Neuropharm III

Question 1

How are neuroactive peptides inactivated? Where are they frequently seen physiologically?

Answer 1

by extracellular peptidases

often in gut and endocrine tissues

Question 2

What are locations with the greatest diversity of neuroactive peptides? (top three)

Answer 2

hypothalamus

2. amygdala
3. autonomic nuclei

Question 3

How do neuroactive peptides work (type of receptor, features of receptor)

Answer 3

All work through G-protein coupled receptors. often slow but long lasting modulators of synaptic function. These tend to be HIGH AFFINITY receptor. All show desensitization in the continued presence of peptides

Question 4

What are the magnocellular hypothalamic neuroactive peptides?

Answer 4

oxytocin and vasopressin: released to general circulation

Question 5

What are the other kinds of hypothalamic neuroactive peptides?

Answer 5

those released by nuerons that project to the anterior pituitary via the portal circ., and those that project diffusely to autonomic and limbic areas of the brain

Question 6

What peptides modulate pain in the brain?

Answer 6

substance P and calcitonin gene-related peptide (CGRP)

Question 7

What peptides modulate central analgesia?

Answer 7

opioid peptides (enkephalins beta endorphin, dynorphin) in spinal cord

Question 8

Describe the low-threshold spike

Answer 8

after an AP, hyperpolarization occurs.
in some cells, there are T-type voltage gated Ca channels.
These channels open during hyperpolarization.
Ca enters the cell and the cell depolairzes. This gives rise to an Na spike with prolonged Ca-induced depolarization. This is because Ca T channels stay open longer than Na channels.
Important for arousal and sleep regulation, but may be a problem in epilepsy.