Peptides
in Processes of Learning and Memory by Yoshimasa Yamaguchi, Seiichiro Kawashima, Hideshi Kobayashi
It
is well known that transmitters such as acetylcholine (ACh),
adrenaline, dopamine and serotonin are involved in the process
of learning and memory (15, 27, 30, 60). In addition, the participation
of hormonal peptides, such as adrenocorticotropic hormone (ACTH),
melanocyte-stimulating hormone (MSH), vasopressin and cholecystokinin,
in the learning and memory processes has been reported m the
latter half of the 1980s (see 2, 12, 13, 31 for reviews)
We have studied the effects of several peptides on learning
and memory, and observed that the results are often ambiguous
or contradictory, when we do not consider carefully the following
points: doses of peptides, routes of administration, kinds of
tasks for evaluation of efficacy. Further, it is also important
to determine the active part of the ammo acid sequence of effective
peptides, locations of their receptors in the brain and the
bioactivity of their analogs. Further, antagonists are useful
for analysis of the mechanisms of peptide actions. In this article,
we describe several experiments concerning cognitive effects
of vasoactive intestinal peptide (VIP) and pituitary adenylate
cyclase activating polypeptide (PACAP), and we discuss some
of the important issues mentioned above, referring the list
(Table 1), summarizes recent data obtained by others on the
effects of other peptides on learning and memory For more detailed
descriptions of these phenomena, there are recent excellent
reviews by De Wied (12) and by Kovacs and De Wied (37).
