Objective       To determine the effect of repeated propofol sedation on the morphology of newborn neurons in rat hippocampus dentate gyrus and on the spatial learning and memory abilities in rats.       Methods       A total

of 48 SD rats were randomly divided into 2 groups

propofol group and control group. The rats were given intraperitoneal injection of 1% propofol (100 mg/kg) or intralipid at same dose twice per day for 7 consecutive days

respectively. Spatial learning and memory was assessed by Morris water maze test in 28 d after the first treatment. 5-Bromo-2′-deoxyuridine (BrdU) was injected after first treatment

and the numbers of BrdU positive cells in the subgranular zone (SGZ) of dentate gyrus were counted in 1

14 and 28 d after first treatment. Dendritic length and branch of the newborn neurons in the dentate gyrus were assessed in 14 d after first treatment by confocal microscopy.       Results       Repeated propofol sedation exerted significant delay in rats to find hidden objects in 28 d after first treatment (14.55±1.25

vs

9.36±2.54 s

P

<

0.05). The number of BrdU positive cells in SGZ of propofol group had no change in 1 d after the first treatment

and then significantly decreased in 14 d(2 560.58±42.76

vs

2 941.42±46.66

P

<

0.05) and 28 d (1 297.75±31.99

vs

2 273.75±40.29

P

<

0.05) when compared with the control group. Total dendritic length and branch number of newborn neurons in dentate gyrus were obviously decreased in 14 d after first treatment in rats of propofol group than control group (267.25±14.20

vs

394.33±32.59 μm，

P

<

0.05; 2.92±0.29

vs

5.67±0.49

P

<

0.05).       Conclusion       Repeated propofol sedation is detrimental to learning and memory abilities and to dendritic complexity of newborn neurons in adult rats.