mod5-7 vocab

Synapse

• The junction between two neurons where information is transmitted.

Synaptic Cleft

• The small gap between the presynaptic and postsynaptic membranes where neurotransmitters diffuse.

aplysia californica

sea slug used to learn studying and memory.

• Gill-siphon withdrawal reflex

• Simple reflex used to study habituation & sensitization.

• Habituation

• Reduced response to repeated stimulation.

• Sensitization

• – Increased response after a strong stimulus.

• Long-term potentiation (LTP)

• – Strengthening of synapses; basis of learning & memory.

• NMDA channel

Allows Ca²⁺ entry, crucial for LTP induction.

• LTP induction

• Requires NMDA receptor activation & Ca²⁺ influx.

• LTP Maintenance

Strengthened synapse through AMPA receptor insertion.

• Monoamine oxidase inhibitor (MAOI)

Prevents breakdown of serotonin, dopamine, norepinephrine, increasing their levels.

• Selective serotonin reuptake inhibitor (SSRI)

• – Blocks serotonin reuptake, increasing serotonin availability (e.g., Prozac).

• Psychedelics

Alter perception & consciousness (e.g., LSD, psilocybin).

PCP (Phencyclidine)

– Blocks NMDA receptors, mimicking schizophrenia-like symptoms.

THC (Tetrahydrocannabinol)

– Active ingredient in marijuana; binds cannabinoid receptors, altering mood & memory.

Opiate/Opioid

Pain-relieving drugs (e.g., morphine, heroin).

• Morphine

• – Natural opioid; strong painkiller.

• Heroin

• Synthetic opioid; highly addictive, converts to morphine in the brain.

Codeine

– Milder opioid, used in cough medicine

• Cocaine –

• Blocks dopamine reuptake, increasing dopamine effects in the brain.

• Amphetamine –

• Increases dopamine & norepinephrine by blocking reuptake and stimulating release.

• Anticonvulsants

• – Reduce seizure activity by enhancing GABA or blocking excitatory signals.

• Benzodiazepines

• – GABA agonists, used for anxiety; enhance inhibitory effects.

• Barbiturates

• – GABA agonists, cause sedation; can be deadly when combined with benzodiazepines.

• Nicotine

• – ACh agonist at nicotinic receptors, leading to increased stimulation.

• Curare

• – Blocks nicotinic ACh receptors, leading to paralysis.

• Botulin Toxin

• – Blocks ACh release, leading to paralysis (used in Botox).

• Antagonist

• – A substance that blocks neurotransmitter action (e.g., curare blocks ACh).

• Agonist

• – A substance that mimics or enhances neurotransmitter action (e.g., nicotine for ACh).

G-Protein Pathway Order

"Neuro-GDP-GTP-Effect-Second-Protein-Gene"

• Neurotransmitter binds GPCR.

• GDP → GTP (activates G-protein).

• Effector protein (e.g., adenylyl cyclase) activated.

• Second messenger (e.g., cAMP) produced.

• Protein kinase (e.g., PKA) activated.

• Gene transcription activated (long-term changes).

• c-fos –

• Immediate early gene activated by neuronal stimulation.

• CREB (cAMP response element-binding protein)

• – Transcription factor activated by PKA.

• Transcription factor

• – Protein that regulates gene expression.

• PKA regulatory subunit

• – Keeps PKA inactive until cAMP binds.

• PKA catalytic subunit

• – Active portion of PKA after binding cAMP.

• – Removes phosphate groups.

• Phosphatase

• Phosphorylation

• Adds phosphate (PO₄³⁻) to proteins → activates or deactivates them.

Protein kinase

– Enzyme that phosphorylates proteins (e.g., PKA, PKC).

• cAMP

• – Second messenger that activates PKA.

Adenylyl cyclase –

Enzyme that converts ATP → cAMP (activated by G-proteins)

Cyclic nucleotide –

Includes cAMP & cGMP; relays signals

Second messenger

– Intracellular signal (e.g., cAMP, Ca²⁺, IP₃)

GDP

– Inactive G-protein state.

GTP

– Active G-protein state

Heterotrimeric G-protein –

Has α, β, and γ subunits; activated by GPCRs.

cell permeant vs. cell impermeant molecules –

Cell permeant can cross membranes (e.g., steroids), while cell impermeant need receptors (e.g., neurotransmitters).

• Signal amplification

• – A single molecule triggers a large cascade.

• Dopamine (DA)

• – Reward, movement (Parkinson’s = dopamine loss).

• Epinephrine

• – Fight-or-flight hormone.

• Norepinephrine (NE)

• – Involved in attention & arousal.

• Catecholamines

• – Dopamine, norepinephrine, epinephrine (made from tyrosine).

• Serotonin (5-HT)

• – Mood, sleep, appetite.

• Neurotransmitter transporter –

• Reuptakes neurotransmitters from the synaptic cleft (e.g., DAT for dopamine, SERT for serotonin).

• Vesicular transporter

• – Loads neurotransmitters into vesicles (e.g., VMAT for dopamine).

• AMPA receptor

• – Fast ionotropic receptor for glutamate.

NMDA receptor

– Ionotropic glutamate receptor involved in LTP (learning & memory); requires Mg²⁺ removal for activation.

Major Neurotransmitters

• Glutamate – Major excitatory neurotransmitter in the CNS.

• GABA – Major inhibitory neurotransmitter in the CNS.

• Glycine – Another inhibitory neurotransmitter, mainly in spinal cord.

• Acetyl CoA – A molecule used in energy production; provides acetyl for ACh synthesis.

• Choline Acetyltransferase (ChAT) – Enzyme that synthesizes acetylcholine (ACh).

• Acetylcholinesterase (AChE) – Enzyme that breaks down ACh, stopping its action.

• Nicotinic ACh receptor – Ionotropic, fast, found in neuromuscular junction.

• Muscarinic ACh receptor – Metabotropic, slow, found in brain & heart.

• Myasthenia gravis – Autoimmune disease where antibodies block nicotinic ACh receptors, causing muscle weakness.