Psychology 304: Brain and Behaviour Lecture 15

Neurotransmitters and Neuropharmacology 1. What neurotransmitters have been identified? 2. How do drugs affect the conduction and transmission of electrochemical neural signals?

By the end of today’s class, you should be able to: 1. distinguish between classes of neurotransmitters in terms of function and location. 2. define the terms: agonist and antagonist. 3. describe the mechanisms by which agonists and antagonists produce their effects.

What neurotransmitters have been identified? Four classes of small-molecule neurotransmitters have been identified: 1. Acetylcholine (ACh) One of the most widespread neurotransmitters. Found at neuromuscular synapses, synapses in the autonomic nervous system, and synapses in parts of the central nervous system.

Associated with movement, autonomic function, learning and memory. Deficiency associated with Alzheimer’s disease. 2. Monoamine neurotransmitters Found in neurons whose cell bodies are largely located in the brain stem. These neurons give rise to terminal buttons throughout the brain.

Subdivided into two groups: Catecholamines: Dopamine: associated with movement, attention, reinforcement/reward, verbal learning, and planning. Deficiency associated with Parkinson’s disease and ADHD. Excessive levels associated with schizophrenia.

Production of the Catecholamines

Epinephrine (adrenalin): associated with Epinephrine (adrenalin): associated with attention, arousal, and energy. Norepinephrine (noradrenaline): associated with attention, arousal, vigilance, mood, feeding, and sexual behaviour. Deficiency associated with depression.

(b) Indoleamines: Serotonin: associated with mood, sleep, feeding, sexual behaviour, and pain. Deficiency associated with depression. Melatonin: associated with sleep. .

3. Amino acid neurotransmitters Found in fast-acting neurons in the central nervous system. Include glutamate, gamma-aminobutyric acid (GABA), glycine, and aspartate. Of these, glutamate and GABA are most important: .

Glutamate: the principle excitatory Glutamate: the principle excitatory neurotransmitter in the CNS; associated with learning and memory. Deficiency associated with impaired performance on learning tasks.

GABA: the principle inhibitory neurotransmitter in the GABA: the principle inhibitory neurotransmitter in the CNS; associated with mood and the “seizure threshold.” Deficiency associated with anxiety disorders and seizures.

4. Soluble gas neurotransmitters Include nitric oxide (NO) and carbon monoxide (CO). Unconventional neurotransmitters. After production in the cytoplasm, they immediately diffuse through the presynaptic cell membrane into the postsynaptic cell, where they stimulate the production of a second messenger.

Function as retrograde transmitters: Diffuse back to Function as retrograde transmitters: Diffuse back to the presynaptic neuron and regulate its activity. Little is known about the functions of CO. NO is associated with autonomic activity, learning, and sensory communication between the thalamus and cortex.

Large-molecule neurotransmitters are neuropeptides: Found largely in neurons of the CNS. Include five categories: pituitary peptides, hypothalamic peptides, brain-gut peptides, opioid peptides, and miscellaneous peptides.

How do drugs affect the conduction and transmission of electrochemical neural signals? Drugs: Exogenous chemicals that are not necessary for normal functioning and significantly alter cellular functioning when taken in relatively low doses. May be introduced into the central nervous system through diverse means.

Drugs may be classified as agonists or antagonists. Agonists facilitate the effects of neurotransmitters. Antagonists inhibit the effects of neurotransmitters. Agonists and antagonists may influence synaptic transmission in a number of ways:

Mechanisms of Agonist and Antagonist Drug Effects

Neurotransmitters and Neuropharmacology 1. What neurotransmitters have been identified? 2. How do drugs affect the conduction and transmission of electrochemical neural signals?