Serotoinin - Pharmacological Effects Flashcards
What occurs when doses of serotonin are closely spaced?
Tachyphylaxis (quick tolerance)
What does activation of 5HT-1 receptors on large intracranial vessels produce?
Vasoconstriction, which counteracts headache. Serotonin can also cause vasodilation, partly by acting on endothelial cells to release nitric oxide and inhibiting release of norepinephrine from sympathetic nerve terminals.
What 5HT-3 receptor mediated action can serotonin elicit?
Reflex bradycardia
What type of blood pressure response is seen following injection of serotonin?
A triphasic effect (decreased – increase – decrease)
The serotonin facilitate or prevent platelet aggregation?
Facilitates
What does serotonin facilitate the release of at bronchial vagal nerve endings?
Acetylcholine. It usually inhibits their release but not here.
Why are few CNS effects seen with serotonin?
Injected serotonin poorly crosses the blood brain barrier.
What does depletion of serotonin cause?
Insomnia, while treatment with serotonin precursors accelerates sleep onset and prolongs total sleep time.
Does serotonin increase or decrease aggression and impulsivity?
Decreases it
Which psychotropic drugs are chemically similar to serotonin?
bufotenine, psilocin, psilocybin, LSD, DMT
Activation of afferent vagal nerve endings by serotonin is associated with what?
Chemo receptor reflex consisting of bradycardia, hypotension, and apnea.
High levels of serotonin found in the G.I. tract play a role in controlling what?
Intestinal motility
What do tumors of the enterochromaffin cells release?
Large amounts of serotonin, bradykinin, epinephrine, and histamine. They produce wide swings in blood pressure, colic, and bronchial constriction
Activation of 5HT-4 receptors in the enteric nervous system cause release of what and thereby mediates the motility enhancing (prokinetic) effects of 5HT-4 agonists such as cisapride?
Acetylcholine
Blockers of what serotonin receptor has been shown in animal models of anesthetic neuromuscular junction block or induced malignant hyperthermia to be useful for treating the condition but not effective in preventing it?
5HT-2 blockers
