Alterations in Serum BDNF and GDNF Levels after 12 Weeks of Antidepressant Treatment in Female Outpatients with Major Depressive Disorder

Interactions between neurotrophins, mood, and physical activity under the conditions of sleep deprivation

Sleep deprivation (DS) is the forced elimination of sleep. While brain-derived neurotrophic factor (BDNF) has been extensively studied in the context of in mood changes following DS, the role of other neurotrophins remains elusive. This study explores the impact of DS on BDNF, glial cell line-derived neurotrophic factor (GDNF), neurotrophin-3 (NT3), and neurotrophin-4 (NT4) at mRNA and protein level, considering their potential links to mood disturbances. The study involved 81 participants subjected to polysomnography (PSG) and DS. Blood samples, mood assessments, and actigraphy data were collected twice, after PSG and DS. NT mRNA expression and serum protein concentrations of BDNF, GDNF, NT3, and NT4 were measured. Participants were divided into Responders and Non-Responders based on mood improvement after DS. DS reduced BDNF mRNA expression in all participants, with no change in serum BDNF protein. GDNF protein decreased in Non-Responders, while Responders exhibited reduced GDNF mRNA. NT3 protein increased in both groups, while NT3 mRNA decreased in Respondents. NT4 protein rose universally post-DS, but NT4 mRNA remained unchanged. Physical activity (PA) negatively correlated with mRNA expression of BDNF, GDNF, and NT3 post-DS. The study's short DS duration and exclusion of immature NT forms limit comprehensive insights. GDNF, together with NT3, might play an important role in mood response to DS. PA during DS seems to impair the mRNA expression of NTs in leukocytes. Future studies on the subject of sleep deprivation might consider investigating the relationship between BDNF and NT4 in the context of their apparent redundancy.

Naringin corrects renal failure related to Lesch-Nyhan disease in a rat model via NOS-cAMP-PKA and BDNF/TrkB pathways

This study explored the effect of naringin (NAR) on HGPRT1 deficiency and hyperuricemia through NOS-cAMP-PKA and BDNF/TrkB signaling pathways induced by caffeine (CAF) and KBrO3 in a rat model. Sixty-three adult male albino rats were randomly assigned into nine (n = 7) groups. Group I: control animals, Group II was treated with 100 mg/kg KBrO3 , Group III was treated with 250 mg/kg CAF, Group IV was treated with 100 mg/kg KBrO3  + 250 mg/kg CAF, Group V was administered with 100 mg/kg KBrO3  + 100 mg/kg haloperidol, Group VI was administered with 100 mg/kg KBrO3  + 50 mg/kg NAR, Group VII was administered with 500 mg/kg CAF + 50 mg/kg NAR, and Group VIII was administered with 100 mg/kg KBrO3  + 250 mg/kg CAF + 50 mg/kg NAR. Finally, group IX was treated with 50 mg/kg NAR. The exposure of rats to KBrO3 and CAF for 21 days induced renal dysfunction linked with Lesch-Nyhan disease. NAR obliterated renal dysfunction linked with Lesch-Nyhan disease by decreasing uric acid, renal malondialdehyde level, inhibiting the activities of arginase, and phosphodiesterase-51 (PDE-51) with corresponding upregulation of brain derived-neurotrophic factor and its receptor (BDNF-TrkB), Bcl11b, HGPRT1, and DARPP-32. Additionally, renal failure related to Lesch-Nyhan disease was remarkably corrected by NAR as shown by the reduced activities of AChE and enzymes of ATP hydrolysis (ATPase, AMPase, and ADA) with affiliated increase in the NO level. This study therefore validates NAR as nontoxic and effective chemotherapy against kidney-related Lesch-Nyhan disease by mitigating effects of toxic food additives and enzymes of ATP-hydrolysis via NOS-cAMP-PKA and BDNF/TrkB signaling pathways.

Putative role of glial cells in treatment resistance depression: An updated critical literation review and evaluation of single-nuclei transcriptomics data

AIMS

Major depressive disorder (MDD) is a prevalent global mental illness with diverse underlying causes. Despite the availability of first-line antidepressants, approximately 10-30 % of MDD patients do not respond to these medications, falling into the category of treatment-resistant depression (TRD). Our study aimed to elucidate the precise molecular mechanisms through which glial cells contribute to depression-like episodes in TRD.

