Potential molecular mechanism study of motherwort in treating postpartum abdominal pain based on network pharmacology
Postpartum abdominal pain, also known as “uterine contraction pain” or “postpartum pain”, refers to the pain that occurs in the abdomen of a pregnant woman within 1-3 days after delivery, similar to menstrual cramps, due to the recovery effect of uterine contractions. In clinical practice, Western medicine often uses opioid analgesics such as sufentanil to intervene in patients with severe postpartum abdominal pain. However, these analgesics often cause certain degrees of adverse reactions, such as nausea and vomiting caused by excitation of the vomiting center, or digestive dysfunction caused by excitation of the vagus nerve. According to traditional Chinese medicine theory, postpartum abdominal pain is often caused by poor circulation of qi and blood, including two types of syndromes: blood deficiency and blood stasis. In clinical practice, the treatment of postpartum abdominal pain in traditional Chinese medicine mainly uses the method of warming meridians and dispelling disorders to remove blood stasis and relieve pain, while also using the method of nourishing qi and blood to promote blood circulation.
Leonurus japonicas Houtt, a plant in the family Lamiaceae, is the fresh or dried aboveground part of Leonurus japonicas Houtt. It has the effects of promoting blood circulation and regulating menstruation, promoting diuresis and reducing swelling. It is commonly used in clinical practice for diseases such as blood stasis, menstrual cramps, and edema, and is known as the “holy medicine of gynecology”. The book “Bencao Mengqi” records that it “can regulate all the symptoms of pregnancy and childbirth, so it is named as beneficial to the mother and has the effects of removing stillbirths, stabilizing the fetus, promoting blood stasis, and generating new blood”. Modern pharmacological studies have shown that extracts of motherwort have anti-inflammatory, analgesic, antioxidant, and antibacterial effects. In addition, the extract of motherwort has a bidirectional regulatory effect on uterine tissue. The extract of alkaloids from motherwort 0.5% hydrochloric acid aqueous solution has an excitatory effect on mouse uterus in vitro, while the extract of alkaloids from motherwort chloroform has an inhibitory effect on uterus in vitro. The excitatory effect of matrine in Yimucao injection on the uterus may also be related to the species of animals. In addition, motherwort has hemostatic and repairing effects on the postpartum endometrium, which is beneficial for postpartum uterine recovery.

Traditional Chinese medicine has the characteristics of multi-component, multi-target, and multi pathway effects, which play a therapeutic role in diseases as a whole. However, the research on its material basis and mechanism of action is weak, which affects the modernization process of traditional Chinese medicine development. Network pharmacology can comprehensively and systematically study the relationship between drugs and diseases, and make preliminary predictions on active substances, targets, and pathways. It is a new method and means for traditional Chinese medicine research. This article uses network pharmacology research methods to predict the potential targets and mechanisms of action of motherwort in treating postpartum abdominal pain through effective data mining, and further verifies the mechanism of motherwort in treating postpartum abdominal pain based on a drug induced abortion rat model, providing a theoretical basis for the clinical application of motherwort.

Network pharmacology can comprehensively and systematically study the interaction between drugs and diseases, reflecting the characteristics of multi-component, multi-target, and multi pathway interactions in traditional Chinese medicine. It is a new method and tool for studying the mechanism of drug therapy for diseases. Yimucao is a commonly used traditional Chinese medicine with the effects of promoting blood circulation, removing blood stasis, and generating new vitality; Research has shown that extracts of motherwort can activate postpartum endometrial hemostatic repair mechanisms and alleviate uterine spasms. Postpartum abdominal pain is caused by the contraction of the uterus after childbirth. Traditional Chinese medicine believes that postpartum abdominal pain is caused by poor circulation and stagnation of qi and blood, or excessive postpartum blood loss leading to deficiency of both qi and blood. This article uses network pharmacology research methods to explore the targets and mechanisms of action of motherwort in treating postpartum abdominal pain. Ten active ingredients of motherwort and 144 of them target postpartum abdominal pain. Immunohistochemical results show that motherwort can significantly inhibit the upregulation of PGF2 α R and MMP9 proteins and downregulation of TIMP1 and VEGFR2 proteins in the uterine tissue of model rats. Combined with GO and KEGG enrichment results, it suggests that the regulatory effect on estrogen, PI3K Akt, MAPK, and HIF-1 signaling pathways may be the main mechanism of motherwort in treating postpartum abdominal pain. The network analysis results show that the main active ingredients of Leonurus japonicus in treating postpartum abdominal pain may be quercetin, kaempferol, arachidonic acid, etc. Research has shown that quercetin can act as an estrogen receptor modulator, binding to the estrogen receptor (ER) to regulate many substrates and signaling pathways downstream of ER, participating in the regulation of uterine contractions, and exhibiting a regulatory effect on postpartum abdominal pain. Shannai phenol is a flavonoid compound with various biological activities. Studies have shown that Shannai phenol can significantly reduce the gene and protein levels of adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM1), integrin, and monocyte chemoattractant protein-1 (MCP-1) in rabbit arterial blood, indicating that Shannai phenol can improve vascular stasis. Arachidonic acid is not only a precursor substance for inflammatory reactions, but also directly participates in regulating the activity of various enzymes and ion channels in the body’s cells. Acting on Ca2+channels, it can directly regulate the entry and exit of Ca2+in cells, thereby affecting tissue contraction and relaxation. Uterine contraction also depends on the regulation of Ca2+by smooth muscle cells in uterine tissue. Therefore, kaempferol also has a regulatory effect on postpartum abdominal pain.
The protein interaction network shows that the active ingredients in Leonurus japonicus may act on common disease targets through drugs such as PIK3R1, CXCL8, IL6, JUN, VEGFA, NFKB1, IL1B, MMP9, etc. PIK3R1, also known as phosphatidylinositol 3-kinase in Chinese, plays an important role in insulin metabolism, and mutations in this gene are associated with insulin resistance. CXCL8, also known as IL-8, is a member of chemokines. Recent studies have found that it is involved in the entire reproductive process of mammals and is also related to certain reproductive pathological processes. VEGFA, also known as vascular endothelial growth factor A, can specifically act on endothelial cells and has multiple effects, such as increasing vascular permeability, inducing angiogenesis, inducing endothelial cell growth, and promoting cell migration. In addition, the topology analysis of PPI network showed that various apoptosis inhibitors, cell proliferation factors, etc. were also involved in this process, such as CUL7, AKT1, TP53, etc. One of the major causes of postpartum abdominal pain is damage to the endometrium, which can lead to continuous bleeding or lochia. Therefore, the initiation of hemostatic repair mechanisms is particularly important for treating postpartum abdominal pain.

