This study adopted a three-dimensional "effect-dose-mechanism" evaluation system to screen the optimal regimen of Yuxuebi Tablets(YXB) combined with ibuprofen(IBU) for chronic musculoskeletal pain(CMP) intervention and elucidate its pharmacological mechanism, so as to provide a scientific basis for the clinical application of the regimen. The experiments were conducted using 8-week-old ICR mice, which were randomly divided into sham operation(sham) group, model(CFA) group, IBU group, YXB group, stasis paralysis tablets combined with ibuprofen low-dose group(IBU-L-YXB), stasis paralysis combined with ibuprofen high-dose group(IBU-H-YXB), stasis paralysis tablets combined with ibuprofen high-dose with ibuprofen discontinuation on the 10th day of administration(IBU-10-YXB), and stasis paralysis tablets combined with ibuprofen high-dose with ibuprofen halving on the 10th day of administration(IBU-1/2-YXB) group. An animal model was established using the CFA plantar injection method. On D0(the second day post-modeling), the success of model establishment was assessed, followed by continuous drug administration for 18 consecutive days from D1 to D18. During this period, mechanical pain threshold was measured by the Von Frey test; thermal hyperalgesia was detected by the hot plate test, and depression-like behavior was observed by the tail suspension test. After treatment, peripheral blood was collected from all groups for complete blood biochemical analysis, and the injected feet of the sham, CFA, IBU, YXB, IBU-YXB, and IBU-10-YXB groups were subjected to oxylipin metabolomics analysis. Immunofluorescence double staining was further performed to detect the co-expression of key oxylipin metabolic enzymes(COX2, LTA4H, and 5/12/15-LOX) and macrophage marker CD68 in the sham, CFA, IBU, and YXB-L/M/H groups. Subsequently, confirmatory analysis of positive indicators was conducted in the sham, CFA, IBU, YXB, IBU-YXB, and IBU-10-YXB groups. On D6(acute phase), mechanical pain sensitivity data showed that compared with the CFA group, only the three combination groups(IBU-YXB, IBU-10-YXB, and IBU-1/2-YXB) exhibited significantly increased paw withdrawal thresholds. On D17(chronic phase), only the IBU-10-YXB group showed a mechanical pain threshold significantly higher than all other monotherapy and combination groups. On D17, thermal pain data showed that compared with the CFA group, all groups except IBU-1/2-YXB had significantly prolonged paw withdrawal latency. On D18, tail suspension data showed that compared with the CFA group, the YXB, IBU-YXB, and IBU-10-YXB groups had significantly reduced immobility time. In summary, IBU-10-YXB stably improved the core symptoms of acute and chronic inflammatory pain. Complete blood count data showed that compared with the sham group, the CFA group had significantly increased mean platelet volume(MPV), while compared with the CFA group, the IBU-YXB and IBU-10-YXB groups had significantly reduced MPV. Moreover, the platelet distribution width(PDW) of the IBU-10-YXB group was further reduced compared with the CFA group. These data suggest that the IBU-10-YXB combination regimen has superior effects on inflammation and blood circulation improvement compared with other treatment groups. At the mechanistic level, each treatment group differentially regulated pro-inflammatory and pro-resolving oxylipin(SPM). Specifically, compared with the CFA group, the IBU and IBU-YXB groups significantly inhibited the synthesis of the prostaglandin family downstream of COX2, reducing pro-inflammatory oxylipins PGD2 and 6-keto-PGF1α but inhibiting PGE1 and PGE2, which played positive roles in peripheral circulation, vasodilation, and inflammation resolution. Compared with the CFA group, the YXB group tended to inhibit the pro-inflammatory oxylipin LTB4 downstream of LTA4H and increase SPMs such as LXA4. The IBU-10-YXB group bidirectionally regulated pro-inflammatory oxylipins and SPMs. Compared with IBU, IBU-10-YXB significantly inhibited the pro-inflammatory mediator 5-HETE. Meanwhile, IBU-10-YXB broadly upregulated SPMs, as evidenced by significant upregulation of LXA4 compared with the CFA group, significant upregulation of LXA5 compared with the IBU and IBU-YXB groups, significant upregulation of RvD1 compared with the CFA group and all other treatment groups, and significant upregulation of RvD5 compared with the sham group. Immunofluorescence double staining results were as follows: compared with the CFA group, the IBU group specifically inhibited the oxylipin metabolic enzyme COX2. In the YXB group, COX2, LTA4H, and 5/12-LOX were significantly inhibited. Within the optimal analgesic dose range, YXB's inhibitory effects on COX2 and LTA4H were dose-dependent, while its inhibitory effects on 5/12-LOX were inversely dose-dependent. The two combination groups(IBU-YXB and IBU-10-YXB) inhibited COX2 and LTA4H without significantly affecting 5-LOX, while IBU-10-YXB further significantly inhibited 12-LOX. These results suggest that the IBU-10-YXB combination regimen effectively maintains stable inhibition of COX2, LTA4H, and 12-LOX while enhancing 5-LOX expression. This combinatorial strategy effectively suppresses pro-inflammatory oxylipins and promotes SPM biosynthesis, overcoming IBU's analgesic ceiling effect and its blockade of pain resolution pathways while compensating for YXB's inability to effectively intervene in acute pain and inflammation. Therefore, it achieves more stable anti-inflammatory, analgesic, and antidepressant effects.
Animals ; Ibuprofen/administration & dosage* ; Mice ; Mice, Inbred ICR ; Drugs, Chinese Herbal/administration & dosage* ; Male ; Musculoskeletal Pain/immunology* ; Tablets ; Humans ; Chronic Pain/metabolism* ; Drug Therapy, Combination ; Disease Models, Animal

