Exam 1 - Neurotransmitters and Pharmacology Flashcards
Synaptic transmission steps
- NT synthesis and storage
- NT release
- Receptor action
- Inactivation
What does synaptic transmission produce?
Postsynaptic potentials which are brief, hyperpolarizations or depolarizations that increase or decrease the firing rate of the postsynaptic axon
Neurotransmitter (NT)
the chemical released from the synaptic axon terminal that serves as the basis of communication between neurons
Neuromodulator (NM)
acts like an NT, but NOT restricted to the synaptic cleft and diffuses throughout extracellular fluid. They can be excitatory (EPSP) or inhibitory (IPSP). Almost all drugs work by altering synaptic transmission and use NMs
7 Classes of NTs
amino acids
acetylcholine
monoamines
peptides
lipids
nucleosides
soluble gases
Amino acids (AA)
responsible for most synaptic communication in the brain. The 3 most common are glutamate, GABA, and Glycine
Glutamate (Glu)
(type of AA), main excitatory NT in the CNS. Binds to MANY receptors (ionotropic and metabotropic receptors). Drugs that affect Glu do so by interacting with its receptors. Glu released from presynaptic neuron and is removed from synapse by excitatory AA transporters and broken up by enzyme so never taken back to presynaptic neuron. Too much Glu can lead to prolonged over excitation in neurons and cause damage like irregular heartbeat and high blood pressure
How many types of ionotropic receptors and metabotropic receptors does Glu bind to?
3 ionotropic - NMDA, AMPA, Kainate. 1metabotropic - metabotropic Glu receptor
GABA - Gamma-aminobutyric acid
(type of AA) main inhibitory NT widely distributed throughout CNS. Reduction of GABA (ex. abnormality of GABA secreting neurons or GABA receptors) contributes to likelihood of seizures. Has MANY receptors that drugs interact with (Ex. Xanax and Vial mimic GABA to produce calming effect)
Acetylcholine (Ach)
Neurons that release Ach are found in specific pathways in CNS. Functions: role in REM sleep, facilitates learning, modulates formation of memories. Secreted in PNS –> muscle contraction. Binds to ionotropic receptors and metabotropic receptors.
What types of ionotropic receptors and metabotropic receptors does Ach bind to?
Ionotropic receptors like Nicotinic are stimulated by nicotine (drug from tobacco leaves). Metabotropic receptors like muscarinic are stimulated by muscarine (drug from poison mushroom)
Monoamines
most somas located in the brain stem, allow a lot of terminal buttons to be distributed throughout many regions of the brain. Involved in activating/deactivating several regions of the brain. classified into 3 categories –> catecholamines, indolamine, ethylamine
Dopamine (DA)
(type of Monoamine - catecholamines) produces both EPSPs and IPSPs, depending on the receptor. Functions: movement, attention, learning, reinforcement (pleasure, satisfaction, motivation). Pathophysiology –> Parkinson’s disease and schizophrenia. Several drugs stimulate or block specific DA receptors. Antipsychotics block dopamine
Norepinephrine (NE) aka noradrenaline AND epinephrine aka adrenaline
(type of Monoamine - catecholamines), part of fight or flight response, increase vigilance, increase and maintain blood pressure, increase energy use by the body.
Norepinephrine affects the blood vessels.
Epinephrine affects the heart. Secreted by adrenal medulla
Serotonin (5-HT)
(type of Monoamine - Indolamine). Functions: mood regulation, eating, sleep, arousal, regulation of pain. Drugs that inhibit reuptake of 5-HT are commonly used in treatment of mental illness
Histamine
(type of Monoamine - ethylamine). Functions: wakefulness, digestive system, immune system. Antihistamines are drugs that block histamine receptors cause drowsiness Ex. Benadryl
Peptides
2 or more amino acids that are linked together. They are created in the soma of the neuron and transported down the axon. All peptides are destroyed by enzymes so there is no reuptake. The main family is the “endogenous opioids.” Opioid drugs stimulate opioid neurons Ex. heroin, oxycodone, morphine. Functions: emotions, pain, appetite, reinforcement
Lipids
They appear to be synthesized on demand (only produced and released as needed and not stored in synaptic vessels). Endocannabinoids are the most important. Natural ligands for the receptors are responsible for the physiological effects of marijuana. Functions: appetite regulation, produces analgesia (absence of feeling pain), cognitive effects
Nucleosides
compound of a sugar molecule bound with a purine or pyrimidine base. Ex. adenosine - neuromodulator, released by astrocytes when a neuron in the CNS needs extra oxygen or energy, involved in dilation of blood vessels. Adenosine receptors open potassium channels and produce an inhibitory effect
Soluble Gases
used for interneuron communication Ex. nitric oxide dilates blood vessels, near metabolically active parts of the brain, possible role in learning (facilitation neural changes) Ex. carbon monoxide
Neurotransmitters have what 2 effects
They can be excitatory (EPSP) or inhibitory (IPSP).
Autoreceptors
receptors on the presynaptic neuron that regulate the production and release of NT, They are mainly inhibitory