Probiotics improves abnormal behavior and hippocampal injury in pregnant-stressed offspring rats

During pregnancy, pregnant women are prone to stress reactions due to external stimuli, affecting their own health and fetal development. At present, there is no good treatment for the stress reactions from pregnant women during pregnancy. This study aims to explore the effect of probiotics on abnormal behavior and hippocampal injury in pregnant stressed offspring.

SD pregnant rats were divided into a control group, a stress group, and a probiotics group, with 6 rats in each group. The control group was untreated; the stress group was given restraint stress on the 15th-20th day of pregnancy; the probiotics group was given both bifidobacterium trisporus capsules and restraint stress on the 15th-20th day of pregnancy, and the offspring continued to be fed with probiotics until 60 days after birth (P60). The offspring rats completed behavioral tests such as the open field test, the elevated plus maze test, the new object recognition test, and the barnes maze test at 60-70 d postnatally. Nissl's staining was used to reflect the injury of hippocampal neurons; immunohistochemical staining was used to detect the expression of microglia marker ionized calcium binding adapter molecule 1 (IBA-1) which can reflect microglia activation; ELISA was used to detect the content of plasma TNF-α and IL-1β; Western blotting was used to detect the expression of Bax, Bcl-2, and caspase-3.

The retention time of offspring rats in the stress group in the central area of the open field was significantly less than that in the control group (P<0.01), and the retention time of offspring rats in the probiotic group in the central area of the open field was significantly more than that in the stress group (P<0.05). The offspring rats in the stress group stayed in the open arm for a shorter time than the control group (P<0.05) and entered the open arm less often than the control group (P<0.01); the offspring rats in the probiotic group stayed in the open arm for a longer time than the stress group and entered the open arm more often than the stress group (both P<0.05). The discrimination ratio for new to old objects in the offspring rats of the stress group was significantly lower than that of the control group (P<0.01), and the discrimination ratio for new to old objects in the offspring rats of the probiotic group was significantly higher than that of the stress group (P<0.05). The offspring rats in the stress group made significantly more mistakes than the control group (P<0.05), and the offspring rats in the probiotic group made significantly fewer mistakes than the stress group (P<0.05). Compared with the control group, the numbers of Nissl bodies in CA1, CA3, and DG area were significantly reduced in the offspring rats of the stress group (all P<0.001), the number of activated microglia in DG area of hippocampus was significantly increased (P<0.01), the contents of TNF-α and IL-1β in peripheral blood were significantly increased (P<0.05 or P<0.01), the protein expression level of Bcl-2 was significantly down-regulated, and the protein expression levels of Bax and caspase-3 were significantly up-regulated (all P<0.001). Compared with the stress group, the numbers of Nissl bodies in CA1, CA3, and DG area were significantly increased in the probiotic group offspring rats (P<0.001, P<0.01, P<0.05), the number of activated microglia in the DG area of hippocampus was significantly reduced (P<0.05), and the TNF-α and IL-1β levels in peripheral blood were significantly decreased (both P<0.05), the protein expression level of Bcl-2 was significantly up-regulated, and the protein expression levels of Bax and caspase-3 were significantly down-regulated (all P<0.001).

Probiotic intervention partially ameliorated anxiety and cognitive impairment in rats offspring of pregnancy stress, and the mechanism may be related to increasing the number of neurons, inhibiting the activation of hippocampal microglia, and reducing inflammation and apoptosis.