The amidated PACAP1-23 fragment is a potent reduced-size neuroprotective agent.
BACKGROUND
Neurodegenerative disorders, such as Parkinson's disease (PD), are characterized by neuronal death involving, among other events, mitochondrial dysfunction and excitotoxicity. Along these lines, several attempts have been made to slow this pathology but none have been yet discovered. Based on its capacity to cross the blood-brain barrier and provide neuronal protection in vitro and in vivo, the pituitary adenylate cyclase-activating polypeptide (PACAP) represents a promising lead molecule. Pharmacological studies showed that PACAP interacts with three different G protein-coupled receptors, i.e. PAC1, VPAC1 and VPAC2. However, only PAC1 is associated with neuronal anti-apoptotic actions, whilst VPAC activation might cause adverse effects. In the context of the development of PAC1-selective agonists, PACAP(1-23) (PACAP23) appears as the shortest known PACAP bioactive fragment.


METHODS
Hence, the capacity of this peptide to bind PACAP receptors and protect neuroblastoma cells was evaluated under conditions of mitochondrial dysfunction and glutamate excitotoxicity. In addition, its ability to activate downstream signaling events involving G proteins (Gαs and Gαq), EPAC, and calcium was also assessed.


RESULTS
Compared to the endogenous peptide, PACAP23 showed a reduced affinity towards PAC1, although this fragment exerted potent neuroprotection. However, surprisingly, some disparities were observed for PACAP23 signaling compared to full length PACAP, suggesting that downstream signaling related to neuroprotection is distinctly regulated following subtle differences in their PAC1 interactions.


CONCLUSIONS
Altogether, this study demonstrates the potent neuroprotective action of amidated PACAP23.


GENERAL SIGNIFICANCE
PACAP23 represents an attractive template for development of shorter PACAP-derived neuroprotective molecules.
['Lamine|A|A|', 'Poujol de Molliens|M|M|', 'Létourneau|M|M|', 'Hébert|T E|TE|', 'Vaudry|D|D|', 'Fournier|A|A|', 'Chatenet|D|D|']
D000818:Animals D016466:CHO Cells D020013:Calcium Signaling D003412:Cricetulus D006801:Humans D018696:Neuroprotective Agents D010455:Peptides D051219:Pituitary Adenylate Cyclase-Activating Polypeptide D051239:Receptors, Vasoactive Intestinal Peptide, Type II D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I
Neuroprotection Neurodegenerative disorder Mitochondrial dysfunction Excitotoxicity PACAP PAC1