Alterations of monoamine neurotransmitters, HPA-axis hormones, and inflammation cytokines in reserpine-induced hyperalgesia and depression comorbidity rat model

The Sanbi Decoction alleviates intervertebral disc degeneration in rats through intestinal flora and serum metabolic homeostasis modulation

BACKGROUND

Intervertebral disc degeneration (IVDD) is an essential cause of low back pain (LBP), the incidence of which has risen in recent years and is progressively younger, but treatment options are limited, placing a serious economic burden on society. Sanbi decoction (SBD) is an important classical formula for the treatment of IVDD, which can significantly improve patients' symptoms and is a promising alternative therapy.

PURPOSE

The aim of this study is to investigate the safety and efficacy of SBD in the treatment of IVDD and to explore the underlying mechanisms by using an integrated analytical approach of microbiomics and serum metabolomics, as well as by using molecular biology.

METHODS

A rat IVDD puncture model was established and treated by gavage with different concentrations of SBD, and clean faeces, serum, liver, kidney, and intervertebral disc (IVD) were collected after 4 weeks. We assessed the safety by liver and kidney weighing, functional tests and tissue staining, the expression of tumor necrosis factor-alpha (TNF-ɑ), interleukin 1β (IL-1β) and interleukin 6 (IL-6) inflammatory factors in serum was detected by ELISA kits, and X-ray test, magnetic resonance imaging (MRI) examination, immunohistochemistry (IHC), western blotting (WB), hematoxylin-eosin (HE) staining and safranin O-fast green (SO/FG) staining were used to assess the efficacy. Finally, we performed 16S rRNA sequencing analysis on the faeces of different groups and untargeted metabolomics on serum and analyzed the association between them.

RESULTS

SBD can effectively reduce the inflammatory response, regulate the metabolic balance of extracellular matrix (ECM), improve symptoms, and restore IVD function. In addition, SBD can significantly improve the diversity of intestinal flora and maintain the balance. At the phylum level, SBD greatly increased the relative abundance of Patescibacteria and Actinobacteriota and decreased the relative abundance of Bacteroidota. At the genus level, SBD significantly increased the relative abundance of Clostridia_UCG-014, Enterorhabdus, and Adlercreutzia, and decreased the relative abundance of Ruminococcaceae_UCG-005 (p < 0.05). Untargeted metabolomics indicated that SBD significantly improved serum metabolites and altered serum expression of 4alpha-phorbol 12,13-didecanoate (4alphaPDD), euscaphic acid (EA), alpha-muricholic acid (α-MCA), 5-hydroxyindoleacetic acid (5-HIAA), and kynurenine (Kyn) (p < 0.05), and the metabolic pathways were mainly lipid metabolism and amino acid metabolism.

CONCLUSIONS

This study demonstrated that SBD can extensively regulate intestinal flora and serum metabolic homeostasis to reduce inflammatory response, inhibit the degradation of ECM, restore IVD height and water content to achieve apparent therapeutic effect for IVDD.

The Fibromyalgia Pain Experience: A Scoping Review of the Preclinical Evidence for Replication and Treatment of the Affective and Cognitive Pain Dimensions

Fibromyalgia is a chronic, widespread pain disorder that is strongly represented across the affective and cognitive dimensions of pain, given that the underlying pathophysiology of the disorder is yet to be identified. These affective and cognitive deficits are crucial to understanding and treating the fibromyalgia pain experience as a whole but replicating this multidimensionality on a preclinical level is challenging. To understand the underlying mechanisms, animal models are used. In this scoping review, we evaluate the current primary animal models of fibromyalgia regarding their translational relevance within the affective and cognitive pain realms, as well as summarize treatments that have been identified preclinically for attenuating these deficits.

Role of soluble epoxide hydrolase in pain and depression comorbidity

The coexistence of chronic pain and depression in clinical practice places a substantial social burden and profoundly impacts in patients. Although a clear correlation exists, the underlying mechanism of comorbidity between chronic pain and depression remains elusive. Research conducted in recent decades has uncovered that soluble epoxide hydrolase, a pivotal enzyme in the metabolism of polyunsaturated fatty acids, plays a crucial role in inflammation. Interestingly, this enzyme is intricately linked to the development of both pain and depression. With this understanding, this review aims to summarize the roles of soluble epoxide hydrolase in pain, depression, and their comorbidity. Simultaneously, we will also explore the underlying mechanisms, providing guidance for future research and drug development.

