Histamine and Serotonin Overview
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Questions and Answers

What is the physiological effect of histamine on bronchiolar smooth muscle, particularly in asthma patients?

  • Bronchoconstriction of the airways (correct)
  • Inhibition of mucus secretion
  • Relaxation of smooth muscle in the bronchioles
  • Vasodilation of blood vessels in the lungs

Which component of the histamine triple response is characterized by an irregular red flare surrounding the injection site?

  • Contraction of smooth muscle in the vicinity
  • Red spot due to dilation of blood vessels
  • Flare caused by an axon reflex reaction (correct)
  • Edema forming a wheal at the injection site

What role does epinephrine play in relation to the effects of histamine?

  • It potentiates the release of histamine from mast cells
  • It enhances the effects of histamine on bronchoconstriction
  • It acts as a physiological antagonist to reverse bronchoconstriction (correct)
  • It blocks the H1 receptors exclusively

What distinguishes H2 receptor blockers introduced in 1972 from traditional antihistamines?

<p>Functionality as gastric acid reducers (B)</p> Signup and view all the answers

What is a potential effect of high levels of histamine on the gastrointestinal system?

<p>Contraction of intestinal smooth muscle causing diarrhea (A)</p> Signup and view all the answers

Which cells are primarily responsible for storing histamine in the body?

<p>Basophils and mast cells (B)</p> Signup and view all the answers

Which of the following conditions is NOT caused by the release of histamine?

<p>Muscle spasms (A)</p> Signup and view all the answers

What is the precursor amino acid from which histamine is synthesized?

<p>L-histidine (A)</p> Signup and view all the answers

Which histamine receptor type is primarily found in the gastric mucosa?

<p>H2 receptor (B)</p> Signup and view all the answers

What type of reaction leads to the immunological release of histamine?

<p>IgE antibody binding to mast cells (A)</p> Signup and view all the answers

Which of the following is NOT considered a histamine receptor?

<p>H5 (D)</p> Signup and view all the answers

Which drugs are mentioned as capable of causing histamine release from mast cells?

<p>Opiates like morphine (B)</p> Signup and view all the answers

What is the main effect of histamine binding to H3 receptors in the brain?

<p>Neuromodulation and inhibition of neurotransmitter release (A)</p> Signup and view all the answers

Which of the following effects is associated with the nervous system's response to insect bites?

<p>Stimulation of sensory nerve endings (B)</p> Signup and view all the answers

What is a clinical use of buspirone?

<p>Sedative for anxiety treatment (C)</p> Signup and view all the answers

Which ergot alkaloid is specifically known for causing vasoconstriction leading to gangrene?

<p>Ergotamine (C)</p> Signup and view all the answers

What condition can occur due to ingestion of grains contaminated with ergots?

<p>Gangrene of the extremities (B)</p> Signup and view all the answers

Which of the following serotonin antagonists is used to treat nausea and vomiting?

<p>Ondansetron (A)</p> Signup and view all the answers

What is one of the main effects of serotonin agonists on the cardiovascular system?

<p>Contraction of vascular smooth muscle (D)</p> Signup and view all the answers

What is a significant characteristic of carcinoid tumors related to serotonin?

<p>They secrete large amounts of 5-HT. (C)</p> Signup and view all the answers

Which ergot alkaloid induces prolonged uterine contractions?

<p>Ergonovine (A)</p> Signup and view all the answers

Which of the following histamine receptor antagonists is primarily used to treat motor disorders induced by other medications?

<p>diphenhydramine (C)</p> Signup and view all the answers

Which adverse drug reaction is most commonly associated with first-generation antihistamines?

<p>Orthostatic hypotension (C)</p> Signup and view all the answers

What are significant clinical uses of doxylamine?

<p>Preventing nausea during the first trimester of pregnancy (C), Treating motion sickness (A)</p> Signup and view all the answers

Which characteristic differentiates second-generation antihistamines from first-generation ones?

<p>They do not readily enter the CNS. (A)</p> Signup and view all the answers

Which neurotransmitter is involved in mood regulation, anxiety, and migraine, and has several receptor sub-types?

<p>Serotonin (D)</p> Signup and view all the answers

Which of the following side effects can be caused by first-generation antihistamines due to their anti-muscarinic actions?

<p>Blurred vision (D)</p> Signup and view all the answers

What can excessive use of first-generation antihistamines lead to due to their sedative effects?

