Neonatal exposure to isoflurane (ISO) or PDZ2WT peptide causes a subtle but significant decrease in acute recognition memory. (A) Plots showing percent of time animals spent investigating novel or known objects among experimental groups (wild type [WT] naïve, n = 11, P < 0.0001; WT control [CON], n = 14, P < 0.0001; WT isoflurane, n = 18, P = 0.005; PSD93KO CON, n = 10, P = 0.001; PDZ2MUT, n = 14, P < 0.0001; PDZ2WT, n = 16, P = 0.001). The double hit animals were unable to significantly discriminate between novel and known objects (PSD93KO isoflurane, n = 10, P = 0.098; PDZ2WT + isoflurane, n = 8, P = 0.227). The data were plotted as mean and SD. The data were analyzed with two-tailed t tests, known versus novel. (B) Plots showing discrimination index as percent of time animals spent investigating novel object over the total time investigating novel and known objects multiplied by 100. Isoflurane-exposed WT animals have a subtle but significant decrement in recognition memory as compared with controls (WT naïve vs. WT isoflurane, P = 0.022; WT CON vs. WT isoflurane, P = 0.043; WT naïve vs. WT CON, P >0.999). PSD93 deficiency did not have a significant effect on recognition memory (WT naïve vs. PSD93KO CON, P > 0.999; WT CON vs. PSD93KOCON, P > 0.999). Isoflurane-exposed PSD93KO animals were not significantly different from PSD93KO controls (PSD93KO CON vs. PSD93KO isoflurane, P = 0.176). Isoflurane-exposed PSD93KO animals differed from WT controls (WT naïve vs. PSD93KO isoflurane, P = 0.011; WT CON vs. PSD93KO isoflurane, P = 0.022). Active peptide exposed animals have a subtle but significant decrement in recognition memory as compared with inactive peptide controls (PDZ2MUT vs. PDZ2WT, P = 0.038; PDZ2MUT vs. PDZ2WT + isoflurane, P < 0.001). Isoflurane exposure did not further significantly impair peptide-exposed animals (PDZ2WT vs. PDZ2WT + isoflurane, P = 0.385). Data from individual animals are plotted and color-coded by sex (red = female and blue = male). The data were analyzed with Kruskal–Wallis followed by post hoc Dunn’s test. The data were plotted as median and interquartile (IQ) range. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.