MATERIALS AND METHODS

We conducted a comprehensive literature search using the PubMed and Scopus electronic databases with search terms carefully selected to be specific to our topic. We strictly followed inclusion and exclusion criteria during the article selection process, adhering to PRISMA guidelines. Additionally, we carried out an in-depth analysis of postmortem brain tissue obtained from patients with TRD using single-nucleus transcriptomics (sn-RNAseq).

KEY FINDINGS

Our data confirmed the involvement of multiple glia-specific markers (25 genes) associated with TRD. These differentially expressed genes (DEGs) primarily regulate cytokine signaling, and they are enriched in important pathways such as NFκB and TNF-α. Notably, DEGs showed significant interactions with the transcription factor CREB1. sn-RNAseq analysis confirmed dysregulation of nearly all designated DEGs; however, only Cx30/43, AQP4, S100β, and TNF-αR1 were significantly downregulated in oligodendrocytes (OLGs) of TRD patients. With further exploration, we identified the GLT-1 in OLGs as a hub gene involved in TRD.

SIGNIFICANCE

Our findings suggest that glial dysregulation may hinder the effectiveness of existing therapies for TRD. By targeting specific glial-based genes, we could develop novel interventions with minimal adverse side effects, providing new hope for TRD patients who currently experience limited benefits from invasive treatments.

Plasma Brain-Derived Neurotrophic Factor Levels in First-Episode and Recurrent Major Depression and before and after Bright Light Therapy in Treatment-Resistant Depression

Brain-derived neurotrophic factor (BDNF) is implicated in the etiology and treatment response in major depressive disorder (MDD). However, peripheral BDNF concentrations have not been compared across different MDD stages. Bright light therapy (BLT) offers some potential in treatment-resistant depression (TRD), but its effects on BDNF levels are unknown. This study included a cross-sectional analysis of plasma BDNF concentration in females with TRD, unmedicated MDD patients, and healthy controls (HC), and measurements of longitudinal BLT effects on plasma BDNF levels in TRD patients. The present study included 55 drug-naïve, first-episode patients, 25 drug-free recurrent-episode MDD patients, 71 HC participants, and 54 TRD patients. Patients were rated by Hamilton Depression Rating Scale (HAMD)-17 and the Montgomery-Åsberg Depression Rating Scale (MADRS). Patients with TRD received BLT during 4 weeks. The total HAMD-17 and MADRS scores decreased following BLT. All patient groups had lower plasma BDNF than HC, but BDNF levels did not differ between first- and recurrent-episode BDNF patients and TRD patients before or after BLT. However, responders and remitters to BLT had higher post-treatment plasma BDNF concentrations than patients who did not achieve response or remission. The changes in plasma BDNF levels may be candidates for biomarkers of treatment response to BLT in TRD patients.

Disorders of Hippocampus Facilitated by Hypertension in Purine Metabolism Deficiency is Repressed by Naringin, a Bi-flavonoid in a Rat Model via NOS/cAMP/PKA and DARPP-32, BDNF/TrkB Pathways

Individuals who are hypertensive have a higher tendency of predisposition to other genetic diseases including purine metabolism deficiency. Therefore, the search for nontoxic and effective chemo protective agents to abrogate hypertension-mediated genetic disease is vital. This study therefore investigated the repressive effect of naringin (NAR) against disorder of hippocampus facilitated by hypertension in purine metabolism deficiency. Male albino rats randomly assigned into nine groups (n = 7) were treated for 35 days. Group I: control animals, Group II was treated with 100 mg/kg KBrO₃, Group III was treated with 250 mg/kg caffeine, and Group IV was treated with 100 mg/kg KBrO₃ + 250 mg/kg caffeine. Group V was administered with 100 mg/kg KBrO₃ + 100 mg/kg haloperidol. Group VI was administered with 100 mg/kg KBrO₃ + 50 mg/kg NAR. Group VII was administered with 250 mg/kg caffeine + 50 mg/kg NAR, and Group VIII was administered with 100 mg/kg KBrO₃ + 250 mg/kg caffeine + 50 mg/kg NAR. Finally, group IX was treated with 50 mg/kg NAR. The sub-acute exposure to KBrO₃ and CAF induced hypertension and mediated impairment in the hippocampus cells. This was apparent by the increase in PDE-5¹, arginase, and enzymes of ATP hydrolysis (ATPase and AMPase) with a simultaneous increase in cholinergic (AChE and BuChE) and adenosinergic (ADA) enzymes. The hypertensive-mediated hippocampal impairment was associated to alteration of NO and AC signaling coupled with lower expression of brain-derived neurotrophic factor and its receptor (BDNF-TrkB), down regulation of Bcl11b and DARPP-32 which are neurodevelopmental proteins, and hypoxanthine accumulation. However, these features of CAF-mediated hippocampal damage in KBrO₃-induced hypertensive rats were repressed by post-treatment with NAR via production of neuro-inflammatory mediators, attenuation of biochemical alterations, stabilizing neurotransmitter enzymes, regulating NOS/cAMP/PKA and DARPP-32, BDNF/TrkB signaling, and restoring hippocampal tissues.

