Melatonin activates an outward current and inhibits Ih in rat suprachiasmatic nucleus neurons

Zhi Gen Jiang, Cole Stanley Nelson, Charles Norman Allen

Research output: Contribution to journalArticle

88 Scopus citations

Abstract

Whole-cell voltage-clamp recordings were made from suprachiasmatic nucleus (SCN) neurons maintained in horizontal brain slices. The majority of neurons exibited spontaneous and evoked excitatory and inhibitory synaptic currents (EPSC and IPSC), mediated by glutamate and GABA respectively. Melatonin had no effect on either the spontaneous or evoked EPSC or IPSC. Application of melatonin (0.1-30 μM) during circadian time (CT) 9-12 activated an outward current at -60 mV and increased the membrane conductance in a concentration-dependent manner. The current was augmented by depolarization, reduced by hyperpolarization and, in some cells, reversed its polarity near the potassium equilibrium potential. Some neurons also responded to melatonin during other time of the circadian day CT 3-9 or CT 12-15). Hyperpolarizing steps, in a portion of cells, activated an inward cation current which resembled the Ih described in other neurons. Melatonin (10 μM) inhibited activation of the Ih. These data indicate that melatonin may inhibit SCN neurons by activating a potassium current and inhibiting the Ih.

Original languageEnglish (US)
Pages (from-to)125-132
Number of pages8
JournalBrain research
Volume687
Issue number1-2
DOIs
StatePublished - Jul 31 1995

Keywords

  • Circadian rhythm
  • H-current
  • Melatonin
  • Potassium conductance
  • Suprachiasmatic nucleus

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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