Animal study on primary dysmenorrhoea treatment at different administration times

Involvement of a neutrophil-mast cell axis in the effects of Piper malacophyllum (C. PESL) C. DC extract and its isolated compounds in a mouse model of dysmenorrhoea

The effects of Piper malacophyllum (C. Pesl) C. DC extracts and its isolated compounds were analysed in a mouse model of primary dysmenorrhoea (PD). Female Swiss mice (6-8 weeks old) on proestrus were intraperitoneally treated with estradiol benzoate for 3 days, to induce PD. Twenty-four hours later, animals were treated 24 h later with vehicle, plant extract, gibbilimbol B, 4,6-dimethoxy-5-E-phenylbutenolide, mixture of 4,6-dimethoxy-5-E-phenylbutenolide and 4,6-dimethoxy-5-Z-phenylbutenolide, or ibuprofen. One hour later, oxytocin was injected and the numbers of abdominal writhing were counted. Then, mice were euthanized and uteri were collected for morphometrical and histological analyses. The effects of P. malacophyllum in inflammation were investigated in mouse peritoneal neutrophils culture stimulated with LPS or fMLP (chemotaxis and mediator release). Finally, uterus contractile and relaxing responses were assessed. Similar to ibuprofen, P. malacophyllum extract and isolated compounds reduced abdominal writhing in mice with PD. Histology indicated a marked neutrophil and mast cell infiltrate in the uterus of PD animals which was attenuated by the extract. The compounds and the extract reduced neutrophil chemotaxis and inflammatory mediator release by these cells. Reduced TNF levels were also observed in uteri of PD mice treated with P. malacophyllum. The extract did not affect spontaneous uterine contractions nor those induced by carbachol or KCl. However, it caused relaxation of oxytocin-induced uterine contraction, an effect blunted by H1 receptor antagonist. Overall the results indicate that P. malacophyllum may represent interesting natural tools for reliving PD symptoms, reducing the triad of pain, inflammation and spasmodic uterus behaviour.

The Establishment of a Mouse Model of Recurrent Primary Dysmenorrhea

Primary dysmenorrhea is one of the most common reasons for gynecologic visits, but due to the lack of suitable animal models, the pathologic mechanisms and related drug development are limited. Herein, we establish a new mouse model which can mimic the periodic occurrence of primary dysmenorrhea to solve this problem. Non-pregnant female mice were pretreated with estradiol benzoate for 3 consecutive days. After that, mice were injected with oxytocin to simulate menstrual pain on the 4th, 8th, 12th, and 16th days (four estrus cycles). Assessment of the cumulative writhing score, uterine tissue morphology, and uterine artery blood flow and biochemical analysis were performed at each time point. Oxytocin injection induced an equally severe writhing reaction and increased PGF_2α accompanied with upregulated expression of COX-2 on the 4th and 8th days. In addition, decreased uterine artery blood flow but increased resistive index (RI) and pulsatility index (PI) were also observed. Furthermore, the metabolomics analysis results indicated that arachidonic acid metabolism; linoleic acid metabolism; glycerophospholipid metabolism; valine, leucine, and isoleucine biosynthesis; alpha-linolenic acid metabolism; and biosynthesis of unsaturated fatty acids might play important roles in the recurrence of primary dysmenorrhea. This new mouse model is able to mimic the clinical characteristics of primary dysmenorrhea for up to two estrous cycles.

Estrogen metabolites increase nociceptor hyperactivity in a mouse model of uterine pain

Pain emanating from the female reproductive tract is notoriously difficult to be treated and the prevalence of transient pelvic pain has been placed as high as 70-80% in women surveyed. Although sex hormones, especially estrogen, are thought to underlie enhanced pain perception in females, the underlying molecular and cellular mechanisms are not completely understood. Here we show that the pain-initiating TRPA1 channel is required for pain-related behaviors in a mouse model of estrogen-induced uterine pain in ovariectomized female mice. Surprisingly, 2- and 4-hydroxylated estrogen metabolites (HEMs) in the estrogen hydroxylation pathway, but not estrone, estradiol and 16-HEMs, directly increase nociceptor hyperactivity through TRPA1 and TRPV1 channels, and picomolar concentrations of 2- and 4-hydroxylation estrone (OHE1) can sensitize TRPA1 channel function. Moreover, both TRPA1 and TRPV1 are expressed in uterine-innervating primary nociceptors and their expressions are increased in the estrogen-induced uterine pain model. Importantly, pretreatment of 2- or 4-OHE1 recapitulates estrogen-induced uterine pain-like behaviors and intraplantar injections of 2- and 4-OHE1 directly produce a TRPA1-dependent mechanical hypersensitivity. Our findings demonstrate that TRPA1 is critically involved in estrogen-induced uterine pain-like behaviors, which may provide a potential drug target for treating female reproductive tract pain.

Untargeted metabolomics reveals the synergistic mechanisms of Yuanhu Zhitong oral liquid in the treatment of primary dysmenorrhea

Primary dysmenorrhea is a prevalent gynecological disorder that severely affects the quality of life in women. Yuanhu Zhitong oral liquid (YZOL) is a standardized herbal preparation frequently used in clinical practice and is a promising alternative therapy for primary dysmenorrhea. The findings of previous studies show that YZOL exhibits significant analgesic and spasmolytic effects, however, the involved mechanism remains unclear. Herein, we performed an untargeted plasma metabolomic analysis on a mouse model of oxytocin-induced primary dysmenorrhea to investigate the underlying mechanism of YZOL. We used multivariate and pathway-driven analyses to uncover the treatment targets linked with YZOL therapy and verified the possible mechanisms through biochemical assays. Therefore, we identified 47 plasma biomarkers primarily associated with sphingolipid metabolism, amino acid metabolism, arachidonic acid metabolism, and biosynthesis of steroid hormone as well as primary bile acid. We established that the analgesic effect of YZOL on primary dysmenorrhea relies on multiple constituents that act on multiple targets in multiple pathways. Our correlation analysis showed significant correlations between the biomarkers and biochemical indicators, which is of considerable significance in elucidating the YZOL mechanisms. Moreover, we identified some novel prospective biomarkers linked to primary dysmenorrhea, including bile acids. Collectively, these data provide new insights into the mechanism of YZOL and provide evidence for the analgesic effect of YZOL in the treatment of primary dysmenorrhea.