Serum Glial Cell Line-Derived Neurotrophic Factor (sGDNF) Is a Novel Biomarker in Predicting Cirrhosis in Patients with Chronic Hepatitis B

OBJECTIVES

We assessed the potential of glial cell line-derived neurotrophic factor (GDNF) as a useful biomarker to predict cirrhosis in chronic hepatitis B (CHB) patients.

METHODS

A total of 735 patients from two medical centers (385 CHB patients and 350 healthy controls) were included to determine the association of serum and tissue GDNF levels with biopsy-proven cirrhosis. The diagnostic accuracy of serum GDNF (sGDNF) was estimated and compared with other indices of cirrhosis.

RESULTS

We showed significantly higher levels of sGDNF in CHB patients with fibrosis (28.4 pg/ml vs. 11.6 pg/ml in patients without) and patients with cirrhosis (33.8 pg/ml vs. 23.5 pg/ml in patients without). The areas under receiver operating curve (AUROCs) of sGDNF were 0.83 (95% confidence interval (CI): 0.80-0.87) for predicting liver fibrosis and 0.84 (95% CI: 0.79-0.89) for cirrhosis. Findings from the serum protein level and hepatic mRNA expression were consistent. Using the best cutoff to predict cirrhosis, we categorized the patients into sGDNF-high and sGDNF-low groups. The sGDNF-high group had significantly larger Masson's trichrome and reticulin staining-positive area, higher Scheuer score, and METAVIR fibrosis stage (all p < 0.001) but not steatosis. On multivariable regression, sGDNF was independently associated with cirrhosis with an odds ratio of 6.98 (95% CI: 1.10-17.94). Finally, we demonstrated that sGDNF outperformed AST to platelet ratio index, FIB-4, fibroscore, forn index, and fibrometer in differentiating F4 vs. F3.

CONCLUSION

Using serum, tissue mRNA, and biopsy data, our study revealed a significant potential of sGDNF as a novel noninvasive biomarker for cirrhosis in CHB patients.

Increased prefrontal cortex connectivity associated with depression vulnerability and relapse

BACKGROUND

Major depressive disorder (MDD) is a highly prevalent mood disorder, characterized by depressed mood, reduced capabilities to concentrate, impaired cognition, as well as a high risk of relapse. Unaffected siblings who have high risks for MDD development and yet without clinical symptoms may be helpful for understanding the neural mechanisms of MDD traits.

METHODS

We investigated both regional fluctuation and inter-regional synchronization in 31 fully remitted MDD patients, 29 unaffected siblings and 43 age, gender, and educational level matched helathy controls (HCs) using resting-state functional magnetic resonance imaging (rs-fMRI). The 17-item HAMD and neurocognitive scales were performed. Fractional amplitude of low-frequency fluctuation (fALFF) and functional connectivity (FC) strength were investigated.

RESULTS

Compared with healthy control group, patients with remitted MDD and unaffected siblings showed increased fALFF in the left dorsomedial prefrontal cortex (dmPFC) and increased FC between the left dmPFC and the right ventromedial prefrontal cortex (vmPFC). In addition, a negative correlation was observed between the fALFF value in the left dmPFC and the speed of Trail Making Test in the remitted MDD patients. Higher vmPFC-dmPFC FC was positively correlated with Wisconsin Card Sorting Test (WCST) total correct, and negatively correlated with WCST random errors.

CONCLUSIONS

In the absence of clinical symptoms, individuals with remitted MDD and unaffected siblings showed increased fALFF in left dmPFC as well as the vmPFC-dmPFC connectivity. These results suggest a specific trait abnormality in the default mode network associated with vulnerability to MDD, which may have implications for developing effective therapies using this network as a target.

