Standardized fenugreek seed extract alleviates menopausal sleep disturbances via GABAA, melatonin, and adenosine receptors in ovariectomized (OVX) rodents

Abstract

Fenugreek seed (Trigonella foenum-graecum L.), a dietary component traditionally used in food and herbal medicine, is known for its wide range of health-promoting properties. However, its effects on menopause-associated sleep disturbances remain largely unexplored. This study investigated the potential of a standardized fenugreek seed extract (FSE), enriched in trigonelline (1.72%), protodioscin (6.17%), and 4-hydroxy-L-isoleucine (2.55%), to alleviate sleep impairments in ovariectomized (OVX) mice, a model of menopause-related symptoms. FSE administration significantly improved OVX-induced sleep disturbances by increasing the sleep duration in a pentobarbital-induced hypnotic test. Mechanistic investigations showed that FSE activated GABAA and melatonin receptor 1A (MTNR1A), confirmed by antagonist treatment with picrotoxin, flumazenil, and luzindole. Electroencephalogram (EEG) analysis revealed enhanced delta activity during NREM sleep, indicating improved sleep quality. FSE restored neurochemical and hormonal balance by elevating GABA and dopamine levels while reducing cortisol. It also increased the expression of estrogen receptors ERα, ERβ, and GPR30, without altering systemic estradiol levels. Furthermore, the adenosine A2A receptor (ADORA2A) was significantly elevated. Administration of trigonelline, protodioscin, and 4-hydroxy-L-isoleucine, either individually or in combination, replicated the sleep-promoting effects of FSE, supporting their role in the overall bioactivity. This study highlights FSE and its bioactive compounds as promising functional food ingredients for improving menopausal sleep disorders by modulating GABAergic, melatonergic, and adenosinergic signaling pathways, as well as estrogen receptor expression and neurohormonal homeostasis.