Tagged: polypeptide

PACAP and a snail model of Parkinson’s

We are going to talk about a snail model of Parkinson’s disease. I kid you not.

Love them or hate them, recent research on snails is helping us to better understand a potential therapeutic target for Parkinson’s disease, called Pituitary adenylate cyclase-activating polypeptide (or PACAP).

In today’s post we will look at what PACAP is, outline the new snail research, and discuss what they mean for people living with Parkinson’s disease.


Snail2

The humble snail. Source: Warrenphotographic

In a recent post, I talked about a class of drugs called Dipeptidyl peptidase-4 (or DPP-4) inhibitors (Click here to read that post). DPP-4 is a ubiquitous enzyme (it is present on most cells in your body) that breaks down certain proteins.

In that post, I listed some of the proteins that DPP-4 targets – they include:

  • Gastrin-releasing peptide (GRP)
  • Glucagon
  • Glucagon-like peptide-1 (GLP-1)
  • Glucagon-like peptide-2 (GLP-2)
  • Granulocyte-macrophage colony-stimulating factor (GM-CSF)
  • GHRH and IGF-1
  • High-mobility group box 1 (HMGB1)
  • Macrophage-derived chemokine (MDC)
  • Macrophage inflammatory protein-1 α (MIP-1 α), chemokine (C-C motif) ligand 3-like 1 (CCL3L1), or LD78β
  • Pituitary adenylate cyclase-activating polypeptide (PACAP)
  • Neuropeptide Y (NPY)
  • Regulated on activation, normal T cell expressed and secreted (Rantes)
  • Stromal cell-derived factor-1 (SDF-1)
  • Substance P (SP)

Lots of interesting proteins with regards to Parkinson’s disease on this list, including GLP-1 which has been turned in the drug Exenatide (which has demonstrated positive effects in recent clinical trials for Parkinson’s disease – click here and here to read more about this). Another interesting protein on the list is ‘Granulocyte-macrophage colony-stimulating factor‘ (GM-CSF) which we have also discussed in a previous post (Click here to read that post). A synthetic version of GM-CSF (called Sargramostim) has recently been tested in a clinical trial of Parkinson’s disease in Nebraska, and the results of that Phase I trial have been very encouraging.

By treating people with DPP-4 inhibitors (also known as ‘gliptins’), one would be blocking the breaking down of these potentially beneficial proteins – increasing the general amount of GLP-1 and GMCSF that is floating around in the body.


EDITOR’S NOTE: DPP-4 inhibitors have not yet been clinically tested in Parkinson’s disease, and thus we have no idea if they are safe in people with this condition. They are being mentioned here purely as part of an academic discussion.


One protein on the list of DPP-4 targets above that we have not yet discussed is Pituitary adenylate cyclase-activating polypeptide (or PACAP).

And today we are going to have a look at it.

Why?

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