NTs

iontropic how many subunits

multiple

metabotropic how many subunits

one

Small molecules are

amino acids and amines

GABA synthesis

by glutamate that converts into GABA by GAD

GABA inactivation

reuptake by astrocytes and presynaptic terminal

Glutamate synthesis

Glutamine is converted into glutamate via glutaminase

Glutamate inactivation

reuptake by astrocytes (converts glutamine to glutamate) and presynaptic terminal

ACh type

amine, quarternary

ACh function

- muscle contractions

- sleep/wake cycles

- In PNS: PNS activity 

- In CNS: cognition and alzheimers

ACh type of receptor

Nicotinic ACh receptors: ionotropic

Muscarinic ACh receptors: metabotropic

ACh pathway

Basal forebrain to cortex, amygdala, hippocampus

What NTs depolarize

dopamine, ACh, NE, glutamate, 5-HT3

What is all metabotropic

dopamine, NE, histamine, adenosine, opioid peptides

DOP

analgesia (painkillers), reinforcement/rewarding effect

KOP

dysphoria (unhappiness), temperature control

MOP

euphoria and analgesia (painkillers), respiratory depression

Neuropeptide synthesis

1. Peptides and enzymes for synthesis synthesize in soma

2. Piece parts  transport down axon via axonal transport

3. NT is synthesized in terminal via enzymes working on peptides

neuropeptides inactivated via

enzymatic degradation

NT release steps

1. NTs are synthesized in the terminal button and packaged into synaptic vesicles.

2. AP reaches the terminal button in the presynaptic terminal. 

3. AP opens v-gated Ca++ channels and an influx of Ca++ flows through the presynaptic terminal.

4. Influx of Ca++ moves the synaptic vesicles to the presynaptic membrane or the transmitting side. This is where specialized proteins on the synaptic wall and proteins on the synaptic membrane interact.

5. This leads to exocytosis, where synaptic vesicles release NT molecules into the synaptic cleft.

Dopamine pathway

Mesostriatal: Substantia nigra to basal ganglia (movement)

Mesolimbocortical: VTA → nucleus accumbens and cortex (drugs/pleasure)

Serotonin pathway

Innervates neurons along the midbrain and raphe nuclei

Raphe nucelus → forebrain and spinal cord

NE pathway

Locus coerelus → forebrain

Lateral tegmental area → brainstem and spinal cord

Nonadrenergic neurons: in the locus coereleus and lateral tegmental area → through the cerebrum (cerebral cortex, limbic system, thalamic nuclei)

Histamine pathway

Hypothalamus → cerebral cortex