Simple Pharmanotes

  Synthesis and Significance of 5-HT: Also called “ Serotonin ”. There are three main types of cells that store serotonin ( 5-hydroxytryptamine ) - Blood platelets Neurons in the brain and the intestinal myenteric plexus, Mucosa of the gastrointestinal tract contains enterochroma ffi n cells. The enterochromaffin cells and serotonergic neurons produce serotonin from L-tryptophan,   Platelets uptake the serotonin from blood . In the cytosol of brain cells , the enzyme L-tryptophan hydroxylase (TPH) is involved in the synthesis of serotonin through the conversion of L-tryptophan to 5-hydroxytryptophan.  Serotonin synthesis in neurons is regulated by this enzyme in a similar fashion to that by the related enzyme L-tyrosine hydroxylase, which converts L-tyrosine to L-dihydroxyphenylalanine (L-DOPA).  Functions of Serotonin: Mood elevator. Involved in bone metabolism. Involved in cardiovascular health. Involved in eye health. Involved in blood clotting. Involved in neurological disorders.

  Introduction: The aromatic amino acids phenylalanine (Phe) and tyrosine (Tyr) have almost similar structure. It is important to consume foods high in phenylalanine.  Consuming tyrosine-rich foods, on the other hand, is not required.   After being incorporated into proteins, phenylalanine has no other function than to convert to tyrosine.  Tyrosine can thus reduce the body's need for phenylalanine. Tyrosine's sparing action on phenylalanine is known as the “sparing action.' Catabolism of phenylalanine and tyrosine. Both phenylalanine and tyrosine metabolism are interconnected and are degraded in the liver by the same pathway . The p-hydroxyphenylpyruvate is produced by transamination of tyrosine .  Enzyme : Tyrosine transaminase . p hydroxyphenylpyruvate is decarboxylated and its phenyl ring is hydroxylated to form homogentisate . Ascorbic acid is needed for this reaction. The benzene ring is removed by homogentisate oxidase , resulting in the formation of 4- Maleylac

  Introduction: Amino acid metabolism produces toxic ammonia which is converted into urea in the liver.  Urea cycle takes place in Mitochondria and cytosol of the liver cells.  A faulty Urea cycle results in toxic levels of ammonia (NH3) within the body, resulting in many symptoms such as lethargy, incoordination, cerebral edema, and asterixis (neurological disorder that causes a person to lose motor control of certain areas of the body). Location: Mitochondria and cytosol of the liver cells. Steps of Urea Cycle: Transport of nitrogen to the liver. Reactions of the urea cycle. Transport of nitrogen to the liver: Ammonia is very toxic, especially to the CNS . The concentration of ammonia and ammonium ions in the blood is normally very low. (NH3 + H+ ↔ NH4+) Ammonia travels to the liver from other tissues, mainly in the form of alanine and glutamine . It is released from amino acids in the liver by a series of transamination and deamination reactions. Ammonia is also produced by bacteria