AUTONOMIC NERVOUS SYSTEM-PART-VIII

ADRENERGIC AGONISTS-INDIRECT

These drugs are indirectly stimulating the adrenergic nerves by causing the release of catecholamines (mainly noradrenaline).

1.Tyramine:-

Tyramine is a byproduct of tyrosine metabolism and tyrosine is the precursor for dopamine, epinephrine, and norepinephrine. Tyramine on ingestion can release catecholamines such as norepinephrine, epinephrine, and dopamine from their storage vesicles. However, tyramine cannot cross the blood-brain barrier but can cause peripheral sympathetic hypertensive crisis and headaches if taken along with a Monoamine Oxidase Inhibitor (MAOI) as it is mainly metabolized by the enzyme MAO.

Hence because of this effect, those who are taking MAOI should not take tyramine rich foods such as spoiled or decayed meats, fish, pork, poultry, beef, cheese, chocolate, and alcoholic beverages.

Recent researches have proved that tyramine has a little directly acting effect at the postganglionic adrenergic receptors and it can cross the blood-brain barrier.

Tyramine has no therapeutic values so for.

Toxicity

1.Hypertensive crisis in those who consume MAOIs since tyramine is compromised by these drugs by preventing its metabolism by MAO.

Hence these people should avoid taking foods such as red wine, beer, chocolate, cheese, and decayed meats.

2.Amphetamine 

Similar to tyramine it releases the stored catecholamines such as norepinephrine and dopamine from their storage.

It can readily cross into the blood-brain barrier and produce serious CNS effects, such as sleeplessness, dizziness, etc.

Amphetamine is clinically used to treat,

1.Attention Deficit Hyperactivity Disorder(ADHD) 2.Narcolepsy, a chronic neurological disorder in which there is a loss of brain control over the sleep-wake cycles.

3.Appetite suppression.

Toxicology

1.Psychological and physical dependence

2.Psychoses

3.Confusion

4.Insomnia

5.Headache

6.Restlessness

7.Palpitations

8.Tachycardia

9.Impotence