TY - JOUR
T1 - Melatonin activates an outward current and inhibits Ih in rat suprachiasmatic nucleus neurons
AU - Jiang, Zhi Gen
AU - Nelson, Cole Stanley
AU - Allen, Charles Norman
N1 - Funding Information:
This work was supported by Grant 1POIAG10794 from the National Institutes of Health. The authors thank Dr. P. Spencer for critical reading of the manuscript and Y. Yang for providing excellent technical assistance.
PY - 1995/7/31
Y1 - 1995/7/31
N2 - 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.
AB - 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.
KW - Circadian rhythm
KW - H-current
KW - Melatonin
KW - Potassium conductance
KW - Suprachiasmatic nucleus
UR - http://www.scopus.com/inward/record.url?scp=0029149427&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029149427&partnerID=8YFLogxK
U2 - 10.1016/0006-8993(95)00478-9
DO - 10.1016/0006-8993(95)00478-9
M3 - Article
C2 - 7583297
AN - SCOPUS:0029149427
SN - 0006-8993
VL - 687
SP - 125
EP - 132
JO - Brain research
JF - Brain research
IS - 1-2
ER -