Lecture 7 Neurotransmitters

LA 1: Q: How do neurotransmitters, neuromodulators, neurohormones, and cotransmitters differ?

A: Neurotransmitters act quickly at synapses; neuromodulators act slowly via GPCRs; neurohormones travel in blood; cotransmitters are co-released to support the primary signal.

LA 2: Q: What are the major neurotransmitters and neuromodulators and their key traits?

A: Major neurotransmitters include glutamate (excitatory), GABA (inhibitory), glycine (inhibitory), acetylcholine (muscle activation), dopamine (reward/movement), serotonin (mood), and norepinephrine (alertness); neuromodulators adjust neuronal activity over time, often using G-protein pathways.

LA 3: Q: How do neurotransmitters and neuromodulators affect ion channels?

A: Neurotransmitters and neuromodulators affect ion channels by binding to receptors that either directly open ion channels (ionotropic) or activate second messenger systems that modulate channel activity (metabotropic).

Q: What are neurotransmitters and how do they work?

A: Neurotransmitters are chemicals released by presynaptic neurons into synapses to bind receptors and change the electrical properties of target cells.

Q: How do neurotransmitters differ from hormones?

A: Neurotransmitters act over tiny synaptic distances, while hormones travel through the blood to distant targets.

Q: What are the 4 criteria for identifying a neurotransmitter?

A: Presence in the neuron, Ca²⁺-dependent release, specific postsynaptic receptors, and a removal mechanism.

Q: What are neuromodulators and how do they function?

A: Neuromodulators act via GPCRs to produce slow, long-lasting effects that enhance or dampen neurotransmitter activity.

Q: What are neurohormones and how are they different?

A: Neurohormones are secreted by neuroendocrine cells into the blood, affecting distant targets like hormones.

Q: What are cotransmitters and their role?

A: Cotransmitters are released alongside primary neurotransmitters and modulate or extend their effects.

Q: What are gliotransmitters?

A: Gliotransmitters are signaling chemicals released by glial cells that influence neuron and glia communication.

Q: What is epinephrine’s role in the CNS and periphery?

A: In the CNS, epinephrine regulates respiration and cardiac function; in the periphery, it acts as a hormone on adrenergic receptors.

Q: What are the functions of histamine in the CNS?

A: Histamine regulates arousal, attention, and balance, and its receptors are targets for antihistamines and motion sickness drugs.

Q: What does serotonin (5-HT) regulate and how is it targeted pharmacologically?

A: Serotonin regulates sleep and mood, and is targeted by SSRIs and hallucinogens at various 5-HT receptors.

Q: What are the main excitatory amino acid neurotransmitters and their receptors?

A: Glutamate and aspartate act via ionotropic (AMPA, NMDA, kainate) and metabotropic receptors to excite CNS neurons.

Q: What are the major inhibitory amino acid neurotransmitters?

A: GABA and glycine open Cl⁻ channels to hyperpolarize neurons; GABA is derived from glutamate.

Q: What are neuropeptides and some examples of their functions?

A: Neuropeptides like endorphins, substance P, and neuropeptide Y modulate pain, feeding, and emotional responses.

Q: What are examples of novel neurotransmitters and how do they act?

A: ATP, nitric oxide (NO), and endocannabinoids act unconventionally, often via retrograde signaling or without vesicle storage.