Biochem: 5HT, NE, Hist

Question 1

Major sites of cell bodies of neurons that produce Serotonin (5-HT).

Answer 1

Raphe Nuclei
(located in midbrain, pons, and medulla right along the midline)

Question 2

Describe the 2 steps required to make 5-HT.

Answer 2

1. Tryptophan –> 5-Hydroxytryptophan
   (tryptophan hydroxylase)
2. 5-Hydroxytryptophan –> 5- Hydroxytriptamine
   (amino acid decarboxylase or DOPA decarboxylase)

Question 3

Melatonin can be made from 5-HT. Where in the brain is the main site where this occurs and what is the function of melatonin?

Answer 3

Occurs in the pineal gland. Regulates endocrine rhythms.

Question 4

Name the major enzyme that degrades 5-HT and the final product produced that can be measured in the urine.

Answer 4

Monoamine Oxidase A

5-hydroxyindole Acetic Acid (5-HIAA)

Question 5

Type of histological abnormality in brain tissue seen in schizophrenia patients.

Answer 5

Abnormal arrangements of hippocampal pyramidal cells in the medial temporal lobe.

Question 6

Describe the hyperdopaminergia hypothesis for schizophrenia.

Answer 6

Patients with schizophrenia had brain tissue with excess amounts of Dopamine (DA) and excess amounts of D2 receptors produced.

This has lead many to believe a correlation between schizo and high DA levels.

Question 7

What is the mechanism of action of “atypical antipsychotics” and a common side effect.

Answer 7

Block 5-HT2 receptors to combat excess 5-HT. Can have parkinson-like symptoms but are still very well tolerated.

Question 8

Describe the signaling and function of 5-HT 1 receptors.

Answer 8

Inhibitory - decreases cAMP

-over stimulation leads to migraines

Question 9

Describe the signaling and function of 5-HT 2 receptors.

Answer 9

Excitatory - increase IP3 and DAG

• involved in hallucinations, LSD activates these.
• site where atypical anti-psychotics block

Question 10

Describe the signaling and function of 5-HT 3 receptors.

Answer 10

Excitatory - ligand gated sodium channels

-involved in nausea, target for anti-nausea agents used for chemotherapy patients

Question 11

Name the two sites in the CNS where MT-1 (melatonin-1) receptors are most common.

Answer 11

1. Pars Tuberalis of Pituitary Gland

2. Suprachiasmatic Nucleus of hypothalamus

Question 12

Name the site in the CNS where MT-2 (melatonin-2) receptor are most common.

Answer 12

Retina

Question 13

Name the 2 locations that contains cell bodies of neurons that produce Norepinephrine (NE) in the CNS.

Answer 13

1. Locus Ceruleus: pons

2. Lateral Tegmental Area: medulla

Question 14

DA is metabolized to NE using the enzyme Dopamine Beta-hydroxylase. What two minerals are required from the diet for this reaction to occur?

Answer 14

1. Copper

2. Vitamin C

Question 15

Name the major enzyme that degrades DA.

Answer 15

Monoamine Oxidase B

Question 16

Name the major enzyme that degrades NE.

Answer 16

Monoamine Oxidase A

also metabolizes 5-HT, and Epi

Question 17

Final product of NE metabolism that can be measured in the urine.

Answer 17

Vanillylmandelic Acid (VMA)

Question 18

Describe the signal cascade that occurs in the 2 alpha and 3 beta adrenergic receptors.

Answer 18

Alpha-1: Gq - increase in IP3 and DAG
Alpha-2: Gi - decrease cAMP

Beta-1,2,3: Gs - increase cAMP

Question 19

Location in the CNS where neuronal cell bodies that produce histamine are located.

Answer 19

Tuberomamillary Nucleus in Hypothalamus

Question 20

Describe the 1-step synthesis of histamine.

Answer 20

Histidine —> histamine

histidine decarboxylase

Question 21

Explain the signaling cascade of the histamine receptors.

Answer 21

H1: increase IP3 and DAG (excitatory)
H2: increases cAMP (excitatory)
H3 and H4: decreases cAMP (inhibitory)