Introduction

Major Depressive Disorder (MDD) stands as one of the most prevalent and debilitating mental health conditions globally, impacting a vast number of individuals across all demographics.1,2 The World Health Organization has underscored its significance, identifying depression as a leading contributor to the global burden of disease and projecting it to become the primary cause by 2030.3,4 Characterized by persistent low mood, anhedonia (loss of interest or pleasure), feelings of worthlessness, and significant disruptions in sleep and appetite, MDD profoundly impairs an individual’s capacity to function in social, occupational, and personal spheres.5 Despite the existence of various therapeutic approaches, including psychotherapy and antidepressant medications, a considerable segment of patients experiences inadequate response or fails to achieve full remission, underscoring the critical need for novel therapeutic strategies and a deeper understanding of its pathophysiology.6,7

Celecoxib is a non-steroidal anti-inflammatory drug (NSAIDs) that acts as a selective inhibitor of cyclooxygenase-2 (COX-2).8,9 The COX-2 enzyme is primarily induced at sites of inflammation and plays a crucial role in the synthesis of prostaglandins, key mediators involved in inflammatory responses, pain, and fever.10,11 By selectively inhibiting COX-2, celecoxib exerts potent anti-inflammatory and analgesic effects with a potentially reduced risk of gastrointestinal side effects compared to non-selective NSAIDs. It is widely prescribed for managing pain and inflammation associated with conditions such as osteoarthritis12 and rheumatoid arthritis.13

In recent years, a compelling body of evidence has emerged linking inflammatory processes to the pathophysiology of MDD.14,15 Numerous studies have reported elevated levels of pro-inflammatory cytokines, including Tumor Necrosis Factor-alpha (TNF-α),16,17 Interleukin-1 beta (IL-1β),17 and Interleukin-6 (IL-6),18 in the peripheral blood and central nervous system of patients with depression. Furthermore, inflammatory challenges have been shown to induce depressive-like symptoms in both preclinical models and humans, supporting a causal role for inflammation in depression. This “inflammatory hypothesis” of depression suggests that targeting inflammatory pathways could represent a viable therapeutic approach for MDD, particularly for patients exhibiting inflammatory profiles.19,20

Previous preclinical studies have suggested that chronic stress has been associated with changes in cyclooxygenase-2-related prostaglandin signaling, cytokine production, microglial reactivity, and hypothalamic-pituitary-adrenal axis activity.21,22 Celecoxib has therefore attracted interest as a potential adjunctive treatment for depressive symptoms. However, evidence from clinical and preclinical studies remains heterogeneous, and the behavioral and biological effects of celecoxib may depend on the stress paradigm, dose, treatment timing, and inflammatory status of the subjects. In addition, many studies have evaluated behavioral effects without simultaneously examining endocrine, histological, and ultrastructural outcomes.

In this study, we established a chronic restraint stress model in male Sprague-Dawley rats and evaluated the effects of celecoxib on behavioral outcomes using the open field test, forced swimming test, Y-maze test, and sucrose preference test. We additionally examined cytokine and corticosterone concentrations, hippocampal IBA-1 immunoreactivity, hippocampal histological changes, adrenal histology, and hippocampal ultrastructure. The primary aim was to determine whether celecoxib treatment was associated with improvements in behavioral and tissue-related outcomes in CRS-exposed rats. We further explored whether these effects were accompanied by changes in inflammatory and endocrine markers, while avoiding causal mechanistic conclusions that were not directly tested.

