Neural Regeneration Research ›› 2020, Vol. 15 ›› Issue (9): 1748-1756.doi: 10.4103/1673-5374.276358

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Interleukin-18 levels in the hippocampus and behavior of adult rat offspring exposed to prenatal restraint stress during early and late pregnancy

Mo-Xian Chen1, #, Qiang Liu2, #, Shu Cheng3 , Lei Lei4 , Ai-Jin Lin1 , Ran Wei5 , Tomy C.K. Hui6 , Qi Li6, 7, * , Li-Juan Ao1, * , Pak C. Sham6, 7, 8   

  1. 1 School of Rehabilitation, Kunming Medical University, Kunming, Yunnan Province, China 2 Department of Surgery, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China 3 Department of Rehabilitation, China Resources & WISCO General Hospital, Wuhan, Hubei Province, China 4 Department of Rehabilitation Medicine, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China 5 Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan, Shandong Province, China 6 Department of Psychiatry, The University of Hong Kong, Hong Kong Special Administrative Region, China 7 State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong Special Administrative Region, China 8 Centre for Genomic Sciences, The University of Hong Kong, Hong Kong Special Administrative Region, China
  • Online:2020-09-08 Published:2020-09-17
  • Contact: Li-Juan Ao, MS, lijuanao@hotmail.com; Qi Li, PhD, liqi@hku.hk.

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Abstract: Exposure to maternal stress during prenatal life is associated with an increased risk of neuropsychiatric disorders, such as depression and anxiety, in offspring. It has also been increasingly observed that prenatal stress alters the phenotype of offspring via immunological mechanisms and that immunological dysfunction, such as elevated interleukin-18 levels, has been reported in cultures of microglia. Prenatal restraint stress (PRS) in rats permits direct experimental investigation of the link between prenatal stress and adverse outcomes. However, the majority of studies have focused on the consequences of PRS delivered in the second half of pregnancy, while the effects of early prenatal stress have rarely been examined. Therefore, pregnant rats were subjected to PRS during early/middle and late gestation (days 8–14 and 15–21, respectively). PRS comprised restraint in a round plastic transparent cylinder under bright light (6500 lx) three times per day for 45 minutes. Differences in interleukin-18 expression in the hippocampus and in behavior were compared between offspring rats and control rats on postnatal day 75. We found that adult male offspring exposed to PRS during their late prenatal periods had higher levels of anxiety-related behavior and depression than control rats, and both male and female offspring exhibited higher levels of depression-related behavior, impaired recognition memory and diminished exploration of novel objects. Moreover, an elevated level of interleukin-18 was observed in the dorsal and ventral hippocampus of male and female early- and late-PRS offspring rats. The results indicate that PRS can cause anxiety and depression-related behaviors in adult offspring and affect the expression of interleukin-18 in the hippocampus. Thus, behavior and the molecular biology of the brain are affected by the timing of PRS exposure and the sex of the offspring. All experiments were approved by the Animal Experimentation Ethics Committee at Kunming Medical University, China (approval No. KMMU2019074) in January 2019.

Key words: behavior, depression, dorsal hippocampus, interleukin-18, prenatal restraint stress, recognition memory, sex, ventral hippocampus