Grounded in the theory of "all marrows dominated by brain", this study explored the therapeutic mechanism of Zuogui Pills in modulating the oxytocin(OXT)/oxytocin receptor(OXTR) feed-forward loop in the treatment of postmenopausal osteoporosis(PMOP). A PMOP rat model was established using ovariectomy, and 70 Sprague-Dawley female rats were randomly divided into the following groups: sham operation group, model group, estradiol group(17β-estradiol, 0.05 mg·kg~(-1)·d~(-1)), Zuogui Pills low, medium, and high dose groups(0.2, 0.4, 0.8 g·kg~(-1)·d~(-1), respectively), and an antagonist group(atosiban 0.9 mg·kg~(-1)·d~(-1) + 17β-estradiol 0.05 mg·kg~(-1)·d~(-1) + Zuogui Pills 0.4 g·kg~(-1)·d~(-1)). After 12 weeks of model establishment, treatment was administered by gavage once daily for another 12 weeks, followed by sample collection. Enzyme-linked immunosorbent assay(ELISA) was used to measure serum levels of estrogen(E_2), OXT, tartrate-resistant acid phosphatase(TRACP-5b), and bone alkaline phosphatase(BALP). Histopathological changes in the left distal femur were observed through hematoxylin and eosin(HE) staining. Micro-computed tomography(micro-CT) was used to analyze the microstructure of the right distal femur. Western blot was employed to detect the expression levels of OXTR, small GTP-binding protein Ras, Raf1 proto-oncogene(Raf1), mitogen-activated protein kinase kinase 1/2(MEK1/2), and extracellular signal-regulated kinase 1/2(ERK1/2), and their phosphorylated forms in tibial tissues. Compared with the model group, the Zuogui Pills medium and high dose groups showed significantly increased levels of E_2, OXT, and BALP, with a notable decrease in TRACP-5b levels. Morphologically, the trabeculae in the left distal femur were more tightly arranged. The fibrous structure in the right distal femur was significantly improved in the Zuogui Pills high dose group. Additionally, the expression of OXTR, Ras, p-Raf1, p-MEK1/2, and p-ERK1/2 proteins in tibial tissues was significantly increased. The therapeutic effect of the Zuogui Pills high dose group was partially inhibited when an OXTR antagonist was administered. These findings suggest that Zuogui Pills can regulate the OXT/OXTR feed-forward loop, activate the phosphorylation of the downstream Ras/Raf1/MEK/ERK signaling pathway, and ultimately improve bone mineral density, thereby exerting therapeutic effects in PMOP.
Animals ; Rats, Sprague-Dawley ; Rats ; Female ; Drugs, Chinese Herbal/administration & dosage* ; Oxytocin/genetics* ; Receptors, Oxytocin/genetics* ; Humans ; Osteoporosis, Postmenopausal/genetics* ; Bone and Bones/drug effects* ; Brain/drug effects* ; Bone Marrow/drug effects*

