Effect of Black Pepper (Piper nigrum) Extract on Caffeine-Induced Sleep Disruption and Excitation in Mice

Heukharang (Lactuca sativa L.) extracts enhanced the sleep behavior of mice: potential involvement of adenosine A1 and A2A receptors

A significant proportion of the world's population suffers from insomnia, a disorder characterized by complications in initiating and maintaining sleep. Many medications used to treat insomnia target the γ-aminobutyric acid (GABA) neurotransmitter system. However, these substances, such as benzodiazepines, induce significant adverse consequences, including dependence and memory impairment, after prolonged use. Thus, current studies are aimed at developing therapeutic hypnotics derived from natural sources that may cause less severe side effects. Heukharang is a variety of lettuce from Korea that was discovered to contain sleep-promoting compounds. Therefore, we investigated the potential effects of sub-chronic administration of Heukharang extract (FSD-LS) on sleep behavior (pentobarbital-induced sleeping test), brain wave activity and sleep architecture (electroencephalography), and physiological behavior (open-field test and rota-rod) in mice, along with radioligand binding assays (GABAA, adenosine A1 and A2A receptors). We found that FSD-LS prolonged the total sleep duration and reduced the onset time of sleep, and enhanced delta wave power and non-rapid eye movement (NREM) sleep duration, all indicating persistent sleep-enhancing effects. FSD-LS lacked adverse effects on the spontaneous locomotor activity and motor coordination of mice, unlike diazepam. Pharmacological blocking using caffeine and bicuculline supported the possible involvement of adenosine receptors in the sleep-promoting effects of FSD-LS, with partial contribution from GABA receptor activity. Overall, our study recommends FSD-LS as a potential source for the development of sleep-aiding therapeutics.

Chrysanthemum morifolium and Its Bioactive Substance Enhanced the Sleep Quality in Rodent Models via Cl- Channel Activation

Dried Chrysanthemum morifolium (Chry) flowers have been used in Korea as a traditional insomnia treatment. In this study, the sleep-promoting activity and improving sleep quality of Chry extract (ext) and its active substance linarin were analyzed by pentobarbital-induced sleep experiment in mice and electroencephalography (EEG), electromyogram (EMG) analysis in rats. In a dose-dependent manner, Chry ext and linarin promoted longer sleep duration in the pentobarbital-induced sleep test compared to pentobarbital-only groups at both hypnotic and subhypnotic doses. Chry ext administration also significantly improved sleep quality, as seen in the relative power of low-frequency (delta) waves when compared with the control group. Linarin increased Cl- uptake in the SH-SY5Y human cell line and chloride influx was reduced by bicuculline. After administration of Chry ext, the hippocampus, frontal cortex, and hypothalamus from rodents were collected and blotted for glutamic acid decarboxylase (GAD)65/67 and gamma-aminobutyric acid (GABA)A receptors subunit expression levels. The expression of α1-subunits, β2-subunits, and GAD65/67 of the GABAA receptor was modulated in the rodent brain. In conclusion, Chry ext augments pentobarbital-induced sleep duration and enhances sleep quality in EEG waves. These effects might be due to the activation of the Cl- channel.

Effects of Chronic Administration of Green Tea Ethanol Extract on Sleep Architecture in Mice: A Comparative Study with a Representative Stimulant Caffeine

Wakefulness is defined as a state in which individuals can react to a change in situations. The number of people staying awake and compensating for lack of sleep has increased in recent years. Caffeine, a representative stimulant, is the most extensively consumed compound globally and is mainly consumed through coffee. Although green tea (Camellia sinensis L.) contains high caffeine content like coffee, its arousal-inducing effects have not yet been studied. In the present study, we aimed to identify the arousal-inducing effect of GT during a chronic administration period (three weeks) using analysis of sleep architecture. Treatment with GT (1500 mg/kg) significantly elevated the sleep latency and wakefulness throughout the treatment period, and chronic administration of GT consistently maintained an increase in wakefulness for up to 3 h. During the treatment period, the arousal-inducing effect of GT (1500 mg/kg) occurred without any change in the tolerance phenomenon or withdrawal symptoms, similar to that observed with caffeine (25 mg/kg). GT (1500 mg/kg) containing 95.6 mg/kg of caffeine did not produce a better arousal-inducing effect than caffeine at 25 mg/kg. These results indicate that the arousal-inducing effect of GT persisted for three weeks without adverse effects and that GT can control the arousal-inducing effects of caffeine due to the hypnotic effects of its other constituents.

First evaluation of the anxiolytic-like effects of a bromazepam‑palladium complex in mice

A significant fraction of patients are affected by persistent fear and anxiety. Currently, there are several anxiolytic drug options, however their clinical outcomes do not fully manage the symptoms. Here, we evaluated the effects of a bromazepam‑palladium derivative [2-{(7-bromo-2-oxo-1,3-dihydro-2H-1,4-benzodiazepin-5-il)pyridinyl-κ²-N,N}chloropalladium(II)], [(BMZ)PdCl₂], on fear/anxiety and memory-related behavior in mice. For this, female Swiss mice were treated intraperitoneally (i.p.) with saline (NaCl 0.9%) or [(BMZ)PdCl₂] (0.5, 5.0, or 50 μg/kg). After 30 min, different tests were performed to evaluate anxiety, locomotion, and memory. We also evaluated the acute toxicity of [(BMZ)PdCl₂] using a cell viability assay (neutral red uptake assay), and whether the drugs mechanism of action involves the γ-aminobutyric acid type A (GABA_A) receptor complex by pre-treating animals with flumazenil (1.0 mg/kg, i.p., a competitive antagonist of GABA_A-binding site). Our results demonstrate that [(BMZ)PdCl₂] induces an anxiolytic-like phenotype in the elevated plus-maze test and that this effect can be blocked by flumazenil. Furthermore, there were no behavioral alterations induced by [(BMZ)PdCl₂], as evaluated in the light-dark box, open field, and step-down passive avoidance tests. In the acute toxicity assay, [(BMZ)PdCl₂] presented IC₅₀ and LD₅₀ values of 218 ± 60 μg/mL and 780 ± 80 mg/kg, respectively, and GSH category 4. Taken together, our results show that the anxiolytic-like effect of acute treatment with [(BMZ)PdCl₂] occurs through the modulation of the benzodiazepine site in the GABA_A receptor complex. Moreover, we show indications that [(BMZ)PdCl₂] does not promote sedation and amnesia and presents the same toxicity as the bromazepam prototype.