総説・解説等

Background: The biological reproductive process requires the precise coordination of annual and daily signals to adapt to environmental shifts. Humans and animals have developed shared neuroendocrine systems that have adapted to process daily and seasonal light signals within the hypothalamic–pituitary —gonadal axis. However, the stability of circadian and seasonal biological processes is at risk due to industrialization and contemporary round-the-clock lifestyles. These threats include skipping breakfast, excessive artificial illumination during inappropriate hours because of irregular work schedules, nighttime urban lighting, and widespread environmental pollution from endocrine-disrupting chemicals. This review aimed to explore the interplay between lifestyle factors, circadian rhythms, and reproductive functions. Methods: This review examined the reciprocal influences of circadian clocks on reproductive hormones, exploring the underlying mechanisms and their implications for fertility and reproductive health. We emphasized key findings regarding molecular clock components, endocrine pathways, and the critical importance of synchronizing circadian rhythms with hormonal cycles. Main Findings: The intersection of reproductive endocrinology and circadian biology reveals complex interactions between hormonal regulation and circadian rhythms. Circadian rhythm misalignments due to environmental factors, including late-night work and skipping breakfast, negatively impact endocrine and reproductive functions. Conclusions: More strategies are needed to mitigate the effects of circadian disruption on reproductive functions.

The article, Indications for fertility preservation not included in the 2017 Japan Society of Clinical Oncology Guideline for Fertility Preservation in Pediatric, Adolescent, and Young Adult Patients treated with gonadal toxicity, including benign diseases written by Masanori Ono, Kimikazu Matsumoto, Narikazu Boku, Nobuharu Fujii, Yumi Tsuchida, Tatsuro Furui, Miyuki Harada, Yoshinobu Kanda, Akira Kawai, Mitsuru Miyachi, Atsuko Murashima, Robert Nakayama, Hiroyuki Nishiyama, Chikako Shimizu, Kazuhiko Sugiyama, Yasushi Takai, Keishi Fujio, Ken‑Ichirou Morishige, Yutaka Osuga, and Nao Suzuki was originally published Online First without Open Access. With the author(s)’ decision to opt for Open Choice the copyright of the article changed on February 16, 2022 to © Author(s) 2021 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0. The original article has been corrected.