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Flashcards in Neurotransmitters Deck (15):
1

Glutamate

Major excitatory NT in CNS
Post-synaptic receptor type can be ionotropic or metabotropic
Ionotropic receptor: NMDA, kainate AMPA
When receptor is ionotropic, always excitatory
When receptor is metabotropic, can be excitatory or inhibitory
Amino acid
Function:
1.Excitatory neurotransmission-AMPA/Kainate receptor
2.Modulation of synaptic plasticity-NMDA receptor
3.Activation of second messenger system-Metabotropic receptor

Cell bodies and projections in CNS






2

GABA

Amino acid
Major inhibitory NT of CNS
Ionic and metabotropic post-synaptic receptors
Function:
1. Inhibitory neurotransmission

Receptors:
Entire CNS: GABA a, GABA, b
Retina: GABA c

Transmission impacted by many drugs, such as anti-anxiety, hypnotics, anti-epileptics, and aesthetics

3

Dopamine

Cell bodies in midbrain (substantia nigra, pars compacta, and ventral tegmental area)

Project on striatum, prefrontal cortex, lambic cortex, nucleus accumbens, amygdala

Receptor D1-5

Causes neuromodulation; involved in reward-motivated behavior and motor pathways
CNS neurons originate in brainstem regions

3 pathways: mesolimbic (reward pathway/addiction), nigrostriatal (control of movement), and mesocortical (working memory)

Drugs that influence dopamine transmission: antipsychotics, nicotine, Cochin, methamphetamine, amphetamines, and methylphenidate

4

Serotonin

Cell bodies in midbrain and pons (raphe nuclei) and project onto entire CNS

Receptors: 5-HT1A-F, 5HT2A-C', 5HT3-7

Neuromodulation

5

Histamine

Cell bodies in hypothalamus and project onto brain

Receptor: H1-3

Mainly excitatory neuromodulation

6

Definition of NTs

1. Synthesized in pre-synaptic neuron

2. Reside in synaptic terminal, usually vesicles

3. Elicit same response when tested under in-vitro conditions

4. Bind to specific receptors on post-synaptic membrane

5. Inactivated in or removed from synaptic cleft

7

Major 6 NTs

Glutamate (excitatory AA)
GABA (inhibitory AA)
Dopamine (biogenic amine)
Norepinephrine (biogenic amine)
Serotonin (biogenic amine)
Acetylcholine

8

Synaptic vesicles

Protect NT from degradation

Transported to nerve terminals and aggregate in presynaptic region

Motored by V-type H+ ATPase: uses a proton gradient to exchange H+ for NT

9

NMDA Receptor

Voltage gated and ligand gated Ca2+ glutamate ionotropic receptor

Activated by the binding of glutamate to AMPA, which allows for Na+ to enter post-synaptic neuron and depolarize the cell. Once depolarized, Mg2+ is displaced and NMDA is active

Blocked by Mg2+ at RMP

When blocked by PCP and ketamine, causes hallucinations that resemble schizophrenia

Important for development of synapses, regulating neural circuits, and long term potentiation (increased responsiveness of post-synaptic neurons after repeated stimulation)

10

Glutamate exotoxicity

Occurs in many diseases such as ALS, Alzheimer's, tumors, oxygen deficiency, ischemia, trauma, and repeated seizures.

When there is increased glutamate release or decreased glutamate reuptake, causing increased Ca2+ leakage into cells

Increased Ca2+ causes increased water uptake and stimulation of intracellular enzymes that degrade proteins, lipids, and nucleic acids

Cell death

11

Neuromodulators

Subclass of NTs that usually originate in the brainstem and project widely throughout the cortex

Affect wakefulness, attention, personality, motivation, reward pathway, etc

Muscarinic receptors

Excitatory or inhibitory depending on the receptor

Target for many psychiatric drugs

12

ANS receptor of dilator muscle in eye

Alpha adrenergic

When epi or norepi bind, cause pupillary contraction to increase pupil size (mydriasis)

13

ANS receptor of sphincter (pupillary constrictor muscle)

Muscarinic

When ACh binds, mediates contraction causing miosis

14

ANS receptor of ciliary muscle

Muscarinic

Binding of ACh, controls accommodating and contraction puts tension on trabecular mesh work to facilitate aqueous humor outflow.

15

ANS receptor of ciliary epithelium

Beta adrenergic

Promotes secretion of aqueous humor by