Inhibiting glycogen synthase kinase-3 reduces endotoxaemic acute renal failure by down-regulating inflammation and renal cell apoptosis

Background and purpose:

Excessive inflammation and apoptosis are pathological features of endotoxaemic acute renal failure. Activation of glycogen synthase kinase-3 (GSK-3) is involved in inflammation and apoptosis. We investigated the effects of inhibiting GSK-3 on lipopolysaccharide (LPS)-induced acute renal failure, nuclear factor-κB (NF-κB), inflammation and apoptosis.

Experimental approach:

The effects of inhibiting GSK-3 with inhibitors, including lithium chloride (LiCl) and 6-bromo-indirubin-3′-oxime (BIO), on LPS-treated (15 mg·kg⁻¹) C3H/HeN mice (LiCl, 40 mg·kg⁻¹ and BIO, 2 mg·kg⁻¹) and LPS-treated (1 µg·mL⁻¹) renal epithelial cells (LiCl, 20 mM and BIO, 5 µM) were studied. Mouse survival was monitored and renal function was analysed by histological and serological examination. Cytokine and chemokine production, and cell apoptosis were measured by enzyme-linked immunosorbent assay and terminal deoxynucleotidyl transferase-mediated dUTP–biotin nick-end labelling staining, respectively. Activation of NF-κB and GSK-3 was determined by immunostaining and Western blotting, respectively.

Key results:

Mice treated with GSK-3 inhibitors showed decreased mortality, renal tubular dilatation, vacuolization and sloughing, blood urea nitrogen, creatinine and renal cell apoptosis in response to endotoxaemia. Inhibiting GSK-3 reduced LPS-induced tumour necrosis factor-α (TNF-α) and CCL5/RANTES (released upon activation of normal T-cells) in vivo in mice and in vitro in murine kidney cortical collecting duct epithelial M1 cells. Inhibiting GSK-3 did not block TNF-α-induced cytotoxicity in rat kidney proximal tubular epithelial NRK52E or in M1 cells.

Conclusions and implications:

These results suggest that GSK-3 inhibition protects against endotoxaemic acute renal failure mainly by down-regulating pro-inflammatory TNF-α and RANTES.     

Flavocoxid, a dual inhibitor of cyclooxygenase-2 and 5-lipoxygenase, reduces pancreatic damage in an experimental model of acute pancreatitis

BACKGROUND AND PURPOSE

Acute pancreatitis is an autodigestive process resulting in acute inflammation of the pancreas. Accumulating evidence indicates the essential contribution of cyclooxygenase (COX)-2 and 5-lipoxygenase (5-LOX) to acute pancreatitis. We studied the effects of flavocoxid, a plant-derived dual inhibitor of COX-2 and 5-LOX, in a model of caerulein (CER)-induced acute pancreatitis.

EXPERIMENTAL APPROACH

Rats were given CER (80 µg·kg⁻¹ for each of four injections at hourly intervals) or vehicle (Sham-CER). Animals were then randomized to receive flavocoxid (20 mg·kg⁻¹ i.p.) or vehicle, 30 min after the first CER injection. Two hours after the last CER injection, we evaluated damage to the pancreas by histological methods; serum levels of amylase, lipase_, leukotriene (LT)B₄ and prostaglandin (PG)E₂; pancreatic expression of COX-2 and 5-LOX and tumour necrosis factor-α (TNF-α) gene expression by real-time polymerase chain reaction.

KEY RESULTS

Caerulein induced inflammatory changes in the pancreas and raised values of the other variables measured. In CER-treated animals, but not in those given saline, flavocoxid inhibited COX-2 and 5-LOX expression, reduced serum levels of lipase and amylase and the degree of pancreatic oedema. Treatment with flavocoxid blunted the increased pancreatic TNF-α mRNA expression, serum leukotriene B₄ and prostaglandin E₂ levels, and protected against histological damage in terms of vacuolization and leukocyte infiltration.

CONCLUSIONS AND IMPLICATIONS

Our results confirm the key role of both COX-2 and 5-LOX in the inflammatory response to acute pancreatitis. Flavocoxid may provide a potential therapeutic approach to the treatment of patients at high risk of developing this life-threatening condition.     

