Oestrogen receptor ERα and ERβ agonists ameliorate oxidative brain injury and improve memory dysfunction in rats with an epileptic seizure

Selective estrogen receptor activation prior to global cerebral ischemia in female rats impacts microglial activation and anxiety-like behaviors without effects on CA1 neuronal injury

Estrogen receptor (ER) activation by 17-ß estradiol (E2) can attenuate neuronal injury and behavioral impairments following global cerebral ischemia (GCI) in rodents. This study sought to further examine the discrete roles of ERs through characterization of the effects of selective ER activation on post-ischemic pro-inflammatory microglial activation, hippocampal neuronal injury, and anxiety-like behaviors. Forty-six ovariectomized (OVX) adult female Wistar rats received daily s.c injections (100 μg/kg/day) of propylpyrazole triol (PPT; ERα agonist), diarylpropionitrile (DPN; ERβ agonist), G-1 (G-protein coupled ER agonist; GPER), E2 (activating all receptors), or vehicle solution (VEH) for 21 days. After final injection, rats underwent GCI via 4-vessel occlusion (n=8 per group) or sham surgery (n=6, vehicle injections). The Open Field Test (OFT), Elevated Plus Maze (EPM), and Hole Board Test (HBT) assessed anxiety-like behaviors. Microglial activation (Iba1, CD68, CD86) in the basolateral amygdala (BLA), CA1 of the hippocampus, and paraventricular nucleus of the hypothalamus (PVN) was determined 8 days post-ischemia. Compared to sham rats, Iba1 activation and CA1 neuronal injury were increased in all ischemic groups except DPN-treated rats, with PPT-treated ischemic rats also showing increased PVN Iba1-ir expression. Behaviorally, VEH ischemic rats showed slightly elevated anxiety in the EPM compared to sham counterparts, with no significant effects of agonists. While no changes were observed in the OFT, emotion regulation via grooming in the HBT was increased in G-1 rats compared to E2 rats. Our findings support selective ER activation to regulate post-ischemic microglial activation and coping strategies in the HBT, despite minimal impact on hippocampal injury.

SARS-CoV-2 Causes Brain Damage: Therapeutic Intervention with AZD8797

Elevated CX3CL1 is associated with severe COVID-19 and neurologic symptoms. We aimed to investigate the potential protective effects of selective CX3CR1 antagonist AZD8797 on SARS-CoV-2-induced neuronal damage, and to identify the underlying mechanisms. K18-hACE2 transgenic mice (n = 37) were randomly divided into control groups and SARS-CoV-2 groups, with and without intraperitoneal administration of vehicle or AZD8797 (2.5 mg/mL/day), following exposure to either a single dose of SARS-CoV-2 inhalation or no exposure. Object recognition and hole board tests were performed to assess memory function. Postinfection 8 days, brain tissues were analyzed for histopathological changes, viral, glial, apoptotic, and other immunohistochemical markers, along with measuring malondialdehyde, glutathione, and myeloperoxidase activities. Serum samples were analyzed for proinflammatory cytokines. The SARS-CoV-2 group showed significant weight loss, neuronal damage, oxidative stress, and impaired object recognition memory, while AZD8797 treatment mitigated some of these effects, especially in weight, apoptosis, glutathione, and MCP-1. Histopathological analyses supported the protective effects of AZD8797 against SARS-CoV-2-induced damage. The CX3CL1-CX3CR1 signaling pathway could offer a promising target for reducing SARS-CoV-2's neurological impact, but additional research is needed to confirm these findings in combination with other therapies and assess the clinical significance.

Subchronic exposure to Tamoxifen modulates the hippocampal BDNF/ERK/Akt/CREB pathway and impairs memory in intact female rats