Astrocytes in depression and Alzheimer's disease

Astrocytes are an abundant subgroup of cells in the central nervous system (CNS) that play a critical role in controlling neuronal circuits involved in emotion, learning, and memory. In clinical cases, multiple chronic brain diseases may cause psychosocial and cognitive impairment, such as depression and Alzheimer's disease (AD). For years, complex pathological conditions driven by depression and AD have been widely perceived to contribute to a high risk of disability, resulting in gradual loss of self-care ability, lower life qualities, and vast burden on human society. Interestingly, correlational research on depression and AD has shown that depression might be a prodrome of progressive degenerative neurological disease. As a kind of multifunctional glial cell in the CNS, astrocytes maintain physiological function via supporting neuronal cells, modulating pathologic niche, and regulating energy metabolism. Mounting evidence has shown that astrocytic dysfunction is involved in the progression of depression and AD. We herein review the current findings on the roles and mechanisms of astrocytes in the development of depression and AD, with an implication of potential therapeutic avenue for these diseases by targeting astrocytes.

N-3 polyunsaturated fatty acids promote astrocyte differentiation and neurotrophin production independent of cAMP in patient-derived neural stem cells

Evidence from epidemiological and laboratory studies, as well as randomized placebo-controlled trials, suggests supplementation with n-3 polyunsaturated fatty acids (PUFAs) may be efficacious for treatment of major depressive disorder (MDD). The mechanisms underlying n-3 PUFAs potential therapeutic properties remain unknown. There are suggestions in the literature that glial hypofunction is associated with depressive symptoms and that antidepressants may normalize glial function. In this study, induced pluripotent stem cells (iPSC)-derived neuronal stem cell lines were generated from individuals with MDD. Astrocytes differentiated from patient-derived neuronal stem cells (iNSCs) were verified by GFAP. Cells were treated with eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) or stearic acid (SA). During astrocyte differentiation, we found that n-3 PUFAs increased GFAP expression and GFAP positive cell formation. BDNF and GDNF production were increased in the astrocytes derived from patients subsequent to n-3 PUFA treatment. Stearic Acid (SA) treatment did not have this effect. CREB activity (phosphorylated CREB) was also increased by DHA and EPA but not by SA. Furthermore, when these astrocytes were treated with n-3 PUFAs, the cAMP antagonist, RP-cAMPs did not block n-3 PUFA CREB activation. However, the CREB specific inhibitor (666-15) diminished BDNF and GDNF production induced by n-3 PUFA, suggesting CREB dependence. Together, these results suggested that n-3 PUFAs facilitate astrocyte differentiation, and may mimic effects of some antidepressants by increasing production of neurotrophic factors. The CREB-dependence and cAMP independence of this process suggests a manner in which n-3 PUFA could augment antidepressant effects. These data also suggest a role for astrocytes in both MDD and antidepressant action.

Variable alterations in plasma erythropoietin and brain-derived neurotrophic factor levels in patients with major depressive disorder with and without a history of suicide attempt

It is hypothesized that major depression disorder (MDD) is associated with impaired neuronal plasticity, and that antidepressant treatments restore neuroplasticity. Brain-derived neurotrophic factor (BDNF) and erythropoietin (Epo) show neurotrophic and neuroprotective effects. We evaluated plasma Epo and BDNF levels in 50 MDD inpatients before treatment and in 50 healthy controls. The MDD inpatients consisted of 20 MDD patients without and 30 MDD patients with a recent suicide attempt. The plasma Epo level was significantly higher in nonsuicidal and suicidal MDD patients than in healthy controls (p ≤ 0.001), while the plasma BDNF level was significantly lower in suicidal MDD than in nonsuicidal MDD patients and healthy controls (p ≤ 0.001). When classifying study participants into low-Epo and high-Epo and low-BDNF and high-BDNF subgroups based on the cutoff of Epo or BDNF calculated using receiver operating characteristics (ROC) curve analysis, logistic regression analysis revealed that high-Epo and low-BDNF status correlated with a respective significant odds ratio of 7.367 (p = 0.015) and 33.123 (p ≤ 0.001) for suicidal MDD. In conclusion, plasma BDNF level was decreased in untreated MDD patients, which was presumed to be a dysfunctional effect of the onset of MDD. However, an increase in plasma Epo was observed in MDD in connection with a recent suicide attempt, indicating that this triggers hypoxic stress to induce a compensatory increase in Epo.