Cancer pain is one of the most common symptoms in patients with advanced cancer. In this study, we aimed to investigate the effects of the Mas-related gene C (MrgC) receptors on bone cancer pain. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured after the inoculation of Walker 256 mammary gland carcinoma cells into the tibia of adult Sprague-Dawley rats. The effects of MrgC receptor agonist bovine adrenal medulla 8-22 (BAM8-22) on nociceptive behaviors were investigated after intrathecal injection on days 16 and 17. Glial fibrillary acidic protein (GFAP)-positive cells in the spinal dorsal cord, and calcitonin gene related peptide (CGRP)-, neuronal nitric oxide synthase (nNOS)- and IL-1β-positive neurons in the dorsal root ganglia (DRG) were examined by immunofluorescence staining. The expression of nNOS and IL-1β proteins in the spinal dorsal horn and the DRG was examined by Western blotting after treatment with (Tyr6)-γ2-MSH-6-12 (MSH), which was another MrgC receptor agonist. The results showed that intrathecal injection of BAM8-22 (30 nmol) attenuated mechanical allodynia in a rat model of bone cancer pain and the effects could last for about 60 min, and single administration of BAM8-22 for two consecutive days reduced mechanical allodynia by about half on the third day. Moreover, the number of GFAP-positive cells in the spinal dorsal horn, and the number of CGRP-, nNOS- and IL-1β-positive neurons in the DRG were decreased. Similarly, intrathecal administration of MSH (15 nmol) reduced the expression of nNOS and IL-1β in the spinal dorsal horn and the DRG. In conclusion, activation of MrgC receptors suppresses the activation of astrocytes in the spinal dorsal cord and the expression of CGRP, nNOS, and IL-1β in the spinal dorsal cord and/or DRG, which may underlie the inhibition of bone cancer pain. These findings provide a novel strategy for the treatment of bone cancer pain.
Animals ; Cancer Pain/drug therapy* ; Rats ; Rats, Sprague-Dawley ; Bone Neoplasms/complications* ; Ganglia, Spinal/metabolism* ; Spinal Cord Dorsal Horn/metabolism* ; Receptors, G-Protein-Coupled/genetics* ; Female ; Calcitonin Gene-Related Peptide/genetics* ; Interleukin-1beta/metabolism* ; Peptide Fragments/metabolism* ; Nitric Oxide Synthase Type I/genetics* ; Disease Models, Animal

OBJECTIVE: To investigate the inhibitory effect of ANA-12 that blocks brain-derived neurotrophic factor (BDNF)/ tropomyosin receptor kinase B (TrkB) signaling on inflammatory pain in rats and explore the underlying mechanism. METHODS: Forty-two adult SD rats were randomized into BDNF-induced acute pain group (n=24) and CFA-induced chronic pain group. The former group were randomly divided into 4 subgroups, including a control group, ANA-12 treatment group, BDNF treatment group, and BDNF+ANA-12 treatment group; the latter group were subgrouped into control group, CFA treatment group (CFA) and CFA + ANA-12 treatment group. The effects of ANA-12 treatment on pain behaviors of the rats with BDNF-induced acute pain and CFA-induced chronic inflammatory pain were observed. Western blotting was used to examine TrkB signaling and expressions of microglia marker protein Iba1 and TNF-α in the spinal cord of the rats. RESULTS: BDNF injection into the subarachnoid space significantly increased the number of spontaneous paw withdrawal of the rats (P < 0.05), which was obviously reduced by ANA-12 treatment (P < 0.05). The rats with intraplantar injection of CFA, showed significantly increased ipsilateral mechanical stimulation sensitivity (P < 0.05), and ANA-12 treatment obviously increased the ipsilateral foot withdrawal threshold (P < 0.05). Treatment with either BDNF or CFA significantly increased the phosphorylation level of TrkB (Y705) in the spinal cord of the rats (P < 0.05), which was significantly lowered by ANA-12 treatment (P < 0.05). Treatment with BDNF and CFA both significantly up-regulated the expressions of Iba1 and TNF-α in the spinal cord (P < 0.05), but ANA-12 significantly reduced their expression levels (P < 0.05). CONCLUSION ANA-12 can reduce spinal cord inflammation and relieve acute and chronic pain in rats by targeted blocking of BDNF/TrkB signaling.
Animals ; Brain-Derived Neurotrophic Factor/metabolism* ; Chronic Pain/drug therapy* ; Inflammation ; Rats ; Rats, Sprague-Dawley ; Receptor, trkB/metabolism*

