Neurotrasmettitori | NEUROSCIENZE - Lezione 7

Summary

This lecture delves into the world of neurotransmitters, the chemical messengers that transmit signals across synapses in the nervous system. It explains the role of neurotransmitters like glutamate, acetylcholine, dopamine, GABA, and serotonin, highlighting their excitatory or inhibitory effects and their significance in various brain functions, including learning, memory, mood regulation, and reward pathways. The importance of receptor interaction in determining the signal's nature and the impact of neurotransmitter imbalances in conditions like depression and Parkinson's disease are also discussed, offering insights into the complex communication within our nervous system.

Takeaways

• 🧠 Neurotransmitters are substances that carry information between neurons through synapses, with over a hundred known types.
• 🚀 The release of neurotransmitters occurs when a stimulus reaches the presynaptic terminal, causing synaptic vesicles to merge with the presynaptic membrane and release their contents into the synaptic cleft.
• 🔄 Neurotransmitters must be received by a receptor on the postsynaptic neuron to continue the signal transmission, which can be either excitatory or inhibitory.
• 🌀 After their release, neurotransmitters need to be removed from the synaptic cleft to prevent continuous signaling; this can be done through reuptake by the presynaptic terminal or glial cells.
• 📈 Neurotransmitters can be classified based on their molecular structure and size, with smaller molecules typically acting more quickly and larger molecules having a slower, more prolonged effect.
• 🥕 Examples of neurotransmitters include amino acids like GABA and glycine, biogenic amines like dopamine and norepinephrine, and peptides like endorphins and neuropeptide Y.
• 🏃‍♂️ Glutamate is the primary excitatory neurotransmitter in the central nervous system and is involved in learning and memory processes.
• 🔌 Acetylcholine is involved in both the central and peripheral nervous systems, playing a role in muscle movement and the parasympathetic nervous system.
• 🎢 Dopamine is a catecholamine neurotransmitter crucial for movement control, pleasure sensation, reward circuits, and various cognitive functions.
• 🛌 GABA is the primary inhibitory neurotransmitter in the brain, with three types of receptors all leading to inhibitory effects.
• 💊 Antidepressant medications called SSRIs work by blocking the reuptake of serotonin, increasing its availability in the synaptic cleft and prolonging its interaction with receptors.
• 🔄 The effect of a neurotransmitter is not solely determined by its nature but also by the type of receptor it binds to, which can be either excitatory or inhibitory.

Q & A

What is the primary function of neurotransmitters?

The primary function of neurotransmitters is to convey information between neurons through synapses.

Where are neurotransmitters stored within the neuron?

Neurotransmitters are stored in vesicles called synaptic vesicles within the presynaptic terminal.

What happens to the synaptic vesicles when a nerve stimulus is received?

When a nerve stimulus is received, the synaptic vesicles fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.

What is the role of receptors in the transmission of the nerve impulse?

Receptors on the postsynaptic neuron must receive the neurotransmitter to continue the transmission of the impulse to subsequent neurons. The binding of neurotransmitters to their receptors can trigger an excitatory or inhibitory response in the postsynaptic neuron.

How are neurotransmitters cleared from the synaptic cleft after they have been released?

After release, neurotransmitters can be taken back up into the presynaptic terminal through a process called reuptake, or they can be broken down by enzymes or taken up by glial cells, such as astrocytes.

What is the difference between small-molecule neurotransmitters and neuropeptides?

Small-molecule neurotransmitters, such as amino acids like GABA, glutamate, or glycine, are simpler in structure. Neuropeptides are larger, consisting of a chain of amino acids, and have longer-lasting effects on the nervous system.

Which neurotransmitter is considered the primary excitatory neurotransmitter in the central nervous system?

Glutamate is considered the primary excitatory neurotransmitter in the central nervous system.

What neurotransmitter is responsible for the transmission of signals from sensory organs to the brain and motor commands to muscles?

Acetylcholine is the neurotransmitter responsible for the transmission of signals from sensory organs to the brain and motor commands to muscles.

What neurotransmitter is associated with the regulation of movement, pleasure sensation, reward circuitry, and cognitive functions such as attention?

Dopamine is associated with the regulation of movement, pleasure sensation, reward circuitry, and cognitive functions such as attention.

Which neurotransmitter is the main inhibitory neurotransmitter in the central nervous system and is targeted by most sedative medications?

GABA (gamma-aminobutyric acid) is the main inhibitory neurotransmitter in the central nervous system and is targeted by most sedative medications.

How do selective serotonin reuptake inhibitors (SSRIs) work in treating depression?

SSRIs work by inhibiting the reuptake of serotonin, thereby increasing its availability in the synaptic cleft and allowing it to interact with its receptors for a longer period, which contributes to their antidepressant activity.

What determines whether a neurotransmitter's signal is excitatory or inhibitory?

The nature of the neurotransmitter's signal as excitatory or inhibitory is determined by the type of receptor it binds to. For example, serotonin is not inherently excitatory or inhibitory; its effect depends on the specific receptor it interacts with.