Fig. 4.

Dihexa increases time in the target quadrant during day 9 probe trials. Time spent in the target quadrant was recorded for each experimental group following i.c.v., i.p., and oral delivery of dihexa. (A) in the i.c.v. study, the scopolamine group performed below the chance level (30 s) and was significantly different from the vehicle control group and the scopolamine→dihexa 1-nmol group (P < 0.001), whereas the scopolamine→dihexa 1-nmol and vehicle control groups were not different (P > 0.05). (B) in the i.p. delivery study, the scopolamine→PBS group performed below the chance level and was different from the vehicle control group (P < 0.001). Each of the treatment groups was different from the scopolamine→PBS group (P < 0.001–P < 0.05), whereas each of the treatment groups was different from one another (P < 0.001–P < 0.05), exhibiting the same dose-response relationship observed in the initial water maze study (Fig. 3). (C) in the oral delivery study, the scopolamine→H₂O group performed near the chance level and was different from the vehicle control group (P < 0.001). Both of the treatment groups were different than the scopolamine→H₂O group (P < 0.05 and P < 0.001, respectively), whereas both of the treatment groups were different from one another (P < 0.001), exhibiting the same dose-response relationship observed in the initial water maze study (Fig. 3). Mean ± S.E.M.; n = 8–10.