Effects of acupoint-stimulation for the treatment of primary dysmenorrhoea compared with NSAIDs: a systematic review and meta-analysis of 19 RCTs

Background

Primary dysmenorrhoea (PD), defined as painful menses in women with normal pelvic anatomy, is one of the most common gynaecological syndromes. Acupoint-stimulation could potentially be an effective intervention for PD. Our aim was to determine the effectiveness of acupoint-stimulation compared with Non-Steroidal Anti-Inflammatory Drugs (NASIDs) in the treatment of PD.

Methods

Six databases were searched to December 2014. Sixteen studies involving 1679 PD patients were included. We included randomized controlled trials that compared acupoint-stimulation with NASIDs for the treatment of PD. The main outcomes assessed were clinical effectiveness rate, symptom score, visual analogue score, variation in peripheral blood prostaglandin F2α (PGF2α) and side effects. All analyses were performed using Comprehensive Meta-Analysis statistical software.

Results

(1) The total efficacy was better than control group: odds ratio = 5.57; 95% confidence interval (95% CI) = 3.96, 7.83; P < 0.00001; (2) The effect of intervention was positive in relieving the severity of PD symptoms: mean difference (MD) = 2.99; 95%CI = 2.49, 3.49; P < 0.00001; (3) No statistical difference existed between two groups in terms of a reduction in the VAS: MD = 1.24; 95%CI = −3.37, 5.85; P = 0.60; (4) The effect of intervention on the variation in peripheral blood PGF2α between two groups was positive: MD = 7.55; 95%CI = 4.29,10.82; P < 0.00001; (5) The side effects of control groups was more than the acupoint-stimulation group: OR = 0.03; 95%CI =0.00,0.22; P = 0.0005.

Conclusions

According to this article, acupoint-stimulation can relieve pain effectively in the treatment of PD and offers advantages in increasing the overall effectiveness.

Flucrypyrim, a novel uterine relaxant, has antinociceptive and anti-inflammatory effects in vivo

Consequences of primary dsysmenorrhea (PD) can be severe. Increased prostaglandin production leads to uterine contraction and insufficient blood flow to the endometrium causing ischemia and pain symptoms. Protein tyrosine kinase/phosphatase activities contribute to the modulation of uterine contraction. In our previous study, we found the synthetic β-methoxyacrylates compound Fluacrypyrim (FAPM), significantly increased protein tyrosine phosphatases (PTPs) activity, resulting in dephosphorylation of tyrosine kinases. In the present study, we found that FAPM near completely inhibited prostaglandin F2α (PGF_2α)-, oxytocin-, acetylcholine-, and high K⁺-induced uterine contractions in rats in vitro, and decreased rat myometrial myosin light chain (MLC₂₀) phosphorylation induced by PGF_2α. A structure–activity relationship assay indicated that the β-methoxyacrylates structure of FAPM is crucial for the inhibition of PGF_2α-induced uterine contractions. FAPM caused a concentration-dependent parallel rightward shift of the concentration–response curve induced by oxytocin, dose-dependently reduced the number of abdominal constrictions and increased the latency time in PGF_2α- and acetic acid-induced writhing test in mice in vivo. Furthermore, FAPM considerably inhibited the development of Carr-induced rat paw edemas and thexylene-induced mouse ear edemas. Taken together, our results indicate that FAPM exerts antinociceptive and anti-inflammatory effects in vivo with considerable potential as a novel uterine relaxant.

Potential of Essential Oils as Penetration Enhancers for Transdermal Administration of Ibuprofen to Treat Dysmenorrhoea

The present study was conducted to evaluate and compare five essential oils (EOs) as penetration enhancers (PEs) to improve the transdermal drug delivery (TDD) of ibuprofen to treat dysmenorrhoea. The EOs were prepared using the steam distillation method and their chemical compositions were identified by GC-MS. The corresponding cytotoxicities were evaluated in epidermal keartinocyte HaCaT cell lines by an MTT assay. Furthermore, the percutaneous permeation studies were carried out to compare the permeation enhancement effect of EOs. Then the therapeutic efficacy of ibuprofen with EOs was evaluated using dysmenorrheal model mice. The data supports a decreasing trend of skin cell viability in which Clove oil >Angelica oil > Chuanxiong oil > Cyperus oil > Cinnamon oil >> Azone. Chuanxiong oil and Angelica oil had been proved to possess a significant permeation enhancement for TDD of ibuprofen. More importantly, the pain inhibitory intensity of ibuprofen hydrogel was demonstrated to be greater with Chuanxiong oil when compared to ibuprofen without EOs (p < 0.05). The contents of calcium ion and nitric oxide (NO) were also significantly changed after the addition of Chuanxiong oil (p < 0.05). In summary, we suggest that Chuanxiong oil should be viewed as the best PE for TDD of ibuprofen to treat dysmenorrhea.

Evaluation and optimization of biomarkers in a primary dysmenorrhea model using ultra performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry combined with a support vector machine

A plasma metabolic profiling analysis method was established to find and optimize the potential biomarkers of a primary dysmenorrhea model.