GABAergic mechanisms in the suprachiasmatic nucleus that influence circadian rhythm. Issue 1 (3rd July 2020)

• Record Type: Journal Article
• Authors: Ono, Daisuke; Honma, Ken‐ichi; Honma, Sato
• Other Names: Stehle Jörg H. guestEditor.; Hausmann Laura guestEditor.
• Is Part Of: Journal of neurochemistry. Volume 157:Issue 1(2021)
• Page Start: 31
• Page End: 41
• Publication Date: 2020-07-03
• Subjects: circadian rhythm -- GABA -- neuronal network -- suprachiasmatic nucleus; Neurochemistry -- Periodicals; 616.8042
• DOI: 10.1111/jnc.15012
• Languages: English
• ISSNs: 0022-3042

Abstract

Abstract: The mammalian central circadian clock is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN contains multiple circadian oscillators which synchronize with each other via several neurotransmitters. Importantly, an inhibitory neurotransmitter, γ‐amino butyric acid (GABA), is expressed in almost all SCN neurons. In this review, we discuss how GABA influences circadian rhythms in the SCN. Excitatory and inhibitory effects of GABA may depend on intracellular Cl ‐ concentration, in which several factors such as day‐length, time of day, development, and region in the SCN may be involved. GABA also mediates oscillatory coupling of the circadian rhythms in the SCN. Recent genetic approaches reveal that GABA refines circadian output rhythms, but not circadian oscillations in the SCN. Since several efferent projections of the SCN have been suggested, GABA might work downstream of neuronal pathways from the SCN which regulate the temporal order of physiology and behavior. Abstract : Gamma‐amino butyric acid (GABA) is known as an inhibitory neurotransmitter in the brain. In this review, we discuss functional roles of GABA in the central circadian clock, suprachiasmatic nucleus (SCN). Importantly, almost all SCN neurons are GABAergic. Excitability of GABA is modulated by several factors such as day‐length, time of day, and development, which influences cellular coupling in the SCN. Recent study shows that GABA refines circadian output rhythms, but does not affect molecular rhythms in the SCN. GABA may work in the neuronal pathways from the SCN which regulate variety of physiological functions in mammals.