Potential anxiolytic- and antidepressant-like effects of salvinorin A,the main active ingredient of Salvia divinorum,in rodents

Background and purpose:

Drugs targeting brain κ-opioid receptors produce profound alterations in mood. In the present study we investigated the possible anxiolytic- and antidepressant-like effects of the κ-opioid receptor agonist salvinorin A, the main active ingredient of Salvia divinorum, in rats and mice.

Experimental approach:

Experiments were performed on male Sprague-Dawley rats or male Albino Swiss mice. The anxiolytic-like effects were tested by using the elevated plus maze, in rats. The antidepressant-like effect was estimated through the forced swim (rats) and the tail suspension (mice) test. κ-Opioid receptor involvement was investigated pretreating animals with the κ-opioid receptor antagonist, nor-binaltorphimine (1 or 10 mg·kg⁻¹), while direct or indirect activity at CB₁ cannabinoid receptors was evaluated with the CB₁ cannabinoid receptor antagonist, N-(piperidin-1-yl) -5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251, 0.5 or 3 mg·kg⁻¹), binding to striatal membranes of naïve rats and assay of fatty acid amide hydrolase in prefrontal cortex, hippocampus and amygdala.

Key results:

Salvinorin A, given s.c. (0.001–1000 µg·kg⁻¹), exhibited both anxiolytic- and antidepressant-like effects that were prevented by nor-binaltorphimine or AM251 (0.5 or 3 mg·kg⁻¹). Salvinorin A reduced fatty acid amide hydrolase activity in amygdala but had very weak affinity for cannabinoid CB₁ receptors.

Conclusions and implications:

The anxiolytic- and antidepressant-like effects of Salvinorin A are mediated by both κ-opioid and endocannabinoid systems and may partly explain the subjective symptoms reported by recreational users of S. divinorum.     

Lobolide,a diterpene,blockades the NF-κB pathway and p38 and ERK MAPK activity in macrophages in vitro

Aim:

Recent studies have shown that constitutive activation of the nuclear factor κB (NF-κB) plays a key role in chronic inflammation and cancers. The aim of this study was to characterize lobolide, a cembrane diterpene, as a drug candidate targeting the NF-κB signaling pathway.

Methods:

A HEK 293/NF-κB-Luc stable cell line was constructed to evaluate the effect of lobolide on NF-κB activation. THP-1 human monocytes and peripheral blood mononuclear cells (PBMCs) from healthy volunteers were tested. Lipopolysaccharide (LPS)-induced TNFα and IL-1β production and activation of the TAK1-IKK-NF-κB pathway were studied using ELISA and Western blot analysis.

Results:

In HEK 293/NF-κB-Luc stable cells, lobolide (0.19–50 μmol/L) inhibited NF-κB activation in a concentration-dependent manner with an IC₅₀ value of 4.2±0.3 μmol/L. Treatment with lobolide (2.5–10 μmol/L) significantly suppressed LPS-induced production of TNFα and IL-1β in both THP-1 cells and PBMCs. In THP-1 cells, the suppression was partially caused by blockade of the translocation of NF-κB from the cytoplasm to the nucleus via affecting the TAK1-IKK-NF-κB pathway and p38 and ERK MAPK activity.

Conclusion:

Lobolide is a potential inhibitor of the NF-κB pathway, which blocks the translocation of NF-κB from the cytoplasm to the nucleus. Lobolide inhibits LPS-stimulated TNFα and IL-1β release, suggesting that the compound might be an anti-inflammatory compound.     

Pioglitazone ameliorates memory deficits in streptozotocin-induced diabetic mice by reducing brain β-amyloid through PPARγ activation

Aim:

To examine the effects of pioglitazone, a PPARγ agonist, on memory performance and brain amyloidogenesis in streptozotocin (STZ)-induced diabetic mice.

Methods:

ICR male mice were injected with STZ (150 mg/kg, iv) to induce experimental diabetes. Pioglitazone (9 and 18 mg·kg^-1·d^-1, po) was administered for 6 weeks. Passive avoidance and Morris water maze (MWM) tests were used to evaluate cognitive function. The blood glucose and serum insulin levels were detected using the glucose oxidase method and an ELISA assay, respectively. β-amyloid (Aβ), β-amyloid precursor protein (APP), β-amyloid precursor protein cleaving enzyme 1 (BACE1), NF-κB p65, the receptor for advanced glycation end products (RAGE) and PPARγ in the brains were analyzed using Western blotting assays.