OBJECTIVE: To observe the effect of early intervention of bone-nearby acupuncture (BNA) combined with electroacupuncture (EA) on the expression of histone deacetylase1(HDAC1), histone deacetylase 2 (HDAC2) andμ-opioid recepter (MOR) in dorsal root ganglia (DRG) of bone cancer pain-morphine tolerance (BCP-MT) rats, and to explore its possible mechanism. METHODS: A total of 35 SD rats were randomized into a sham BCP group (=6), a BCP group (=7), a MT group (=7), a BNA+EA group (=8) and a shame BNA group (=7). Except of the sham BCP group, cancer cell inoculation operation at left tibia was given in the other 4 groups to establish the bone cancer pain model. In the MT group, the BNA+EA group and the shame BNA group, intraperitoneal injection of morphine hydrochloride was given to establish the morphine tolerance model. After the operation, bone-nearby acupuncture combined with electroacupuncture was applied at "Zusanli" (ST 36) and "Kunlun" (BL 60) in the BNA+EA group, with dilatational wave, 2 Hz/100 Hz in frequency, 0.5 to 1.5 mA in intensity. Intervention in the shame BNA group was applied at the same time and acupoints as those in the BNA+EA group, the needles were pierced the skin without any electrical stimulation. The needles were retained for 30 min, once a day for continuous 7 days in both BNA+EA and shame BNA groups. Before and 10, 11, 15, 22 days after the operation, the left paw withdrawal threshold (PWT) was measured in the 5 groups. The levels of HDAC1, HDAC2 and MOR in DRG were detected by Western blot. RESULTS: Ten days after the cancer cell inoculation operation, the PWT of the BCP, MT, BNA+EA and sham BNA groups was decreased compared with the sham BCP group (<0.01). Eleven days after the operation, the PWT of the MT, BNA+EA and sham BNA groups was increased compared with the BCP group (<0.01). Twenty-two days after the operation, the difference was no significant between the BCP group and MT group (>0.05); the PWT of the BNA+EA group was increased compared with the MT and sham BNA group (<0.01). In the BCP group, the DRG levels of HDAC1 and HDCA2 were increased, while the level of MOR was decreased compared with the sham BCP group (<0.05, <0.01). In the MT group, the DRG level of HDAC1 was increased compared with the BCP group (<0.05). In the BNA+EA group, the DRG level of HDAC1 was decreased compared with the MT group and the sham BNA group (<0.01, <0.05), while the level of MOR was increased (<0.01). CONCLUSION Early intervention of bone-nearby acupuncture combined with electroacupuncture can relieve the morphine tolerance in bone cancer pain rats, it may relate to down-regulating the expression of HDAC1 and up-regulating the expression of MOR in the dorsal root ganglia.
Acupuncture Points ; Animals ; Bone Neoplasms ; complications ; Cancer Pain ; therapy ; Drug Tolerance ; Electroacupuncture ; Ganglia, Spinal ; metabolism ; Histone Deacetylases ; metabolism ; Morphine ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, mu ; metabolism

OBJECTIVE: To observe the effect of cinobufagin on transient outward potassium current () in rat dorsal root ganglion cells of cancer-induced bone pain (CIBP) and explore the possible analgesic mechanism of cinobufagin. METHODS: Whole cell patch clamp technique was used to examine the effect of cionbufagin on in acutely isolated dorsal root ganglion (DRG) cells from normal SD rats and rats with bone cancer pain. RESULTS: The DRG cells from rats with CIBP showed obviously decreased current density, an activation curve shift to the right, and an inactivation curve shift to the left. Cinobufagin treatment significantly increased the current density and reversed the changes in the activation and inactivation curves in the DRG cells. CONCLUSIONS current is decreased in DRG neurons from rats with CIBP. Cinobufagin can regulate the activation and inactivation of current in the DRG cells, which may be related to its analgesic mechanism.
Analgesics ; pharmacology ; Animals ; Bufanolides ; pharmacology ; Cancer Pain ; drug therapy ; Cells, Cultured ; Ganglia, Spinal ; drug effects ; Patch-Clamp Techniques ; Potassium Channels ; metabolism ; Rats ; Rats, Sprague-Dawley