Materials and Methods Animals, Model Generation, and Treatment

A total of 40 male Sprague-Dawley rats weighing 200–220 g (from the Experimental Animal Science Center of Anhui Medical University, Hefei, China) were selected. After a one-week period of acclimatization, the rats were randomly assigned to either a Control group (n=10, no CRS or intervention) or a Model group (n=30, subjected to CRS). The Model group underwent chronic restraint stress for four weeks, where each rat was individually placed into a ventilated polypropylene tube (7 cm in diameter, 16 cm in length, featuring a 2 cm aperture in the tube wall for ventilation) for 4 hours daily (14:00–18:00) across 6 weeks.23 In contrast, rats in the Control group were maintained under normal, unstressed conditions for the same duration. At the start of the fifth week, the animals in the CRS group were further divided into three subgroups (each n=10): Model, celecoxib-treated, and fluoxetine-treated. The celecoxib group received celecoxib (SparkJade, SJ-MX0525) by oral gavage at 20 mg/kg for 2 weeks,24 while the fluoxetine group was administered fluoxetine (MCE, HY-B0102) by oral gavage at 10 mg/kg for 2 weeks.25 Celecoxib was administered during the latter phase of CRS exposure. Therefore, the present design evaluates an intervention administered during ongoing stress exposure rather than a treatment initiated after complete establishment of a behavioral phenotype. Accordingly, the results should not be interpreted as demonstrating reversal of an established depressive-like state. Both the Control and Model rats received a vehicle solution in the same volume as the treatment groups. During this phase, animals in the Model, celecoxib, and fluoxetine subgroups continued to undergo daily restraint stress, whereas the Control rats were simply provided standard housing and care. Because only one dose of celecoxib was tested, the present study cannot determine dose-response relationships or identify an optimal dose. A schematic timeline of the experimental procedures is presented in (Figure 1A).

Figure 1 Celecoxib alleviated depression-like behavior induced by CRS in rats. (A) Construction of CRS induced depression model and schematic diagram of pharmacological intervention during ongoing CRS exposure. (B) Typical trajectory diagram of open field experiment and rat exploration during open field experiment. Celecoxib reversed CRS-induced center move distance and total ambulatory distance. Center move distance in the OFT. The Model group versus the control group P< 0.001, the Model group versus the celecoxib group P= 0.033, the Model group versus the fluoxetine group P=0.001, n=10, F= 20.03 Total ambulatory distance in the OFT. The Model group versus the control group P< 0.001, the Model group versus the celecoxib group P= 0.007, the Model group versus the fluoxetine group P< 0.001, n=10, F= 14.47 (C) Diagram of Y-maze test. Celecoxib reversed the CRS-induced less time proportion in exploration in the new zone. The Model group versus the control group P= 0.005, the Model group versus the celecoxib group P< 0.001, the Model group versus the fluoxetine group P< 0.001, n=10, F= 11.150 (D) Celecoxib can increase swimming time in CRS induced depression rats. The Model group versus the control group P< 0.001, the Model group versus the celecoxib group P< 0.001, the Model group versus the fluoxetine group P< 0.001, n=10, F= 30.50 (E) Celecoxib increases sucrose preference index. The data are presented as means ± SEM (n = 10 rats per group). **P < 0.01, ***P < 0.001 represent the Model group (CRS) compared to the Control group (no CRS, no treatment), and #P < 0.05, ##P < 0.05, ###P < 0.001 represent the Celecoxib and Fluoxetine treatment groups (CRS+treatment) compared to the Model group.

Behavioral Tests

All behavioral tests were conducted in a quiet laboratory, with testing times scheduled between 08:00 and 12:30 to ensure consistent conditions across all groups. Prior to each experiment, the rats were acclimated to the behavioral laboratory environment to minimize anxiety and hyperactivity. After each experiment, all equipment and utensils were thoroughly cleaned and wiped with 75% alcohol to prevent any residual odors or excrement that could potentially impact the behavior of subsequent rats. The ANY-maze video imaging software (Stoelting Co, Wood Dale, USA) was utilized to record and analyze the performance of the rats in the behavioral tests.

Sucrose Preference Test (SPT)

The sucrose preference test was performed using a two-bottle choice procedure. After 12 h of food and water deprivation, each rat was given simultaneous access to one bottle containing water and one bottle containing 1% sucrose solution for 6 h. Sucrose preference was calculated as sucrose solution intake divided by total fluid intake multiplied by 100. Bottle positions were alternated between animals or across testing sessions to minimize side-preference bias. Baseline preference was measured before CRS induction, and subsequent measurements were obtained at the prespecified time points.