Results:

The STZ-induced diabetic mice characterized by hyperglycemia and hypoinsulinemia performed poorly in both the passive avoidance and MWM tests, accompanied by increased Aβ_1–40/Aβ_1–42, APP, BACE1, NF-κB p65 and RAGE levels and decreased PPARγ level in the hippocampus and cortex. Chronic pioglitazone treatment significantly ameliorated the memory deficits and amyloidogenesis of STZ-induced diabetic mice, and suppressed expression of APP, BACE1, RAGE and NF-κB p65, and activated PPARγ in the hippocampus and cortex. However, pioglitazone did not significantly affect blood glucose and insulin levels.

Conclusion:

Pioglitazone ameliorates memory deficits in STZ-induced diabetic mice by reducing brain Aβ level via activation of PPARγ, which is independent of its effects on blood glucose and insulin levels. The results suggest that pioglitazone may be used for treating the cognitive dysfunction in type 1 diabetes mellitus.     

Inhibitory effects of rosiglitazone on paraquat-induced acute lung injury in rats

Aim:

To investigate the effects of the PPAR-γ agonist rosiglitazone on acute lung injury induced by the herbicide paraquat (PQ) and the underlying mechanisms of action.

Methods:

Male Sprague-Dawley rats were injected with PQ (20 mg/kg, ip). Rosiglitazone (3 or 10 mg/kg, ip) was administered 1 h before PQ exposure. Peripheral blood was collected at 4, 8, 24 and 72 h after PQ exposure for measuring the levels of MDA, TNF-α and IL-1β, and the SOD activity. Lung tissues were collected at 72 h after PQ exposure to determine the wet-to-dry (W/D) ratios and lung injury scores, as well as the protein levels of NF-κBp65, PPAR-γ, Nrf2, IκBα and pIκBα.

Results:

At 72 h after PQ exposure, the untreated rats showed a 100% cumulative mortality, whereas no death was observed in rosiglitazone-pretreated rats. Moreover, rosiglitazone pretreatment dose-dependently attenuated PQ-induced lung edema and lung histopathological changes. The pretreatment significantly reduced the levels of TNF-α, IL-1β and MDA, increased SOD activity in the peripheral blood of PQ-treated rats. The pretreatment also efficiently activated PPAR-γ, induced Nrf2 expression and inhibited NF-κB activation in the lung tissues of PQ-treated rats. Furthermore, the pretreatment dose-dependently inhibited IκB-α degradation and phosphorylation, thus inhibiting NF-κB activation.

Conclusion:

Pretreatment with rosiglitazone protects rats against PQ-induced acute lung injury by activating PPAR-γ, inducing Nrf2 expression and inhibiting NF-κB activation.     

Tanshinone IIA therapeutically reduces LPS-induced acute lung injury by inhibiting inflammation and apoptosis in mice

Aim:

To study the effects of tanshinone IIA (TIIA) on lipopolysaccharide (LPS)-induced acute lung injury in mice and the underlying mechanisms.

Methods:

Mice were injected with LPS (10 mg/kg, ip), then treated with TIIA (10 mg/kg, ip). Seven hours after LPS injection, the lungs were collected for histological study. Protein, LDH, TNF-α and IL-1β levels in bronchoalveolar lavage fluid (BALF) and myeloperoxidase (MPO) activity in lungs were measured. Cell apoptosis and Bcl-2, caspase-3, NF-κB and HIF-1α expression in lungs were assayed.

Results:

LPS caused marked histological changes in lungs, accompanied by significantly increased lung W/D ratio, protein content and LDH level in BALF, and Evans blue leakage. LPS markedly increased neutrophil infiltration in lungs and inflammatory cytokines in BALF. Furthermore, LPS induced cell apoptosis in lungs, as evidenced by increased TUNEL-positive cells, decreased Bcl-2 content and increased cleaved caspase-3 content. Moreover, LPS significantly increased the expression of NF-κB and HIF-1α in lungs. Treatment of LPS-injected mice with TIIA significantly alleviated these pathological changes in lungs.

Conclusion:

TIIA alleviates LPS-induced acute lung injury in mice by suppressing inflammatory responses and apoptosis, which is mediated via inhibition of the NF-κB and HIF-1α pathways.     

