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. 2008 Feb 6;28(6):1374–1384. doi: 10.1523/JNEUROSCI.3632-07.2008

Figure 5.

Figure 5.

Effects of subchronic and chronic fluoxetine on hippocampal synaptic plasticity. A, B, Chronic fluoxetine (28d Flx; B) but not subchronic fluoxetine (5d Flx; A) reduces paired-pulse depression in both sham (Sham) and x-irradiated (x-ray) animals at stimulation intensity that elicited one-third of the maximal response compared with the vehicle group (Veh) (ANOVA, F (1,29) = 9.05, *p = 0.005 for chronic treatment; F (1,29) = 0.95, p = 0.34 for irradiation; F (1,23) = 0.17, p = 0.68 for subchronic treatment; F (1,23) = 0.31, p = 0.58 for irradiation). Inset, Representative traces of first response (1) and second response (2) (PPR, paired-pulse ratio, second response/first response). C, D, Both subchronic (C) and chronic (D) fluoxetine increased input–output relationships in both sham and x-irradiated animals (ANOVA, F (1,36) = 11.46, p = 0.0017 in subchronic group for treatment; F (1,36) = 0.62, p = 0.44 for irradiation; F (1,27) = 16.72, p = 0.0003 in chronic group for treatment; F (1,27) = 0.23, p = 0.63 for irradiation). Curves are fitted with a four-parameter logistic formula (McNaughton, 1980). E, Subchronic fluoxetine suppressed ACSF–LTP, and x-irradiation completely eliminates ACSF–LTP. F, ANOVA performed on the last 10 min of LTP recording revealed a significant main effect of irradiation (F (1,25) = 7.28, p = 0.012) as well as a main effect of subchronic fluoxetine (F (1,25) = 4.84, p = 0.037) (F). S, Sham; X, x-irradiation, V, vehicle; F, fluoxetine; Fisher's post hoc analysis were performed between individual groups (*p < 0.05). G, Chronic fluoxetine enhanced ACSF–LTP, and x-irradiation completely blocked LTP. Insets show averages of five consecutive fEPSPs at baseline (1) and in the last 10 min of LTP recordings (2). H, ANOVA performed on the last 10 min of LTP recording revealed a significant main effect of irradiation (F (1,27) = 63.01, p < 0.0001), a main effect of chronic fluoxetine (F (1,27) = 4.61, p = 0.041), as well as an irradiation × treatment interaction (F (1,27) = 6.21, p = 0.019). Fisher's post hoc analysis were performed between individual groups (*p < 0.05).