Yiliyasi Mayila1, Toshiya Matsuzaki2, Takeshi Iwasa3, Altankhuu Tungalagsuvd4, Munkhsaikhan Munkhzaya5, Kiyohito Yano3, Rie Yanagihara3, Takako Tokui3, Saki Minato3, Asuka Takeda3, Sachiko Endo3, Takaaki Maeda3, Minoru Irahara3. 1. Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan. Electronic address: maira2309@yahoo.co.jp. 2. Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan; Division of Obstetrics and Gynecology, Yoshinogawa Medical Center, 120 Aza-Nishichiejima, Kamojima-cho, Tokushima 776-8511, Japan. 3. Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan. 4. Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan; Division of Obstetrics and Gynecology, National Center for Maternal and Child Health, Khuvisgalchid Street, Bayangol District, Ulaanbaatar 160660, Mongolia. 5. Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan; Department of Gynecology, The First Maternity Hospital of Mongolia, Peace Avenue, 1st Khoroo, Sukhbaatar District, Ulaanbaatar 14210, Mongolia.
Abstract
PURPOSE: We examined the mechanism by which neonatal immune stress reduces the sexual behavior of female rats in adulthood. METHODS: Neonatal female rats were randomly divided into 3 groups: control (n = 11), postnatal day 10 lipopolysaccharide (PND10LPS) (n = 23), and PND25LPS (n = 11) groups, which received intraperitoneal injections of LPS (100 μg/kg) or saline on PND10 and 25. Daily inspections of the vaginal opening (VO) were performed from PND27 to PND37. Thereafter, the frequency of estrus was assessed for 15 days. Female rats (at 11-12 weeks of age) were placed in a cage with male rats, and their sexual behavior was monitored for 30 min. The hypothalamic mRNA expression levels of factors related to sexual behavior were examined via real-time PCR. RESULTS: VO occurred later and the frequency of estrus was lower in the PND10LPS group compared to the control group. The number of lordosis behaviors and the total number of mounts performed by male partners were lower in the PND10LPS and PND25LPS groups than in the control group. Acceptability: The lordosis quotient and lordosis rating were lower in the PND10LPS group than in the control group. Proceptive behavior: the number of ear wiggling events was lower in the PND10LPS group than in the other groups, and the number of hops/darts was lower in the PND10LPS group than in the control group. The hypothalamic mRNA expression level of progesterone receptors (PR)A + B was lower in the PND10LPS group than in the control group, and the hypothalamic PRB mRNA expression level was lower in the PND10LPS and PND25LPS groups than in the control group. CONCLUSION: Neonatal immune stress impeded sexual behavior and hypothalamic PR mRNA expression in female rats. Decreased progesterone activity in the hypothalamus might explain the reduction in sexual behavior seen in these rats.
PURPOSE: We examined the mechanism by which neonatal immune stress reduces the sexual behavior of female rats in adulthood. METHODS: Neonatal female rats were randomly divided into 3 groups: control (n = 11), postnatal day 10 lipopolysaccharide (PND10LPS) (n = 23), and PND25LPS (n = 11) groups, which received intraperitoneal injections of LPS (100 μg/kg) or saline on PND10 and 25. Daily inspections of the vaginal opening (VO) were performed from PND27 to PND37. Thereafter, the frequency of estrus was assessed for 15 days. Female rats (at 11-12 weeks of age) were placed in a cage with male rats, and their sexual behavior was monitored for 30 min. The hypothalamic mRNA expression levels of factors related to sexual behavior were examined via real-time PCR. RESULTS: VO occurred later and the frequency of estrus was lower in the PND10LPS group compared to the control group. The number of lordosis behaviors and the total number of mounts performed by male partners were lower in the PND10LPS and PND25LPS groups than in the control group. Acceptability: The lordosis quotient and lordosis rating were lower in the PND10LPS group than in the control group. Proceptive behavior: the number of ear wiggling events was lower in the PND10LPS group than in the other groups, and the number of hops/darts was lower in the PND10LPS group than in the control group. The hypothalamic mRNA expression level of progesterone receptors (PR)A + B was lower in the PND10LPS group than in the control group, and the hypothalamicPRB mRNA expression level was lower in the PND10LPS and PND25LPS groups than in the control group. CONCLUSION: Neonatal immune stress impeded sexual behavior and hypothalamic PR mRNA expression in female rats. Decreased progesterone activity in the hypothalamus might explain the reduction in sexual behavior seen in these rats.