GI Motility - Enteric Nervous System Pharmacology

Question 1

Although sympathetic and parasympathetic nerves project onto the submucosal and myenteric plexuses, can the ENS independently regulate gastrointestinal motility and secretion?

Answer 1

Yes

Question 2

The endpoint of enteric neural regulation of motility function is the release of what?

Answer 2

Acetylcholine by cholinergic excitatory motor neurons and the release of nitric oxide and VIP by inhibitory motor neurons onto smooth muscle

Question 3

Why are the myenteric interneurons important?

Answer 3

They are important in controlling the peristaltic reflex.

Question 4

What receptors on circular smooth muscle cells does excitatory acetylcholine stimulate?

Answer 4

M3 (also M2)

Question 5

Serotonin acting at presynaptic 5HT-4 receptors increases the release of what from the submucosal IPANs and also from myenteric neurons at intra-ganglionic synapses?

Answer 5

Acetylcholine and CGRP

Question 6

Which macrolide antibiotic can act as an agonist at the motilin receptors to enhance gastric motility?

Answer 6

Erythromycin

Question 7

What gastrointestinal peptide can act either directly by stimulating its receptors on antral and duodenal smooth muscle or indirectly by stimulating excitatory motor neurons?

Answer 7

Motilin

Question 8

How is gastric motility inhibited?

Answer 8

By sympathetic stimulation

Question 9

Activation of what receptors within the G.I. tract inhibits cholinergic smooth muscle contraction?

Answer 9

Dopamine

Question 10

Which agent in the intestine is pro-motility but it delays gastric emptying in the stomach?

Answer 10

CCK

Question 11

What causes gastric hypomotility?

Answer 11

• Diabetic neuropathy
• anorexia nervosa with achlohydria
• gastric surgery
• in most cases the cause is unknown

Question 12

Is cholinergic innervation at the gut pro-or anti-motility?

Answer 12

Pro-motility

Question 13

Is sympathetic innervation at the gut pro-or anti-motility?

Answer 13

Anti-motility