SEROTONINOPTOM FASLU MUHAMMED

5-HYDROXYTRYPTAMINE( 5-HT, Serotonin)

-90% : localized in intestine-rest : platelets and brain.

-also found in plants : banana, pear, pineapple, tomato.

STORAGE, SYNTHESIS & DISTRIBUTION

- It is synthesised from amino acid tryptophan.

- degraded primarily by MAO and to a small extent by dehydrogenase.

- 5-HT is actively taken up by an amine pump serotonin transporter (SERT), a Na+ dependant carrier, which operates at the membrane of platelets and serotonergic nerve endings.

- This is inhibited by selective serotonin reuptake inhibitors (SSRIs)

SEROTONIN RECEPTORS- Based on pharmacological criteria : - musculotropic ( D type) - neurotropic ( M type)

- 5 HT receptor types : ( 5 HT1, 5 HT2, 5 HT3, 5 HT4 etc..)

ACTIONS

- CVS : arteries are constricted (by action on smooth muscle ) as

well as dilated (through EDRF release) by direct action of 5-HT.

- SMOOTH MUSCLES Potent stimulator of g.i.t both by direct action as well as

through enteric plexuses.5HT containing neurons may regulate peristalsis

GLANDS

- inhibits gastric secretion ( both acid and pepsin) - Ulcer protective property- NERVE ENDINGS AND ADRENAL MEDULLA- Afferent nerve endings are activated – tingling and

pricking sensation, pain.

-

RESPIRATION

- stimulation of respiration and hyperventilation.

PLATELETS- cause change in shape of platelets- It’s a weak aggregator of platelets- at the site of injury

CNS

- given i.v, it does not produce central effects because it poorly crosses blood brain barrier.

- It’s an inhibitory transmitter.

- Direct injection in the brain produces sleepiness, changes in body temperature, hunger and a variety of behavioral effects.

5 HT receptor agonists

D-lysergic acid diethyl amide (LSD)AzapironesSumatriptanCisapride

5-HT ANTAGONISTS.

CYPROHEPTADINE

-CLOZAPINERISPERIDONEONDANSETRON