Monoamines Inhibit GABAergic Neurons in Ventrolateral Preoptic Area That Make Direct Synaptic Connections to Hypothalamic Arousal Neurons

• Published in: The Journal of neuroscience Vol. 38; no. 28; pp. 6366 - 6378
• Main Authors: 長谷川 恵美, 櫻井 武, Saito Yuki C., Maejima Takashi, Nishitani Mitsuhiro, Hasegawa Emi, Yanagawa Yuchio, Mieda Michihiro, SAKURAI Takeshi
• Format: Journal Article
• Language: English
• Published: United States Society for Neuroscience 11.07.2018
• Subjects: Animals; Arousal; Arousal - physiology; GABAergic Neurons - cytology; GABAergic Neurons - physiology; Histidine; Histidine decarboxylase; Hypothalamic Area, Lateral - cytology; Hypothalamic Area, Lateral - physiology; Hypothalamus; Hypothalamus (lateral); Male; Mice; Mice, Transgenic; Monoamines; Neural networks; Neural Pathways - cytology; Neural Pathways - metabolism; Neurons; Noradrenaline; Norepinephrine; Norepinephrine - metabolism; Orexins; Preoptic area; Preoptic Area - cytology; Preoptic Area - physiology; Rodents; Serotonin; Serotonin - metabolism; Sleep; Sleep - physiology; Sleep and wakefulness; Synapses; Tuberomammillary nucleus; Ventrolateral preoptic nucleus; Wakefulness; γ-Aminobutyric acid; sleep; tracing; noradrenaline; histamine; orexin; wakefulness
• ISSN: 0270-6474; 1529-2401; 1529-2401
• DOI: 10.1523/jneurosci.2835-17.2018

The hypothalamus plays an important role in the regulation of sleep/wakefulness states. While the ventrolateral preoptic nucleus (VLPO) plays a critical role in the initiation and maintenance of sleep, the lateral posterior part of the hypothalamus contains neuronal populations implicated in maintenance of arousal, including orexin-producing neurons (orexin neurons) in the lateral hypothalamic area (LHA) and histaminergic neurons in the tuberomammillary nucleus (TMN). During a search for neurons that make direct synaptic contact with histidine decarboxylase-positive (HDC+), histaminergic neurons (HDC neurons) in the TMN and orexin neurons in the LHA of male mice, we found that these arousal-related neurons are heavily innervated by GABAergic neurons in the preoptic area including the VLPO. We further characterized GABAergic neurons electrophysiologically in the VLPO (GABAVLPO neurons) that make direct synaptic contact with these hypothalamic arousal-related neurons. These neurons (GABAVLPO→HDC or GABAVLPO→orexin neurons) were both potently inhibited by noradrenaline and serotonin, showing typical electrophysiological characteristics of sleep-promoting neurons in the VLPO. This work provides direct evidence of monosynaptic connectivity between GABAVLPO neurons and hypothalamic arousal neurons and identifies the effects of monoamines on these neuronal pathways.