Open Field Test (OFT)

The open field test (OFT) was conducted using a black, non-transparent box measuring 100×100 cm with a height of 30 cm. The floor was marked with white lines to create 16 equally sized squares. Each rat was placed individually into the apparatus, positioned with its back facing one wall, and permitted to explore the area freely for 5 minutes. Parameters recorded included total distance traveled, frequency of entry into the central square, average movement speed, duration of rearing behavior, and time spent grooming.

Forced Swimming Test (FST)

The FST was conducted according to the protocol used in our previous study.26,27 The forced swimming test consisted of a 15-min pre-test session followed by a 5-min test session 24 h later. During the test session, immobility time and active swimming or struggling time were recorded separately by an observer or by validated video-analysis criteria. The 15-min session was used as a pre-test and was not included in the statistical analysis of depressive-like behavior.

Y-Maze Test (YMT)

The Y-maze apparatus was composed of three black opaque plexiglass arms. The size of each arm was 45 cm × 30 cm × 15 cm. This task consisted of 2 sessions (training and test) and was conducted on 2 successive days. In the training session, the novel arm was closed, and the rats were placed at the end of the starting arm facing the wall and allowed to explore in the maze for 10 min. Twenty-four hours later, the test session was performed. The novel arm was opened, and the rats were permitted to explore the three arms for 5 min. The ambulatory distance in each arm was recorded, and the ratio of moving distance in the novel arm to that in the to arm was taken as the preference index of the novel arm. The Y-maze test was used primarily to assess spontaneous alternation or spatial working-memory-related behavior. Because this paradigm is not specific to depression-like behavior, Y-maze findings were interpreted as changes in exploratory or working-memory-related performance rather than direct evidence of an antidepressant effect.

Measurement of IL-6, TNF-α, IL-1β and Corticosterone Concentration in Hippocampal Homogenates Tissue

Isoflurane was purchased from Ruiwode Life Technology Co., Ltd. (Shenzhen, China). Twenty-four hours after the last behavioral test, SD rats were euthanized via abdominal aortic blood sampling under isoflurane anesthesia (induction 5%, maintenance 0.5–1%). The concentrations of IL‑6, TNF‑α, IL‑1β, and CORT in hippocampal homogenates were measured using the respective commercially available enzyme‑linked immunosorbent assay (ELISA) kits (J&L Biological, Shanghai, China) according to the manufacturer’s instructions.

Immunofluorescence Staining

After cardiac perfusion, first with PBS, and then with a 4% paraformaldehyde solution, the brains of the rats were fixed in paraformaldehyde, embedded in paraffin, and sliced into 5-μm-thick sections. The sections were cleared in xylene, epitope retrieval was performed using citrate, and the samples were permeabilized with Triton X-100 for 30–60 min at 37 °C. After blocking in goat serum, the sections were incubated with an antibody against IBA-1 (1:100; 10,904-1-ap, Proteintech Group, Inc.) for 60 min, followed by incubation with a secondary FITC-labeled goat anti-rabbit IgG antibody (Ebiogo, B029, 1026109) at 37 °C for 30 min. The samples were then sealed with anti-fluorescence quenching mounting medium containing DAPI (S2110, Solarbio) and scanned with an automatic digital slide scanner (Pannoramic Midi). Representative images are presented for qualitative comparison.

Hematoxylin-Eosin (H&E)

For hematoxylin and eosin (H&E) staining, hippocampal tissues from five rats per group were harvested, fixed in 10% neutral-buffered formalin, embedded in paraffin, sectioned at a thickness of 5 μm, and stained using the H&E protocol. The resulting tissue sections were evaluated with a light microscope (Nikon 80i, Nikon, Tokyo, Japan) by a pathologist blinded to group allocation. Representative images are presented for qualitative comparison. Because a standardized quantitative histopathological score was not obtained, the histological findings are interpreted descriptively.

Nissl Staining

For Nissl staining, the slices of the ventricles were degreased with xylene, stained with Nissl solution to dark blue, and washed with double distilled water, and an appropriate amount of differentiation solution was added dropwise for differentiation. Then, the sections were dehydrated with gradient alcohol, degreased again with xylene, and finally sealed with neutral gum. The slices were placed in a fume hood to dry for 2 h, and then images were observed and collected with a microscope. Quantitative analysis of Nissl bodies was carried out using ImageJ.

