Exam 1 - Holmes' NTs and GPCRs

Question 1

acetylcholine

Answer 1

Choline ester:
Acetylcholine – excitatory
Acts on ACh receptors:
Nicotinic: ionotropic/cation channel
Muscarinic: metabotropic/GPCR
Seen in NMJ, parasympathetic/sympathetic nervous system, adrenal medulla

Question 2

Glutamate

Answer 2

AA’s:
Glutamate – major CNS excitatory NT
Acts on glutamate receptors:
ionotropic receptors- cation channels (AMPA, NMDA, Kainate),
ionotropic receptors – GPCRs (mGluR)

Question 3

GABA

Answer 3

AA
GABA – major CNS inhibitory NT
Made from glutamate.
Acts on GABA receptors:
GABAA: ionotropic receptors/ Cl- channels
GABAB: metabotropic receptors / GPCRS
Seen in GABAergic neurons in CNS

Question 4

Glycine

Answer 4

AA
Glycine – major CNS inhibitory NT
Acts on glycine receptors:
GlyR: ionotropic receptors/ Cl- channels. Seen in glycinergic neurons in CNS

Question 5

Histamine

Answer 5

Biogenic amine:
Histamine – excitatory and inhibitory
Acts on His receptors H1-4:
H1 neurons in hypothalamus that regulate circadian cycle.
H3 in CNS inhibits release of Ach, dopamine, norepi, 5HT, GABA

Question 6

Serotonin

Answer 6

Biogenic amine:
Serotonin – excitatory and inhibitory
   Made from Tryptophan
   Acts on serotonin receptors: metabotropic/GPCRs
   Seen in brain and GI tract

Question 7

Dopamine

Answer 7

Biogenic amine:
Dopamine – catecholamine, made from tyrosine, both inhibitory and excitatory
Neurohormone, inhibits release of prolactin
Acts on dopaminergic receptors: metabotropic/GPCRs
Seen in NT and dopaminergic neurons

Question 8

Norepinephrine

Answer 8

Biogenic amine:
Norepinephrine – catecholamine, made from tyrosine, both inhibitory and excitatory
Stress hormone, flight or fight
Acts on adrenergic receptors: metabotropic/GPCRs
Seen in NT and adrenergic neurons

Question 9

Epinephrine

Answer 9

Biogenic amine:
Epinephrine – catecholamine, made from tyrosine, both inhibitory and excitatory
Stress hormone, flight or fight
Acts on adrenergic receptors: metabotropic/GPCRs
Seen in adrenal medulla

Question 10

NO

Answer 10

Neuropeptide:
NO
Membrane permeable gas, freely diffuses and covalently modifies effectors, no vesicles needed

Question 11

Purines-ATP

Answer 11

Neuropeptide:
Purines – ATP
NT released w noradrenaline and neuropeptide Y
Acts at postjunctional P2X receptors to evoke vascular smooth muscle contraction
Extracellular ATP also plays role in immune system

Question 12

GPCR receptor types:

alpha 1 receptors

Answer 12

●α1 adrenoceptors:

• found mostly postsynaptically in CNS
• excitatory function
• Gq  phospholipase C  Ca release  protein kinase C  phosphorylates effectors (like ion channel)
• found in smooth muscle of skin, skeletal muscle, splanchic region, sphincters, iris
• respond to only high conc catecholamines. Not activated by norepi/epi in bloodstream

Question 13

GPCR receptor types:

alpha 2 receptors

Answer 13

● α2 adrenoceptors:

• found both pre and post synaptically in CNS
• inhibitory function
• Gi  inhibits adenylyl cyclase and thus cAMP

Question 14

GPCR receptor types:

beta 1 receptors

Answer 14

●β1-adrenoceptors:
-norepi  activates Gs  adenylyl cyclase  cAMP  protein kinase A  phosphorylates
various effectors like ion channels
-in heart: increases heart rate, conduction velocity and contractility.
*flight or fight response!
-also in kidney

Question 15

GPCR receptor types:

beta 2 receptors

Answer 15

●β2-adrenoceptors:

• found in skeletal muscle, GI tract and bladder, bronchioles
• flight or fight response!
• activated by epi
• can also be coupled to Gi (β1 is only Gs!)
• activated by lower conc of catecholamines than the α receptors (epi/norepi can activate them!)