The effects of administration of amylin into the lateral brain ventric
le on active and passive avoidance behavior and open field activity we
re studied in rats. Amylin increased the latency of passive avoidance
behavior in a dose-dependent manner between 250 ng and 1 mu g, but 50
and 100 ng and 2 mu g were ineffective when given immediately after pa
ssive avoidance conditioning. As concerns active avoidance behavior, t
he extinction was facilitated in a dose-dependent manner. The locomoti
on in an open field was inhibited at 3 h at 500 ng and 1 mu g doses an
d at 6 h at 250 and 500 ng and 1 mu g doses. However, the action was s
till present 24 h after administration of a large dose(1 mu g). The re
aring activity was increased 3 and 6 h after administration of 1 mu g.
Smaller doses (50, 100, 250, and 500 ng) were ineffective. Twenty-fou
r hours following administration, none of the doses used exhibited any
effect. The grooming activity was increased 3, 6, and 24 h after admi
nistration of 1 mu g amylin. Other doses were ineffective. The results
suggest that amylin influences the behavioral reaction in these parad
igms mainly by acting on locomotion, and not by modifying learning and
memory processes.