Neurotransmitters and Their Functions

Neurotransmitters Overview

  • The focus of this screencast is on neurotransmitters.

  • By the end of this lesson, you should be able to understand the functions of:

    • Acetylcholine (ACh)

    • Dopamine

    • Serotonin

    • Norepinephrine (NE)

    • GABA (Gamma-Aminobutyric Acid)

    • Substance P

    • Endorphins

    • Glutamate

Introduction to Neurotransmitters

  • Neurotransmitters are chemical messengers in the brain that facilitate communication between neurons.

  • Over 100 known neurotransmitters exist, but this lesson will focus on eight commonly studied neurotransmitters related to mental health.

Video Clip Introduction

  • A video clip is shown depicting the life of a man named John Ratlin, who exhibits symptoms of schizophrenia:

    • The narrative highlights his eccentricities and mental illness.

    • His condition has led him to have grand delusions and paranoia, hallucinating voices and claiming to be a deity.

    • Reflects how various mental illnesses are linked to neurotransmitter imbalances.

Importance of Neurotransmitter Balance

  • Mental illnesses such as depression, bipolar disorder, and schizophrenia may arise from chemical imbalances in neurotransmitters.

  • These conditions are not chosen; they stem from biological and chemical processes in the body.

Acetylcholine (ACh)

  • Definition: Acetylcholine is the first neurotransmitter discovered in 1905.

  • Functions:

    • Involved in every waking moment of existence.

    • Responsible for motor movement - it sends signals to muscles for movement (e.g., heart beating, lungs contracting).

    • Important for memory function, particularly in Alzheimer’s disease.

  • Neurological Implications:

    • Loss of ACh-producing neurons in Alzheimer’s leads to significant memory impairment (up to 90% loss).

    • Blocking ACh receptors can impact memory.

  • Examples of Effects:

    • Curetre Poison: Used by a tribe in South America, blocks ACh receptors leading to paralysis and asphyxiation.

    • Black Widow Spider Venom: Causes an excess release of ACh, resulting in tachycardia (rapid heart rate).

Dopamine

  • Definition: A neurotransmitter often associated with reward and pleasure.

  • Functions:

    • Influences emotion and positive feelings; affects motor movement.

    • Low levels can lead to tremors (e.g., Parkinson’s disease).

  • Clinical Importance:

    • Recreational drugs increase dopamine levels, causing euphoric feelings.

    • Thorazine, a common antipsychotic used for schizophrenia, lowers dopamine levels.

    • Patients may experience symptoms resembling Parkinson's disease (known as the "Thorazine shuffle").

  • Connections to Love:

    • When falling in love, dopamine levels significantly increase, leading to emotions similar to those experienced under the influence of cocaine.

    • Love influences perceptions and pleasure centers of the brain.

Serotonin

  • Definition: A neurotransmitter primarily involved in mood regulation.

  • Functions:

    • Regulates mood and contributes to feelings of happiness.

    • Linked to sleepiness and appetite regulation.

  • Clinical Relevance:

    • Low serotonin levels are commonly associated with depression.

    • SSRIs (Selective Serotonin Reuptake Inhibitors) like Prozac and Zoloft work to block the reuptake of serotonin, allowing it more time to bind to receptors.

  • Mechanism of Action for SSRIs:

    • Blockers prevent excess serotonin from being sucked back too quickly, allowing prolonged binding to postsynaptic receptors.

Norepinephrine (NE)

  • Definition: A neurotransmitter linked to mood, arousal, and alertness.

  • Functions:

    • Released during stress to prepare for fight or flight responses.

  • Clinical Implications:

    • Imbalances can lead to depression and bipolar disorder.

    • Levels are assessed to determine the cause of depression, alongside serotonin levels.

GABA (Gamma-Aminobutyric Acid)

  • Definition: An inhibitory neurotransmitter that reduces neuronal excitability.

  • Functions:

    • Helps control anxiety; low levels can result in increased anxiety.

  • Clinical Correlation:

    • Anxiety can be managed by increasing GABA activity; for instance, techniques like controlled breathing can help stabilize GABA function.

Substance P

  • Definition: A neurotransmitter associated with the sensation of pain.

  • Functions:

    • Responsible for transmitting pain signals to the brain.

    • Binds in specific areas of the brain to indicate where pain is felt.

Conclusion

  • Neurotransmitters are crucial for managing several neurological and psychological functions.

  • Imbalances can lead to various mental health conditions, underscoring the importance of neurotransmitter research in understanding mental health disorders.