Hiromasa Seno

Monoamine Oxidase A Activity and Norepinephrine Level in Hippocampus Determine Hyperwheel Running in SPORTS Rats

An understanding of neurological mechanisms for wheel running by rodents, especially with high exercise activity, would be applicable to a strategy for promotion of exercise motivation in humans. One of several brain regions that are candidates for the regulation of physical exercise is the hippocampus. Here we examined the running activity of Spontaneously-Running-Tokushima-Shikoku (SPORTS) rat, a new animal model for high levels of wheel-running activity, and its relation with the hippocampal norepinephrine (NE) system including the levels of NE, adrenergic receptors, and degradation enzymes for monoamines. In the hippocampus of SPORTS rats, the level of NE in extracellular fluid was augmented, whereas the level in the homogenate of the whole tissue was decreased even for sedentary conditions. Elevated extracellular NE caused downregulation of α2-adrenergic receptors in the hippocampus of SPORTS rats. Local administration of α2-adrenergic receptor antagonist yohimbine, but not of α2-agonist clonidine, into the hippocampus suppressed high running activity in SPORTS rats. The protein expression and the activity levels of monoamine oxidase A (MAOA), a critical enzyme for the degradation of NE, were decreased in the hippocampus of SPORTS rats to increase extracellular NE level. Thus, inhibition of oxidase activity in normal Wistar rats markedly increased wheel-running activity. These results indicate that decreased MAOA activity, elevation of extracellular NE, and α2-adrenergic receptors in the hippocampus determine the neural basis of the psychological regulation of exercise behavior in SPORTS rats.

Influence of cedar essence on spontaneous activity and sleep of rats and human daytime nap

Abstract We investigated whether exposure to the odor of extracted cedar essence (CE) has (i) an influence on spontaneous activity and Sleep‐wake states of rats and (ii) a sleep‐promoting effect on human daytime nap after taking an ordinary nights sleep. In rats exposed to CE, spontaneous activities and amount of wake were significantly decreased, while the amount of non‐rapid eye movement (NREM) sleep was significantly increased. In human daytime nap, NREM sleep stage 2 latency was significantly shortened after exposure to CE.

Effect of ultrasound application on fat mobilization

The aim of this experimental trial was to study the effect of ultrasound application on the lipolysis in adipose tissue. Rats were administered to pentobarbital (Nembutal) anesthesia and their abdomens were shaved. Rat abdomen was subjected to 24 kHz-1 MHz ultrasound for 10 min to investigate frequency and power-intensity dependency for fat mobilization. Blood was taken from the tail vein to estimate plasma free fatty acids (FFA). For frequency dependency two regions around 100 kHz and 300-500 kHz were effective for fat mobilization. For power-intensity dependency, effective regions were found to be from 24 to 1090 kHz. In the effective regions on frequency and power-intensity, application of ultrasound caused increases in plasma FFA and norepinephrine concentration of extra-cellular fluid of perirenal adipose tissue. These results suggest that ultrasound application stimulates fat mobilization through a local increase in norepinephrine secretion under the conditions of effective frequency and intensity.

Response of the Sleep-Wake Rhythm to an 8-Hour Advance of the Light-Dark Cycle in the Rat

We have studied the effects of an 8-h advance of the environmental light-dark (LD) cycle on the sleep-wake rhythm in the rat. Electroencephalograms and electromyograms were recorded simultaneously on chart paper through a two-channel telemetry system for 3 days before phase shift (baseline) and 8 days during and after phase shift. Phase advance of the LD cycle led to an increase in both non-rapid eye movement (NREM) and REM sleep. The amount of NREM sleep in the light period correlated positively with that in the preceding dark period for 4 days after phase advance. The duration of REM sleep in the light period correlated negatively with that in the preceding dark period. The results suggest that homeostatic control of the amount of NREM sleep between the preceding dark period and the following light period is disturbed by phase advance of the LD cycle.

Clock mutant mice with Jcl/ICR background shows an impaired learning ability in water maze, but not in passive avoidance, at the beginning of dark phase

ABSTRACT  We observed the learning ability in Clock mutant mice with Jcl/ICR background (Clockj), a mice model of evening‐type individuals, in the early part of dark phase. In order to estimate the learning ability, Morris water maze (WM) and passive avoidance (PA) test were performed. Release of acetylcholine, 5 hydroxytryptophan (5‐HT) and dopamine (DA) in hippocampus was measured by in vivo microdialysis method. Clockj showed the impaired learning ability in the WM, but not in PA test. Hippocampal acetylcholine release was significantly attenuated in the Clockj in comparison to the wild‐type mice. Neither 5‐HT nor DA in the hippocampus was affected by the Clock mutation. Clock, an essential gene controlling circadian rhythm, may have an important role on the spatial learning and hippocampal cholinergic function, at least, at the beginning of the dark phase.

Effects of inhibitors of protein or RNA synthesis on turnover rate of messenger RNA in rat liver

Abstract The administration of various inhibitors of protein or RNA synthesis to rats was shown to cause a prolongation of the half-life of liver mRNA. These inhibitors, however, caused no change in the levels of various ribonucleases present in the liver cells. It is concluded that the rate of mRNA turnover is not determined by the levels of ribonuclease activities. Using these data, along with current knowledge on the mechanism of action of various inhibitors, a model for the control of mRNA degradation is proposed.

Postoperative changes of rat EEG variance

Concerning an EEG parameter variance, the long-term postoperative changes were observed in rats chronically implanted with bipolar depth electrodes for EEG recordings. The cortico-hippocampal EEG signals were continuously digitized and their variances were computed for each 1 min in real time. Daily mean of the EEG variance gradually increased over 2 weeks after surgery for the implantation of chronic electrodes and, then, reached a plateau. To observe the absolute quantity of the depth EEG in the rat, at least 2 weeks are required before data collections.

Real-Time Monitoring of Slow-Wave Sleep by Electroencephalogram Variance

Based on statistical variance as an index of electroencephalogram (EEG) parameters, we monitored slow-wave sleep in both humans and rats in real time and on-line with a widely used personal computer. This EEG variance method may be a useful tool to carry out biological rhythm research, including sleep studies.