Serotonin: Functions and Pharmacological Effects

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Questions and Answers

What percentage of serotonin is present in the enterocromafin cells in the intestine?

90%

What is the primary role of 5-HT3 receptors in the GIT and vomiting center in the medulla?

Play a role in vomiting center

What is the effect of serotonin on bronchiolar smooth muscle?

Small direct stimulant effect

What is the role of 5-HT2 receptors on skeletal muscle membranes?

Physiologic role is not understood Signup and view all the answers

What is the effect of 5-HT2A agonists on intraocular pressure in animal models of glaucoma?

Reduce intraocular pressure Signup and view all the answers

What is the effect of serotonin on vascular smooth muscle?

Causes contraction Signup and view all the answers

What is the triphasic blood pressure response seen following injection of serotonin in experimental animals?

Initial decrease, followed by increase, and then decrease again Signup and view all the answers

What is the effect of serotonin on gastrointestinal smooth muscle?

Increases tone and facilitates peristalsis Signup and view all the answers

What is the role of serotonin in the regulation of pain?

Involved in perception of pain Signup and view all the answers

What is the percentage of serotonin present in the CNS?

2% Signup and view all the answers

What is the condition associated with restlessness, hyperthermia, and skeletal muscle contractions?

Serotonin syndrome Signup and view all the answers

What is the function of Buspirone?

It is a 5-HT1A agonist and a nonbenzodiazepine anxiolytic. Signup and view all the answers

What is the action of Triptans?

They are 5-HT1B agonists used for migraine headache. Signup and view all the answers

What is the action of Cisapride?

It is a 5-HT4 agonist used for gastroesophageal reflux and motility disorders. Signup and view all the answers

What is the action of Tegaserod?

It is a 5-HT4 partial agonist used for irritable bowel syndrome with constipation. Signup and view all the answers

What is the action of Fluoxetine and other selective serotonin reuptake inhibitors (SSRIs)?

They block the reuptake of serotonin. Signup and view all the answers

What is the action of Phenoxybenzamine?

It blocks 5-HT2 receptors. Signup and view all the answers

What is the action of Cyproheptadine?

It blocks H1-receptors and 5-HT2 actions. Signup and view all the answers

What is the action of Ondansetron?

It is a 5-HT3 antagonist. Signup and view all the answers

What is the action of Ergot alkaloids?

They are partial agonists at serotonin receptors. Signup and view all the answers

What is the possible cause of migraine due to arterial dilation?

Extracranial and intracranial arterial dilation Signup and view all the answers

What type of receptor do triptans act on?

Serotonin receptors Signup and view all the answers

What is the common adverse effect of dihydroergotamine?

Nausea Signup and view all the answers

Why should triptans not be used in coronary artery disease?

Due to elevation of blood pressure Signup and view all the answers

What is the class of drugs that includes sumatriptan and naratriptan?

Triptans Signup and view all the answers

What is the symptomatic treatment of acute migraine?

Nonsteroidal anti-inﬂammatory drugs, antiemetics, opioids, β-adrenoceptor blockers, calcium channel blockers, tricyclic antidepressants, and several antiseizure agents. Signup and view all the answers

What is the derivative of ergotamine used to treat migraine?

Dihydroergotamine Signup and view all the answers

What is the neuroactive molecule released due to stretching of intracranial vasculature?

Substance P Signup and view all the answers

What is the example of β-adrenoceptor blocker used to treat migraine?

Propranolol Signup and view all the answers

What is the example of tricyclic antidepressant used to treat migraine?

Amitriptyline Signup and view all the answers

What is the primary physiological function of serotonin in the regulation of appetite?

Regulation of appetite, among other functions such as sleep, temperature regulation, and perception of pain. Signup and view all the answers

What is the effect of 5-HT on the nervous system, specifically on pain and itch sensory endings?

Stimulation of pain and itch sensory endings. Signup and view all the answers

How does serotonin affect the cardiovascular system, particularly in terms of blood pressure regulation?

Serotonin causes contraction of vascular smooth muscle, leading to vasoconstriction, and also causes reflex bradycardia. Signup and view all the answers

What is the role of serotonin in the regulation of depression and anxiety?

