Fig 1.

Impact of multiple anaesthesia/surgery exposure on anxiety-like behaviours, hippocampal 5-HT transmission and stress response in juvenile rats. (a) Illustration of experimental design. (b–i) Multiple anaesthesia/surgery exposures resulted in anxiety-like behaviours shown in the open field test (OF, b–e) and elevated plus maze test (EPM, f–i). (b) Representative routes of rats in the OF test. No statistical difference was found between the two groups in distance moved (c) and total distance (e), whereas rats in the Multiple AS group showed a significant reduction in time spent in the centre of the open field (d). (f) Representative routes of rats in the EPM test between different groups. Rats in the Multiple AS group exhibited a markedly lower number of open-arm entries (g) along with less time spent in the open arms (h). (j) Hippocampal 5-HT, 5-HIAA, GABA, Glu, and ACh concentrations evaluated using liquid chromatography–mass spectrometry. Significantly elevated 5-HT and 5-HIAA levels in the hippocampus were detected in the Multiple AS group. (k) Quantitative real-time polymerase chain reaction analysis of major subtypes of 5-HT receptors (Htr1a, Htr2c, Tph2, and Htr6) in the hippocampus relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The mRNA levels of Htr1a, Htr2c, and Htr6 in the hippocampus significantly changed after multiple anaesthesia/surgery exposures. (l) Cortisol concentrations at baseline and after stress of the two groups were analysed via enzyme-linked immunosorbent assay. The cortisol concentration in the Multiple AS group after stress was significantly higher than in the control group. n=10 for each group. Data are shown as the mean (sem) of triplicate wells in three different experiments. ∗P<0.05. 5-HIAA, 5-hydroxyindoleacetic acid; 5-HT, 5-hydroxytryptamine; ACh, acetylcholine; GABA, gamma-aminobutyric acid; Glu, glutamic acid; Multiple AS, multiple sevoflurane/surgery exposure; PND, postnatal day.