Depression risk in chronic tonsillitis patients underwent tonsillectomy: a global federated health network analysis

Background: Tonsillectomy is a common surgery in the US, with possible postoperative complications. While small studies indicate postoperative depressive symptoms may occur, large-scale evidence is lacking on the tonsillectomy-depression link. Methods: We conducted a retrospective cohort study using the TriNetX US collaborative network, offering de-identified electronic health data from 59 collaborative healthcare organizations (HCOs) in the United States. In this study, people being diagnosed of chronic tonsillitis between January 2005 and December 2017 were enrolled. Patients deceased, with previous record of cancers or psychiatric events before index date were excluded. 14,874 chronic tonsillitis patients undergoing tonsillectomy were propensity score matched 1:1 to controls for age, sex, and race. New-onset depression risks were evaluated over 5 years post-tonsillectomy and stratified by age and sex. Confounders were adjusted for including demographics, medications, comorbidities and socioeconomic statuses. Results: After matching, the difference of key baseline characteristics including age, sex, comedications status and obesity status was insignificant between tonsillectomy and non-tonsillectomy groups. Tonsillectomy had a 1.29 times higher 5-year depression risk versus matched controls (95% CI, 1.19-1.40), with elevated risks seen at 1 year (HR=1.51; 95% CI, 1.28-1.79) and 3 years (HR=1.30; 95% CI, 1.18-1.43). By stratifications, risks were increased for both males (HR=1.30; 95% CI, 1.08-1.57) and females (HR=1.30; 95% CI, 1.18-1.42), and significantly higher in ages 18-64 years (HR=1.37; 1.26-1.49), but no significance observed for those 65 years and older. After performing sensitivity analyses and applying washout periods of 6, 12, and 36 months, the outcome remained consistent with unadjusted results. Conclusion: This real-world analysis found tonsillectomy was associated with a 30% higher 5-year depression risk versus matched non-tonsillectomy patients with chronic tonsillitis. Further mechanistic research is needed to clarify the pathophysiologic association between depression and tonsillectomy. Depression is not commonly mentioned in the current post-tonsillectomy care realm; however, the outcome of our study emphasized the possibility of these suffering condition after operation. Attention to psychological impacts following tonsillectomy is warranted to support patient well-being, leading to better management of post-tonsillectomy individuals.

Effects of Remifentanil Gradual Withdrawal Combined with Postoperative Infusion on Postoperative Hyperalgesia in Patients Undergoing Laparoscopic hysterectomy: A Factorial Design, Double-Blind, Randomized Controlled Trial

Background

Remifentanil-induced hyperalgesia (RIH) increases the risk of persistent postoperative pain, making early postoperative analgesic therapy ineffective and affecting postoperative patient satisfaction. This study aimed to verify the effects of gradual withdrawal of remifentanil combined with postoperative pump infusion of remifentanil on postoperative hyperalgesia and pain in patients undergoing laparoscopic hysterectomy.

Methods

This trial was a factorial design, double-blind, randomized controlled trial. Patients undergoing laparoscopic hysterectomy were randomly allocated to the control group, postoperative pump infusion of remifentanil group, gradual withdrawal of remifentanil group, or gradual withdrawal plus postoperative pump infusion of remifentanil group (n = 35 each). The primary outcome was postoperative mechanical pain thresholds in the medial forearm. The secondary outcomes included postoperative mechanical pain thresholds around the incision, pain numeric rating scale scores, analgesic utilization, awakening agitation or sedation scores, a 15-item quality of recovery survey, and postoperative complications.

Results

Gradual withdrawal of remifentanil significantly increased postoperative pain thresholds versus abrupt discontinuation (P < 0.05), whereas postoperative infusion did not show significant differences compared to the absence of infusion (P > 0.05). The combined gradual withdrawal and postoperative infusion group exhibited the highest thresholds and had the lowest postoperative pain scores and analgesic requirements as well as the highest quality of recovery scores (P < 0.05). No significant differences were observed for agitation scores, sedation scores, or complication rates (P > 0.05).

Conclusion

The novel combined gradual withdrawal and postoperative infusion of remifentanil uniquely attenuates postoperative hyperalgesia, pain severity, analgesic necessity, and improves recovery quality after laparoscopic hysterectomy.