Transmission Electron Microscopy (TEM)

Following completion of behavioral assessments, small hippocampal tissue blocks (about 1 mm3) were rapidly collected from three rats in each group. The samples were initially fixed in 2.5% glutaraldehyde prepared in 0.1 M phosphate buffer (pH 7.4) at room temperature for 2 hours, followed by post-fixation in 1% osmium tetroxide within the same buffer system. Subsequently, the tissues were dehydrated using a graded ethanol series and embedded in beem capsules. Ultrathin sections (50–70 nm thick) were then sliced, mounted on grids, and left to air-dry overnight. Afterwards, the grids were stained with 2% uranyl acetate for 30 minutes, followed by 15 minutes in lead citrate, and finally examined using a transmission electron microscope (JEOL, JEM 1400). Representative images are presented for qualitative comparison.

Statistical Analysis

The data are presented as the mean ± SEM using SPSS software (version 26.0; SPSS Inc., Chicago, IL, USA). Significant differences were determined by one-way analysis of variance (Data that conforms to normal distribution and homogeneity of variance will be tested for one-way ANOVA, while data that does not conform will be tested for Kruskal–Wallis test) followed by Bonferroni’s post-hoc test for comparison between multiple groups. The degree of significance was set at P < 0.05.

Results Celecoxib Alleviated Depression-Like Behavior Induced by CRS in Rats

Typical trajectories for rats in the OFT was shown in (Figure 1B), respectively. As depicted in (Figure 1B), within the context of the OFT, the model group rats showed significant reduction in center move distance and total ambulatory distance compared with the control group rats. Comparable to the model group, celecoxib reversed these alterations. In the YMT, rats in the model group had a lower preference index for the novel arm compared with those in the control group. While the preference index of rats for new arms increased after celecoxib treatment (Figure 1C). As shown in (Figures 1D), celecoxib treatment significantly extended the struggling time of rats in FST. Furthermore, the sucrose preference index in the SPT significantly decreased in the model group, and celecoxib reversed these changes (Figures 1E). In conclusion, our research shows that celecoxib treatment can significantly improve depression-like behavior in CRS rats.

Celecoxib Reversed the Expression of Hippocampal Homogenates Tissue Related Cytokines and IBA-1 in CRS Rats

To investigate the expression of hippocampal homogenates tissue related cytokines in rats after celecoxib treatment, we collected rats hippocampal homogenates tissue homogenates. Celecoxib treatment markedly decreased the concentrations of TNF-α, IL-1β and IL-6 in hippocampal homogenates tissue, suggesting that celecoxib can alleviate central inflammation in CRS rats (Figure 2A). In addition, IBA-1 immunoreactivity, a marker commonly used to identify microglia, was evaluated. Increased IBA-1 immunoreactivity may reflect increased microglial density or reactivity, but it does not by itself establish a specific microglial activation phenotype. The results showed that celecoxib treatment significantly reduced IBA-1 expression in the hippocampus, suggesting that celecoxib was associated with reduced hippocampal IBA-1 immunoreactivity. (Figure 2B).

Figure 2 Celecoxib reversed the expression of hippocampal homogenates tissue related cytokines, and IBA-1 in CRS rats (A) Concentration of TNF-α, IL-1β, IL-6 in hippocampal homogenates tissue. Concentration of TNF-α in hippocampal homogenates tissue. The Model group versus the control group P< 0.001, the Model group versus the celecoxib group P< 0.001, the Model group versus the fluoxetine group P< 0.001, n=6, F= 290.9. (B) Concentration of IL-1β in hippocampal homogenates tissue. The Model group versus the control group P< 0.001, the Model group versus the celecoxib group P< 0.001, the Model group versus the fluoxetine group P< 0.001, n=6, F= 150.6. (C) Concentration of IL-6 in hippocampal homogenates tissue. The Model group versus the control group P< 0.001, the Model group versus the celecoxib group P< 0.001, the Model group versus the fluoxetine group P< 0.001, n=6, F= 290.4 (B) Immunofluorescence of IBA-1 in hippocampal tissue. The data are presented as means ± SEM (n = 6 rats per group). ***P < 0.001 represents the Model group (CRS) compared to the Control group (no CRS, no treatment), and ###P < 0.001 represent the Celecoxib and Fluoxetine treatment groups (CRS+treatment) compared to the Model group.