The pathophysiology of visceral pain in patients with irritable bowel syndrome remains largely unknown. Our previous study showed that neonatal maternal deprivation (NMD) does not induce visceral hypersensitivity at the age of 6 weeks in rats. The aim of this study was to determine whether NMD followed by adult stress at the age of 6 weeks induces visceral pain in rats and to investigate the roles of adrenergic signaling in visceral pain. Here we showed that NMD rats exhibited visceral hypersensitivity 6 h and 24 h after the termination of adult multiple stressors (AMSs). The plasma level of norepinephrine was significantly increased in NMD rats after AMSs. Whole-cell patch-clamp recording showed that the excitability of dorsal root ganglion (DRG) neurons from NMD rats with AMSs was remarkably increased. The expression of β adrenergic receptors at the protein and mRNA levels was markedly higher in NMD rats with AMSs than in rats with NMD alone. Inhibition of β adrenergic receptors with propranolol or butoxamine enhanced the colorectal distention threshold and application of butoxamine also reversed the enhanced hypersensitivity of DRG neurons. Overall, our data demonstrate that AMS induces visceral hypersensitivity in NMD rats, in part due to enhanced NE-β adrenergic signaling in DRGs.
Adrenergic Agents ; pharmacology ; Animals ; Ganglia, Spinal ; drug effects ; Hyperalgesia ; drug therapy ; physiopathology ; Hypersensitivity ; drug therapy ; Male ; Maternal Deprivation ; Neurons ; drug effects ; Patch-Clamp Techniques ; methods ; Rats, Sprague-Dawley ; Signal Transduction ; drug effects ; Stress, Physiological ; physiology ; Visceral Pain ; chemically induced ; metabolism

Isoflavones are widely consumed by people around the world in the form of soy products, dietary supplements and drugs. Many isoflavones or related crude extracts have been reported to exert pain-relief activities, but the mechanism remains unclear. Voltage-gated sodium channels (VGSCs) play important roles in excitability of pain sensing neurons and many of them are important nociceptors. Here, we report that several isoflavones including 3'-methoxydaidzein (3MOD), genistein (GEN) and daidzein (DAI) show abilities to block VGSCs and thus to attenuate chemicals and heat induced acute pain or chronic constriction injury (CCI) induced pain hypersensitivity in mice. Especially, 3MOD shows strong analgesic potential without inducing addiction through inhibiting subtypes Na1.7, Na1.8 and Na1.3 with the IC of 181 ± 14, 397 ± 26, and 505 ± 46 nmol·L, respectively, providing a promising compound or parent structure for the treatment of pain pathologies. This study reveals a pain-alleviating mechanism of dietary isoflavones and may provide a convenient avenue to alleviate pain.
Analgesics ; administration & dosage ; chemistry ; Animals ; Humans ; Isoflavones ; administration & dosage ; chemistry ; Male ; Mice ; Mice, Inbred C57BL ; Pain ; drug therapy ; genetics ; metabolism ; Voltage-Gated Sodium Channel Blockers ; administration & dosage ; Voltage-Gated Sodium Channels ; genetics ; metabolism

Cognition and pain share common neural substrates and interact reciprocally: chronic pain compromises cognitive performance, whereas cognitive processes modulate pain perception. In the present study, we established a non-drug-dependent rat model of context-based analgesia, where two different contexts (dark and bright) were matched with a high (52°C) or low (48°C) temperature in the hot-plate test during training. Before and after training, we set the temperature to the high level in both contexts. Rats showed longer paw licking latencies in trials with the context originally matched to a low temperature than those to a high temperature, indicating successful establishment of a context-based analgesic effect in rats. This effect was blocked by intraperitoneal injection of naloxone (an opioid receptor antagonist) before the probe. The context-based analgesic effect also disappeared after optogenetic activation or inhibition of the bilateral infralimbic or prelimbic sub-region of the prefrontal cortex. In brief, we established a context-based, non-drug dependent, placebo-like analgesia model in the rat. This model provides a new and useful tool for investigating the cognitive modulation of pain.
Action Potentials ; drug effects ; physiology ; Analgesics ; pharmacology ; therapeutic use ; Animals ; Disease Models, Animal ; Electric Stimulation ; Female ; In Vitro Techniques ; Naloxone ; pharmacology ; Narcotic Antagonists ; pharmacology ; Optogenetics ; Pain ; drug therapy ; pathology ; physiopathology ; Pain Measurement ; drug effects ; Pain Threshold ; drug effects ; physiology ; Patch-Clamp Techniques ; Physical Stimulation ; Prefrontal Cortex ; drug effects ; metabolism ; pathology ; Pyramidal Cells ; drug effects ; physiology ; Rats ; Rats, Sprague-Dawley ; Time Factors

