Yimu San improves obstetric ability of pregnant mice by increasing serum oxytocin levels and connexin 43 expression in uterine smooth muscle

Histological Features of Uterine Myometrial Dysfunction: Possible Involvement of Localized Inflammation

OBJECTIVE

The latest perspective suggests that elevated levels of inflammation and cytokines are implicated in atonic postpartum hemorrhage. Lipopolysaccharide (LPS) has been widely used to induce inflammation in animal models. Therefore, this study aimed to induce uterine inflammation using LPS to investigate whether local inflammation triggers dysfunction and atrophy in the myometrium, as well as the potential underlying molecular mechanisms involved.

METHODS

In vivo, an animal model was established by intraperitoneal injection of 300 μg/ kg LPS in rats on gestational day 21. Hematoxylin-eosin (H&E) staining and Masson staining were employed to determine morphological changes in the rat uterine smooth muscle. Enzyme-linked immunosorbent assay (ELISA) was used to detect inflammatory cytokines. Immunohistochemistry, tissue fluorescence, and Western blotting were conducted to assess the expression levels of the uterine contraction-related proteins Toll-like receptor 4 (TLR4) and the nuclear factor kappa-B (NF-κB) signaling pathway. In vitro, human uterine smooth muscle cells (HUtSMCs) were exposed to 2 μg/mL LPS to further elucidate the involvement of the TLR4/NF-κB signaling pathway in LPS-mediated inflammation.

RESULTS

In this study, LPS induced uterine myometrial dysfunction in rats, leading to a disorganized arrangement, a significant increase in collagen fiber deposition, and widespread infiltration of inflammatory cells. In both in vivo animal models and in vitro HUtSMCs, LPS elevated IL-6, IL-1β, and TNF-α levels while concurrently suppressing the expression of connexin 43 (Cx43) and oxytocin receptor (OXTR). Mechanistically, the LPS-treated group exhibited TLR4 activation, and the phosphorylation levels of p65 and IκBα were notably increased.

CONCLUSION

LPS triggered the TLR4/NF-κB signaling pathway, inducing an inflammatory response in the myometrium and leading to uterine myometrial dysfunction and uterine atony.

The Role of Oxytocin in Domestic Animal’s Maternal Care: Parturition, Bonding, and Lactation

Oxytocin (OXT) is one of the essential hormones in the birth process; however, estradiol, prolactin, cortisol, relaxin, connexin, and prostaglandin are also present. In addition to parturition, the functions in which OXT is also involved in mammals include the induction of maternal behavior, including imprinting and maternal care, social cognition, and affiliative behavior, which can affect allo-parental care. The present article aimed to analyze the role of OXT and the neurophysiologic regulation of this hormone during parturition, how it can promote or impair maternal behavior and bonding, and its importance in lactation in domestic animals.

Improvement in post-partum uterine involution in rats treated with Apios americana

OBJECTIVE

Apios americana, a plant used as a staple ingredient of native American diets, has various properties, including anti-cancer, anti-hyperglycemic, hypotensive, and anti-inflammatory activity. In Japan, Apios is used as a post-natal medication. After parturition, women undergo a period of recovery as they return to pre-pregnancy conditions. However, few health products that aid post-partum recovery are on the market. We explored whether Apios can accelerate the post-partum recovery process, in particular the involution of the uterus.

METHODS

Female rats kept in individual cages were mated with two male rats, with the exception of the control group (female rats without mating, on basal diet; n=6). After delivery, rats were divided into five groups based on their diet: basal diet (model; n=6); basal diet+oral intake at 5.4 g/kg of Chanfukang granules (a Chinese patent medicine preparation for post-partum lochia) (positive; n=6); basal diet containing 10% Apios powder (low; n=6); basal diet containing 20% Apios powder (medium; n=6); basal diet containing 40% Apios powder (high; n=6). Five days later, uteri and spleens were weighed. Uterus and spleen indices for each rat were calculated by dividing visceral weight by the total weight. Hormone and cytokine concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Histological analysis of uteri was completed using hematoxylin and eosin (H&E) staining. Expression of matrix metalloproteinases and inhibitors in uteri was measured by western blotting.

RESULTS

Our results showed that Apios treatment reduced the post-partum uterus index and regulated the hormone concentrations. Moreover, we found that the process of uterine involution was accelerated, based on morphological changes in the uterus. In addition, our results indicated that Apios alleviated the inflammatory response induced by the involution process. Transforming growth factor β was also found to be regulated by Apios. There were significant downregulation of matrix metalloproteinases and upregulation of their inhibitors by Apios, which suggested that Apios increased the rate of the collagen clearance process.

CONCLUSIONS

These results, based on experimental observations at the molecular and protein levels, verified our hypothesis that Apios can improve uterine involution, and demonstrated the potential application of Apios in post-partum care.