Tamoxifen (TAM), a Selective Estrogen Receptor Modulator (SERM), is commonly used to treat and prevent breast cancer. Memory impairment has been noticed in patients who experience hormone therapy in the case of TAM and other SERMs. Animal studies that mimic the TAM longer exposure effects are needed to better elucidate the adverse effects of continuous treatment in humans. This study evaluated the effects of TAM subchronic administration on the memory performance and hippocampal neural plasticity of intact female Wistar rats. Animals were treated intragastrically with TAM (0.25 and 2.5 mg/kg) for 59 days. The rats were subjected to the Object Location Test (OLT) and Object Recognition Test (ORT) to evaluate memory performance. After euthanasia, the hippocampus samples were excised and the protein levels of the BDNF/ERK/Akt/CREB pathway were evaluated. The rat's locomotor activity and hippocampal TrkB levels were similar among the experimental groups. TAM at both doses reduced the memory performance of female rats in the OLT and short-term memory of ORT, and impaired hippocampal levels of mBDNF, proBDNF, and pCREB/CREB. TAM only at the dose of 2.5 mg/kg reduced the memory performance of rats in the long-term memory of ORT and hippocampal pERK/ERK and pAkt/Akt ratios. TAM subchronic administration induced amnesic effects and modulated the hippocampal BDNF/ERK/Akt/CREB pathway in intact young adult female Wistar rats.

Astragalin alleviates cognitive deficits and neuronal damage in SAMP8 mice through upregulating estrogen receptor expression

Senile plaques composed of β-amyloid protein (Aβ) and neurofibrillary tangles (NFTs) composed of intracellular hyper-phosphorylated tau are major causes of cognitive impairment and neuronal damage in Alzheimer disease (AD). Astragalin (AST), a naturally-occurring flavonoid compound, was reported to have neuroprotective effects in the brain, but its effects in AD remain unknown. Herein, the learning and memory deficits were alleviated and neuronal damage in the hippocampus were inhibited after the senescence-accelerated mouse prone 8 (SAMP8) mouse were given AST (5 mg/kg or 10 mg/kg) daily by gavage for 2 months. Furthermore, AST reduced Aβ_1-40 and Aβ_1-42 deposition, decreased β-carboxyl-terminal fragment (β-CTF) protein level and tau hyper-phosphorylation, but increased α-CTF protein level and glycogen synthase kinase-3beta (GSK-3β) phosphorylation in hippocampus of SAMP8 mice. Meanwhile, the effects of AST on AD were also explored in vitro by treating primary neurons with amyloid-β1-42 oligomers (Aβ_1-42O). Consistently, AST also alleviated amyloid-β1-42 oligomers (Aβ_1-42O)-induced neuronal damage, amyloid plaques, and tau phosphorylation in vitro model. Of note, estrogen receptor (ER)α and ERβ expression in the hippocampus of SAMP8 mice and Aβ_1-42O-treated neurons was significantly decreased but their levels were increased by AST. Moreover, in vivo and in vitro experiments revealed that ER antagonist, Fulvestrant, reversed the effects caused by AST. Altogether, our investigation indicates that AST may ameliorate cognitive deficits and AD-type pathologies in SAMP8 mice and Aβ_1-42O-treated neurons through upregulating ERα and ERβ expression. Our findings indicate the value of AST as a potential reagent for AD treatment.

Melatonin Alleviates Ovariectomy-Induced Cardiovascular Inflammation in Sedentary or Exercised Rats by Upregulating SIRT1

We aimed to evaluate the impact of hormone replacement, melatonin, or exercise alone or their combination on oxidative damage and functional status of heart, brain, and aorta of ovariectomized (OVX) rats and to determine whether the signaling pathway is dependent on sirtuin-1 (SIRT1). Ovariectomized Sprague Dawley rats were orally given either a hormone replacement therapy (1 mg/kg/day,17β estradiol; HRT) or melatonin (4 mg/kg/day) or HRT + melatonin treatments or tap water, while each group was further divided into sedentary and exercise (30 min/5 days/week) groups. After the heart rate measurements and memory tests were performed, trunk blood was collected at the end of the 10th week to determine metabolic parameters in serum samples. Tissue samples of abdominal aorta, heart, and brain were taken for biochemical measurements and histopathological evaluation. Heart rates and memory performances of the OVX rats were not changed significantly by none of the applications. Melatonin treatment or its co-administration with HRT upregulated the expressions of IL-10 and SIRT1, reduced the expressions of IL-6 and TNF-α, and reduced DNA damage in the hearts and thoracic aortae of non-exercised rats. Co-administration of melatonin and HRT to exercised OVX rats reduced inflammatory response and upregulated SIRT1 expression in the aortic and cardiac tissues. The present study suggests that melatonin treatment, either alone or in combination with exercise and/or HRT, upregulates SIRT1 expression and alleviates oxidative injury and inflammation in the hearts and aortas of OVX rats. Melatonin should be considered in alleviating cardiovascular disease risk in postmenopausal women.

