Neurotransmitter regulation of circadian rhythms

A study explores the role of vasopressin-producing neurons in regulating the activity of the mammalian circadian clock. The suprachiasmatic nucleus is a brain region that functions as the central circadian clock in mammals and includes neurons that use GABA as a neurotransmitter. However, the role of GABA-mediated circadian signaling in the brain is unclear. Michihiro Mieda and colleagues generated mice lacking the ability to release GABA from a specific set of neurons, the arginine vasopressin-producing neurons, which form the shell of the suprachiasmatic nucleus. The mice exhibited normal circadian rhythm at the clock-gene level, but aberrant behavioral rhythm in which their activity period during each daily cycle was lengthened. Neuronal activity in the suprachiasmatic nucleus showed an aberrant bimodal pattern correlated with the behavioral rhythm, suggesting that GABA release from the vasopressin neurons likely acted to regulate suprachiasmatic neuronal firing and constrain circadian behavior to appropriate time-windows, with respect to the clock gene-based molecular clock of the suprachiasmatic nucleus. According to the authors, the results suggest that gene-based molecular clocks are necessary but not sufficient to generate the circadian rhythm, with intercellular communication, such as GABA release from vasopressin neurons, providing an additional regulatory influence.

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Article #20-10168: “GABA from vasopressin neurons regulates the time at which suprachiasmatic nucleus molecular clocks enable circadian behavior,” by Takashi Maejima et al.

MEDIA CONTACT: Michihiro Mieda, Kanazawa University, JAPAN; email: <

[email protected]

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