Altered expression of NUCB2/nesfatin-1 in plasma, hypothalamus and brainstem is associated with HPA axis activity and TPH expression in chronically stressed rats.

Carboxypeptidase E Alleviates Depressive-Like Behaviors in Mice by Regulating BDNF/Nrf2 Axis-Mediated Ferroptosis

NDP-MSH rescues LPS-induced neuroinflammation, synaptic deficits, and depressive-like behaviors in mice: involvement of MC1R–cAMP/PKA signaling

Introduction Inflammatory processes contribute significantly to the pathophysiology of depression. Although the melanocortin system is well known to regulate inflammation, the specific contribution of melanocortin 1 receptor (MC1R) and its endogenous ligand, α-melanocyte-stimulating hormone (α-MSH), to inflammation-associated depression remains unclear. Methods Systemic lipopolysaccharide (LPS) administration was used to establish an inflammation-associated depression model in mice. Depressive-like behaviors, synaptic functions, and metabolic alterations were evaluated using behavioral tests, patch-clamp recordings, and untargeted metabolomic profiling. To examine the functional involvement of MC1R, adeno-associated virus (AAV)-mediated selective Mc1r overexpression was performed in the medial prefrontal cortex (mPFC). Results LPS administration induced depressive-like behaviors in mice, accompanied by microglial activation and a significant reduction in MC1R expression in the prefrontal cortex (PFC). Treatment with MC1R endogenous ligand α-MSH mimetic Nle4-DPhe7-α-MSH (NDP-MSH) markedly attenuated LPS-induced depressive-like behaviors, enhanced MC1R, postsynaptic density protein 95 (PSD95), glutamate receptor 1 (GluA1) and protein kinase A (PKA) phosphorylation. PKA inhibitor H89-mediated inhibition of the cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) pathway partially but robustly abolishes the behavioral, anti-inflammatory, and synaptic protective effects of NDP-MSH. Additionally, untargeted metabolomics confirmed that NDP-MSH effectively corrected LPS-induced metabolic dysregulation, a therapeutic effect that was robustly suppressed by H89; this metabolic remodeling was closely associated with purine metabolism, pantothenate, and coenzyme A biosynthesis. Critically, AAV-mediated Mc1r overexpression in the mPFC was sufficient to rescue LPS-induced depressive-like phenotypes. Conclusion This study highlights MC1R-related signaling in the PFC as an important contributor to inflammation-associated depression and suggests that NDP-MSH alleviates inflammation-associated depressive-like behaviors in association with melanocortin signaling involving MC1R and downstream cAMP/PKA activation.

Immunohistochemical evidence of glutamatergic modulation of Nesfatin-1 neurons in the rat supraoptic nucleus during inflammatory stress.

BACKGROUND Stress triggers a complex network of neuroendocrine, immune, and behavioral responses aimed at maintaining homeostasis. Nesfatin-1, a hypothalamic peptide initially identified for its anorexigenic effects, has also been increasingly implicated in stress-related processes. METHODS This study investigated whether acute inflammatory stress induced by lipopolysaccharide (LPS) activates Nesfatin-1 neurons in the supraoptic nucleus (SON) and examined the modulatory role of glutamatergic receptor antagonists. Female and male Sprague-Dawley rats were assigned to control, LPS, MK-801 + LPS, and CNQX + LPS groups. Neuronal activation was assessed using dual immunohistochemical staining for c-Fos and Nesfatin-1, followed by quantitative analysis of co-localized neurons in the SON. RESULTS LPS administration significantly increased the proportion of c-Fos-positive Nesfatin-1 neurons in both female and male rats compared to controls (p = 0.001). Pretreatment with MK-801 and CNQX attenuated this activation (p < 0.01), indicating the involvement of both NMDA and non-NMDA glutamatergic pathways. CONCLUSION Acute inflammatory stress activates Nesfatin-1 neurons in the SON, and this response is modulated by glutamatergic signaling. These findings provide new immunohistochemical evidence linking glutamatergic transmission to stress-induced Nesfatin-1 activation, with potential implications for the neurobiological interaction between inflammation, energy homeostasis, and stress-related processes.

CRHR2 activation by urocortins regulates splenic microbiota-immune-brain axis in a single prolonged stress model of post-traumatic stress in male rats.

