Antidepressant-like Effects of Five Essential Oils Inhaled in Reserpine-induced Depressed Mouse Models

Area of Science:

• Neuroscience
• Pharmacology
• Natural Products Chemistry

Background:

• Depression is a major global health concern with limited treatment options.
• Current pharmacological treatments for depression have efficacy limitations and side effects.
• Essential oils (EOs) offer a potential avenue for novel antidepressant therapies.

Purpose of the Study:

• To investigate the antidepressant potential of five EOs: Jasminum sambac (JSEOs), Rosa rugosa, Magnolia denudata, Aloysia citriodora (ACEOs), and Abies balsamea.
• To explore the underlying molecular mechanisms of EO-induced antidepressant effects.
• To assess EO inhalation as an adjunctive therapy for depression.

Main Methods:

• Reserpine-induced mouse model of depression.
• Gas chromatography-mass spectrometry (GC-MS) for EO chemical analysis.
• Behavioral tests: forced swim test (FST) and tail suspension test (TST).
• Nissl staining for neuronal assessment.
• Immunohistochemistry (IHC), Western blot, and RT-qPCR for gene expression analysis.

Main Results:

• GC-MS identified oxygenated monoterpenes, sesquiterpene hydrocarbons, and oxygenated sesquiterpenoids as primary EO components.
• All five EOs demonstrated antidepressant-like effects, reducing immobility in FST and TST.
• JSEOs and ACEOs exhibited the most significant antidepressant efficacy.
• EO treatment increased intact neuron counts in the hippocampus and hypothalamus.
• EOs modulated the expression of key genes: 5-HT1A, 5-HT2A, BDNF, CRF, and TrkB.

Conclusions:

• Inhalation of EOs, particularly JSEOs and ACEOs, shows significant antidepressant-like effects.
• EOs may exert antidepressant actions by protecting neurons and regulating neurotransmitter-related gene expression.
• EO inhalation presents a promising adjunctive therapeutic strategy for depression management.