<p>Physical dependence (B)</p> Signup and view all the answers

Which of the following is a reason for using first-generation antihistamines in treating motion sickness?

<p>Increased sedation in the CNS (C)</p> Signup and view all the answers

Match each histamine receptor to its location

<p>H3 = presynaptic autoreceptors, neurons, brain H1 = smooth muscle, endothelium, brain H2 = gastric mucosa, cardiac muscle, mast cells, brain H4 = eosinophils, neutrophils, CD T white cells</p> Signup and view all the answers

Match each to its response to histamine

<p>Bronchiolar Smooth Muscle: = bronchoconstriction, especially in asthma patients with over reactive airways Nervous System = stimulates sensory nerve endings mediating pain, itching. H1 receptors, mediate reactions to insect bites Cardiovascular System = variable and mixed, edema can result from increased histamine levels GI = contraction of intestinal smooth muscle (diarrhea)</p> Signup and view all the answers

What are the characteristics of the histamine triple response?

<p>Red spot, edema and flare</p> Signup and view all the answers

Match each component of the histamine triple response to its description

<h1>Red Spot = at the site of dermal injection; due to dilation of small blood vessels Edema = an edema wheal at the injection site Flare = red irregular flare surrounding the wheal caused by an axon reflex reaction</h1> Signup and view all the answers

Histamine is frequently used as a drug

<p>False (B)</p> Signup and view all the answers

What can histamine from spoiled fish cause?

<p>Scombroid fish poisoning. (A)</p> Signup and view all the answers

Which of the following is a physiological antagonist of histamine?

<p>Epinephrine (A)</p> Signup and view all the answers

Which receptor agonists can block histamine release?

<p>beta2 agonists (D)</p> Signup and view all the answers

Match each generation of anti-histamines to its description/ drugs

<p>First Generation = enter the CNS and induce sedation Second Generation = do not readily enter the CNS, less sedating to mostly non-sedating First Generation = diphenhydramine (Benadryl); hydroxyzine (Atarax); brompheniramine (Dimetane); promethazine (Phenergan) Second Generation = fexofenadine (Allegra); loratadine (Claritin); cetirizine (Zyrtec)</p> Signup and view all the answers

All H1 histamine receptor antagonists are reversible competitive inhibitors.

<p>True (A)</p> Signup and view all the answers

Match each drug to its use

<p>diphenhydramine = Anti-Parkinsonism Effects:used to treat the motor disorders induced by some drugs doxylamine = Anti-nausea and antiemetic: sold to prevent motion sickness. Sold for many years to prevent the nausea of the first trimester of pregnancy promethazine = Adrenoceptor-Blocking Actions:can block alpha receptors and cause orthostatic hypotension diphenhydramine = Local Anesthetics:can act like local anesthetics through block of sodium axonal channels;is a more potent local anesthetic compare to procaine</p> Signup and view all the answers

Which of the following is a neurotransmitter and local hormone in the gut that is involved in the platelet clotting process and may also play an important role in migraines?

<p>Serotonin (5HT) (C)</p> Signup and view all the answers

Match each system to Serotonin's effect on it

<p>Respiratory System = stimulates bronchiolar smooth muscle Cardiovascular System = contracts vascular smooth muscle, except in the heart GI Tract = facilitates peristalsis Nervous System = stimulates itch and pain in nerve endings (like histamine) following insect bite and dermal plant contact</p> Signup and view all the answers

What is a major metabolic disorder caused by excess 5-HT in the CNS that is potentially lethal?

<p>Serotonin Syndrome (A)</p> Signup and view all the answers

Match each serotonin drug agonist to its description

<h1>lorcaserin = used to treat obesity</h1> <p>buspirone = a sedative drug used to treat anxiety sumatriptan = used to treat migraine, which may be caused by vasodilation</p> Signup and view all the answers

Match each serotonin antagonist to its description

<h1>=</h1> <p>phenoxybenzamine = used to block NE, EP, 5-HT in patients with adrenal tumors (pheochromocytomia) ondansetron = used to treat nausea and vomiting especially after gas anesthesia and cancer chemotherapy</p> Signup and view all the answers

What organism secretes ergots?