OBJECTIVES: To investigate the role of a neural pathway from oxytocin (OXT) neurons in the paraventricular hypothalamic nucleus (PVN) to γ-aminobutyric acid (GABA) neurons (GABAergic neurons) in the trigeminal nucleus caudalis (TNC) in regulating pain sensitization in a mouse model of chronic migraine and to explore the underlying mechanisms. METHODS: A chronic migraine mouse model was established by intraperitoneal injection of nitroglycerin (NTG, 1 mg/mL, 10 mg/kg) on days 1, 3, 5, 7, and 9. The study consisted of four parts: PartⅠ: 24 male wild-type C57BL/6J mice were divided into four groups (n=6 in each), receiving single or repeated injection of NTG or saline, respectively. Immunofluorescence was used to detect c-Fos and OXT expression in the PVN. Part Ⅱ: 6 male OXT-Cre transgenic C57BL/6J mice were used for anterograde monosynaptic tracing combined with RNAscope and immunofluorescence to identify neural projections from PVN OXT neurons to TNC GABAergic neurons. Part Ⅲ: 30 male OXT-Cre transgenic C57BL/6J mice were bilaterally injected Cre-dependent chemogenetic activation virus into the PVN. These mice were randomly divided into five groups, with six mice in each group. Mice in the clozapine N-oxide (CNO) group and the control group were intra-peritoneally injected with 0.1 mg/mL of CNO solution (1 mg/kg) and the same volume of isotonic normal saline, respectively. 3 hours after the injection, the brain tissues were harvest and c-Fos immunofluorescence staining was performed to verify the efficiency of chemogenetic activation virus. Mice in the model control group and the CNO activated model group were subjected to chronic migraine modeling, with bilateral TNC injection of isotonic normal saline and CNO, respectively, on day 10. The mice in the negative control group were bilaterally intra-TNC injected with isotonic normal saline. After 30 minutes, the Von-Frey filament and acetone tests were used to assess the mechanical pain threshold and cold pain response time in the periorbital region of the mice in these three groups. Part Ⅳ: 24 male OXT-Cre transgenic C57BL/6J mice were bilaterally injected with the Cre-dependent chemogenetic activation virus into the PVN. These mice were randomly divided into four groups, with six mice in each group. Mice in the model control group, the CNO activated model group and the atosiban group were subjected to chronic migraine modeling. On day 10, mice in the negative control group and the model control group were intraperitoneally injected with isotonic normal saline, while mice in the CNO activated model group and the atosiban group were intraperitoneally injected with CNO. After 15 minutes, mice in the atosiban group were bilaterally intra-TNC injected with atosiban, while mice in other three groups were bilaterally intra-TNC injected with isotonic normal saline containing 1% dimethyl sulfoxide. After 15 minutes, the Von-Frey filament and acetone tests were used to assess the mechanical pain threshold and cold pain response time in the periorbital region of the mice. The GABA content in the bilateral TNC was detected by high-performance liquid chromatography (HPLC). RESULTS: Mice with chronic migraine models exhibited reduced periorbital mechanical pain thresholds and increased periorbital cold pain reaction time, accompanied by an increase in both the number of c-Fos⁺ neurons and the percentage of c-Fos⁺ OXT neurons in the PVN (all P<0.05). The anterograde tracing virus and RNAscope combined with immunofluorescence staining showed that PVN OXT neurons projected to TNC GABAergic neurons. Immuno-fluorescence staining demonstrated that compared with the control group, the percentage of c-Fos⁺ OXT neurons in the PVN of CNO group increased (P<0.05). In bilateral intra-TNC drug administration experiments, compared with the model control group, the periorbital mechanical pain threshold increased, and the periorbital cold pain reaction time decreased in the CNO activated model group (both P<0.05). In intraperitoneal drug administration experiments, compared with the CNO activate model group, the periorbital mechanical pain threshold decreased, and the periorbital cold pain reaction time increased in the atosiban group (both P<0.05). HPLC analysis showed that, compared with the negative control group, the model control group and the atosiban group, GABA level of TNC in the CNO activated model group increased (all P<0.05). CONCLUSIONS PVN OXT neurons exert a descending facilitatory effect on GABAergic neurons in the TNC via OXT release, thereby ameliorating pain sensitization in chronic migraine.
Animals ; Paraventricular Hypothalamic Nucleus/physiopathology* ; Male ; Mice, Inbred C57BL ; Migraine Disorders/physiopathology* ; Mice ; GABAergic Neurons/physiology* ; Oxytocin/physiology* ; Disease Models, Animal ; Neurons/physiology* ; Mice, Transgenic ; Neural Pathways ; Chronic Disease

The oxytocin receptor (OXTR) has garnered increasing attention for its role in regulating both mature behaviors and brain development. It has been established that OXTR mediates a range of effects that are region-specific or period-specific. However, the current studies of OXTR expression patterns in mice only provide limited help due to limitations in resolution. Therefore, our objective was to generate a comprehensive, high-resolution spatiotemporal expression map of Oxtr mRNA across the entire developing mouse brain. We applied RNAscope in situ hybridization to investigate the spatiotemporal expression pattern of Oxtr in the brains of male mice at six distinct postnatal developmental stages (P7, P14, P21, P28, P42, P56). We provide detailed descriptions of Oxtr expression patterns in key brain regions, including the cortex, basal forebrain, hippocampus, and amygdaloid complex, with a focus on the precise localization of Oxtr⁺ cells and the variance of expression between different neurons. Furthermore, we identified some neuronal populations with high Oxtr expression levels that have been little studied, including glutamatergic neurons in the ventral dentate gyrus, Vgat⁺Oxtr⁺ cells in the basal forebrain, and GABAergic neurons in layers 4/5 of the cortex. Our study provides a novel perspective for understanding the distribution of Oxtr and encourages further investigations into its functions.
Animals ; Receptors, Oxytocin/metabolism* ; Male ; Brain/growth & development* ; Mice ; Mice, Inbred C57BL ; Neurons/metabolism* ; Single-Cell Analysis ; Gene Expression Regulation, Developmental ; RNA, Messenger/metabolism* ; Animals, Newborn

