| Object:To investigate the ionic base of the independent circadian rhythem of habenular nucleus and the effects of melatonin on habenular nucleus.Methods:1. The habenular neurons of two-week Wistar rats were freshly isolated. Delayed rectifier potassium current were recorded by whole–cell patch clamp configuration from different phases(day CT10-12;CT12-14;CT14-16; and nightCT20-22 ; CT22-24 ; CT0-2). 2. The different concentrations(10-4mol/L, 10-5 mol/L) of MT were used by gravity volume in different phases. The changes of delayed rectifier potassium current were recorded in different phases.Result:1. Delayed rectifier potassium current at night(1.189±0.077 nA) were significantly higher than it in the day(1.017±0.099nA).2.Application of melatonin 10-5mol/L , the current was increased 9.4±1.5%; Application of melatonin 10-4mol/L, the current was increased 14.5±3.2%.3. Application of melatonin 10-4mol/L , the increasing amplitude of delayed rectifier potassium current at night (0.197±0.04nA)were higher than the current in the day(0.084±0.051nA).Discussion:1.Delayed rectifier potassium current of the habenular nucleus neurons was circadian. In mammals, The suprachiasmatic nucleus (SCN) is commonly considered to contain the main pacemaker of behavioral and hormonal circadian rhythms. Among its efferent targets are the habenular nucleus (Hb), especially the lateral Hb (LHb), which plays an important role in conveying input from the limbic forebrain to midbrain structures. 1978, Moutet who destroyed suprachiasmatic nucleus indicate that the habenula may play a role in linking circadian and motivational systems and may contribute to photic...
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