Fluoxetine mitigates depressive-like behaviors in mice via anti-inflammation and enhancing neuroplasticity

Neuroplasticity and inflammation represent a common final pathway for effective antidepressant treatment. SSRIs are the most commonly prescribed medications for depression and have demonstrated efficacy in reducing depressive symptoms. However, the precise impact of SSRIs on neuroplasticity and inflammation remains unclear. In this study, we aimed to investigate the influence of long-term treatment with SSRIs on hippocampal neuron, inflammation, synaptic function and morphology. Our findings revealed that fluoxetine treatment significantly alleviated behavioral despair, anhedonia, and anxiety in reserpine-treated mice. Moreover, fluoxetine mitigated hippocampal neuron impairment, inhibited inflammatory release, and increased the expression of synaptic proteins markers (SYP and PSD95) in mice. Notably, fluoxetine also suppressed reserpine-induced synapse loss in the hippocampus. Based on these results, fluoxetine has been demonstrated effectively to ameliorate depressive mood and cognitive dysfunction, possibly through the enhancement of synaptic plasticity. Overall, our study contributes to a further understanding of the mechanisms underlying the therapeutic effects of fluoxetine and its potential role in improving depressive symptoms and cognitive impairments.

Repeated reserpine treatment induces depressive-like behaviors accompanied with hippocampal impairment and synapse deficit in mice

Depression remains a significant public health concern, and current animal models of depression are limited in their ability to accurately mimic human depression. However, studying the new development of antidepressants requires the use of progressive animal models. In this study, the mice were exposed to a low dose of reserpine (0.5 mg/kg) once daily for 14 days, followed by a 14-day period to allow for the development of spontaneous depression. We have successfully established a repeated reserpine-induced depressive animal model, which was characterized by emotional symptoms (anhedonia), cognitive symptoms, and psychomotor agitation or retardation. Our study demonstrated that repeated treatment with low-dose reserpine increased immobility time in the TST and FST. It also decreased the sucrose consumption ratio and induced anxiety-like behaviors. These anxiety-like behaviors were evidenced by decreased time spent in the center zone, longer first latency to center zone, and fewer entries into the center zone in the open field test. These findings support the utility of the low-dose reserpine repeated injection animal model for studying the pathogenesis of depression and the development of novel antidepressant treatments. Additionally, this study provides valuable insights into the potential of low-dose reserpine as a tool for modeling chronic depression in animals. Furthermore, our findings suggest that prolonged low-dose reserpine treatment could result in chronic depression. These findings have significant implications for the use of reserpine as a therapeutic agent for various conditions and emphasize the importance of closely monitoring patients' mental health.

Chinese Materia Medica in Treating Depression: The Role of Intestinal Microenvironment

Depression is a highly heterogeneous mental illness. Drug treatment is currently the main therapeutic strategy used in the clinic, but its efficacy is limited by the modulation of a single target, slow onset, and side effects. The gut-brain axis is of increasing interest because intestinal microenvironment disorders increase susceptibility to depression. In turn, depression affects intestinal microenvironment homeostasis by altering intestinal tissue structure, flora abundance and metabolism, hormone secretion, neurotransmitter transmission, and immune balance. Depression falls into the category of "stagnation syndrome" according to Traditional Chinese Medicine (TCM), which further specifies that "the heart governs the spirit and is exterior-interior with the small intestine". However, the exact mechanisms of the means by which the disordered intestinal microenvironment affects depression are still unclear. Here, we present an overview of how the Chinese materia medica (CMM) protects against depression by repairing intestinal microenvironment homeostasis. We review the past five years of research progress in classical antidepressant TCM formulae and single CMMs on regulating the intestinal microenvironment for the treatment of depression. We then analyze and clarify the multitarget functions of CMM in repairing intestinal homeostasis and aim to provide a new theoretical basis for CMM clinical application in the treatment of depression.