Serotonin is involved in the regulation of depression and anxiety. Signup and view all the answers

In which cells are the majority of serotonin stores found in the human body?

Enterocromaffin cells in the intestine. Signup and view all the answers

What is the effect of serotonin on the gastrointestinal tract?

Serotonin is a powerful stimulant of gastrointestinal smooth muscle, increasing tone and facilitating peristalsis. Signup and view all the answers

What is the relationship between serotonin and migraine?

Serotonin is involved in the regulation of migraine. Signup and view all the answers

What is the effect of serotonin on platelets?

Serotonin is present in platelets. Signup and view all the answers

How does serotonin affect the eye, specifically in terms of intraocular pressure?

5-HT2A agonists reduce intraocular pressure in animal models of glaucoma. Signup and view all the answers

What is the role of serotonin in regulating temperature?

Serotonin is involved in temperature regulation. Signup and view all the answers

What is the effect of serotonin on vascular smooth muscle?

Constriction Signup and view all the answers

What is the condition associated with restlessness, hyperthermia, and skeletal muscle contractions?

Serotonin syndrome Signup and view all the answers

What is the function of Buspirone?

Nonbenzodiazepine anxiolytic Signup and view all the answers

What type of receptor does Triptans act on?

5-HT1B Signup and view all the answers

What is the action of Cisapride?

5-HT 4 agonist Signup and view all the answers

What is the action of Tegaserod?

5-HT 4 partial agonist Signup and view all the answers

What is the action of Phenoxybenzamine?

Blocks 5-HT 2 receptors Signup and view all the answers

What is the action of Cyproheptadine?

Blocks H1-receptor and 5-HT2 actions Signup and view all the answers

What is the action of Ondansetron?

5-HT 3 antagonist Signup and view all the answers

What is the action of Ergot alkaloids?

Partial agonists at serotonin receptors Signup and view all the answers

What is the main mechanism by which arterial dilation leads to migraine?

The stretching of intracranial vasculature releases neuroactive molecules such as substance P. Signup and view all the answers

What is the purpose of using antiemetics in the treatment of acute migraine?

To control vomiting. Signup and view all the answers

What is the class of drugs that includes verapamil and is used to treat migraine?

Calcium channel blockers. Signup and view all the answers

What is the specific receptor type that triptans act on?

Serotonin receptors. Signup and view all the answers

Why are triptans contraindicated in patients with coronary artery disease?

Because they can cause elevation of blood pressure. Signup and view all the answers

What is the common adverse effect of dihydroergotamine?

Nausea. Signup and view all the answers

What is the role of substance P in the development of migraine symptoms?

It is a neuroactive molecule released due to stretching of intracranial vasculature. Signup and view all the answers

What is the purpose of using β-adrenoceptor blockers in the treatment of migraine?

To prevent frequent attacks. Signup and view all the answers

What is the class of drugs that includes amitriptyline and is used to treat migraine?

Tricyclic antidepressants. Signup and view all the answers

What is the effect of triptans on nausea compared to dihydroergotamine?

Triptans cause less nausea than dihydroergotamine. Signup and view all the answers

What is the cause of migraine due to arterial dilation?

extracranial and intracranial arterial dilation Signup and view all the answers

What type of receptors do triptans act on?

serotonin receptors Signup and view all the answers

What is the common adverse effect of dihydroergotamine?

nausea Signup and view all the answers

Why should triptans not be used in coronary artery disease?

due to elevation of blood pressure Signup and view all the answers

What is the class of drugs that includes sumatriptan and naratriptan?

triptans Signup and view all the answers

What is the symptomatic treatment of acute migraine?

Nonsteroidal anti-inflammatory drugs and antiemetics Signup and view all the answers

What is the derivative of ergotamine used to treat migraine?

dihydroergotamine Signup and view all the answers

What is the neuroactive molecule released due to stretching of intracranial vasculature?

substance P Signup and view all the answers

What is the example of β-adrenoceptor blocker used to treat migraine?

propranolol Signup and view all the answers

What is the example of tricyclic antidepressant used to treat migraine?

amitriptyline Signup and view all the answers

What is the condition associated with restlessness, hyperthermia, and skeletal muscle contractions?