Celecoxib Inhibited the Activation of HPA Axis

CRS led to hyperactivation of the hypothalamic-pituitary-adrenal (HPA) axis and sustained high levels of glucocorticoids like corticosterone (CORT), which can exert detrimental effects on brain structures, particularly the hippocampus. Celecoxib inhibited the release of CORT (Figure 3A) as shown by biochemical assays and alleviated adrenal gland damage (Figure 3B).

Figure 3 Celecoxib alleviates the expression of CORT in rat hippocampal homogenates and histopathological changes in adrenal gland tissue. (A) Concentration of CORT in hippocampal homogenates tissue. The Model group versus the control group P< 0.001, the Model group versus the celecoxib group P< 0.001, the Model group versus the fluoxetine group P< 0.001, n=6, F= 64.82 (B) Representative images of the Hematoxylin and eosin (H&E) stained-adrenal gland sections (100μm). The data are presented as means ± SEM (n = 6 rats per group). ***P < 0.001 represents the Model group (CRS) compared to the Control group (no CRS, no treatment), and ###P < 0.001 represent the Celecoxib and Fluoxetine treatment groups (CRS+treatment) compared to the Model group.

Celecoxib Ameliorated the Pathological Changes of Hippocampus in CRS Rats

Illustrative micrographs from hematoxylin-eosin (H&E) and Nissl staining in the hippocampal dentate gyrus region for all groups are shown in (Figure 4). H&E staining indicated that neurons in the control group had a uniform shape, tight packing, large round nuclei with clear nucleoli. Conversely, the model group exhibited distorted neuronal forms, sparse arrangement, shrinkage, intensified staining, and blurred nuclear-cytoplasmic boundaries. Celecoxib administration substantially restored normal hippocampal pathology, as seen in (Figure 4A). Nissl staining, which assesses neuronal integrity and Nissl body presence, corroborated these observations. In the control group, neurons were densely organized with distinct round nucleoli and abundant purple-stained Nissl bodies (Figure 4B). The model group showed significant neuronal depletion, looser packing with wider gaps, condensed nuclei often irregular in shape, and reduced or absent Nissl bodies, leading to paler staining. Celecoxib treatment enhanced neuronal density in the dentate gyrus, normalized cell structure and arrangement, and boosted Nissl body numbers, evidenced by deeper purple staining (Figure 4C). Collectively, these results demonstrate that celecoxib alleviates CRS-induced hippocampal injury in rats.

Figure 4 Celecoxib ameliorates the pathological changes of hippocampus in CRS rats. (A) Representative images of the Hematoxylin and eosin (H&E) stained-brain sections (100μm). (B) Representative images of the Nissl stained-brain sections (100μm). (C) Changes in the number of Nissl bodies. The Model group versus the control group P< 0.001, the Model group versus the celecoxib group P< 0.001, the Model group versus the fluoxetine group P< 0.001, n=5, F= 44.79. The data are presented as means ± SEM (n = 5 rats per group). ***P < 0.001 represents the Model group (CRS) compared to the Control group (no CRS, no treatment), and ###P < 0.001 represent the Celecoxib and Fluoxetine treatment groups (CRS+treatment) compared to the Model group.

Celecoxib Alleviated Damage to Hippocampal Neurons in Rats

To assess whether celecoxib treatment influences related neural cells, we utilized transmission electron microscopy to observe the ultrastructure of hippocampal neurons across four groups (Figure 5A). In the control group, hippocampal neurons displayed intact cell membranes, smooth nuclear envelopes, and uniformly distributed nuclear chromatin. The cytoplasm appeared clear and was rich in organelles. In contrast, neurons in the model group exhibited reduced cell body size, nuclear condensation or deformation, and mitochondrial damage. Notably, celecoxib treatment led to improvements in the ultrastructural morphology of hippocampal neurons.