Chemogenetic Activation of Oxytocin Neurons Improves Pain in a Reserpine-induced Fibromyalgia Rat Model

Fibromyalgia (FM) is a syndrome characterized by chronic pain with depression as a frequent comorbidity. However, efficient management of the pain and depressive symptoms of FM is lacking. Given that endogenous oxytocin (OXT) contributes to the regulation of pain and depressive disorders, herein, we investigated the role of OXT in an experimental reserpine-induced FM model. In FM model, OXT-monomeric red fluorescent protein 1 (OXT-mRFP1) transgenic rats exhibited increased depressive behavior and sensitivity in a mechanical nociceptive test, suggesting reduced pain tolerance. Additionally, the development of the FM-like phenotype in OXT-mRFP1 FM model rats was accompanied by a significant reduction in OXT mRNA expression in the magnocellular neurons of the paraventricular nucleus. OXT-mRFP1 FM model rats also had significantly fewer tryptophan hydroxylase (TPH)- and tyrosine hydroxylase (TH)-immunoreactive (ir) neurons as well as reduced serotonin and norepinephrine levels in the dorsal raphe and locus coeruleus. To investigate the effects of stimulating the endogenous OXT pathway, rats expressing OXT-human muscarinic acetylcholine receptor (hM3Dq)-mCherry designer receptors exclusively activated by designer drugs (DREADDs) were also assessed in the FM model. Treatment of these rats with clozapine-N-oxide (CNO), an hM3Dq-activating drug, significantly improved characteristic FM model-induced pathophysiological pain, but did not alter depressive-like behavior. The chemogenetically induced effects were reversed by pre-treatment with an OXT receptor antagonist, confirming the specificity of action via the OXT pathway. These results indicate that endogenous OXT may have analgesic effects in FM, and could be a potential target for effective pain management strategies for this disorder.

Inflammation and decreased cardiovagal modulation are linked to stress and depression at 36th week of pregnancy in gestational diabetes mellitus

Stress and depression have been reported in gestational diabetes mellitus (GDM). Though inflammation and oxidative stress are associated with depression, there are no reports of link of cardiometabolic risks (CMR) to stress and depression in GDM. Normal pregnant women (control group, n = 164) and women with GDM (study group, n = 176) at 36th week of gestation were recruited for the study. Blood pressure (BP), body composition, heart rate variability (HRV), glycated hemoglobin (HbA1C), markers of insulin resistance, oxidative stress, inflammation and endothelial dysfunction, were assessed. Perceived stress score (PSS), quality of life (QoL) scale, Indian diabetic risk score (IDRS) and Edinburg postnatal depression score (EPDS) were assessed. Association of potential contributors to PSS and EDPS were assessed by correlation and regression analyses. There was significant increase in PSS, EPDS, IDRS scores, HbA1C, malondialdehyde (MDA) (oxidative stress marker) and high-sensitive C-reactive protein and interleukin-6 (inflammatory markers), and significant decrease in total power (TP) of HRV (marker of cardiovagal modulation), QoL and nitric oxide (endothelial dysfunction marker) in study group compared to control group. Though many cardiometabolic risk parameters were correlated with PSS and EPDS, the significant independent association was observed for TP, HbA1C, MDA and interleukin-6. However, interleukin-6 had maximum contribution to PSS (β = 0.550, p < 0.001) and EPDS (β = 0.393, p < 0.001) as demonstrated by multiple regression analysis. Inflammation, oxidative stress, glycation status and decreased cardiovagal modulation are associated with stress and depression at 36th week of gestation in GDM.

Effect of traditional Chinese medicine on postoperative depression of breast cancer: a systematic review and meta-analysis

Background: Depression is one of the common complications in patients with postoperative breast cancer (BC). Conventional therapies for postoperative depression of BC always have modest treatment outcomes and undesirable side effects. Clinical practice and many studies have shown that traditional Chinese medicine (TCM) has a good effect on postoperative depression of BC. This meta-analysis aimed to assess the clinical effect of TCM as an add-on treatment for postoperative depression of BC. Methods: A systematic and thorough search was conducted on eight online electronic databases up to 20 July 2022. The control group received conventional therapies, and intervention groups received what control groups received plus TCM treatment. Review Manager 5.4.1 was used for statistical analysis. Results: Nine RCTs involved 789 participants who met the inclusion standards. The results showed the intervention group was better at decreasing the score of the Hamilton rating scale for depression (HAMD) (mean difference, MD = -4.21, 95% CI -5.54 to -2.88) and the self-rating depression scale (SDS) (MD = -12.03, 95% CI -15.94 to -8.13), improving clinical efficacy (RR = 1.25, 95% CI 1.14-1.37), increasing the levels of 5-hydroxytryptamine (5-HT) (MD = 0.27, 95% CI 0.20-0.34), dopamine (DA) (MD = 26.28, 95% CI 24.18-28.77), and norepinephrine (NE) (MD = 11.05, 95% CI 8.07-14.04), and influencing the immune index, including the levels of CD3⁺ (MD = 15.18, 95% CI 13.61-16.75), CD4⁺ (MD = 8.37, 95% CI 6.00-10.74), and CD4⁺/CD8⁺ (MD = 0.33, 95% CI 0.27-0.39). The level of CD8⁺ (MD = -4.04, 95% CI -11.98 to 3.99) had no obvious difference between the two groups. Conclusion: The meta-analysis stated that a therapeutic regimen involving TCM could better improve the depression status in postoperative BC.