Bovine glycomacropeptide induces cytokine production in human monocytes through the stimulation of the MAPK and the NF-κB signal transduction pathways

Background and purpose:

Bovine glycomacropeptide (BGMP) is a natural milk peptide that is produced naturally in the gastrointestinal tract during digestion. Glycomacropepide has intestinal anti-inflammatory activity, but the mechanism of action is unknown. Here we have characterized the effects of BGMP on monocytes.

Experimental approach:

We have used human THP-1 cells as an in vitro monocyte model. The effect of BGMP on the secretion of tumour necrosis factor (TNF), interleukin (IL)-1β and IL-8 was assessed, as well as the involvement of the NF-κB and MAP kinase signalling pathways. The stimulatory effect of BGMP was also tested in human peripheral blood monocytes.

Key results:

BGMP up-regulated the secretion of TNF, IL-1β and IL-8 in a concentration-dependent fashion. The biological activity was exerted by the intact peptide, because cytokine secretion was not affected by protease inhibitors. The secretion of IL-8 and specially TNF and IL-1β was blocked by PD98059, SP600125, SB203580 and Bay11-7082, suggesting the involvement of the MAP kinases p38, c-Jun N-terminal kinase and ERK and particularly the NF-κB pathway, although IL-8 secretion was independent of p38. BGMP was shown to elicit the phosphorylation of IκB-α and the nuclear translocation of the NF-κB subunits p50 and p65. The effect of BGMP on cytokine secretion was validated in human primary blood monocytes.

Conclusions and implications:

BGMP stimulates human monocytes, operating via MAP kinase and NF-κB pathways. BGMP may exert an indirect intestinal anti-inflammatory effect by potentiating host defences against invading microorganisms.     

SAR150640, a selective β3-adrenoceptor agonist,prevents human myometrial remodelling and activation of matrix metalloproteinase in an in vitro model of chorioamnionitis

Background and purpose:

The uterine pathophysiology underlying inflammatory conditions such as chorioamnionitis remains largely unclear. As we have shown that β₃-adrenoceptors act as regulators of myometrial inflammation, we wanted to investigate the potential role of β₃-adrenoceptors in preventing uterine remodelling induced by inflammation.

Experimental approach:

The consequences of human chorioamnionitis on myometrial remodelling were characterized by Sirius Red staining and metalloproteinase (MMP) expression, and compared with the effects of incubating human myometrial samples with Escherichia coli lipopolysaccharide (LPS) in vitro. We also assessed the effect of SAR150640, a selective β₃-adrenoceptor agonist, on the production and activity of MMPs.

Key results:

Chorioamnionitis was associated with a 46% decrease in total collagen, as well as over-expression of MMP2 (+61%) and MMP9 (+84%); both effects were reproduced by incubation with LPS (10 µg·mL⁻¹, 48 h). LPS-induced over-expression of MMP2 and MMP9 in normal human myometrium was paralleled by an overactivity of the proteins. Both over-expression and overactivity were prevented by the β₃-adrenoceptor agonist SAR150640 in a concentration-dependent manner. SAR150640, by itself, did not exhibit any effect on MMP production in control tissues.

Conclusions and implications:

This study shows that inflammation was associated with an intense remodelling of human myometrium, a process likely to be explained by MMP activation. Our study emphasizes the potential therapeutic relevance of β₃-adrenoceptor agonists to the treatment of preterm labour and other uterine inflammatory conditions.     

Sirt1 overexpression protects murine osteoblasts against TNF-α-induced injury in vitro by suppressing the NF-κB signaling pathway

Aim:

Sirtuin 1 (Sirt1) is the class III histone/protein deacetylase that interferes with the NF-κB signaling pathway, thereby has anti-inflammatory function. This study was undertaken to investigate whether Sirt1 could protect osteoblasts against TNF-α-induced injury in vitro.

Methods:

Murine osteoblastic cell line, MC3T3-E1, was used. Overexpress of Sirt1 protein in MC3T3-E1 cells was made by transfection the cells with Sirt1-overexpressing adenovirus. The levels of mRNAs and proteins were determined with qRT-PCR and Western blotting, respectively. The activity of NF-κB was examined using NF-κB luciferase assay. The NO concentration was measured using the Griess method.

