Masakasu Namihira

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Chronic treatment of methamphetamine (MAP) in rats desynchronized the locomotor activity rhythm from the light-dark cycle. When the activity rhythm was completely phase-reversed with respect to a light dark-cycle, 24 h profiles were examined for the clock gene (rPer1, rPer2, rBMAL1, rClock) expressions in several brain structures by in situ hybridization,(More)
A superfamily gene which encodes a bHLH (basic helix-loop-helix)/PAS transcription factor, BMAL1, was cloned and sequenced from rat cDNA. A robust circadian rhythm of rat BMAL1 expression was detected by in situ hybridization in the suprachiasmatic nucleus (SCN), the site of the circadian clock, with the highest level at the subjective night. Less prominent(More)
To clarify whether BMAL1 is involved in the photic signal transduction in the mammalian circadian clock, we examined the effects of a single light pulse on the level of BMAL1 mRNA in the suprachiasmatic nucleus (SCN) of rats by in situ hybridization. Rats were exposed to 30 min light of ca. 300 lux at six different phases in constant darkness and(More)
Circadian expression, light-responsiveness and localization of clock genes, rPer1 and rPer2, were examined in the rat retina under constant darkness. A significant circadian variation was detected in rPer2 transcript levels with a peak at ZT14, but not in the rPer1. A light pulse given after constant darkness of 3 days increased both rPer1 and rPer2(More)
Expression patterns of mammalian clock genes, Clock and BMAL1, were examined by in situ hybridization in the pineal body, olfactory bulb, hippocampus and cerebellum in rats under constant darkness. In the pineal, the level of Clock transcript was significantly higher at ZT18 (subjective night) than at ZT6 (subjective day), while the level of BMAL1(More)
Neuronal activity of a single neuron was monitored continuously for more than 5 days by means of a multi-electrode dish in dispersed cell culture of the rat suprachiasmatic nucleus (SCN). Sixty-seven out of 88 neurons showed a robust circadian rhythm in firing rate. The mean circadian period was 24.2 h, which was almost identical to that of the locomotor(More)
To clarify the role of Clock in the photic signal transduction of rat circadian clock, we cloned and sequenced rat Clock and examined the effect of a single light pulse on the Clock mRNA expression in the suprachiasmatic nucleus (SCN) by in situ hybridization. Rats were exposed to a 30 min light pulse ( approximately 300 lx) at one of six circadian phases(More)
CS mice exhibit a spontaneous splitting in the circadian rhythm of locomotor activity under constant darkness, suggesting that they contain two weakly coupled oscillators in the circadian clock system regulating locomotor activity rhythm. In order to clarify whether the two oscillators are located in the suprachiasmatic nucleus (SCN), a site of the master(More)
Circadian expression and light-responsiveness of the mammalian clock genes, Clock and BMAL1, in the rat retina were examined by in situ hydbribization under constant darkness. A small but significant daily variation was detected in the Clock transcript level, but not in BMAL1. Light increased the Clock and BMAL1 expressions significantly when examined 60(More)
The CS mouse is a mutant strain which displays spontaneous splitting in the circadian locomotor rhythm under continuous darkness. To clarify whether the rhythm splitting occurs in the suprachiasmatic nucleus (SCN) where the mammalian circadian clock is located, the circadian rhythmicities of mammalian clock genes, mPer1, mBMAL1 and mClock, were examined in(More)