Figure 5 Representative transmission electron micrographs of hippocampal tissue from CRS-exposed rats. Representative ultrastructural images from the control, CRS model, celecoxib-treated, and fluoxetine-treated groups are shown. Because the analysis included three animals per group and was descriptive, the images are interpreted as representative morphological observations.

Discussion

Celecoxib, a selective COX-2 inhibitor widely recognized for its anti-inflammatory efficacy, has emerged as a potential therapeutic agent for conditions beyond its traditional use, including potentially Major Depressive Disorder (MDD).28,29 In our study, we employed the chronic restraint stress (CRS) model in SD rats, a well-established paradigm for inducing depression-like phenotypes, to evaluate the efficacy of celecoxib in mitigating these behaviors. Our investigations integrated behavioral assays with neurochemical and histological analyses. The results consistently demonstrated that celecoxib administration significantly ameliorated depression-like behaviors induced by CRS. Furthermore, celecoxib markedly reduced the hippocampal levels of key pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), the stress hormone corticosterone (CORT) and IBA-1. Concurrently, histological and ultrastructural examinations revealed that celecoxib treatment attenuated CRS-induced pathological damage within the hippocampus. These findings collectively suggest that celecoxib holds promise as an efficacious approach for ameliorating stress-induced depression-like states.

The therapeutic action of celecoxib stems from its specific inhibition of the COX-2 enzyme, which is upregulated during inflammatory processes and contributes to the synthesis of pro-inflammatory prostaglandins.30 While clinically established for managing inflammatory pain in conditions like arthritis,13 its application in neuropsychiatric disorders is an area of growing interest. Given the accumulating evidence implicating neuroinflammation in the pathophysiology of depression, investigating the effects of a targeted anti-inflammatory agent like celecoxib represents a mechanistically plausible strategy.31 Unlike broad-spectrum anti-inflammatories or non-pharmacological interventions, celecoxib offers a specific molecular target (COX-2), allowing for a more focused interrogation of this particular inflammatory pathway in depression models.

MDD remains a significant global health challenge, characterized by a complex interplay of genetic predispositions, environmental stressors, and neurobiological alterations.32 Its core symptoms, including persistent sadness, anhedonia, and functional impairment, often prove difficult to manage effectively with existing treatments.32 Standard pharmacotherapies (e.g, SSRIs, SNRIs) and psychotherapies benefit many, but substantial rates of treatment resistance and problematic side effects persist, highlighting an urgent need for alternative or adjunctive therapeutic strategies.33,34 The potential for celecoxib to modulate key neuroinflammatory and stress-related pathways implicated in depression presents a compelling avenue for addressing this unmet clinical need.

The pathophysiological mechanisms underlying MDD are increasingly understood to involve dysregulation of the immune system, particularly chronic low-grade inflammation, alongside alterations in the stress response system and neurotrophic support.35 Elevated levels of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6 have been consistently reported in depressed patients and are known to negatively impact neurogenesis, synaptic plasticity, and neurotransmitter metabolism.36 Furthermore, chronic stress, a major trigger for depression, leads to hyperactivation of the hypothalamic-pituitary-adrenal (HPA) axis and sustained high levels of glucocorticoids like corticosterone (CORT), which can exert detrimental effects on brain structures, particularly the hippocampus.37 In addition to cytokine changes, microglial activation—often assessed by increased expression of IBA-1, a specific marker for activated microglia—has been implicated in the neuroinflammatory processes associated with depression. Elevated IBA-1 levels reflect enhanced microglial activation, which can further contribute to neuronal dysfunction and depressive-like behaviors. In the present study, we observed that celecoxib treatment effectively counteracted the CRS-induced elevations in hippocampal TNF-α, IL-1β, IL-6, CORT and IBA-1. This strongly suggests that celecoxib exerts its antidepressant-like effects, at least in part, by suppressing neuroinflammation and normalizing HPA axis hyperactivity within the hippocampus, key pathological features associated with stress-induced depression.38 The reduction in these specific mediators via COX-2 inhibition points towards the importance of the prostaglandin pathway in mediating the detrimental effects of stress.