Female mice lacking ERβ display excitatory/inhibitory synaptic imbalance to drive the pathogenesis of temporal lobe epilepsy

Epilepsy is a highly prevalent and drug-refractory neurological disorder characterized by spontaneous recurrent seizures. Estrogen is identified to be proconvulsant and lowers the seizure threshold of female epilepsy. Estrogen receptor β (ERβ) has been proposed to mediate neuroprotection in epilepsy, although the underlying mechanism remains unknown. Rationale: In this study, we investigated the role of ERβ in the epileptogenesis of female temporal lobe epilepsy (TLE). Methods: Immunohistochemistry, immunofluorescence, western blots, Golgi staining, ¹H MRS and whole-cell patch-clamp were used to evaluate ERβ expression, pathological changes, and synaptic excitation /inhibition (E/I) balance in female TLE patients and ovariectomized (OVX) chronic epileptic mice. Electroencephalogram (EEG) recordings were recorded to evaluate the epileptic susceptibility in OVX WT and ERβ^-/- mice. And high-throughput RNA-sequence was performed to identify differential expression genes (DEGs) which can elucidate the potential mechanism of ERβ regulating the seizure susceptibility. Results: ERβ expression was decreased in the brains of female TLE patients and OVX chronic epileptic mice. ERβ deletion enhanced seizure susceptibility and exacerbated the imbalance of synaptic E/I in hippocampal CA1 area of OVX epileptic mice. In line with these observations, RNA-sequence data further identified glutamine ligase (GLUL) as the target of ERβ involved in regulating synaptic E/I in CA1. Furthermore, ERβ agonist WAY-200070 markedly suppressed epileptic phenotypes and normalized GLUL expression in CA1 region of kainic acid (KA) induced OVX chronic epileptic model. Conclusions: Our data provide novel insight into the pathogenesis of female TLE, and indicate ERβ provides a new therapeutic strategy for female TLE patients.

Influence of progestational stress on BDNF and NMDARs in the hippocampus of male offspring and amelioration by Chaihu Shugan San

BACKGROUND

Progestational stress has been proven to be a risk for the neural development of offspring, especially in the hippocampus. However, whether Chaihu Shugan San (CSS) can ameliorate hippocampal neural development via the regulation of brain-derived neurotrophic factor (BDNF), and N-methyl-D-aspartate receptors (NMDAR) 2A (NR2A) and 2B (NR2B), and the mechanism of such action remains unclear.

METHODS

Thirty-six female rats were randomly allocated into control, chronic immobilization stress (CIS) and CSS groups according to the random number table, respectively. The male offspring were fed for 21 days after birth then randomly divided into the same three groups (6 rats/group) as the female rats. Female rats, except for the control group, underwent 21-day CIS to established a progestational stress anxiety-like model which was evaluated by body weight, the elevated plus-maze (EPM) test and serum dopamine (DA) measured using an enzyme-linked immunosorbent assay (ELISA). The expression levels of estrogen receptors (ERα/ERβ) and progesterone receptor (PR) in female rat ovaries were quantified by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. The hippocampal tissue in the 21-day offspring was observed by hematoxylin-eosin (HE) staining. The concentration of BDNF, NR2A, and NR2B were measured by RT-qPCR and immunohistochemistry in the CA3 and dentate gyrus (DG) regions of offsprings' hippocampus.

RESULTS

Compared with the female control group, significant differences in body weight, EPM test and DA concentration were observed in the CIS group, meanwhile, the concentration of ERα (P < 0.05), PR (P < 0.05) and ERβ in the ovaries were decreased. In the offsprings' hippocampus of the CIS group, the chromatin of the nucleus was edge set and with condensed and irregular morphology nucleus, and the cytoplasm was unevenly stained with spaces around the cells, moreover, the expression levels of BDNF, NR2A, and NR2B were also declined (P < 0.05). However, Chaihu Shugan San reversed these changes, especially the BDNF in the DG region (P < 0.05), and NR2A and NR2B in the CA3 and DG region (P < 0.05).