Post-traumatic stress disorder (PTSD) is associated with dysfunction of the hypothalamo-pituitary-adrenocortical (HPA) axis, accompanied by alterations in immune function, microbiota composition, and brain regions, including the hippocampus. CRHR2 receptor agonists, urocortin 2 (UCN2) and urocortin 3 (UCN3), regulate stress-related neuroendocrine activity. The present study aimed to investigate how a single intranasal administration of UCN2 or UCN3 modulates bacterial composition and inflammatory activity in the spleen/isolated splenocytes and alters the expression of neuroinflammatory and neurogenic markers in the dorsal (dHipp) and ventral hippocampus (vHipp) in male rats exposed to single prolonged stress (SPS) model of PTSD. SPS increased Enterobacteriaceae 16S rRNA levels and slightly reduced Lactobacillus abundance, while both urocortins prevented these effects. In the spleen, SPS suppressed expression of immune cell function markers, whereas UCN3 mitigated these effects. In isolated splenocytes stimulated ex vivo with lipopolysaccharide, UCN2 and UCN3 restored the reduced mRNA expression of proinflammatory markers, including IL-1β, IL-12p40, NOS, and CD69. Alterations in inflammatory markers correlated with Enterobacteriaceae and Lactobacillus. In the brain, SPS-induced changes were observed primarily in the vHipp, where expression of neuroinflammatory markers, including Iba1, TREM2, and CX3CR1, were decreased and restored by urocortin treatment. Conversely, SPS increased DCX mRNA levels, whereas UCN2 and UCN3 reduced them. Neuroinflammatory markers in the vHipp correlated with splenic microbiota and inflammatory markers. Overall, these findings suggest that CRHR2 stimulation by intranasal UCN2/UCN3 administration prevents PTSD-induced alterations through interconnected effects on splenic microbiota composition, peripheral immune responses, and hippocampal synaptic plasticity and neuroinflammatory markers.

Aldolase C and T helper 1 polarization in postpartum depression: a novel perspective on disease mechanisms.

PURPOSE Postpartum depression (PPD) is common, yet its pathophysiology remains unclear and reliable early biomarkers are lacking. METHODS Mendelian randomization, bioinformatics analyses, and animal experiments were integrated. A prenatal stress-induced rat model of PPD was established. Depressive-like behaviors were assessed using the open field and forced swim tests, and brain histopathology was examined by hematoxylin-eosin staining. Serum HPA-axis hormones, ALDOC, lactic acid, and Th1/Th2 cytokines were measured by ELISA. ALDOC was analyzed by Western blot. T-bet and GATA3 mRNA expression in peripheral blood mononuclear cells was detected by qRT-PCR, and the T-bet/GATA3 ratio was calculated. RESULTS Sixteen overlapping genes were identified, suggesting the involvement of Th cells in PPD and highlighting ALDOC as a potential candidate biomarker associated with Th1-related immune alterations. PPD rats showed depressive-like behaviors and HPA-axis activation, with increased CRH and ACTH but unchanged CORT levels. ALDOC and lactic acid levels were significantly increased, accompanied by elevated Th1-related cytokines (IFN-γ, TNF-α, and IL-1β) and an increased IFN-γ/IL-4 ratio, whereas Th2-related cytokines showed no significant changes. Consistently, T-bet expression increased, GATA3 expression decreased, and the T-bet/GATA3 ratio was elevated, further supporting a possible Th1-skewed immune response. Brain histopathology showed cellular damage and reduced cell density. In the PFC, ALDOC upregulation was accompanied by increased pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), which may suggest coordinated central neuroinflammation and peripheral immune imbalance. CONCLUSIONS ALDOC may contribute to PPD pathogenesis by promoting Th1 polarization and inflammatory activation.

Stigmasterol alleviates central precocious puberty by targeting the IGF-1/PI3K/Akt/mTOR signaling pathway and modulating the Kisspeptin/GnRH axis.

BACKGROUND Central precocious puberty (CPP) results from premature activation of the hypothalamic-pituitary-gonadal axis, causing early sexual development and related health risks. Stigmasterol (ST), a natural phytosterol with diverse pharmacological activities, has not been fully evaluated for CPP. METHODS This study integrated network pharmacology, molecular docking, and molecular dynamics simulations to identify ST targets in CPP. Experimental validation used an N-Methyl aspartic acid-induced CPP rat model and high-glucose high-fat-stimulated GT1-7 hypothalamic neurons. Techniques included histology, ELISA, qPCR, western blot, and flow cytometry. RESULTS In silico analyses demonstrated favorable binding of ST to core proteins within the IGF-1/PI3K/Akt/mTOR signaling pathway. In vivo, ST treatment significantly delayed vaginal opening, reduced serum levels of estradiol and testosterone, and ameliorated pathological abnormalities in uterine and ovarian tissues. At the molecular level, ST suppressed the hypothalamic overactivation of the IGF-1/PI3K/Akt/mTOR pathway and attenuated neuronal damage and apoptosis. In vitro, ST inhibited HGHF-induced proliferation, inflammatory cytokine release, and apoptosis in GT1-7 cells, while concurrently modulating the expression of key puberty-related genes and proteins, including those within the Kisspeptin/GnRH axis. Conversely, pharmacological reactivation of PI3K signaling with the agonist 740YP attenuated selected protective effects the protective effects of ST, supporting the functional involvement the PI3K/Akt/mTOR pathway in mediating these benefits. CONCLUSIONS Stigmasterol exhibits significant therapeutic effects against CPP by concurrently targeting the IGF-1/PI3K/Akt/mTOR and Kisspeptin/GnRH signaling pathways. These findings provide robust preclinical evidence supporting ST as a promising multi-targeted natural candidate for CPP management.