High Estrogen Level Modifies Postoperative Hyperalgesia via GPR30 and MMP-9 in Dorsal Root Ganglia Neurons

Estrogen-immuno-neuromodulation disorders in menopausal depression

A significant decrease in estrogen levels puts menopausal women at high risk for major depression, which remains difficult to cure despite its relatively clear etiology. With the discovery of abnormally elevated inflammation in menopausal depressed women, immune imbalance has become a novel focus in the study of menopausal depression. In this paper, we examined the characteristics and possible mechanisms of immune imbalance caused by decreased estrogen levels during menopause and found that estrogen deficiency disrupted immune homeostasis, especially the levels of inflammatory cytokines through the ERα/ERβ/GPER-associated NLRP3/NF-κB signaling pathways. We also analyzed the destruction of the blood-brain barrier, dysfunction of neurotransmitters, blockade of BDNF synthesis, and attenuation of neuroplasticity caused by inflammatory cytokine activity, and investigated estrogen-immuno-neuromodulation disorders in menopausal depression. Current research suggests that drugs targeting inflammatory cytokines and NLRP3/NF-κB signaling molecules are promising for restoring homeostasis of the estrogen-immuno-neuromodulation system and may play a positive role in the intervention and treatment of menopausal depression.

GPER involvement in inflammatory pain

Chronic pain is a worldwide refractory health disease that causes major financial and emotional burdens and that is devastating for individuals and society. One primary source of pain is inflammation. Current treatments for inflammatory pain are weakly effective, although they usually replace analgesics, such as opioids and non-steroidal anti-inflammatory drugs, which display serious side effects. Emerging evidence indicates that the membrane G protein-coupled estrogen receptor (GPER) may play an important role in the regulation of inflammation and pain. Herein, we focus on the consequences of pharmacological and genetic GPER modulation in different animal models of inflammatory pain. We also provide a brief overview of the putative mechanisms including the direct action of GPER on pain transmission and inflammation.

Trimetazidine alleviates paclitaxel-induced peripheral neuropathy through modulation of TLR4/p38/NFκB and klotho protein expression

Chemotherapy-induced peripheral neuropathy is a common adverse effect associated with a number of chemotherapeutic agents including paclitaxel (PTX) which is commonly used in a wide range of solid tumors. Development of PTX-induced peripheral neuropathy (PIPN) during cancer treatment requires dose reduction which limits its clinical benefits. This study is conducted to investigate the role of toll like receptor-4 (TLR4) and p38 signaling and Klotho protein expression in PIPN and the role of Trimetazidine (TMZ) in this pathway. Sixty-four male Swiss albino mice were divided into 4 groups (n = 16); Group (1) injected intraperitoneally (IP) with ethanol/tween 80/saline for 8 successive days. Group (2) received TMZ (5 mg/kg, IP, day) for 8 successive days. Group (3) treated with 4 doses of PTX (4.5 mg/kg, IP) every other day over a period of 8 days. Group (4) received a combination of TMZ as group 2 and PTX as group 3. The Effect of TMZ on the antitumor activity of PTX was studied in another set of mice-bearing Solid Ehrlich Carcinoma (SEC) that was similarly divided as the above-mentioned set. TMZ mitigated tactile allodynia, thermal hypoalgesia, numbness and fine motor dyscoordination associated with PTX in Swiss mice. The results of the current study show that the neuroprotective effect of TMZ can be attributed to inhibition of TLR4/p38 signaling which also includes a reduction in matrix metalloproteinase-9 (MMP9) protein levels as well as the proinflammatory interleukin-1β (IL-1β) and preserving the levels of the anti-inflammatory IL-10. Moreover, the current study is the first to demonstrate that PTX reduces the neuronal levels of klotho protein and showed its modulation via cotreatment with TMZ. In addition, this study showed that TMZ neither alter the growth of SEC nor the antitumor activity of PTX. In conclusion, we suggest that (1) Inhibition of Klotho protein and upregulation of TLR4/p38 signals in nerve tissues may contribute to PIPN. (2) TMZ attenuates PIPN by modulating TLR4/p38 and Klotho protein expression in without interfering with its antitumor activity.

Leonurine hydrochloride-a new drug for the treatment of menopausal syndrome: Synthesis, estrogen-like effects and pharmacokinetics

This research aimed to investigate the estrogen-like effects of Leonurine hydrochloride (Leo). First, we developed a total synthesis of Leo from 3,4,5-trimethoxy-benzoic acid and the structure was confirmed through 1H NMR and mass spectrometry (MS). Then the estrogenic activity of Leo in vitro and in vivo was studied. The proliferation and proliferation inhibitory effects of Leo on MCF-7 cells and MDA-MB-231 cells indicate that Leo exerts estrogen-like effects through estrogen receptor α (ERα) and estrogen receptor β((ERβ) in vitro. Uterotrophic assay in juvenile mice showed that Leo has an estrogen-like effect in vivo, as it can promote the development of the uterus of juvenile mice, increase its uterine coefficient and the size of the uterine cavity, as well as the increased number of uterine glands and the thickened uterine wall. For further research, cyclophosphamide (CTX) was used to establish a mouse model of ovarian function decline. Through this model, we found that Leo can restore the estrous cycle of mice, increase the number of primordial and primary follicles in the ovaries of mice, and regulate the disordered hypothalamic-pituitary-ovarian (HPOA) axis of mice. Finally, the pharmacokinetics of Leo was studied and oral bioavailability of Leo was calculated to be 2.21%. Leo was synthesized and the estrogen-like effect in vitro and in vivo was confirmed as well as its pharmacokinetics.

The Antitumor Peptide ERα17p Exerts Anti-Hyperalgesic and Anti-Inflammatory Actions Through GPER in Mice

Persistent inflammation and persistent pain are major medical, social and economic burdens. As such, related pharmacotherapy needs to be continuously improved. The peptide ERα17p, which originates from a part of the hinge region/AF2 domain of the human estrogen receptor α (ERα), exerts anti-proliferative effects in breast cancer cells through a mechanism involving the hepta-transmembrane G protein-coupled estrogen receptor (GPER). It is able to decrease the size of xenografted human breast tumors, in mice. As GPER has been reported to participate in pain and inflammation, we were interested in exploring the potential of ERα17p in this respect. We observed that the peptide promoted anti-hyperalgesic effects from 2.5 mg/kg in a chronic mice model of paw inflammation induced by the pro-inflammatory complete Freund's adjuvant (CFA). This action was abrogated by the specific GPER antagonist G-15, leading to the conclusion that a GPER-dependent mechanism was involved. A systemic administration of a Cy5-labeled version of the peptide allowed its detection in both, the spinal cord and brain. However, ERα17p-induced anti-hyperalgesia was detected at the supraspinal level, exclusively. In the second part of the study, we have assessed the anti-inflammatory action of ERα17p in mice using a carrageenan-evoked hind-paw inflammation model. A systemic administration of ERα17p at a dose of 2.5 mg/kg was responsible for reduced paw swelling. Overall, our work strongly suggests that GPER inverse agonists, including ERα17p, could be used to control hyperalgesia and inflammation.