Fig. 2.

The percentage of rats showing lower lip retraction after receiving (+)-8-hydroxy-2-(dipropylamino) tetralin hydrobromide (8-OH-DPAT; upper and middle panels) and the minimal effective dose of 8-OH-DPAT for producing lower lip retraction (lower panel) under different feeding conditions. The vertical dashed lines indicate a change in chow type for both groups of rats as follows: initially (week 0) all rats had free access to standard chow; during weeks 1-8 (phase 1) rats in group 1 had free access to standard chow (open circles) and rats in group 2 had free access to high fat chow (closed triangles); during weeks 9-15 (phase 2) rats in group 1 had free access to high fat chow (closed circles) and rats in group 2 had free access to standard chow (closed triangles). In all panels, open symbols indicate results obtained in rats eating standard chow and closed symbols indicate results obtained in rats eating high fat chow. Upper and middle panels: horizontal axes, dose in mg/kg body weight; vertical axes, percentage of animals showing lower lip retraction. Lower panel: horizontal axis: week in the study; vertical axis minimal effective dose (mean ± S.E.M.) in mg/kg body weight. Each symbol represents the mean ± S.E.M. of 8 (group 1) or 9 (group 2) rats. * = significant difference between group 1 and group 2. $ = significant difference between week 0 and week 6 for group 2 (open and closed triangles). # = significant difference between week 6 and weeks 10 and 14 for group 1 (open and closed circles).