Serotonin syndrome Signup and view all the answers

What is the role of serotonin in regulating appetite?

Serotonin has no clinical applications as a drug Signup and view all the answers

What is the effect of serotonin on uterine smooth muscle?

In very small doses, ergot preparations can evoke rhythmic contraction and relaxation of the uterus. At higher concentrations, these drugs induce powerful and prolonged contracture. Signup and view all the answers

What is the use of Ondansetron?

It is used for the prevention and treatment of nausea and vomiting associated with surgery and cancer therapy. Signup and view all the answers

What is the function of Cyproheptadine?

It blocks H1-receptors and 5-HT2 actions, has antimuscarinic effects, causes sedation, and is used for the treatment of carcinoid tumor, urticaria, and as an appetite stimulant. Signup and view all the answers

What is the action of Ergot alkaloids on α adrenoceptors?

Ergot alkaloids are partial agonists at serotonin receptors and affect α adrenoceptors, dopamine receptors, and 5-HT receptors. Signup and view all the answers

What is the role of serotonin in regulating pain?

Serotonin has a role in regulating pain. Signup and view all the answers

What is the action of Triptans?

Triptans are 5-HT1B agonists used for the treatment of migraine headache. Signup and view all the answers

What is the effect of serotonin on vascular smooth muscle?

Serotonin causes vasoconstriction. Signup and view all the answers

What is the action of Fluoxetine?

Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) used for the treatment of depression. Signup and view all the answers

What is the primary function of serotonin in the nervous system, and how does it achieve this function?

Serotonin plays a crucial role in regulating pain, appetite, sleep, and temperature. It achieves this function by stimulating pain and itch sensory endings, and regulating the vomiting center in the medulla. Signup and view all the answers

How does serotonin affect blood pressure, and what are the underlying mechanisms involved?

Serotonin causes a triphasic blood pressure response, initially decreasing blood pressure due to chemoreceptor response, followed by an increase due to vasoconstriction, and finally a decrease due to vasodilation in skeletal muscle vessels. This is mediated by 5-HT2 and 5-HT3 receptors. Signup and view all the answers

What is the role of serotonin in the regulation of appetite, and how does it interact with other physiological processes?

Serotonin is involved in regulating appetite, and its effects on appetite are linked to its regulation of pain, temperature, and mood. Serotonin's effects on appetite are also influenced by its interactions with other neurotransmitters and hormones. Signup and view all the answers

How does serotonin affect the gastrointestinal tract, and what are the underlying mechanisms involved?

Serotonin is a powerful stimulant of gastrointestinal smooth muscle, increasing tone and facilitating peristalsis. This is mediated by 5-HT receptors, which stimulate the contraction of smooth muscle cells. Signup and view all the answers

What is the relationship between serotonin and depression, and how does it contribute to the pathology of this condition?

Serotonin is involved in the regulation of mood, and abnormalities in serotonin levels or function have been implicated in depression. Serotonin's effects on mood are thought to be mediated by its regulation of neurotransmitter release and synaptic plasticity. Signup and view all the answers

How does serotonin affect the cardiovascular system, and what are the underlying mechanisms involved?

Serotonin causes contraction of vascular smooth muscle, leading to vasoconstriction. It also has positive chronotropic and inotropic effects on the heart, and can cause reflex bradycardia through activation of 5-HT3 receptors. Signup and view all the answers

What is the role of serotonin in the regulation of anxiety, and how does it contribute to the pathology of this condition?

Serotonin is involved in the regulation of anxiety, and abnormalities in serotonin levels or function have been implicated in anxiety disorders. Serotonin's effects on anxiety are thought to be mediated by its regulation of neurotransmitter release and synaptic plasticity. Signup and view all the answers

How does serotonin affect the regulation of temperature, and what are the underlying mechanisms involved?