Complementing the biochemical findings, our histological assessments using HE and Nissl staining provided structural evidence for the neuroprotective effects of celecoxib. CRS is known to induce neuronal damage, reduce cell density, and impair morphology in the hippocampus, a brain region critically involved in learning, memory, and mood regulation, and highly vulnerable to stress. Our results showed that celecoxib treatment ameliorated these CRS-induced pathological changes, preserving neuronal integrity. Furthermore, transmission electron microscopy offered a high-resolution view, revealing that celecoxib mitigated ultrastructural damage to hippocampal neurons caused by chronic stress, potentially preserving synaptic structures and organelle health. This observed neuroprotection likely contributes significantly to the behavioral improvements, suggesting that celecoxib not only dampens harmful biochemical cascades (inflammation, CORT) but also preserves the structural and functional integrity of crucial neural circuits affected in depression.

However, several limitations of the current study warrant consideration. First, while we demonstrated effects on key inflammatory cytokines and CORT, the precise downstream molecular cascades and cellular interactions modulated by celecoxib in this CRS model remain to be fully elucidated. Future studies could explore effects on specific glial cell activation states, downstream signaling pathways (e.g, NF-κB), or neurotransmitter systems potentially influenced by inflammation. Second, this study utilized a single dose and duration of celecoxib; dose-response relationships and the effects of longer-term treatment require further investigation. Third, our analysis focused primarily on the hippocampus. Given that depression involves distributed neural networks, examining the effects of celecoxib in other relevant brain regions (e.g, prefrontal cortex, amygdala) would provide a more comprehensive understanding. Finally, translating these findings from rodent models to human MDD requires caution, considering potential species differences and the known systemic side effects (e.g, cardiovascular risks) associated with long-term celecoxib use in humans, which must be carefully weighed against potential benefits for depression.

Conclusions

In conclusion, celecoxib treatment during ongoing chronic restraint stress was associated with improved behavioral parameters and reduced inflammatory, corticosterone-related, histological, and ultrastructural alterations in male Sprague-Dawley rats. These findings provide preliminary evidence that celecoxib may influence stress-related behavioral and biological outcomes. However, because COX-2 signaling and other mechanistic pathways were not directly assessed, the present results do not establish that celecoxib produces these effects through a specific anti-inflammatory or HPA-axis mechanism. Further studies using multiple doses, circulating biomarkers, pathway-specific molecular analyses, and quantitative histological and ultrastructural assessments are required.

Abbreviations

MDD, major depressive disorder; OFT, open field test; SPT, sucrose preference test; FST, forced swimming test; IL-6, interleukin-6; TNF-α, tumor necrosis factor-alpha; IL-1β, interleukin-1 beta; H&E, Hematoxylin-eosin; ELISA, enzyme-linked immunosorbent assay; CRS, Chronic restraint stress; CORT, corticosterone, IBA-1, Ionized calcium binding adapter molecule 1.

Data Sharing Statement

The data sets used and/or analyzed in the current study are available from the corresponding author on reasonable request.

Ethics Approval and Consent to Participate

All animal experimental procedures were reviewed and approved by the Experimental Animal Ethics Committee of Anhui Medical University (Animal Ethics No.: LLSC20221100). All animal manipulations were performed in accordance with the national standard. Guidelines for the ethical review of laboratory animal welfare (GB/T 35892-2018) and the Guidance on Humane Treatment of Laboratory Animals issued by the Ministry of Science and Technology of China. The 3Rs principles (Replacement, Reduction, Refinement) were strictly implemented to minimize animal suffering and distress.

Acknowledgments

The author thanks the Hefei Fourth People’s Hospital offer its funding and equipment support.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Funding

Applied Medicine Research Project of Hefei Health Health Commission (Hwk2025zc013), Anhui Province Medical and Health Research Project(AHWJ2022b094), National Clinical Key Specialty Construction Project of China (grant number: None), Anhui Province Medical and Health Key Specialty Construction Project, Hefei 8th-cycle Key Clinical Specialty Funding.

Disclosure

The authors report no conflicts of interest in this work.

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