Altered levels of interleukins and neurotrophic growth factors in mood disorders and suicidality: an analysis from periphery to central nervous system

Interleukins and neurotrophins levels are altered in the periphery of patients with major depression and suicidal behavior, however it is not clear if similar abnormalities occur in the central nervous system. Our objective was to examine the association of IL-6, IL-1β, BDNF, and GDNF levels between postmortem plasma, cerebrospinal fluid (CSF), and brain tissue in a heterogeneous diagnostic subject groups including normal controls, mood disorders only, mood disorders with AUD/SUD (alcohol abuse disorder, substance abuse disorder), and AUD/SUD without mood disorders. To address these questions we collected postmortem plasma (n = 29), CSF (n = 28), and brain (BA10) (n = 57) samples from individuals with mood disorder, mood disorder with AUD/SUD, AUD/SUD and normal controls. These samples were analyzed using a multiplex based luminex assay with a customized 4-plex cytokine/interleukins- IL-6, IL-1β, BDNF, and GDNF human acute phase based on xMAP technology platform. Protein levels were determined using a Luminex 200 instrument equipped with Xponent-analyzing software. We observed IL-6 (p = 2.1e-07), and GDNF (p = 0.046) were significantly correlated between brain and CSF. In addition, IL-6 (p = 0.031), were significantly correlated between brain and plasma. Overall diagnostic group analysis showed a significant difference with brain GDNF, p = 0.0106. Pairwise comparisons showed that GDNF level is-39.9 ± 12 pg/ml, p = 0.0106, was significantly higher than in the brains derived from mood disorders compared to normal controls, -23.8 ± 5.5 pg/ml, p = 0.034. Brain BDNF was higher in suicide (p = 0.0023), males compared to females (p = 0.017), and psychiatric medication treated vs. non-treated (p = 0.005) individuals. Overall, we demonstrate that blood IL-6, GDNF and BDNF could be informative peripheral biomarkers of brain biology associated with mood disorders, substance disorders, and suicide.

Expression of Selected Genes Involved in Neurogenesis in the Etiopathogenesis of Depressive Disorders

(1) Background: The neurogenic theory suggests that impaired neurogenesis within the dentate gyrus of the hippocampus is one of the factors causing depression. Immunology also has an impact on neurotrophic factors. The aim of the study was to assess the importance of selected genes involved in the process of neurogenesis i.e., nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF) and neuron-restrictive silencer factor (REST gene) in the etiopathogenesis of depressive disorders. (2) Methods: A total of 189 subjects took part in the study (95 depressed patients, 94 healthy controls). Sociodemographic data were collected. The severity of depressive symptoms was assessed using the Hamilton Depression Rating Scale (HDRS). RT-PCR was used to assess gene expression at the mRNA levels, while Enzyme-Linked Immunosorbent Assay (ELISA) was used to assess gene expression at the protein level. (3) Results: Expression of NGF, BDNF, REST genes is lower in depressed patients than in the control group, whereas the expression of GDNF gene is higher in patients with depressive disorders than in the group of healthy volunteers. (4) Conclusions: The expression of selected genes might serve as a biomarker of depression.

Klotho, BDNF, NGF, GDNF Levels and Related Factors in Withdrawal Period in Chronic Cannabinoid Users

Klotho and neurotropic factors have recently been shown to be related to some psychiatric disorders and neurocognitive disorders, but there is no study on this issue within substance users. In this study, brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), glial derived neurotrophic factor (GDNF) and klotho serum levels of a patient group consisting of 27 chronic cannabis users according to the DSM-V and 27 healthy volunteers were compared, and their relationships with other the clinical features of other patients were evaluated. Clinical scales, the Buss-Perry Aggression Scale, and the Substance Craving Scale were repeated on the first day of hospitalisation and on the seventh day of withdrawal. BDNF, GDNF, NGF and klotho levels were analysed using the ELISA method. There was no differences between the cannabinoid use disorder group and the control group regarding their klotho and other neurotrophic levels, but initiation age of cannabis use was negatively correlated with these levels. In addition, there was a relationship between verbal aggression scores and BDNF and NGF levels. There was a positive correlation between klotho and neurotrophic factors in all groups (patient group Day 1, patient group Day 7, control group) (p < 0.01). When comparing the difference between the correlations using the cocor (a comprehensive solution for the statistical comparison of correlations), the klotho-GDNF and klotho-NGF correlations for the first day of the patient group and the control group were different. In this study, rather than a difference in klotho levels and neurotropic factors, a significant relationship between these markers and each other and clinical parameters was demonstrated; further studies are needed to understand the exact mechanism.