Serotonin is involved in the regulation of temperature, and its effects on temperature are linked to its regulation of pain and mood. Serotonin's effects on temperature are thought to be mediated by its regulation of neurotransmitter release and synaptic plasticity. Signup and view all the answers

What is the relationship between serotonin and migraine, and how does it contribute to the pathology of this condition?

Serotonin is involved in the regulation of migraine, and abnormalities in serotonin levels or function have been implicated in the development of migraine. Serotonin's effects on migraine are thought to be mediated by its regulation of neurotransmitter release and synaptic plasticity. Signup and view all the answers

How does serotonin affect the regulation of sleep, and what are the underlying mechanisms involved?

Serotonin is involved in the regulation of sleep, and its effects on sleep are linked to its regulation of pain, temperature, and mood. Serotonin's effects on sleep are thought to be mediated by its regulation of neurotransmitter release and synaptic plasticity. Signup and view all the answers

Study Notes

Serotonin

90% of serotonin is present in the enterocromaffin cells in the intestine, 8% in platelets, and 2% in the CNS.
Physiological functions of serotonin include regulation of sleep, appetite, temperature, perception of pain, blood pressure, depression, anxiety, and migraine.

Pharmacological Effects

The main sites of action of serotonin are the nervous system, airways, skeletal muscle, the eye, cardiovascular system, and gastrointestinal tract.
In the nervous system, serotonin acts on 5-HT3 receptors in the GIT and vomiting center in the medulla.
In airways, serotonin has a small direct stimulant effect on bronchiolar smooth muscle.
In skeletal muscle, 5-HT2 receptors are present, but their physiologic role is not understood.
In the eye, 5-HT 2A agonists reduce intraocular pressure in animal models of glaucoma.
In the cardiovascular system, serotonin causes contraction of vascular smooth muscle through 5-HT2 receptors.
In the gastrointestinal tract, serotonin is a powerful stimulant of gastrointestinal smooth muscle, increasing tone and facilitating peristalsis.

Serotonin Syndrome

Serotonin syndrome is a condition associated with restlessness, hyperthermia, and skeletal muscle contractions.
It is precipitated when MAO inhibitors are given with serotonin agonists, especially antidepressants of the selective serotonin reuptake inhibitor class.

Serotonin Agonists

Buspirone is a 5-HT 1A agonist, used as a non-benzodiazepine anxiolytic.
Triptans, such as sumatriptan, are 5-HT1B agonists used for migraine headaches.
Cisapride, a 5-HT 4 agonist, was used for gastroesophageal reflux and motility disorders.
Tegaserod, a 5-HT 4 partial agonist, is used for irritable bowel syndrome with constipation.

Serotonin-Receptor Antagonists

Phenoxybenzamine blocks 5-HT 2 receptors.
Cyproheptadine blocks H1–receptor and 5-HT2 actions, and is used for treating carcinoid tumor, urticaria, and as an appetite stimulant.
Ketanserin blocks 5-HT 2 receptors on smooth muscle and platelets, and is used to decrease blood pressure.
Ritanaserin is another 5-HT 2 antagonist with little or no α-blocking effect.

Ergot Alkaloids

Ergot alkaloids are produced by Claviceps purpurea, a fungus that infects grasses and grains.
They are partial agonists at serotonin receptors, affecting α adrenoceptors, dopamine receptors, and 5-HT receptors.
Organ system effects include:
- Central nervous system: lysergic acid diethylamide (LSD) is a synthetic, 5-HT 2 antagonist and powerful hallucinogen.
- Vascular smooth muscle: ergotamine and similar compounds constrict most vessels.
- Uterine smooth muscle: ergot preparations can evoke rhythmic contraction and relaxation of the uterus.
- Other smooth muscle organs: ergot alkaloids have little or no significant effect on bronchiolar or urinary smooth muscle.

Clinical Uses

Migraine: ergot derivatives are specific for migraine pain, such as ergotamine tartrate and dihydroergotamine.
Hyperprolactinemia: bromocriptine is used to treat hyperprolactinemia.
Postpartum hemorrhage: oxytocin is the preferred agent, but ergonovine maleate can be used if oxytocin is ineffective.