Results:

Treatment of MC3T3-E1 cells with TNF-α (2.5–10 ng/mL) suppressed Sirt1 protein expression in a concentration-dependent manner. TNF-α (5 ng/mL) resulted in an increase in apoptosis and a reduction in ALP activity in the cells. Overexpression of Sirt1 in the cells significantly attenuated TNF-α-induced injury through suppressing apoptosis, increasing ALP activity, and increasing the expression of Runx2 and osteocalcin mRNAs. Furthermore, overexpression of Sirt1 in the cells significantly suppressed TNF-α-induced NF-κB activation, followed by reducing the expression of iNOS and NO formation. Sirt1 activator resveratrol (10 μmol/L) mimicked the protection of the cells by Sirt1 overexpression against TNF-α-induced injury, which was reversed by the Sirt1 inhibitor EX-527 (5 μmol/L).

Conclusion:

Overexpression of Sirt1 protects MC3T3-E1 osteoblasts aganst TNF-α-induced cell injury in vitro, at least in part, via suppressing NF-κB signaling. Sirt1 may be a novel therapeutic target for treating rheumatoid arthritis-related bone loss.     

Shikonin reduces oedema induced by phorbol ester by interfering with IκBα degradation thus inhibiting translocation of NF-κB to the nucleus

Background and purpose:

In the present paper we studied the effect of shikonin on ear oedema induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), and determined the mechanisms through which shikonin might exert its topical anti-inflammatory action.

Experimental approach:

Acute ear oedema was induced in mice by topical application of TPA. The in vitro assays used macrophages RAW 264.7 cells stimulated with lipopolysaccharide. Cyclooxygenase-2, inducible nitric oxide synthase, protein kinase Cα, extracellular signal-regulated protein kinase (ERK), phosphorylated ERK (pERK), c-Jun N-terminal kinase (JNK), pJNK, p38, p-p38, p65, p-p65, inhibitor protein of nuclear factor-κB (NF-κB) (IκBα) and pIκBα were measured by Western blotting, activation and binding of NF-κB to DNA was detected by reporter gene and electrophoretic mobility shift assay, respectively, and NF-κB p65 localization was detected by immunocytochemistry.

Key results:

Shikonin reduced the oedema (inhibitory dose 50 = 1.0 mg per ear), the expression of cyclooxygenase-2 (70%) and of inducible nitric oxide synthase (100%) in vivo. It significantly decreased TPA-induced translocation of protein kinase Cα, the phosphorylation and activation of ERK, the nuclear translocation of NF-κB and the TPA-induced NF-κB-DNA-binding activity in mouse skin. Moreover, in RAW 264.7 cells, shikonin significantly inhibited the binding of NF-κB to DNA in a dose-dependent manner and the nuclear translocation of p65.

Conclusions and implications:

Shikonin exerted its topical anti-inflammatory action by interfering with the degradation of IκBα, thus inhibiting the activation of NF-κB.     

Short-term exposure to oleandrin enhances responses to IL-8 by increasing cell surface IL-8 receptors

BACKGROUND AND PURPOSE

One of the first steps in host defence is the migration of leukocytes. IL-8 and its receptors are a chemokine system essential to such migration. Up-regulation of these receptors would be a viable strategy to treat dysfunctional host defence. Here, we studied the effects of the plant glycoside oleandrin on responses to IL-8 in a human monocytic cell line.

EXPERIMENTAL APPROACH

U937 cells were incubated with oleandrin (1-200 ng mL⁻¹) for either 1 h (pulse) or for 24 h (non-pulse). Apoptosis; activation of NF-κB, AP-1 and NFAT; calcineurin activity and IL-8 receptors (CXCR1 and CXCR2) were measured using Western blotting, RT-PCR and reporter gene assays.

KEY RESULTS

Pulse exposure to oleandrin did not induce apoptosis or cytoxicity as observed after non-pulse exposure. Pulse exposure enhanced activation of NF-κB induced by IL-8 but not that induced by TNF-α, IL-1, EGF or LPS. Exposure to other apoptosis-inducing compounds (azadirachtin, resveratrol, thiadiazolidine, or benzofuran) did not enhance activation of NF-κB. Pulse exposure to oleandrin increased expression of IL-8 receptors and chemotaxis, release of enzymes and activation of NF-κB, NFAT and AP-1 along with increased IL-8-mediated calcineurin activation, and wound healing. Pulse exposure increased numbers of cell surface IL-8 receptors.