<p>Claviceps purpurea (A)</p> Signup and view all the answers

Which condition may have the following symptoms:

  • Occurs due to the ingestion of grains that contain ergots
  • Severe vasoconstriction of the digits (gangrene)
  • Hallucinations
  • Stimulation of uterine smooth muscles (abortion)?

<p>Ergotism (A)</p> Signup and view all the answers

What is the mechanism of action (MOA) of ergot alkaloids?

<p>They have vasoconstrictive properties (C)</p> Signup and view all the answers

What is lysergic acid diethylamide (LSD) derived from?

<p>ergot alkaloids (A)</p> Signup and view all the answers

Match each ergot derivative to its description

<p>lysergic acid diethylamide (LSD) = Causes major hallucinations bromocriptine, cabergoline, pergolide = act on dopamine receptors as agonists. Involved in Parkinson Syndrome ergotamine = Vascular Smooth Muscle. A potent vasoconstrictor which can lead to gangrene of toes and fingers. ergonovine = Uterine Smooth Muscle. Induce prolonged contraction</p> Signup and view all the answers

What are the main clinical uses of ergots? (Select all that apply)

<p>Migraines (A), Pituitary dysfunction (B)</p> Signup and view all the answers

Which ergot derivative is utilized to treat migraines due to its vasoconstrictive properties in the CNS?

<p>ergotamine (A)</p> Signup and view all the answers

Which ergot drug can be used for hypoprolactinemia (increased tumor production of prolactin by the pituitary can lead to serious metabolic problems such as amenorrhea and infertility)?

<p>Bromocriptine (B)</p> Signup and view all the answers

Which ergot drug is used to treat postpartum hemorrhage due to its vasoconstrictive effects?

<p>Ergonovine (A)</p> Signup and view all the answers

Which of the following is an H2 antihistamine?

<p>cimetidine (A)</p> Signup and view all the answers

What does histamine cause the release of in the parietal cells?

<p>Hydrochloric acid (B)</p> Signup and view all the answers

What is the treatment for scombroid fish syndrome?

<p>Antihistamines (A)</p> Signup and view all the answers

Which of the following can inhibit CYP 3A4, leading to increased levels of H1 antagonists and lethal cardiac arrhythmias?

<p>Ketoconazole (A)</p> Signup and view all the answers

What does fluoxetine treat?

<p>Depression (B)</p> Signup and view all the answers

Which of the following can treat irritable bowel syndrome?

<p>alosetron (A)</p> Signup and view all the answers

Which of the following is a melatonin receptor agonist approved for treating insomnia?

<p>ramelteon (D)</p> Signup and view all the answers

Flashcards

What is histamine?

Histamine is an amino acid that acts as a neurotransmitter in the brain and as a signaling molecule in the immune system, leading to allergic reactions and inflammation.

Histamine Triple Response

A series of reactions caused by injecting histamine intradermally, creating a red spot, edema wheal, and surrounding flare, which helps in allergy testing.

Bronchoconstrictive Potential

The ability of a substance to cause bronchoconstriction, particularly in individuals with asthma.

Histamine Blockers

Drugs that block histamine receptors, categorized as H1 and H2 blockers, used to treat allergies and heartburn respectively.

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Histamine Challenge Test

A way to assess lung response by administering histamine aerosol, used to diagnose asthma or determine the severity of asthma.

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Histamine's Influence on Stomach Acid

Histamine's role in stimulating the stomach's parietal cells to release hydrochloric acid, contributing to the digestive process.

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Serotonin Agonists

A class of drugs that interact with serotonin receptors, causing various effects on the body.

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Serotonin Antagonists

A class of drugs that block serotonin receptors, preventing serotonin from exerting its effects.

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Serotonin Syndrome

A dangerous condition caused by high levels of serotonin in the body, often triggered by combining serotonin-affecting drugs.

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Ergot Alkaloids

A group of natural compounds produced by the fungus Claviceps purpurea found on grains, known for their diverse biological effects.

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Ergotism

A potentially fatal condition caused by ingesting ergots, characterized by severe vasoconstriction (leading to gangrene), hallucinations, and uterine contractions.

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Ergotamine

A potent vasoconstrictor derived from ergot alkaloids, used to treat migraine headaches but can lead to gangrene.

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Bromocriptine

An ergot derivative that acts as a dopamine agonist, used to treat Parkinson's disease but has potential side effects.

