Meranzin hydrate elicits antidepressant effects and restores reward circuitry

Area of Science:

• Neuroscience
• Pharmacology
• Biochemistry

Background:

• Major depressive disorder (MDD) is linked to cardiovascular disorders (CVD) and functional dyspepsia (FD).
• Developing effective antidepressants has been challenging, suggesting novel strategies like neural circuit repair are needed.
• Meranzin hydrate (MH), a compound from Aurantii Fructus Immaturus, shows potential in reversing stress-induced mood and physical disorders.

Purpose of the Study:

• To investigate the antidepressant-like effects of MH.
• To explore the underlying neurobiological mechanisms of MH action.
• To identify key brain regions modulated by MH in a rat model of unpredictable chronic mild stress (UCMS).

Main Methods:

• Utilized a rat model of unpredictable chronic mild stress (UCMS) to induce depression-like behaviors.
• Administered meranzin hydrate (MH) orally for one week.
• Employed blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to analyze brain activity, alongside biochemical assays for stress hormones and neurotrophic factors.

Main Results:

• MH treatment significantly decreased depression-like behaviors in UCMS rats.
• MH increased brain-derived neurotrophic factor (BDNF) in the hippocampus and normalized levels of ACTH, corticosterone (CORT), and acylated ghrelin (AG).
• BOLD fMRI revealed MH attenuated UCMS-induced activation in the brain's reward system, particularly the nucleus accumbens (NAc) and hypothalamus.

Conclusions:

• Meranzin hydrate (MH) demonstrates significant antidepressant-like effects in a preclinical model.
• MH may exert its benefits by modulating the hypothalamic-pituitary-adrenal (HPA) axis, ghrelin levels, and hippocampal BDNF expression.
• The nucleus accumbens and hypothalamus are identified as potential key targets for MH in treating MDD and its comorbidities (CVD, FD).