Correlation between Sexual Maturation and Induction of Persistent Estrus by Continuous Illumination

Takeo, Yuji; Shirama, Kazuhiko; Shimizu, Kiyoshí; Maekawa, Kyutaro

doi:10.1507/endocrj1954.22.453

Cited by 5 publications

(1 citation statement)

References 4 publications

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“…Therefore, the maternal signals were modulated during the same interval from E14 to E19 as in the previous experiment, in which the pregnant rats were exposed to a phase shift in the LD cycle. Exposure of rats to LL may have a more general impact on the course of pregnancy because it has previously been assigned to be a stressor (Honma and Hiroshige, 1978) and was found to potentially affect sex hormone levels (Takeo et al, 1975). Indeed, we revealed that in the LL-ad lib group, the weights of placentas were significantly reduced compared to those in the CTRL group, which was not caused by a decrease in the dams' food intake or a reduction in BW gain during pregnancy.…”

Section: Discussionmentioning

confidence: 60%

Challenging the Integrity of Rhythmic Maternal Signals Revealed Gene-Specific Responses in the Fetal Suprachiasmatic Nuclei

et al. 2021

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During fetal stage, maternal circadian system sets the phase of the developing clock in the suprachiasmatic nuclei (SCN) via complex pathways. We addressed the issue of how impaired maternal signaling due to a disturbed environmental light/dark (LD) cycle affects the fetal SCN. We exposed pregnant Wistar rats to two different challenges – a 6-h phase shift in the LD cycle on gestational day 14, or exposure to constant light (LL) throughout pregnancy – and detected the impact on gene expression profiles in 19-day-old fetuses. The LD phase shift, which changed the maternal SCN into a transient state, caused robust downregulation of expression profiles of clock genes (Per1, Per2, and Nr1d1), clock-controlled (Dbp) genes, as well as genes involved in sensing various signals, such as c-fos and Nr3c1. Removal of the rhythmic maternal signals via exposure of pregnant rats to LL abolished the rhythms in expression of c-fos and Nr3c1 in the fetal SCN. We identified c-fos as the gene primarily responsible for sensing rhythmic maternal signals because its expression profile tracked the shifted or arrhythmic maternal SCN clock. Pathways related to the maternal rhythmic behavioral state were likely not involved in driving the c-fos expression rhythm. Instead, introduction of a behavioral rhythm to LL-exposed mothers via restricted feeding regime strengthened rhythm in Vip expression in the fetal SCN. Our results revealed for the first time that the fetal SCN is highly sensitive in a gene-specific manner to various changes in maternal signaling due to disturbances of environmental cycles related to the modern lifestyle in humans.

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Section: Discussionmentioning

confidence: 60%

Challenging the Integrity of Rhythmic Maternal Signals Revealed Gene-Specific Responses in the Fetal Suprachiasmatic Nuclei

et al. 2021

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Differences in the rate of establishment of permanent estrus in rats after ovarian autografting and certain procedures

Сметанина¹,

Vunder²

1985

Bull Exp Biol Med

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An electron microscopic study of apoptosis in the granulosa layer of ovarian follicles in rats treated with continuous illumination

Takeo¹,

Hokano²

1995

Med Electron Microsc

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Abstract. Polycystic ovarian syndrome was induced in adult rats by treatment with continuous illumination to study follicular atresia. Granulosa cells of regressing antral follicles showed characteristic features of apoptosis ultrastructuralty: condensed nuclei, apoptotic bodies, and phagocytosis of the apoptotic cells andtheir fragments by neighboring cells. In this study, moreover, it was observed that an intact granulosa cell was able to ingest another granulosa cell of normal appearance, presumably indicating an early stage of follicular atresia. The phagocytosing granulosa cell surrounded another granulosa cell to be phagocytosed by elongated cell processes. Gap junctions developed between the phagocytic cell and the phagocytosed cell. The phagocytic cell possessed abundant free ribosomes, well-developed rough endoplasmic reticulum and mitochondria, but few lysosomes. The ingested cell was similar in appearance to the phagocytic cell. In addition, granulosa cells were also observed ingesting karyopyknotic cells and degenerative organelles, both displayed in large vacuoles filled with fragments of nuclei and organelles. These findings suggest a process of apoptosis in the granulosa cells during follicular atresia.

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Correlation between Sexual Maturation and Induction of Persistent Estrus by Continuous Illumination

Cited by 5 publications

References 4 publications

Challenging the Integrity of Rhythmic Maternal Signals Revealed Gene-Specific Responses in the Fetal Suprachiasmatic Nuclei

Challenging the Integrity of Rhythmic Maternal Signals Revealed Gene-Specific Responses in the Fetal Suprachiasmatic Nuclei

Differences in the rate of establishment of permanent estrus in rats after ovarian autografting and certain procedures

An electron microscopic study of apoptosis in the granulosa layer of ovarian follicles in rats treated with continuous illumination

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