The GO annotation results indicate that the core targets after topology are mainly involved in intrinsic apoptosis signaling pathways, regulation of DNA metabolism processes, intracellular receptor signaling pathways, positive regulation of DNA metabolism processes, response to incorrect proteins, DNA biosynthesis and other biological processes; Positioned at sites such as nuclear staining, adhesive plaques, cell matrix junctions, protein DNA complexes, ubiquitin ligase complexes, etc; And it binds to ubiquitin proteins, ubiquitin like proteins, steroid hormone receptors, nuclear receptors, nuclear hormone receptors, etc. The KEGG enrichment analysis results showed that 41 pathways may be involved in the regulation of postpartum abdominal pain in Leonurus japonicus. Among the top 20 pathways, in addition to cancer-related pathways, estrogen signaling pathway, PI3K Akt signaling pathway, MAPK signaling pathway, HIF-1 signaling pathway, etc. are involved. The PI3K Akt signaling pathway plays an important role in regulating various cellular functions, such as metabolism, growth, proliferation, survival, transcription, and protein synthesis. MAPK exists in multiple subtypes, among which ERK is widely present in various tissues and highly involved in the regulation of cell proliferation and differentiation. The postpartum uterus is a hypoxic environment that can activate the HIF-1 signaling pathway, regulate glucose metabolism, cell proliferation, and angiogenesis.

MMP9 is a member of the matrix metalloproteinase family, involved in regulating the estrogen signaling pathway and playing a role in physiological processes such as angiogenesis, cell migration, and wound healing. It can promote uterine angiogenesis and growth during postpartum uterine involution. TIMP1 is a member of the matrix metalloproteinase tissue inhibitory factor family and a downstream effector molecule of the HIF-1 signaling pathway. It can form a complex with MMP9 to inhibit its activity and play an important role in the physiological and pathological processes of postpartum uterus. VEGFA and VEGFR2 are members of vascular endothelial growth factors that participate in the process of endometrial vascular remodeling and play an important role in postpartum uterine involution.
The main causes of postpartum abdominal pain are postpartum uterine blood stasis, rigidity and contraction. When the uterus contracts, it causes vascular ischemia, tissue hypoxia, nerve fiber compression, and produces pain similar to dysmenorrhea. Excessive energy of PGF2 α can cause excessive contraction of uterine smooth muscle, vascular spasm, and result in uterine ischemia and hypoxia, leading to abdominal pain. Postpartum uterine tissue is in a state of damage repair, and the occurrence of blood stasis may be related to microcirculatory disorders during uterine repair, that is, difficulty in repairing and regenerating endometrial blood vessels. Therefore, this study prepared a drug induced abortion rat model using mifepristone and misoprostol, which can induce uterine bleeding and blood stasis in rats, consistent with some clinical symptoms of postpartum abdominal pain. Yimucao ointment was used for intervention, and the protein expression of PGF2 α R, MMP9, TIMP1, VEGFA, and VEGFR2 in uterine tissue was measured. The research results indicate that Leonurus can significantly inhibit the upregulation of PGF2 α R and MMP9 proteins, as well as the downregulation of TIMP1 and VEGFR2 proteins in the uterine tissue of model rats.
In summary, this study analyzed the potential mechanism of action of motherwort in treating postpartum abdominal pain through network pharmacology. The results indicate that motherwort exerts its effect through multi-component, multi-target, and multi pathway approaches in treating postpartum abdominal pain. By further examining the effect of Leonurus heterophyllus on the expression levels of related proteins in the uterine tissue of abortion model rats, some network pharmacology results were validated, namely the PI3K Akt signaling pathway, estrogen signaling pathway, MAPK signaling pathway, and HIF-1 signaling pathway may be the main pathways of action of Leonurus heterophyllus in treating postpartum abdominal pain, providing reliable references for further research on the efficacy and mechanism of action of Leonurus heterophyllus.