Fluoxetine, an anti-depressant drug, has recently been shown to provide neuroprotection in central nervous system injury, but its roles in subarachnoid hemorrhage (SAH) remain unclear. In this study, we aimed to evaluate whether fluoxetine attenuates early brain injury (EBI) after SAH. We demonstrated that intraperitoneal injection of fluoxetine (10 mg/kg per day) significantly attenuated brain edema and blood-brain barrier (BBB) disruption, microglial activation, and neuronal apoptosis in EBI after experimental SAH, as evidenced by the reduction of brain water content and Evans blue dye extravasation, prevention of disruption of the tight junction proteins zonula occludens-1, claudin-5, and occludin, a decrease of cells staining positive for Iba-1, ED-1, and TUNEL and a decline in IL-1β, IL-6, TNF-α, MDA, 3-nitrotyrosine, and 8-OHDG levels. Moreover, fluoxetine significantly improved the neurological deficits of EBI and long-term sensorimotor behavioral deficits following SAH in a rat model. These results indicated that fluoxetine has a neuroprotective effect after experimental SAH.
Animals ; Apoptosis ; drug effects ; Blood-Brain Barrier ; drug effects ; Brain Edema ; drug therapy ; etiology ; Cytokines ; genetics ; metabolism ; Disease Models, Animal ; Fluoxetine ; pharmacology ; therapeutic use ; In Situ Nick-End Labeling ; Male ; Neuroprotective Agents ; pharmacology ; therapeutic use ; Pain Measurement ; Psychomotor Performance ; drug effects ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley ; Subarachnoid Hemorrhage ; complications ; drug therapy ; pathology ; Time Factors ; Vasospasm, Intracranial ; drug therapy ; etiology

Most attempts at rational development of new analgesics have failed, in part because chronic pain involves multiple processes that remain poorly understood. To improve translational success, one strategy is to select novel targets for which there is proof of clinical relevance, either genetically through heritable traits, or pharmacologically. Such an approach by definition yields targets with high clinical validity. The biology of these targets can be elucidated in animal models before returning to the patients with a refined therapeutic. For optimal treatment, having biomarkers of drug action available is also a plus. Here we describe a case study in rational drug design: the use of controlled inhibition of peripheral tetrahydrobiopterin (BH4) synthesis to reduce abnormal chronic pain states without altering nociceptive-protective pain. Initially identified in a population of patients with low back pain, the association between BH4 production and chronic pain has been confirmed in more than 12 independent cohorts, through a common haplotype (present in 25% of Caucasians) of the rate-limiting enzyme for BH4 synthesis, GTP cyclohydrolase 1 (GCH1). Genetic tools in mice have demonstrated that both injured sensory neurons and activated macrophages engage increased BH4 synthesis to cause chronic pain. GCH1 is an obligate enzyme for de novo BH4 production. Therefore, inhibiting GCH1 activity eliminates all BH4 production, affecting the synthesis of multiple neurotransmitters and signaling molecules and interfering with physiological function. In contrast, targeting the last enzyme of the BH4 synthesis pathway, sepiapterin reductase (SPR), allows reduction of pathological BH4 production without completely blocking physiological BH4 synthesis. Systemic SPR inhibition in mice has not revealed any safety concerns to date, and available genetic and pharmacologic data suggest similar responses in humans. Finally, because it is present in vivo only when SPR is inhibited, sepiapterin serves as a reliable biomarker of target engagement, allowing potential quantification of drug efficacy. The emerging development of therapeutics that target BH4 synthesis to treat chronic pain illustrates the power of combining human and mouse genetics: human genetic studies for clinical selection of relevant targets, coupled with causality studies in mice, allowing the rational engineering of new analgesics.
Analgesics ; therapeutic use ; Animals ; Biopterin ; analogs & derivatives ; metabolism ; Chronic Pain ; drug therapy ; genetics ; Disease Models, Animal ; Drug Discovery ; GTP Cyclohydrolase ; genetics ; metabolism ; Humans ; Rodentia ; Signal Transduction ; drug effects ; genetics