Oxytocin is classically termed a 'prosocial neuropeptide' because of its evolutionarily conserved role in promoting affiliative behaviors. Endogenous oxytocin is mainly synthesized by hypothalamic oxytocin neurons and signals through oxytocin receptors (OxtRs). Recent studies with cell type-specific and circuit-specific interrogation have uncovered that oxytocin signals exert pleiotropic neuromodulatory effects through anatomically widespread axonal projections and ubiquitously distributed OxtRs. Dysfunctions of oxytocin signals are closely relevant to brain disorders/diseases. While intranasal oxytocin administration has been demonstrated to be one potential strategy to alleviate some brain disorders/diseases, such as autism, obesity, and anxiety, conflicting clinical outcomes highlight the imperative for precision-targeted neuromodulation strategies. Dissecting the molecular, cellular, and neural circuitry mechanisms underlying oxytocinergic modulation is a prerequisite to achieving this goal. This review provides an overview of the current understanding of the oxytocin system in terms of anatomical structure, neuronal modulation, and signal pathways, and discusses the modulatory roles of oxytocin in social, feeding, emotional, and sensory-related brain functions and brain diseases.
Oxytocin/metabolism* ; Humans ; Animals ; Hypothalamus/physiology* ; Brain/physiology* ; Brain Diseases/physiopathology* ; Receptors, Oxytocin/metabolism*

Magnetic stimulation has made significant strides in the treatment of psychiatric disorders. Nonetheless, current magnetic stimulation techniques lack the precision to accurately modulate specific nuclei and cannot realize deep brain magnetic stimulation. To address this, we utilized superparamagnetic iron oxide nanoparticles as mediators to achieve precise targeting and penetration. We investigated the effects of magnetic fields with varying frequencies on neuronal activity and compared the activation effects on neurons using a 10-Hz precise magneto-stimulation system (pMSS) with repetitive transcranial magnetic stimulation in mice. Oxytocin levels, dendritic morphology and density, and mouse behavior were measured before and after pMSS intervention. Our findings suggest that pMSS can activate oxytocinergic neurons, leading to upregulation of oxytocin secretion and neurite outgrowth. As a result, sociability was rapidly improved after a one-week pMSS treatment regimen. These results demonstrate a promising magneto-stimulation method for regulating neuronal activity in deep brain nuclei and provide a promising therapeutic approach for autism spectrum disorder.
Animals ; Autism Spectrum Disorder/physiopathology* ; Paraventricular Hypothalamic Nucleus/physiology* ; Disease Models, Animal ; Transcranial Magnetic Stimulation/methods* ; Male ; Social Behavior ; Mice ; Oxytocin/metabolism* ; Mice, Inbred C57BL ; Neurons/physiology*

Empathy is crucial for communication and survival for individuals. Whether empathy in pain contagion shows sex differences and its underlying mechanisms remain unclear. Here, we report that pain contagion can occur in stranger female rats, but not in stranger males. Blocking oxytocin receptors in the anterior cingulate cortex (ACC) suppressed pain contagion in female strangers, while oxytocin administration induced pain contagion in male strangers. In vitro, corticosterone reduces neuronal activation by oxytocin. During male stranger interactions, higher corticosterone decreased oxytocin receptor-positive neuronal activity in the ACC, suppressing pain contagion. These findings highlight the role of oxytocin in pain contagion and suggest that sex differences in empathy may be determined by the balance of oxytocin and corticosterone in the ACC. This study suggests an approach for the treatment of certain mental disorders associated with abnormal empathy, such as autism and depression.
Animals ; Oxytocin/pharmacology* ; Gyrus Cinguli/drug effects* ; Male ; Female ; Corticosterone/pharmacology* ; Empathy/drug effects* ; Sex Characteristics ; Receptors, Oxytocin/antagonists & inhibitors* ; Pain/psychology* ; Rats ; Rats, Sprague-Dawley ; Neurons/metabolism*

Arginine vasopressin (AVP) plays a crucial role in various physiological processes including water reabsorption, cardiovascular homeostasis, hormone secretion, and social behavior. AVP acts through three distinct receptor subtypes, i.e., V1a, V1b, and V2. Among them, the vasopressin V2 receptor (V2R) was initially discovered in the principal cells of renal collecting ducts, where it is primarily involved in regulating water reabsorption. However, in recent years, with the advancement of imaging and bioinformatics techniques, there has been a deeper understanding of the microstructure, protein binding capacity, and specific tissue distribution of V2R. Additionally, the pathogenic roles and target effects of V2R in various diseases have been uncovered through ectopic overexpression, activation, or antagonism. This paper aims to provide a brief overview of current research status on the physiological functions, pathophysiological mechanisms, and drug development related to V2R in recent years.
Receptors, Vasopressin/physiology* ; Humans ; Animals ; Antidiuretic Hormone Receptor Antagonists ; Arginine Vasopressin/physiology*