Treatment of Migraine

Types of headaches: migraine, cluster headache, and tension-type headache.
Symptoms of migraine headache: pulsatile, throbbing pain, and may be preceded by visual, sensory, and/or speech or motor disturbances.
Symptomatic treatment of acute migraine: nonsteroidal anti-inflammatory drugs, antiemetics, opioids, β-adrenoceptor blockers, calcium channel blockers, and tricyclic antidepressants.
Specific treatment of migraine: triptans (serotonin agonists) and dihydroergotamine.

Serotonin

90% of serotonin is present in the enterocromaffin cells in the intestine, 8% in platelets, and 2% in the CNS.
Physiological functions of serotonin include regulation of sleep, appetite, temperature, perception of pain, blood pressure, depression, anxiety, and migraine.

Pharmacological Effects

The main sites of action of serotonin are the nervous system, airways, skeletal muscle, the eye, cardiovascular system, and gastrointestinal tract.
In the nervous system, serotonin acts on 5-HT3 receptors in the GIT and vomiting center in the medulla.
In airways, serotonin has a small direct stimulant effect on bronchiolar smooth muscle.
In skeletal muscle, 5-HT2 receptors are present, but their physiologic role is not understood.
In the eye, 5-HT 2A agonists reduce intraocular pressure in animal models of glaucoma.
In the cardiovascular system, serotonin causes contraction of vascular smooth muscle through 5-HT2 receptors.
In the gastrointestinal tract, serotonin is a powerful stimulant of gastrointestinal smooth muscle, increasing tone and facilitating peristalsis.

Serotonin Syndrome

Serotonin syndrome is a condition associated with restlessness, hyperthermia, and skeletal muscle contractions.
It is precipitated when MAO inhibitors are given with serotonin agonists, especially antidepressants of the selective serotonin reuptake inhibitor class.

Serotonin Agonists

Buspirone is a 5-HT 1A agonist, used as a non-benzodiazepine anxiolytic.
Triptans, such as sumatriptan, are 5-HT1B agonists used for migraine headaches.
Cisapride, a 5-HT 4 agonist, was used for gastroesophageal reflux and motility disorders.
Tegaserod, a 5-HT 4 partial agonist, is used for irritable bowel syndrome with constipation.

Serotonin-Receptor Antagonists

Phenoxybenzamine blocks 5-HT 2 receptors.
Cyproheptadine blocks H1–receptor and 5-HT2 actions, and is used for treating carcinoid tumor, urticaria, and as an appetite stimulant.
Ketanserin blocks 5-HT 2 receptors on smooth muscle and platelets, and is used to decrease blood pressure.
Ritanaserin is another 5-HT 2 antagonist with little or no α-blocking effect.

Ergot Alkaloids

Ergot alkaloids are produced by Claviceps purpurea, a fungus that infects grasses and grains.
They are partial agonists at serotonin receptors, affecting α adrenoceptors, dopamine receptors, and 5-HT receptors.
Organ system effects include:
- Central nervous system: lysergic acid diethylamide (LSD) is a synthetic, 5-HT 2 antagonist and powerful hallucinogen.
- Vascular smooth muscle: ergotamine and similar compounds constrict most vessels.
- Uterine smooth muscle: ergot preparations can evoke rhythmic contraction and relaxation of the uterus.
- Other smooth muscle organs: ergot alkaloids have little or no significant effect on bronchiolar or urinary smooth muscle.

Clinical Uses

Migraine: ergot derivatives are specific for migraine pain, such as ergotamine tartrate and dihydroergotamine.
Hyperprolactinemia: bromocriptine is used to treat hyperprolactinemia.
Postpartum hemorrhage: oxytocin is the preferred agent, but ergonovine maleate can be used if oxytocin is ineffective.

Treatment of Migraine

Types of headaches: migraine, cluster headache, and tension-type headache.
Symptoms of migraine headache: pulsatile, throbbing pain, and may be preceded by visual, sensory, and/or speech or motor disturbances.
Symptomatic treatment of acute migraine: nonsteroidal anti-inflammatory drugs, antiemetics, opioids, β-adrenoceptor blockers, calcium channel blockers, and tricyclic antidepressants.
Specific treatment of migraine: triptans (serotonin agonists) and dihydroergotamine.

