 2002). These results of

dopamine and glutamate in the shell of the nucleus accumbens

might be related to the psycho stimulant effects of caffeine

(Solinas et al, 2002).

Studies show that Dopamine2 receptors are needed for

caffeine activation in the brain (Zahniseret al, 2000).

Adenosine receptors, dopamine receptors and GABA have been shown

in studies to be involved in