Seasonal induction of GABAergic excitation in the central mammalian clock

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 26; pp. 9627 - 9632
• Main Authors: Farajnia, Sahar, van Westering, Tirsa L. E., Meijer, Johanna H., Michel, Stephan
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 01.07.2014; National Acad Sciences
• Subjects: Animals; Behavioral neuroscience; Biological Sciences; Brain; Chlorides; Circadian Clocks - physiology; Epilepsy; Excitatory Postsynaptic Potentials - physiology; gamma-Aminobutyric Acid - metabolism; Inhibitory Postsynaptic Potentials - physiology; Male; Mammals; Mice; Mice, Inbred C57BL; Microscopy, Fluorescence; Neurochemistry; Neurons; Neurotransmitters; Patch-Clamp Techniques; Photoperiod; Receptors; Seasons; Statistics, Nonparametric; Suprachiasmatic nucleus; Suprachiasmatic Nucleus - metabolism; Synaptic transmission; chloride; circadian; NKCC1; calcium; excitation/inhibition balance
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1319820111

The balance between excitation and inhibition is essential for the proper function of neuronal networks in the brain. The inhibitory neurotransmitter γ-aminobutyric acid (GABA) contributes to the network dynamics within the suprachiasmatic nucleus (SCN), which is involved in seasonal encoding. We investigated GABAergic activity and observed mainly inhibitory action in SCN neurons of mice exposed to a short-day photoperiod. Remarkably, the GABAergic activity in a long-day photoperiod shifts from inhibition toward excitation. The mechanistic basis for this appears to be a change in the equilibrium potential of GABA-evoked current. These results emphasize that environmental conditions can have substantial effects on the function of a key neurotransmitter in the central nervous system.