• Anna Magdalena Sanetra, Katarzyna Palus-Chramiec, and Marian Henryk Lewandowski.
• Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Gronostajowa Street 9, 30-387 Krakow, Poland. Electronic address: anna.sanetra@doctoral.uj.edu.pl.
• Neuroscience. 2021 Aug 10; 469: 1-16.

AbstractCircadian rhythms are regulated by a set of brain structures, one of which is the Intergeniculate Leaflet of the Thalamus (IGL). The most recognised role of the IGL is the integration of a variety of stimuli affecting rhythmicity, such as lighting conditions, received by the eye, or light-independent (non-photic) cues, the information about which is delivered via the activation of the non-specific projections. One of them is the norepinephrinergic system originating in the brainstem Locus Coeruleus (LC). In order to investigate the effect of norepinephrine (NE) on the IGL neurons we have performed ex vivo recordings using the extracellular multi-electrode array technique as well as the intracellular whole-cell patch clamp. Using both agonists and antagonists of specific NE receptor subtypes, we confirmed the presence of functional α1-, α2- and β-adrenergic receptors within the investigated structure, allowing NE to exert multiple types of effects on different IGL neurons, mainly depolarisation of the neurons projecting to the Suprachiasmatic Nuclei - the master circadian pacemaker, and various responses exhibited by the cells creating the connection with the contralateral IGL. Moreover, NE was shown to affect IGL cells both directly and via modulation of the synaptic network, in particular the miniature inhibitory postsynaptic currents. To the best of our knowledge, these are the first studies to confirm the effects of NE on the activity of the IGL network.Copyright © 2021 IBRO. Published by Elsevier Ltd. All rights reserved.

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