TABLE 31-3
Neuroregulatory Peptides of the Hypothalamus
Hypothalamic Peptide
Neurotransmitter1,2
No.
AA’s
GI Counterpart
Functions in CNS
Inferred or Postulated
Functions in Gut
Cholecystokininoctapeptide
8
CCK-33;T’cellin
Suppression of appetite
Gallbladder contraction;
(CCK-
8
)*
duodenum and jejunum
Opiate antagonist
Pancreatic enzyme secretion
Gastrin*
17
Gastrin-17; “G”cellsin
stomach, duodenum
Appetite regulation?
Gastric acid secretion via histamine release from
APUD cells in gastric mucosa
(enterochromaffin-like (ECL) cells)
(H
2
antagonist-sensitive)
Substance P*
1 1
Neural crest-derived cells,
sensory C fibers
Nociception
Vasoconstriction (local effect)
Mediates immune response to inflammation)?)
Vasoactive Intestinal
Polypeptide (VIP)*
28
Enteric nerve endings
Probably vasomotor
Probably vasomotor
Gastrin-Releasing Peptide(GRP)
(mammalian Bombesin)*
27
Stomach, duodenum
Thermoregulation
Nociception
Gastrin release from G cells in stomach
Somatostatin*
14
Stomach, pancreatic islet,
myenteric plexus
Suppressionof GHRHrelease (?)
SuppressionofTRH release (?)
Suppresses release of glucagon, insulin,
gastrin,CCK, secretin, VIP, GIP
Suppressionof acid production by parietal cells,
pancreatic enzyme and bicarbonate release
Suppressionof proliferative growth in most cells
Neurotensin*
13
“N” cells of Ileum
Suppresses appetite
Not known
/
3
-Endorphin
31
7
Suppresses avoidance/alarm behavior
(fi
j)
Suppressesbehavioral reactiveness to pain,
trauma, stresses (p,j)
Stimulates appetite (p,?)
?
Met-Enkephalin (MENK)*
5
Myenteric neurons
(A<5 and C fibers)
Suppresses nociception (fi)( p,,)
Substance P antagonism (S)( /x,)
Depresses medulla respiratory center
(fi2)
Suppressionof GI motility
(p2)
Stimulation of sphinctertone
(/jl2)
Leu-Enkephalin (LENK) *
5
Myenteric neurons
(AS
and C fibers)
Suppresses nociception (5)( /Xj)
Substance P antagonism
(S)( p. l
)
Depresses medulla respiratory center
(ji2)
Suppressionof GI motility (yu,2)
Stimulation of sphinctertone
(p2)
Dynorphin 1-8
8
?
Stimulates appetite (/<)?
StimulatesADH release (/x)(CNS)
InhibitsADH release (/<)(neurohypophysis)
?
1
* = A “B rain-G ut” peptide; has a counterpart in the gastrointestinal tract.
2 M any are also produced in other regions o f the C N S. F o r exam ple, the enkephalin pentapeptides are produced m ainly in the periaqueductal gray (m esencephalon), the raphe nucleus (pons), and in the
dorsal horn o f the spinal cord, w ith m inor am ounts in the hypothalam us. In contrast, /3-endorphin is produced m ainly in the adenohypophysis and hypothalam us.