This study aimed to investigate the therapeutic effect of Leonuri Herba aqueous decoction on primary dysmenorrhea(PD) and explore the underlying mechanism in conjunction with untargeted metabolomics. Forty adult female rats were randomly divi-ded into a normal group, a model control group, ibuprofen(0.12 g·kg~(-1)) group, and high-and low-dose Leonuri Herba aqueous decoction(5 and 2.5 g·kg~(-1)) groups, with eight rats in each group. The PD rat model was prepared using intramuscular injection of estradiol benzoate combined with intraperitoneal injection of pitocin. Drugs were administered by gavage from the 4th day of modeling for 7 d. After the last administration, pitocin was injected intraperitoneally, and the writhing latency and writhing times within 30 min were recorded. The uterine and ovarian coefficients were determined. Estradiol(E_2), progesterone(Prog), oxytocin(OT), cyclooxyge-nase 2(COX-2), prostaglandin E_2(PGE_2), prostaglandin F_(2α)(PGF_(2α)), and Ca~(2+) levels in uterine tissues were measured by ELISA and biochemical kits. Morphological changes in uterine and ovarian tissues were observed by hematoxylin-eosin(HE) staining. The protein expression of oxytocin receptor(OTR), prostaglandin E_2 receptor 3(EP3), and estrogen receptor alpha(ERα) in uterine tissues was detected by immunohistochemistry. The mRNA expression of OTR, PGE_2 receptors 1-4(EP1, EP2, EP3, and EP4), and PGF_(2α) receptor(FP) in uterine tissues was detected by quantitative real-time PCR. Untargeted metabolomics analysis was performed by ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry(LC-QTOF-MS) technology to screen potential biomarkers and enrich metabolic pathways. The results showed that Leonuri Herba was able to significantly reduce the writhing times in PD rats(P<0.05 or P<0.01), significantly reduce the uterine and ovarian coefficients(P<0.01), and improve their histomorphology. After treatment with Leonuri Herba, PGE_2 content was significantly increased(P<0.05), COX-2, PGF_(2α) and Ca~(2+) content, and PGF_(2α)/PGE_2 was significantly decreased(P<0.05 or P<0.01), and OT content was decreased, while E_2 and Prog content tended to further increase in uterine tissues of PD rats. Correspondingly, OTR and EP3 protein expression was significantly downregulated(P<0.05 or P<0.01) and ERα protein expression was upregulated(P<0.05) in uterine tissues. The mRNA expression of FP and EP4 in uterine tissues was significantly downregulated(P<0.01), and the mRNA expression of EP1, EP3, and OTR showed a decreasing trend. The untargeted metabolomics results showed that 10 differential metabolites were restored in the plasma of PD rats after Leonuri Herba treatment. The results indicate that Leonuri Herba is effective in the prevention and treatment of PD, and the underlying mechanism may be attributed to the regulation of PGs synthesis and corresponding receptor binding.
Humans ; Rats ; Female ; Animals ; Estrogen Receptor alpha ; Oxytocin ; Dysmenorrhea/metabolism* ; Cyclooxygenase 2 ; Dinoprostone ; RNA, Messenger/metabolism* ; Dinoprost

OBJECTIVE: To investigate the effect of Heliotropium indicum L. (H. indicum L.) on uterine involution and its underlying mechanisms in both in vivo and in vitro study. METHODS: For in vivo studies, postpartum rats were randomly divided into 2 groups (n=24 for each): control group and treated group which were orally and daily administered with ethanolic extract of H. indicum L. (250 mg/kg body weight) until day 5 of postpartum. Uteri were collected for analysis of weight, cross-sectional area, collagen cross-sectional area, and collagen content on postpartum day 1, 3, and 5 (n=8 for each) from both groups. Blood samples were collected for hepatotoxicity and 17β-estradiol (E₂) measurement. For in vitro studies, the extract effects on uterine contraction at half maximum effective concentration of 2.50 mg/mL were studied in organ bath system for at least 20 min. RESULTS: Uterine parameters were significantly decreased after treated with extract of H. indicum L. (P<0.05). H. indicum L. extract significantly accelerated the reduction of those parameters and significantly decreased E₂ (P<0.05). The extract facilitated uterine involution with no hepatotoxicity. H. indicum L. extract significantly stimulated uterine contraction (P<0.05) and synergized with oxytocin, prostaglandin and its precursor, linoleic acid. By investigating the different sequencing of the extract with the additional stimulants (added before or after), the two showed antagonistic effects, but still showed potentiated force when compared with control (without the stimulants). CONCLUSIONS The underlying mechanisms by which H. indicum L. facilitated uterine involution might be due to reducing E₂ which induces collagenase activity, leading to decreases in uterine weight and size and stimulating uterine contraction. Our study provides new findings for future drug development for facilitating uterine involution with H. indicum L.
Pregnancy ; Female ; Rats ; Animals ; Heliotropium ; Uterus ; Plant Extracts/pharmacology* ; Oxytocin ; Collagen/pharmacology*

