GALANIN

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GALANIN

• BY NKEM UMEOKOLI
• MSc Neuropharmacology
• University of East London

2

• Galanin is a 29 amino acid neuro-peptide isolated
  from porcine intestine.
• It shows many interesting physiological and
  behavioural actions which may be relevant to some
  disease states and clinical therapeutics.

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• Named from the first and last amino acids in its
  porcine sequence - Glycine and Alanine.
• The first 15 amino acids in its peptide sequence
  is conserved in a variety of species including
  Humans, rats, pigs, cows, dogs, chickens and
  alligators.

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• NMR analysis of Rat galanin indicates a secondary
  structure of two alpha-helices interrupted by a
  bend in the proline-13 amino acid residue.

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• Galanin is widely distributed in both the central
  and the peripheral nervous systems.
• In the CNS hypothalamus/hippocampus, brain stem,
  spinal cord.
• In the peripheral organs pancreas, adrenal
  gland, gastrointestinal tract, genital tract,
  urinary bladder

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• Galanin binds to and acts on G-protein coupled
  receptors.
• Only one galanin receptor subtype has been cloned
  so far - GalR1.
• Pharmacological evidence suggests more than one
  receptor subtype exists.

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• Purified galanin receptors from rat and human
  brain show a single polypeptide of 54-60 kDa.

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• The 1st antagonist for the galanin receptor has
  been synthesised called M15 or Galantide.
• Binding of the antagonist to the galanin receptor
  is 0.2 - 50nM concentration.

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Physiological functions of Galanin

• In Alzheimers disease
• galanin is elevated
• galanin inhibits acetylcholine release
• Galanin receptor antagonists may enhance
  cholinergic transmission.

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• Galanin stimulates
• food consumption
• release of luteinising hormone
• prolactin release
• growth hormone

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• Galanin serves an antinociceptive function in
  the spinal cord.
• Galanin agonists may be clinically useful in
  potentiating the analgesic actions of morphine.

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• Galanin inhibits insulin release, therefore
  causes hyperglycemia.
• Galanin may be involved in some forms of human
  obesity.

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• In conclusion
• Galanin is a 29 amino acid neuro-peptide has
  inhibitory actions
• Exerts biological effects in mammals such as
  feeding, insulin release and growth hormone
  release.
• Is involved in the pathogenesis of Alzheimers
  disease and in antinociception.