Background  Studies have shown that stress during pregnancy can affect the growth and development of fetuses and offspring, and this effect has sex differences, but the results are controversial, and there are few studies on the emotional damage of offspring of different sexes caused by stress during pregnancy.

Objective  This experiment is designed to observe the effect of chronic stress during pregnancy on emotional damage of offspring of different sexes.

Methods  Thirty-two SD female rats were randomly divided into a model group and a control group (16 rats in each group), 24 male rats were divided into a model mating group (n=16) and a control mating group (n=8). Each rat of the model group was reared in a single cage and received chronic unpredictable mild stress (CUMS) for 28 d, including hot water swimming for 5 min, cold water swimming for 5 min, tail pinching for 2 min, crowding for 24 h, moist bedding for 24 h, cage shaking for 30 min, and space restriction for 2 h. One stressor was administered daily and the same stressor did not repeat within 7 d. Blood was collected from the endocanthal vein of the two groups of female rats 1 d before and 1, 7, 14, 21, and 28 d after stress, the plasma was separated by centrifugation, and ¹³¹I radioimmunoassay was used to measure plasma corticosterone concentration. On postnatal day 21 (PND21), 16 offspring rats (half male and half male) were randomly selected from each group, their plasma corticosterone concentration was measured on PND28 and PND42, and their emotional damage was measured on PND42.

Results  The plasma corticosterone levels of dams in the model group on the 14th, 21th, and 28th days of stress (394.02±97.40), (444.12±90.43), and (463.71±107.75) μg·L⁻¹ were higher than those in the control group (285.63±81.64), (341.78±48.39), and (320.42±84.76) μg·L⁻¹ (all P< 0.05). On PND28 and PND42, the plasma corticosterone levels in the female model offspring group (543.30±90.21) and (530.76±83.10) μg·L⁻¹ were higher than those in the female control offspring group (397.77±64.27) and (325.78±61.03) μg·L⁻¹ (both P<0.05). In the sugar water preference test, the total fluid consumption (10.74±1.28) mL, sugar water consumption (5.50±1.30) mL, and 1% sucrose preference percentage (20.36±3.41) % in the female model offspring group were lower than those in the female control offspring group (13.74±2.06) mL, (8.56±2.04) mL, and (62.11±8.05) % (allP<0.05). In the open field test, the horizontal score, vertical score, and cleaning times of the male model offspring group were lower than those of the male control offspring group (allP<0.05). In the tail suspension test, the immobility time of the female and male model offspring groups (126.95±39.88) and (70.24±28.98) s was longer than the control offspring groups of the same sex (54.30±24.99) and (38.63±18.91) s (bothP<0.05), and the duration of immobility time in the female model offspring group was longer (t=3.253, P=0.006). In the forced swimming test, the immobility time of the female model offspring group (7.97±6.66) s was longer than that of the female control offspring group (1.85±2.12) s (t=2.478, P=0.037). On PND42, the plasma corticosterone level of female offspring was negatively correlated with total fluid consumption, sugar water consumption, and 1% sucrose preference percentage (r=−0.621, r=−0.728, r=−0.699; P<0.05), and positively correlated with immobility time in the tail suspension test and immobility time in the forced swimming test (r=0.571, r=0.712; P<0.05), However, there was no correlation between plasma corticosterone and emotional indicators on PND42 in male offspring (P>0.05).

Conclusion  Chronic stress during pregnancy causes emotional damage to the offspring, and female offspring show depression-like behaviors.