CONCLUSIONS

CSS could ameliorate the neural development of the hippocampus in offspring damaged by anxiety-like progestational stress in female rats via regulating the expression levels of ERα, ERβ, and PR in female rat ovaries and BDNF, NR2A, and NR2B in the hippocampus of their offspring.

Sleeve gastrectomy-induced endocrine changes in the remnant stomachs of premenopausal and postmenopausal rats: role of the estrogen receptors

BACKGROUND

Although alterations in the plasma levels of leptin, glucagon-like peptide-1, and gastrin were linked with bariatric surgery outcomes, gastric production of these peptides was not elucidated before.

OBJECTIVE

The aim was to evaluate the impact of estrogen depletion and estrogen receptors (ERs) on sleeve gastrectomy (SG)-induced alterations in gastric hormone production, gastric mucosal integrity, and bone mass.

SETTING

Physiology Research Lab at the University.

METHODS

Female Sprague-Dawley rats underwent ovariectomy or sham operation (control), and 2 months later SG or sham SG was performed. Rats received either nonselective agonist 17 β, ER-α agonist, ER-β agonist, or vehicle for 3 weeks. Trunk blood and gastric tissues were collected for biochemical measurements, while histopathologic examination was performed in gastric and femur samples.

RESULTS

In the presence of intact ovaries, SG-induced weight loss was accompanied by reductions in the gastric synthesis of leptin and gastrin, while gastric glucagon-like peptide-1 was additionally decreased when SG was performed at the postmenopausal state. SG elevated the depleted serum estradiol levels of menopause, implicating a beneficial effect, but the occurrence of severe gastric mucosal injury was triggered. On the other hand, using ER agonists upregulated gastrin-expressing cells, ameliorated gastric injury, and improved bone loss.

CONCLUSIONS

SG, either at premenopausal or postmenopausal state, resulted in considerable loss in bone mass, along with reductions in the gastric levels of gastrin and leptin. Functional status of the ovaries needs to be taken into consideration when monitoring the outcomes of SG, and ER agonists could be of value in controlling SG-induced complications.

Virtual Screening of the Multi-pathway and Multi-gene Regulatory Molecular Mechanism of Dachengqi Decoction in the Treatment of Stroke Based on Network Pharmacology

BACKGROUND

Stroke is ranked second among diseases that cause mortality worldwide. Owing to its complicated pathogenesis, no satisfactory treatment strategies for stroke are available. Dachengqi decoction (DCQD), a traditional Chinese herbal medicine, has been widely used in China for a long time, as it has a good effect on stroke. However, the molecular mechanism underlying this effect of DCQD is unclear.

OBJECTIVE

In the present study, we aimed to reveal and explore the multi-pathway and multi-gene regulatory molecular mechanism of Dachengqi decoction in the treatment of stroke.

METHODS

In this study, a network pharmacology method, in combination with oral bioavailability prediction and drug-likeness evaluation, was employed to predict the active ingredients of DCQD. The target genes of the active components and the traced pathways related to these target genes were predicted. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed using clusterProfiler software package on the R platform and ClueGo+CluePedia plug-ins. Finally, the key DCQD targets were verified using the Gene Expression Omnibus (GEO) dataset.

RESULTS AND DISCUSSION

According to the ADME model, 52 active components were screened from 296 active components of DCQD. After prediction and screening, 215 stroke-related targets were obtained and analyzed via GO and KEGG analyses. GO analysis showed that DCQD targets were mainly involved in the regulation of oxidative stress, lipid metabolism, inflammation, and other biological processes. KEGG pathway analysis further revealed pathways involved in stroke, such as arachidonic acid metabolic, HIF-1 signaling pathway, estrogen signaling pathway, MAPK signaling pathway, PI3K-Akt signaling pathway, platelet activation pathway, VEGF signaling pathway, and cAMP signaling pathway. Network analysis revealed that DCQD might be involved in the regulation of lipid metabolism, blood pressure, inflammation, angiogenesis, neuroprotection, platelet aggregation, apoptosis, and oxidation in stroke treatment. GEO dataset analysis showed that DCQD's therapeutic effects might be exerted via the bidirectional regulation principle.

CONCLUSION

Based on the methods of network pharmacology and GEO analysis, it was found that, during stroke treatment, DCQD regulates and controls multiple genes and multiple pathways in a synergistic manner, providing a new strategy for stroke treatment.