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Related Concept Videos

Adrenergic Neurons: Neurotransmission01:27

Adrenergic Neurons: Neurotransmission

Postganglionic sympathetic fibers (except those supplying the sweat glands) releasing noradrenaline or norepinephrine are called noradrenergic or adrenergic neurons. Noradrenaline, dopamine, adrenaline, or epinephrine are collectively called "catecholamines" as they contain a catechol moiety and an amine side chain. The five stages of neurotransmitter release involve their synthesis, storage, release, reuptake and metabolism.
Synthesis: Catecholamine synthesis requires tyrosine, which is taken...
Adrenergic Receptors: β Subtype01:26

Adrenergic Receptors: β Subtype

β-adrenoceptors have varied sensitivities towards adrenaline, noradrenaline, and isoprenaline. The order of agonist potency is as follows:
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
Adrenergic Agonists: Direct-Acting Agents01:30

Adrenergic Agonists: Direct-Acting Agents

Drugs that mimic the action of endogenous catecholamines like noradrenaline and adrenaline are called adrenergic agonists or sympathomimetics. Based on their mechanism of action, sympathomimetics can be classified as direct-, indirect-, or mixed-acting sympathomimetics. Direct-acting adrenergic agonists activate adrenoceptors without affecting presynaptic neurons, making them independent of neuronal catecholamine-depleting agents like reserpine and guanethidine.
These agents can be classified...
Adrenergic Agonists: Indirect-Acting Agents01:25

Adrenergic Agonists: Indirect-Acting Agents

Indirect-acting adrenergic agonists potentiate the effects of endogenous catecholamines through different mechanisms without directly binding to adrenoceptors.
One mechanism involves depleting stored catecholamines by displacing them from synaptic vesicles. These agents, known as "displacers," are transported into vesicles at the expense of noradrenaline. Examples include amphetamine and tyramine, which lack a catechol moiety, resulting in prolonged action, improved oral bioavailability, and...
Adrenergic Agonists: Therapeutic Uses01:30

Adrenergic Agonists: Therapeutic Uses

Adrenergic agonists have diverse therapeutic uses across various medical conditions and emergencies.
Emergency and Intensive Care Unit (ICU) applications: Pressor agents increase blood pressure, heart rate, and contractility in shock and organ failure situations. Dopamine can induce vasodilation and stimulate adrenoceptors. Endogenous catecholamines are effective in treating cardiogenic shock. α2-agonists like clonidine can reverse anesthesia-induced hypertension.
Allergies and anaphylaxis:...
Sperm Structure and Semen Composition01:22

Sperm Structure and Semen Composition

During ejaculation, males release around 2-5 milliliters of semen, which is a complex mixture of mature sperm and various fluids produced by accessory glands. The mature sperm cells measure approximately 60 micrometers in length and consist of a head, neck, midpiece, and tail. The head is flattened and tapered, measuring about 4 to 5 micrometers in length. It contains a nucleus with condensed chromosomes and an acrosome, a cap-like structure filled with enzymes essential for penetrating the...

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Related Experiment Video

Updated: Jul 16, 2026

Collection of Post-mating Semen from the Female Reproductive Tract and Measurement of Semen Liquefaction in Mice
12:06

Collection of Post-mating Semen from the Female Reproductive Tract and Measurement of Semen Liquefaction in Mice

Published on: November 18, 2017

Catecholamines in bovine semen

P E Lindahl, P Sjöblom, O Tottmar

    Experientia
    |January 1, 1981
    PubMed
    Summary

    Noradrenaline in bull semen induces sperm head-to-head association at concentrations 100 times lower than previously reported. This finding impacts understanding of sperm behavior and reproductive technologies.

    Area of Science:

    • Reproductive Biology
    • Animal Science
    • Biochemistry

    Background:

    • Seminal plasma composition influences sperm function.
    • Catecholamines like noradrenaline play roles in reproductive physiology.
    • Previous studies suggested higher catecholamine levels in semen.

    Purpose of the Study:

    • To investigate the effect of noradrenaline on bull spermatozoa.
    • To quantify catecholamine levels in freshly collected bull semen.
    • To compare current findings with previous reports on catecholamine concentrations.

    Main Methods:

    • Spermatozoa were exposed to specific concentrations of noradrenaline (5 x 10(-6) M).
    • Head-to-head association of spermatozoa was observed and quantified.
    • Catecholamine levels (noradrenaline and adrenaline) in seminal plasma were measured using biochemical assays.

    More Related Videos

    In Vitro Culture Strategy for Oocytes from Early Antral Follicle in Cattle
    09:30

    In Vitro Culture Strategy for Oocytes from Early Antral Follicle in Cattle

    Published on: July 8, 2020

    Recording Electrical Currents across the Plasma Membrane of Mammalian Sperm Cells
    09:37

    Recording Electrical Currents across the Plasma Membrane of Mammalian Sperm Cells

    Published on: February 14, 2021

    Related Experiment Videos

    Last Updated: Jul 16, 2026

    Collection of Post-mating Semen from the Female Reproductive Tract and Measurement of Semen Liquefaction in Mice
    12:06

    Collection of Post-mating Semen from the Female Reproductive Tract and Measurement of Semen Liquefaction in Mice

    Published on: November 18, 2017

    In Vitro Culture Strategy for Oocytes from Early Antral Follicle in Cattle
    09:30

    In Vitro Culture Strategy for Oocytes from Early Antral Follicle in Cattle

    Published on: July 8, 2020

    Recording Electrical Currents across the Plasma Membrane of Mammalian Sperm Cells
    09:37

    Recording Electrical Currents across the Plasma Membrane of Mammalian Sperm Cells

    Published on: February 14, 2021

    Main Results:

    • Noradrenaline at 5 x 10(-6) M was confirmed to induce head-to-head association in bull spermatozoa.
    • The total concentration of noradrenaline and adrenaline in freshly collected semen was found to be 10 ng/ml (5.2 x 10(-8) M).
    • This measured concentration is approximately 100 times lower than levels reported in earlier studies.

    Conclusions:

    • The effective concentration of noradrenaline for inducing sperm association is lower than previously thought.
    • Actual catecholamine levels in bull seminal plasma may be significantly lower than previously estimated.
    • These findings necessitate a re-evaluation of the physiological role of catecholamines in bull reproduction.