CONCLUSIONS AND IMPLICATIONS

Short-term (1 h; pulse) exposure to a toxic glycoside oleandrin, enhanced biological responses to IL-8 in monocytic cells, without cytoxicity. Pulse exposure to oleandrin could provide a viable therapy for those conditions where leukocyte migration is defective.     

Brain protection against ischemic stroke using choline as a new molecular bypass treatment

Aim:

To determine whether administration of choline could attenuate brain injury in a rat model of ischemic stroke and the underlying mechanisms.

Methods:

A rat model of ischemic stroke was established through permanent middle cerebral artery occlusion (pMCAO). After the surgery, the rats were treated with choline or choline plus the specific α7 nAChR antagonist methyllycaconitine (MLA), or with the control drug nimodipine for 10 days. The neurological deficits, brain-infarct volume, pial vessel density and the number of microvessels in the cortex were assessed. Rat brain microvascular endothelial cells (rBMECs) cultured under hypoxic conditions were used in in vitro experiments.

Results:

Oral administration of choline (100 or 200 mg·kg⁻¹·d⁻¹) or nimodipine (20 mg·kg⁻¹·d⁻¹) significantly improved neurological deficits, and reduced infarct volume and nerve cell loss in the ischemic cerebral cortices in pMCAO rats. Furthermore, oral administration of choline, but not nimodipine, promoted the pial arteriogenesis and cerebral-cortical capillary angiogenesis in the ischemic regions. Moreover, oral administration of choline significantly augmented pMCAO-induced increases in the expression levels of α7 nAChR, HIF-1α and VEGF in the ischemic cerebral cortices as well as in the serum levels of VEGF. Choline-induced protective effects were prevented by co-treatment with MLA (1 mg·kg⁻¹·d⁻¹, ip). Treatment of rBMECs cultured under hypoxic conditions in vitro with choline (1, 10 and 100 μmol/L) dose-dependently promoted the endothelial-cell proliferation, migration and tube formation, as well as VEGF secretion, which were prevented by co-treatment with MLA (1 μmol/L) or by transfection with HIF-1α siRNA.

Conclusion:

Choline effectively attenuates brain ischemic injury in pMCAO rats, possibly by facilitating pial arteriogenesis and cerebral-cortical capillary angiogenesis via upregulating α7 nAChR levels and inducing the expression of HIF-1α and VEGF.     

The atypical antidepressant mianserin exhibits agonist activity at κ-opioid receptors

BACKGROUND AND PURPOSE

Antidepressants are known to interact with the opioid system through mechanisms not completely understood. We previously reported that tricyclic antidepressants act as agonists at distinct opioid receptors. Here, we investigated the effect of the atypical antidepressant mianserin at cloned and native opioid receptors.

EXPERIMENTAL APPROACH

Effects of mianserin were examined in CHO cells transfected with human opioid receptors, C6 glioma cells and rat brain membranes by the use of radioligand binding and functional assays including the stimulation of [³⁵S]GTPγS binding and MAPK phosphorylation.

KEY RESULTS

Mianserin displayed 12- and 18-fold higher affinity for κ- than µ- and δ-opioid receptors respectively. In [³⁵S]GTPγS assays, mianserin selectively activated κ-opioid receptors. The agonist activity was antagonized by the selective κ-opioid blocker nor-binaltorphimine (nor-BNI). The mianserin analogue mirtazapine also displayed κ-opioid agonist activity. Mianserin and mirtazapine increased ERK1/2 phosphorylation in CHO cells expressing κ-opioid receptors and C6 cells, and these effects were antagonized by nor-BNI. In rat striatum and nucleus accumbens, mianserin stimulated [35S]GTPγS binding in a nor-BNI-sensitive manner with maximal effects lower than those of the full κ-opioid agonists (–)-U50,488 and dynorphin A. When combined, mianserin antagonized the effects of the full κ-opioid receptor agonists in [³⁵S]GTPγS assays and reduced the stimulation of p38 MAPK and ERK1/2 phosphorylation by dynorphin A.

CONCLUSIONS AND IMPLICATIONS

In different cell systems, mianserin directly activates κ-opioid receptors, displaying partial agonist activity at brain receptors. Thus, this property appears to be a common feature of different classes of antidepressants.