epinephrine

Known as adrenaline. A member of the catecholamine class of neurotransmitters. Epinephrine is formed from tyrosine, via the two other neurotransmitters dopamine and norepinephrine. Acts as a hormone in its ability to stimulate the breakdown of glycogen stored in skeletal muscle and, to a lesser degree, the liver.

Epinephrine binds to the extracelluar portion of a plasma membrane receptor, the result of which is an increase in intracellular levels of cyclic AMP.

L-adrenaline is a hormone and a neurotransmitter. Both of these transfer short lived impulses so they have to work quickly.

Adrenaline is in the family of adrenal medulla hormones. It is synthesized by the neurons in the adrenal medulla. Adrenaline has the opposite effect of insuline, being released when the glucose level in the blood is low. When released, it affects the mobilisation of glycogene from the liver and triacylglycerines (fat tissue). It also increases the rate of metabolism. The rise in blood sugar enables the muscles to ferment glucose.

Adrenaline works also as neurotransmitter which affect on the sympathetic nervous system. This neurotransmitter will be realeased by nervous stimulation in response to physical or mental stress. For instance, if you are in danger, adrenaline is released to help provide the energy to protect yourself or escape (flight or fight). Adrenaline increases the rate and strength of the heartbeat, dilates the bronchi and pupils, causes vasoconstriction and sweating and reduces clotting time of the blood. Blood is transferred from the skin to the skeletal muscles, coronary arteries, liver and brain where it is more use in a time of stress.

L-adrenaline is also used as sympathicomimeticum (a drug that helps the heart to beat), broncholyticum (a drugs that relaxes the brochial muscles) and antiasthmaticum (a drug to help asthma). It also is used to prevent bleeding during surgery. Because adrenaline cause vasoconstriction (contraction of blood vessels), it is administered in combination with local anaesthetics, giving a longer lasting effect which allows smaller doses of local anaesthetic to be used.

Molecular Weight           183.21 g/mol
Melting Point              215°C
Water Solubility           <0.01 g/100mL at 18°C
Standard Heat of Formation -439.17 kJ/mol
 
        HO
          \   H
 HO  //\  /\  N
   \//  \/  \/ \
    |   ||      CH3
    |   ||
   /\\  /
 HO  \\/

Do you remember...

• Your first kiss?
• Where you were when the Challenger exploded?
• Where you were when JFK was killed? or Rabin?
• Where you were when you found out about September 11?
• etc...

Emotional events of any sort - weddings, child birth, and similar events will trigger a release of adrenaline. Most often, this is associated with "butterflies in the stomach" (think back to your first kiss, and the intensity of the memory will likely be directly related to the degree of butterflies).

There have been several experiments with laboratory rats regarding the formation of memory and its role with respect to adrenaline. The classic experiment deals with laboratory rats trying to find a platform submerged in water and having to swim to it - a stressful situation. This test is carried out several times, each time with the platform in the same place. The control group learns where the platform fairly quickly. Rats given an additional shot of adrenaline learned faster, while rats given a beta blocker that combats the effects of adrenaline are much slower to learn in this stressful situation.

A similar experiment was extended to humans. In this, some subjects were either given a beta blocker before viewing a series of images. These images were unpleasant to see (emotionally disturbing). Two weeks later, everyone was asked a series of questions based upon the images shown. The people given the beta blocker were not able to preform as well on the questions of the slides that were emotionally disturbing. Similar tests have been preformed with telling a story with story that had sad and stressful parts to it - those who received the beta blocker could not remember those elements of the story as well as those who received a placebo.

When the experience is stressful in some way, the adrenaline stimulates the amigdula (part of the brain that helps regulate memories) by way of the beta receptor (see beta blocker) on the vagus nerve (there is a large amount of research being done on memory improving drugs based upon this pathway - search Google for "vagus nerve memory" to see a sample of the reports). This extra stimulation in conjunction with a memory being formed directs the amigdula to store a strong memory rather than a weak one.

The usefulness of all the passions consist in their strengthening and prolonging in the soul thoughts which are good for it to conserve. And all the harm they can do consist in their strengthening and conserving these thoughts more than is necessary.
--Rene Descartes

http://www.outreach.nimh.nih.gov/speech_charney.htm
http://www.geocities.com/Nashville/2227/whyavoid.html
http://www.ihf.org/lecture/archive/mcgaugh.html

A chemical produced and secreted by the adrenal glands. It can act as a stimulant, increasing blood pressure, heart rate, and other functions. It is a neurotransmitter, or substance which transmits nerve signals from neuron to neuron, and is also a hormone that helps break glycogen (a polysaccharide) down into glucose (a simple sugar). It has the chemical formula C₉H₁₃NO₃.

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.