Moringa oleifera seed ethanol extract and its active component kaempferol potentiate pentobarbital-induced sleeping behaviours in mice via a GABAergic mechanism

CONTEXT

Moringa oleifera Lam. (Moringaceae) (MO) is an important food plant that has high nutritional and medical value. However, there is limited information on whether its seeds can improve sleep.

OBJECTIVE

This study investigated the effects of MO seed ethanol extracts (EEMOS) on sleep activity improvement and examined the underlying mechanisms.

MATERIALS AND METHODS

Male ICR mice were placed into six groups (n = 12) and treated as follows: Control (sodium carboxymethyl cellulose, 20 mL/kg), estazolam tablets (2 mg/kg), EEMOS (1, 2 g/kg) and kaempferol (1, 2 mg/kg). These samples were successively given intragastric for 14 d. Locomotor activity assay, pentobarbital-induced sleeping and pentetrazol-induced seizures tests were utilized to examine the sedative-hypnotic effects (SHE) of EEMOS.

RESULTS

Compared with the control group, the results revealed that EEMOS (2 g/kg) and KA (2 mg/kg) possessed good SHE and could significantly elevate the levels of γ-aminobutyric acid and reduce the levels of glutamic acid in the mouse hypothalamus (p < 0.05). Moreover, SHE was blocked by picrotoxin, flumazenil and bicuculline (p < 0.05). EEMOS (2 g/kg) and KA (2 mg/kg) significantly upregulated the protein expression levels of glutamic acid decarboxylase-65 (GAD₆₅) and α₁-subunit of GABA_A receptors in the hypothalamus of mice (p < 0.05), not affecting glutamic acid decarboxylase-67 (GAD₆₇) and γ₂-subunit expression levels (p > 0.05). Additionally, they cause a significant increase in Cl^- influx in human cerebellar granule cells at a concentration of 8 µg/mL (p  <  0.05).

DISCUSSION AND CONCLUSIONS

These findings demonstrated that EEMOS could improve sleep by regulating GABA_A-ergic systems, and encourage further clinical trials to treat insomnia.

Moringa oleifera Lam Seed Oil Augments Pentobarbital-Induced Sleeping Behaviors in Mice via GABAergic Systems

Moringa oleifera Lam. (MO), which is widely consumed as both food and herbal medicine in tropical and subtropical regions, has a wide spectrum of health benefits. Yet, whether the oil obtained from MO seeds could affect (improve) the sleep activity remains unclear. Herein, we used the locomotor activity, pentobarbital-induced sleeping, and pentetrazol-induced convulsions test to examine sedative-hypnotic effects (SHE) of MO oil (MOO) and explored the underlying mechanisms. Besides, the main components of MOO like oleic acid, β-Sitosterol, and Stigmasterol were also evaluated. The results showed that they possessed good SHE. Except for oleic acid and Stigmasterol, they could significantly elevate γ-amino butyric acid (GABA) and reduce glutamic acid (Glu) levels in the hypothalamus of mice. Moreover, SHE was blocked by picrotoxin, flumazenil, and bicuculline, except for oleic acid, which could not be antagonized by picrotoxin. Molecular mechanisms showed that MOO and β-Sitosterol significantly upregulated the amount of protein-level expression of Glu decarboxylase-65 (GAD₆₅) and α₁-subunit of GABA_A receptors in the hypothalamus of mice, not affecting GAD₆₇, γ₂ subunits. These data indicated that MOO modulates sleep architectures via activation of the GABA_A-ergic systems.