Memory, cAMP, and PACAP-a phylogenetically conserved function? Studies in Lymnea stagnalis

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a highly conserved polypeptide, which, along with its receptors (PAC1-R, VPAC1, and VPAC2), is expressed in both vertebrate and invertebrate nervous systems. In the first part of the present study, we showed the presence of PACAP in Lymnea stagnalis by mass spectrometry and investigated whether PACAP elevates cAMP in cerebral ganglia. VIP, PACAP, and maxadilan increased cAMP levels by ~47, 79, and 82% of control levels, respectively, and this effect could be blocked by the co-application of the antagonist PACAP6-38 and maxadilan antagonist.