[Neuroprotective effects of novel derivatives of vasoactive intestinal peptide and pituitary adenylate cyclase-activating peptide in two brain ischemic models on mice].

BACKGROUND

Vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase-activating peptide (PACAP), are members of a VIP/secretin/glucagon family. These peptides were demonstrated to possess the neuroprotective properties. However, these peptides are not suited to be developed as a medicine for brain ischemia because of their susceptibilities to endopeptidases.

METHODS

We examined the effects of IK 312548 (IK), VIP derivative, and Ac-PACAP, PACAP derivative, on the 10 min two-vessel occlusion (2 VO) model in C 57 BL/6 N mice lacking a part of the posterior communicating artery, and the 30 min middle cerebral artery occlusion (MCAO) model in ICR mice. A 10 ml x kg(-1) dose of each derivative (final concentration; 1 fmol x kg(-1) and 100 pmol x kg(-1)) was injected intraperitoneally (i.p.) to each animal just after the preparation of brain ischemia.

RESULTS

In 2 VO experiments, the number of neuronal cells in hippocampus was significantly reduced. However IK and Ac-PACAP treatments inhibited such reductions of neuronal cells in a dose-dependent manner. Particularly, between 1 pmol x kg(-1) and 100 pmol x kg(-) IK, and also between 10 fmol x kg(-1) and 1 pmol x kg(-1) Ac-PACAP significantly protected neuronal cell loss. In MCAO experiments, more than 60% of hemisphere was damaged. By treatment of IK (1-100 pmol x kg(-1)) and Ac-PACAP (1 fmol-1 pmol x kg(-1)), the range of brain damage decreased in a dose-dependent manner.

CONCLUSIONS

Ac-PACAP and IK after the brain ischemia could pass the blood-brain barrier and protect brain cell damage.