Antidepressant effect of 4-Butyl-a-agarofuran via HPA axis and serotonin system

Depression is a leading cause of disability worldwide and the psychiatric diagnosis most commonly associated with suicide. 4-Butyl-a-agarofuran (AF-5), a derivative of agarwood furan, is currently in phase III clinical trials for generalized anxiety disorder. Herein, we explored the antidepressant effect and its possible neurobiological mechanisms in animal models. In present study, AF-5 administration markedly decreased the immobility time in mouse forced swim test and tail suspension test. In the sub-chronic reserpine-induced depressive rats, AF-5 treatment markedly increased the rectal temperature and decreased the immobility time of model rats. In addition, chronic AF-5 treatment markedly reversed the depressive-like behaviors in chronic unpredictable mild stress (CUMS) rats by reducing immobility time of forced swim test. Single treatment with AF-5 also potentiated the mouse head-twitch response induced by 5-hydroxytryptophan (5-HTP, a metabolic precursor to serotonin), and antagonized the ptosis and motor ability triggered by reserpine. However, AF-5 had no effect on yohimbine toxicity in mice. These results indicated that acute treatment with AF-5 produced serotonergic, but not noradrenergic activation. Furthermore, AF-5 reduced adrenocorticotropic hormone (ACTH) level in serum and normalized the neurotransmitter changes, including the decreased serotonin (5-HT) in hippocampus of CUMS rats. Moreover, AF-5 affected the expressions of CRFR1 and 5-HT2C receptor in CUMS rats. These findings confirm the antidepressant effect of AF-5 in animal models, which may be primarily related to CRFR1 and 5-HT2C receptor. AF-5 appears to be promising as a novel dual target drug for depression treatment.

Botulinum neurotoxin A ameliorates depressive-like behavior in a reserpine-induced Parkinson's disease mouse model via suppressing hippocampal microglial engulfment and neuroinflammation

Depression is one of the common non-motor symptoms of Parkinson's disease (PD). In the clinic, botulinum neurotoxin A (BoNT/A) has been used to treat depression. In this study, we investigated the mechanisms underlying the anti-depressive effect of BoNT/A in a PD mouse model. Mice were administered reserpine (3 μg/mL in the drinking water) for 10 weeks. From the 10^th week, BoNT/A (10 U·kg^-1·d^-1) was injected into the cheek for 3 consecutive days. We showed that chronic administration of reserpine produced the behavioral phenotypes of depression and neurochemical changes in the substantia nigra pars compacta (SNpc) and striatum. BoNT/A treatment significantly ameliorated the depressive-like behaviors, but did not improve TH activity in SNpc of reserpine-treated mice. We demonstrated that BoNT/A treatment reversed reserpine-induced complement and microglia activation in the hippocampal CA1 region. Furthermore, BoNT/A treatment significantly attenuated the microglial engulfment of presynaptic synapses, thus ameliorating the apparent synapse and spine loss in the hippocampus in the reserpine-treated mice. Moreover, BoNT/A treatment suppressed microglia-mediated expression of pro-inflammatory cytokines TNF-α and IL-1β in reserpine-treated mice. In addition, we showed that BoNT/A (0.1 U/mL) ameliorated reserpine-induced complement and microglia activation in mouse BV2 microglial cells in vitro. We conclude that BoNT/A ameliorates depressive-like behavior in a reserpine-induced PD mouse model through reversing the synapse loss mediated by classical complement induced-microglial engulfment as well as alleviating microglia-mediated proinflammatory responses. BoNT/A ameliorates depressive-like behavior, and reverses synapse loss mediated by classical complement pathway-initiated microglia engulfment as well as alleviates microglia-mediated proinflammatory response in the reserpine-induced Parkinson's disease mouse model.