The role of the GABAergic system on insomnia.

Sleep is an essential activity for the survival of mammals. Good sleep quality helps promote the performance of daily functions. In contrast, insufficient sleep reduces the efficiency of daily activities, causes various chronic diseases like Alzheimer's disease, and increases the risk of having accidents. The GABAergic system is the primary inhibitory neurotransmitter system in the central nervous system. It transits the gamma-aminobutyric acid (GABA) neurotransmitter via GABAA and GABAB receptors to counterbalance excitatory neurotransmitters, such as glutamate, noradrenaline, serotonin, acetylcholine, orexin, and dopamine, which release and increase arousal activities during sleep. Several studies emphasized that dysfunction of the GABAergic system is related to insomnia, the most prevalent sleep-related disorder. The GABAergic system comprises the GABA neurotransmitter, GABA receptors, GABA synthesis, and degradation. Many studies have demonstrated that GABA levels correlate with sleep quality, suggesting that modulating the GABAergic system may be a promising therapeutic approach for insomnia. In this article, we highlight the significance of sleep, the classification and pathology of insomnia, and the impact of the GABAergic system changes on sleep. In addition, we also review the medications that target the GABAergic systems for insomnia, including benzodiazepines (BZDs), non-BZDs, barbiturates, GABA supplements, and Chinese herbal medicines.

Anti-inflammatory and memory-enhancing properties of Chinese herbal extracts: The possible application in Alzheimer's disease.

Alzheimer's disease (AD) is a progressive brain disease that causes cognitive impairment in seniors. The beta-amyloid (Aß) deposition and intracellular neurofibrillary tangles are two pathological hallmarks of AD. The increase of AD hallmarks causes inflammatory response enhancement, reduction of synaptic plasticity, and impaired cognition. The percentage of the aging population is growing along with the number of AD patients; however, effective treatment of AD is still limited. Therefore, developing preventive and therapeutic drugs for AD with fewer adverse side effects is urgently needed. The crude extracts from herbs such as Centella asiatica, Dendrobium catenatum, Litsea cubeba, Nardostachys jatamansi, Convolvulus pluricaulis, Melissa officinalis, Magnolia officinalis, Withania somnifera, and Nigella sativa improved memory performance and reduced inflammation response in various diseases. In addition, herbal blends usually have minimum aversive effects and can be mixed into diet and served as nutritional supplements. Hence, it is promising to develop Chinese herbal extracts to prevent or treat early AD. This review article highlights the currently available treatments of AD and the therapeutic effects of a group of crude extracts from Chinese herbs that can prevent cognitive decline and reduce the excessive inflammatory response. The possible clinical use of these Chinese herbal extracts in AD is also discussed.

Molecular basis for the association between depression and circadian rhythm.

Depression is a life-threatening psychiatric disorder and a major public health concern worldwide with an incidence of 5% and a lifetime prevalence of 15%-20%. It is related with the social disability, decreased quality of life, and a high incidence of suicide. Along with increased depressive cases, health care cost in treating patients suffering from depression has also surged. Previous evidence have reported that depressed patients often exhibit altered circadian rhythms. Circadian rhythm involves physical, mental, and behavioral changes in a daily cycle, and is controlled by the suprachiasmatic nucleus of the hypothalamus in responding to light and darkness in an environment. Circadian rhythm disturbance in depressive patients causes early morning waking, sleep disturbances, diurnal mood variation, changes of the mean core temperature, endocrine release, and metabolic functions. Many medical interventions have been used to treat depression; however, several adverse effects are noted. This article reviews the types, causes of depression, mechanism of circadian rhythm, and the relationship between circadian rhythm disturbance with depression. Pharmaceutical and alternative interventions used to treat depressed patients are also discussed.