Serotonergic neurons in the treatment of mood disorders: The dialogue with astrocytes

Astrocytes were traditionally regarded as cells important to neuronal activity, providing both metabolic and structural supports. Recent evidence suggests that they may also play a crucial role in the control of higher brain functions. In keeping with this hypothesis, it is now well accepted that astrocytes contribute to stress but also react to antidepressant drugs as they express serotonergic transporters and receptors. However, the downstream mechanisms leading to the fine-tuned regulation of mood are still unknown. This chapter pays attention to the role of astrocytes in the regulation of emotional behavior and related serotonergic neurotransmission. In particular, it gives a current state of the clinical and preclinical evidence showing that astrocytes respond to environmental conditions and antidepressant drugs through the release of gliotransmitters and neurotrophic factors which in turn, influence serotonergic tone in discrete brain areas. This state-of-the-art review aims at demonstrating the remarkable potential for novel therapeutic antidepressant strategies targeting these glial cells.

Evaluation of Serum Glial Cell Line-derived Neurotrophic Factor in Bangladeshi Major Depressive Disorder Patients

Background

Major depressive disorder (MDD) is a global health burden in the 21^st century because of its high rate of prevalence linked with disability, morbidity, and mortality. The actual etiology behind the development of MDD is not understood yet. Various genetic, physiological, biological and environmental factors have been predicted to be involved. As there is currently no sufficient laboratory test for the diagnosis of MDD, it is expected that this investigation can assist in better diagnosis and management of MDD. The present study aimed to evaluate glial cell line-derived neurotrophic factor (GDNF) in MDD patients compared to healthy controls (HCs).

Materials and methods

This case-control study was conducted with 167 participants including 85 MDD patients and 82 age- and sex-matched HCs. A qualified psychiatrist evaluated all the study participants according to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5). The severity of depression was measured by the Hamilton depression rating scale (Ham-D) and the participants with Ham-D score ≥ 7 were considered as cases. Serum GDNF levels were determined by enzyme-linked immunosorbent assay (ELISA) kits (Boster Bio, Pleasanton, CA, USA).

Results

MDD patients and HCs were similar in terms of their socio-demographic profiles. Serum GDNF was found to have no significant alterations in MDD patients when compared to HCs (p > 0.05). Moreover, no significant positive or negative correlation was found between serum levels of GDNF and Ham-D scores in MDD patients.

Conclusions

It can be predicted from the above findings that there is no significant relation between serum GDNF levels and the pathophysiology of depression. This study should be treated as preliminary and further studies with a more homogeneous and larger study population are required to establish these findings.

N-Palmitoylethanolamide Exerts Antidepressant-Like Effects in Rats: Involvement of PPARα Pathway in the Hippocampus

N-Palmitoylethanolamide (PEA), an endocannabinoid-like molecule, participates in controlling behaviors associated with mental disorders as an endogenous neuroprotective factor. On the basis of accumulating evidence and our previous data, we tested the hypothesis that the antidepressant-like effects of PEA observed during chronic unpredictable mild stress (CUMS) are mediated by possible targets in the peroxisome proliferator-activated receptor alpha (PPARα) pathway. In this study, rats were subjected to 35 days of CUMS and treated with drugs such as PEA (2.5, 5.0, or 10 mg/kg, by mouth), fluoxetine (10 mg/kg, by mouth), or the combination of PEA and MK886 (1-[(4-chlorophenyl) methyl]-3-[(1,1-dimethylethyl) thio]-α,α-dimethyl-5-(1-methylethyl)-1H-indole-2-propanoic acid). After behavioral tests, the animals were sacrificed and their hippocampi were dissected for subsequent studies. PEA normalized weight gain, sucrose preferences, locomotor activity in an open-field test, and levels of the PPARα mRNA and protein in the hippocampus, and it reduced serum adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels in rats subjected to CUMS. PEA reversed the abnormal levels of several oxidative stress biomarkers and increased the concentrations of two neurotrophic factors in the hippocampus of CUMS-induced rats. In addition, PEA alleviated the decrease in hippocampal weight. However, the aforementioned effects of PEA were completely or partially abolished by MK886, a selective PPARα antagonist. On the basis of these findings, the PPARα pathway in the hippocampus is a possible target of the antidepressant effects of PEA, and the maintenance of a stable hypothalamic-pituitary-adrenal axis, the antioxidant defenses, and normalization of neurotrophic factor levels in the hippocampus are involved in this process.