OBJECTIVE: To observe the effects of electroacupuncture (EA) on NLRP3 inflammasome and its downstream protein gastermin D (GSDMD) in rats with primary dysmenorrhea (PDM), and to explore the potential mechanism of EA on the treatment of PDM. METHODS: Forty healthy female SD rats without pregnancy were randomly divided into a control group, a model group, an EA group and an ibuprofen group, 10 rats in each group. PDM model was prepared by injection of estradiol benzoate and oxytocin. Except the control group, the rats in each group were subcutaneously injected with estradiol benzoate for 10 days, and oxytocin was injected on the 11th day. The rats in the EA group were intervened with EA (dense wave, frequency of 50 Hz) at "Guanyuan" (CV 4) and "Sanyinjiao" (SP 6) at the same time of modeling, once a day, 20 min each time, for 10 consecutive days. The rats in the ibuprofen group were treated with 0.8 mL of ibuprofen by gavage (concentration of ibuprofen solution was 1.25 mg/mL) for 10 consecutive days. After modeling, the writhing reaction was observed. After intervention, the HE staining method was used to observe the histological morphology of uterus and evaluate the pathological damage score of uterus; ELISA method was used to detect the serum levels of prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α); Western blot method was used to detect the protein expression of NLRP3, apoptosis related spot like protein (ASC), caspase-1, GSDMD, GSDMD-N and inflammatory factors (interleukin [IL]-1β, IL-18) in uterine tissue. RESULTS: In the model group, a large number of vacuolar degeneration and death of endometrial epithelial cells, spiral arterioles congestion in lamina propria and neutrophil infiltration were observed. In the EA group, there was a small amount of vacuolar degeneration and death of endometrial epithelial cells, a small amount of spiral arterioles congestion in the lamina propria, and a small amount of neutrophils infiltration. In the ibuprofen group, there was very small number of degeneration and death of endometrial epithelial cells, and no obvious arterial congestion was found in lamina propria, and neutrophil infiltration was occasionally seen. Compared with the control group, in the model group the number of writhing was increased (P<0.01), the writhing reaction score and serum level of PGF2α and PGF2α/PGE2 value were increased (P<0.01), the level of PGE2 was decreased (P<0.01). Compared with the model group, in the EA group and the ibuprofen group the number of writhing were decreased (P<0.05), the latency of writhing was prolonged (P<0.01), the writhing reaction scores and serum levels of PGF2α and PGF2α/PGE2 values were decreased (P<0.05, P<0.01), the levels of PGE2 were increased (P<0.01). Compared with the control group, the protein expression of NLRP3, ASC, caspase-1, GSDMD, GSDMD-N, IL-1β and IL-18 in the uterine tissues of rats was increased in the model group (P<0.01). Compared with the model group, the protein expression of NLRP3, ASC, caspase-1, GSDMD, GSDMD-N, IL-1β and IL-18 in the uterine tissues of rats was decreased in the EA group and the ibuprofen group (P<0.01, P<0.05). There was no significant difference between the EA group and the ibuprofen group in the above indexes (P>0.05). CONCLUSION EA could alleviate pain and uterine tissue injury in rats with PDM. The mechanism may be related to the inhibition of the activation of NLRP3 inflammasome in rat uterine tissues, thereby inhibiting pyroptosis and its inflammatory factors release.
Animals ; Female ; Pregnancy ; Rats ; Caspases ; Dinoprost ; Dinoprostone ; Dysmenorrhea ; Electroacupuncture ; Ibuprofen ; Inflammasomes ; Interleukin-18 ; NLR Family, Pyrin Domain-Containing 3 Protein ; Oxytocin ; Phosphate-Binding Proteins ; Pyroptosis ; Rats, Sprague-Dawley ; Uterus