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LSD (Lysergic Acid Diethylamide)

A substance derived from ergot alkaloids that causes intense hallucinations, known for its mind-altering effects.

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First-generation antihistamines and surgery

First-generation antihistamines like diphenhydramine (Benadryl) can cause drowsiness and are not recommended before surgery due to their sedative effects.

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Second-generation antihistamines and sedation

Second-generation antihistamines, like fexofenadine (Allegra), loratadine (Claritin), and cetirizine (Zyrtec), are less likely to cause drowsiness compared to first-generation antihistamines.

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Antihistamines and local anesthetic effects

Antihistamines like diphenhydramine can act as local anesthetics by blocking sodium channels in nerve axons. This is similar to how lidocaine works.

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Doxylamine and pregnancy

Doxylamine, a first-generation antihistamine, was once used to treat nausea in early pregnancy. However, concerns about teratogenic effects led to its withdrawal from the market for this use.

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Serotonin (5-HT): functions

Serotonin (5-HT) acts as a neurotransmitter, hormone, and platelet component. It plays a role in mood, sleep, appetite, and temperature regulation.

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Clinical uses of antihistamines

Antihistamines can be used to treat allergies, motion sickness, and nausea. The specific antihistamine used depends on the condition and individual needs.

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Antihistamine side effects

Antihistamines can cause side effects like sedation, anti-nausea effects, anti-Parkinsonism effects, anti-muscarinic effects, and adrenoceptor-blocking actions.

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Serotonin receptors

There are seven different 5-HT receptors, making serotonin signaling complex. Understanding these receptors is crucial for developing targeted drugs.

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Study Notes

Histamine, Serotonin, and the Ergot Alkaloids

  • Histamine is an amino acid acting as a neurotransmitter (NT) released by non-neuronal tissues. It's involved in allergic reactions (e.g., urticaria, itching) and inflammatory responses.
  • Histamine is synthesized from the amino acid L-histidine via decarboxylation.
  • Histamine is stored in granules within mast cells and basophils, tissues throughout the body.
  • Mast cells and basophils release histamine in response to various triggers, including:
    • Immunological stimuli: IgE antibodies binding to mast cells upon antigen exposure (e.g., food, allergens)
    • Chemical release: Certain drugs like morphine can trigger histamine release.
  • Histamine has various receptors (H1, H2, H3, H4) that mediate responses in different tissues and organs, affecting nervous, cardiovascular, and GI systems e.g., causing contraction of smooth muscle, pain, itching, bronchoconstriction.
  • Histamine antagonists (blockers) are used to treat conditions involving excessive histamine release, often alleviating allergic reactions and related symptoms.
    • First-generation antihistamines, like diphenhydramine, often cause sedation.
    • Second-generation histamine antagonists are less sedating and better tolerated.
  • Epinephrine is a physiological antagonist of histamine, reversing histamine induced effects e.g. bronchoconstriction.
  • Certain drugs like beta2 agonists can block histamine release.

Serotonin (5-HT)

  • Serotonin is 5-hydroxytryptamine.
  • A neurotransmitter and local hormone found in the gut, platelets, and the CNS.
  • It plays roles in mood, sleep, appetite, and temperature regulation, as well as in migraine.
  • Serotonin syndrome results from excess 5-HT in the CNS and can be potentially lethal.
  • Serotonin agonists, like buspirone, are used to treat anxiety.

Ergot Alkaloids

  • Derived from the fungus Claviceps purpurea growing on grains.
  • Act on various receptors (alpha, serotonin, dopamine) and have diverse effects on numerous organ systems; their effects can be potent vasoconstrictors, causing gangrene.
  • Ergot alkaloids cause potentially lethal conditions like ergotism.
  • Ergot alkaloids can lead to severe vasoconstriction in the digits, as well as hallucinations, and potentially stimulate uterine smooth muscles (e.g., inducing abortion).
  • Drugs derived from ergot alkaloids including bromocriptine, lisuride, cabergoline, pergolide, and ergotamine are used to treat various conditions.

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PM 719 Pharmacology II Chapter 16 Histamine, Serotonin, & Ergot Alkaloids PDF

Description

This quiz explores the roles of histamine and serotonin as neurotransmitters, including their synthesis, storage, and the physiological responses they mediate. You'll learn about the mechanisms of histamine release, its receptors, and implications for allergic reactions and treatment options. Test your knowledge on these vital biological compounds.

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