Infant isoflurane exposure affects social behaviours, but does not impair specific cognitive domains in juvenile non-human primates.

BACKGROUND: Clinical studies show that children exposed to anaesthetics for short times at young age perform normally on intelligence tests, but display altered social behaviours. In non-human primates (NHPs), infant anaesthesia exposure for several hours causes neurobehavioural impairments, including delayed motor reflex development and increased anxiety-related behaviours assessed by provoked response testing. However, the effects of anaesthesia on spontaneous social behaviours in juvenile NHPs have not been investigated. We hypothesised that multiple, but not single, 5 h isoflurane exposures in infant NHPs are associated with impairments in specific cognitive domains and altered social behaviours at juvenile age. METHODS: Eight Rhesus macaques per group were anaesthetised for 5 h using isoflurane one (1×) or three (3×) times between postnatal days 6 and 12 or were exposed to room air (control). Cognitive testing, behavioural assessments in the home environment, and provoked response testing were performed during the first 2 yr of life. RESULTS: The cognitive functions tested did not differ amongst groups. However, compared to controls, NHPs in the 3× group showed less close social behaviour (P=0.016), and NHPs in the 1× group displayed increased anxiety-related behaviours (P=0.038) and were more inhibited towards novel objects (P<0.001). CONCLUSIONS: 5 h exposures of NHPs to isoflurane during infancy are associated with decreased close social behaviour after multiple exposures and more anxiety-related behaviours and increased behavioural inhibition after single exposure, but they do not affect the cognitive domains tested. Our findings are consistent with behavioural alterations in social settings reported in clinical studies, which may guide future research.

Reproducibility and repeatability of optical coherence tomography imaging of the optic nerve head in normal beagle eyes.

OBJECTIVE: To assess the reproducibility and repeatability of an optical coherence tomography (OCT) device for imaging the optic nerve region of normal canines. ANIMALS STUDIED: Twelve clinically healthy beagles. PROCEDURES: All animals were anesthetized, and an OCT device was used to image the optic disk region. Total disk area and retinal nerve fiber layer (NFL) thickness in eight segments were obtained from each image. Images were collected by two operators in succession and each operator took five scans, repositioning the device between measurements. B-scan segmentations and disk outlines were subsequently redrawn to obtain manual measurements, allowing for comparisons between automated measurements. RESULTS: Operator 1 had a mean (±SD) NFL thickness (automatic) and disk area of 73.38 ± 7.41 µm and 3.69 ± 0.52 mm², while operator 2 had 74.27 ± 7.33 µm and 3.67 ± 0.51 mm², respectively. With manual corrections, operator 1 had a NFL thickness and disk area of 86.19 ± 8.26 µm and 3.74 ± 0.68 mm², while operator 2 had 86.85 ± 6.91 µm and 3.81 ± 0.56 mm², respectively. Operators did not obtain significantly different values for any region. Intraclass correlation ranged from 0.33 to 0.97 (average 0.78). Coefficient of variation ranged from 8.8 to 36.2%. CONCLUSION: The OCT device demonstrated high inter-rater reliability. Intrarater reliability was strong for disk area and total NFL; however, the segmental regions demonstrated a higher degree of variability. Manual and automated measurements were significantly different for total NFL and some segmental regions; therefore, users should consistently use one method for longitudinal studies.