Involvement of the monoaminergic system in the antidepressant-like effect of the crude extract of Mentha piperita (Lamiaceae) in the forced swimming test in mice

Analysis of Polyphenolic Composition of a Herbal Medicinal Product-Peppermint Tincture

The pharmacological activity of peppermint leaf (Menthae piperitae folium) for medical use is mainly attributed to the presence of essential oil, which, according to the European Pharmacopoeia (Ph. Eur.), should constitute not less than 12 mL/kg of raw material. The content of polyphenols in peppermint-based preparations, except peppermint leaf dry extract, has not yet been considered as an essential parameter in the pharmacopeial assessment of peppermint quality. This study concerns the evaluation of the presence of representatives of polyphenolic compounds in 23 commercial peppermint tinctures (ethanolic extracts) purchased in pharmacies in Poland. The non-volatile polyphenolic fraction was investigated, and the presence of flavonoids and phenolic acids was quantified. High performance liquid chromatography coupled with a diode-array detector (HPLC-DAD) and an electrospray ionization mass spectrometer (U(H)PLC-ESI-MS) were used in the experiment. The study showed that eriocitrin, luteolin-7-O-rutinoside, and rosmarinic acid were the main polyphenolic components of the peppermint tinctures, as previously reported for peppermint leaf. Despite this, the research shows the extremely diverse content of the mentioned compounds in analyzed commercial medicinal products. In light of these results, it seems that the pharmacopeial assessment for the peppermint leaf (Ph. Eur.) and peppermint tincture (Polish Pharmacopoeia (FP)) requires correction and supplementation.

The antidepressant-like effects of Origanum majorana essential oil on mice through monoaminergic modulation using the forced swimming test

Origanum majorana (L.) is an herb used in the treatment of diseases related to the nervous system in traditional medicine (e.g. as an anticonvulsant and sedative). The present study was conducted to investigate the antidepressant-like effects of Origanum majorana essential oil (OMEO) on mice in the forced swimming test (FST). The animals were intraperitoneally (i.p.) injected with OMEO (10–80 mg/kg) 1 h before the FST. To assess the involvement of the monoaminergic system in the antidepressant activity of OMEO, different pharmacological antagonists were administered 15 min before OMEO administration (80 mg/kg). The administration of OMEO (40 and 80 mg/kg, i.p.) decreased immobility time and increased swimming and climbing times significantly. OMEO did not cause any changes in spontaneous locomotor function in the open-field test (OFT). The pre-treatment of the animals with SCH23390, sulpiride, haloperidol, WAY100135, p-chlorophenylalanine (pCPA), ketanserin, prazosin, yohimbine, reserpine, but not propranolol, inhibited the anti-immobility effect of OMEO in the FST. A combination of sub-effective doses of fluoxetine (5 mg/kg, i.p.) or imipramine (5 mg/kg, i.p.) with OMEO (10 mg/kg, i.p.) increased the antidepressant-like effects. OMEO showed antidepressant-like effects through involvement with the dopaminergic (D₁ and D₂), serotonergic (5HT1_A, 5-HT2_A receptors) and noradrenergic (α₁ and α₂ adrenoceptors) systems.

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Origanum majorana (L.) belongs to the mint family (Labiatae) and is used extensively in traditional medicine (in the treatment of diseases related to the nervous system) and the food and cosmetic industries.

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The main monoterpene alcohols of OMEO (especially terpinene-4-ol) may be resposbile for their antidepressant-like activity.

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The administration of Origanum majorana essential oil decreased immobility time and increased swimming and climbing times significantly in the FST.

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Origanum majorana essential oil showed antidepressant-like effects through involvement with the dopaminergic (D₁ and D₂), serotonergic (5HT1_A, 5-HT2_A receptors) and noradrenergic (α₁ and α₂ adrenoceptors) systems.

Sertraline ameliorates inflammation in CUMS mice and inhibits TNF-α-induced inflammation in microglia cells

Evidence indicates that inflammation plays a crucial role in depression. Therefore, new antidepressants might be identified by screening drugs for their anti-inflammatory actions. Sertraline hydrochloride (SERT), a widely used antidepressant, has anti-inflammatory effects in clinical studies, but the mechanism involved is unclear. In this study, we used cell and molecular biology to determine the possible anti-inflammatory mechanism of SERT in vivo and in vitro. Experimental data from the in vivo study showed that mice exposed to chronic unpredictable mild stress (CUMS) had significantly higher levels of major inflammatory cytokines (tumor necrosis factor-α [TNF-α], interleukin-1β [IL-1β] and inducible nitric oxide synthase [iNOS]) in peripheral and central tissues compared with the control group. Treatment of CUMS mice with SERT significantly reduced the levels of these inflammatory cytokines and inhibited the phosphorylation of nuclear factor-κB (NF-κB) and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκB-α). Moreover, SERT reduced serum levels of transaminase in CUMS mice. Our in vitro study revealed that SERT suppressed TNF-α-induced NF-κB activation in a dose-dependent manner. SERT also inhibited the TNF-α-induced nuclear translocation of NF-κB by inhibiting IκB-α phosphorylation. Furthermore, SERT inhibited TNF-α-induced inflammatory cytokines in BV2 microglia cells. SERT directly bound to TNF-α and TNF-α receptor 1 (TNFR1) to potently block TNF-α/TNFR1-triggered signaling. These results indicate that SERT might treat depression by inhibiting the activation of microglia via the NF-κB signaling pathway. This study provides a basis for the research and development of antidepressants that act to reduce inflammation and the expression of inflammatory mediators.

Nitric oxide involvement in additive antidepressant-like effect of agmatine and lithium in mice forced swim test

Lithium is still the main agent in the management of mood disorders such as depression. Likewise, agmatine protects the central nervous system (CNS) against depression. The aim of the present study was to examine the possible additive antidepressant-like effect of agmatine and lithium in mice forced swim test (FST) as well as exploration of the probable involvement of nitric oxide (NO) pathway in this response. Results showed that pretreatment with a subeffective dose of agmatine (0.01 mg/kg) augmented the antidepressant-like effect of lithium subeffective dose (3 mg/kg) (P < 0.001). L-NG-nitroarginine methyl ester (L-NAME, nonspecific nitric oxide synthase [NOS] inhibitor) at doses of 10 and 30 mg/kg, and 7-nitroindazole (7-NI, neuronal NOS inhibitor) at doses of 15 and 30 mg/kg potentiated the antidepressant-like effect of the subeffective combination of lithium (3 mg/kg) and agmatine (0.001 mg/kg) (P < 0.001, P < 0.01, respectively). However, various doses of aminoguanidine (25 and 50 mg/kg, inducible NOS inhibitor) failed to alter the immobility time of the same combination (P > 0.05). Moreover, pretreatment with subeffective doses of L-arginine (substrate for NOS, 300 and 750 mg/kg) reversed the augmenting antidepressant-like effect of agmatine (0.01 mg/kg) on lithium (3 mg/kg) (P < 0.001). Our results revealed that agmatine enhances the antidepressant-like effects of lithium and the NO pathway might mediate this phenomenon. In addition, constitutive NOS plays a dramatic role in this response.