The mammalian fertilization process takes place in a complex microenvironment within the female genital tract. A member of the chitinase protein family, oviduct-specific glycoprotein (OGP), has been identified in oviductal fluid from various mammalian species, including humans. Although OGP is widely believed to be involved in the process of mammalian fertilization, including spermatozoon function and gamete interactions, based on experimental results obtained in vitro, its physiological significance remains controversial. The present study established OGP gene-null ( ogp (-/-)) mice, and primarily characterized their reproductive properties to study the physiological function(s) of OGP. Results obtained from studies using an in vivo or in vitro system showed that the fertility of ogp (-/-) females was within normal limits. These results indicate that OGP is not essential for the process of in vivo fertilization, at least in mice.
The Asian house shrew, Suncus murinus, is an insectivore (Eulipotyphla,
Mammalia) and an important laboratory animal for life-science studies. The
gastrointestinal tract of Suncus is simple: the length of the entire
intestine is very short relative to body size, the large intestine is quite short, and
there are no fermentative chambers such as the forestomach or cecum. These features imply
that Suncus has a different nutritional physiology from those of humans
and mice, but little is known about whether Suncus utilizes microbial
fermentation in the large (LI) or small (SI) intestine. In addition, domestication may
affect the gastrointestinal microbial diversity of Suncus. Therefore, we
compared the gastrointestinal microbial diversity of Suncus between
laboratory and wild Suncus and between the SI and LI
(i.e., four groups: Lab-LI, Lab-SI, Wild-LI, and Wild-SI) using
bacterial 16S rRNA gene library sequencing analyses with a sub-cloning method. We obtained
759 cloned sequences (176, 174, 195, and 214 from the Lab-LI, Lab-SI, Wild-LI, and Wild-SI
samples, respectively), which revealed that the gastrointestinal microbiota of
Suncus is rich in Firmicutes (mostly lactic acid bacteria), with few
Bacteroidetes. We observed different bacterial communities according to intestinal region
in laboratory Suncus, but not in wild Suncus.
Furthermore, the gastrointestinal microbial diversity estimates were lower in laboratory
Suncus than in wild Suncus. These results imply that
Suncus uses lactic acid fermentation in the gut, and that the
domestication process altered the gastrointestinal bacterial diversity.
Obesity, which disturbs lipid and glucose metabolism, is a recent medical concern. It threatens human health and also has adverse effects on reproductive functions by causing insulin resistance/hyperinsulinemia, especially in women with polycystic ovary syndrome (PCOS). For PCOS patients to prevent these adverse effects, it is important to take into account improving their lifestyles by exercise and proper diets. The relationship between insulin resistance/hyperinsulinemia and reproductive disorders should be understood as fully as possible in order to provide effective treatment. It is well known that insulin resistance and compensatory hyperinsulinemia can be triggered by obesity with visceral fat accumulation. Hyperinsulinemia affects granulosa cells in small follicles and theca cells. This condition induces early response to luteinizing hormones on granulosa cells of small follicles and causes premature differentiation of these cells, which eventually results in anovulation. For improvement of anovulation because of hyperinsulinemia, insulin-sensitizing agents (biguanide and thiazolidinedione derivatives) are useful. Hyperinsulinemia may adversely affect the endometrial functions and environment, and evoke implantation disturbance. Treatment with an insulin-sensitizing agent (metformin) improves the levels of glycodelin, insulin-like growth factor binding protein 1, and blood flow in spiral arteries during the peri-implantation period. It supports endometrial function, improves the endometrial environment, and facilitates embryo implantation. The rate of early pregnancy loss during the first trimester is 30-50% in women with PCOS, which is threefold higher than for normal women. Metformin treatment improves the levels of insulin, the homeostasis model assessment for insulin resistance, and plasminogen activator inhibitor activity, and decreases early pregnancy loss. It goes without saying that lifestyle change is fundamental for improving reproductive performance in addition to treatment with insulin-sensitizing agents.
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