Serotonin

90% of serotonin is present in the enterocromaffin cells in the intestine, 8% in platelets, and 2% in the CNS.
Physiological functions of serotonin include regulation of sleep, appetite, temperature, perception of pain, blood pressure, depression, anxiety, and migraine.

Pharmacological Effects

The main sites of action of serotonin are the nervous system, airways, skeletal muscle, the eye, cardiovascular system, and gastrointestinal tract.
In the nervous system, serotonin acts on 5-HT3 receptors in the GIT and vomiting center in the medulla.
In airways, serotonin has a small direct stimulant effect on bronchiolar smooth muscle.
In skeletal muscle, 5-HT2 receptors are present, but their physiologic role is not understood.
In the eye, 5-HT 2A agonists reduce intraocular pressure in animal models of glaucoma.
In the cardiovascular system, serotonin causes contraction of vascular smooth muscle through 5-HT2 receptors.
In the gastrointestinal tract, serotonin is a powerful stimulant of gastrointestinal smooth muscle, increasing tone and facilitating peristalsis.

Serotonin Syndrome

Serotonin syndrome is a condition associated with restlessness, hyperthermia, and skeletal muscle contractions.
It is precipitated when MAO inhibitors are given with serotonin agonists, especially antidepressants of the selective serotonin reuptake inhibitor class.

Serotonin Agonists

Buspirone is a 5-HT 1A agonist, used as a non-benzodiazepine anxiolytic.
Triptans, such as sumatriptan, are 5-HT1B agonists used for migraine headaches.
Cisapride, a 5-HT 4 agonist, was used for gastroesophageal reflux and motility disorders.
Tegaserod, a 5-HT 4 partial agonist, is used for irritable bowel syndrome with constipation.

Serotonin-Receptor Antagonists

Phenoxybenzamine blocks 5-HT 2 receptors.
Cyproheptadine blocks H1–receptor and 5-HT2 actions, and is used for treating carcinoid tumor, urticaria, and as an appetite stimulant.
Ketanserin blocks 5-HT 2 receptors on smooth muscle and platelets, and is used to decrease blood pressure.
Ritanaserin is another 5-HT 2 antagonist with little or no α-blocking effect.

Ergot Alkaloids

Ergot alkaloids are produced by Claviceps purpurea, a fungus that infects grasses and grains.
They are partial agonists at serotonin receptors, affecting α adrenoceptors, dopamine receptors, and 5-HT receptors.
Organ system effects include:
- Central nervous system: lysergic acid diethylamide (LSD) is a synthetic, 5-HT 2 antagonist and powerful hallucinogen.
- Vascular smooth muscle: ergotamine and similar compounds constrict most vessels.
- Uterine smooth muscle: ergot preparations can evoke rhythmic contraction and relaxation of the uterus.
- Other smooth muscle organs: ergot alkaloids have little or no significant effect on bronchiolar or urinary smooth muscle.

Clinical Uses

Migraine: ergot derivatives are specific for migraine pain, such as ergotamine tartrate and dihydroergotamine.
Hyperprolactinemia: bromocriptine is used to treat hyperprolactinemia.
Postpartum hemorrhage: oxytocin is the preferred agent, but ergonovine maleate can be used if oxytocin is ineffective.

Treatment of Migraine

Types of headaches: migraine, cluster headache, and tension-type headache.
Symptoms of migraine headache: pulsatile, throbbing pain, and may be preceded by visual, sensory, and/or speech or motor disturbances.
Symptomatic treatment of acute migraine: nonsteroidal anti-inflammatory drugs, antiemetics, opioids, β-adrenoceptor blockers, calcium channel blockers, and tricyclic antidepressants.
Specific treatment of migraine: triptans (serotonin agonists) and dihydroergotamine.

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Description

This quiz covers the physiology of serotonin, its functions in the body, and its pharmacological effects. Learn about the role of serotonin in sleep, appetite, pain perception, and more.