Takashi Nishio

Effect of bilateral lesions of the suprachiasmatic nuclei on the circadian rhythm of food-intake.

Recently, it was reported that lesions of the brain involving the bilateral suprachiasmatic nuclei (SCN) abolished the circadian rhythm of drinking and locomotor activity 11, the plasma corticosterone level s, pineal serotonm N-acetyltransferase a, and sleep-wakefulness cycle 5, in rats and locomotor activity in hamstersXL On the other hand, during the stud]es on the mechanism of the circadian rhythm of gluconeogenesis in rat, we found that the rhythm of food-intake was more important than that of illumination in producing the circadian rhythm of enzyme activities in rat liver and kidneyl0,13. Thus, we started to examine the effect of lesions of SCN on food and water mtakes. In the course of this experiment, we found that rats with lesions of the SCN showed no circadian rhythm of food-intake. This paper reports the effects of bilateral lesions of the SCN on the daily rhythm of food and water intakes. Sixty male Wistar strain rats, initially weighing 250-300 g, were used. Rats were housed in individual stainless steel cages with free access to food (Oriental Yeast Co. Ltd., type M) and water. The animal room was maintained at 24 ± l °C and 60 ± 10 ~o RH. It was illuminated by fluorescent lights giving an average intensity of illumination 250 lux in the center of the room and 50 lux in the individual cages. The light-dark cycle (L-D) consisted of a 12 h light (0800-2000) and 12 h dark (20004)800) period. Bilateral lesions of the suprachiasmatic nuclei were made stereotaxically by applicat]on of an anodal direct current (2 mA, 60 sec) through a bipolar electrode consisting of 3 hnes of copper wire insulated by enamel except at the tips of the outer two wires and struck together with varnish. The middle wire was used m order to increase the width. The lesion coordinates were anterior (A): 0.5, lateral (L): 0.0 and ventral (V): --8.6 mm from the surface of the brain, and they were obtained from the atlas of Fifkovfi and Marsala 4. Four sham operated rats received all the same treatments except application

Renal Net Glucose Release In Vivo and Its Contribution to Blood Glucose in Rats

This study describes the contribution of de novo glucose synthesis by the kidney to blood glucose homeostasis in rats. The net glucose release by the kidney in vivo was measured by an isotope-dilution method, which calculated the extent of dilution of injected [(14)C]glucose by glucose newly synthesized in the kidney. The extent of dilution was determined from the difference between the decrease of the actual blood glucose concentration and that of the radioactivity of [(14)C]glucose, after injecting [(14)C]glucose into functionally hepatectomized rats. The results indicate that the net glucose release by the kidney in vivo in normal fed rats was 0.75+/-0.13 mg/dl per min, and that its contribution to blood glucose was 25.9+/-5.0%. When unilateral nephrectomy was performed, under the same conditions, renal net glucose release was one-half of that in rats with two intact kidneys, which indicates the quantitative accuracy of the isotope-dilution method employed in this study. In rats starved for 24 h, the renal net glucose release increased to 0.99+/-0.08 mg/dl per min. Diabetic rats showed a remarkably higher renal net glucose of 2.28+/-0.33 mg/dl per min, which was 360% of the normal level. Treatment of diabetic rats with insulin, restored the renal net glucose release to the normal level. In acidotic rats, renal net glucose release was as great as 1.03+/-0.15 mg/dl per min, which suggests that the acid-base balance participates in control of renal glucose output. Measurements every 6 h throughout the day showed that glucose was supplied from the kidney at a constant rate without any circadian rhythm. These data suggest that renal gluconeogenesis is of physiological importance in the maintenance of homeostasis of blood glucose.

Circadian feeding rhythm after hypothalamic knife-cut isolating suprachiasmatic nucleus

Abstract Bilateral parasagittal knife-cut between the suprachiasmatic nucleus (SCN) and lateral hypothalamic area (LH) or coronal knife-cut between the SCN and ventromedial hypothalamic nucleus (VMH) resulted in a partial loss of the circadian feeding rhythm in rats; after either operation the rats consumed about 30% of their total daily food intake during the light period. However, after the parasagittal and coronal knife-cuts were made in combination, the circadian feeding rhythm was completely lost (50% food intake during the light period). Rats which lost the circadian feeding rhythm partially or completely showed neither obesity nor anorexia. These findings suggest that there are dual informational pathways from the SCN, possibly between the SCN and LH and between the SCN and VMH, through which circadian time signals generated in the SCN are transmitted to the LH and VMH to drive the circadian feeding rhythm.

Bilateral lesions of suprachiasmatic nucleus eliminate circadian rhythms of oxygen consumption and the respiratory quotient in rats.

Bilateral lesions of the suprachiasmatic nucleus of the hypothalamus of rats abolished circadian rhythms of oxygen consumption and of the respiratory quotient (RQ). The RQ remained constant at a level intermediate between the maximum (about 1.0) and minimum (about 0.9) values in control animals.

Benchmark experiment on LiAlO2, Li2TiO3 and Li2ZrO3 assemblies with D–T neutrons–leakage neutron spectrum measurement

For the three materials LiAlO 2 , Li 2 TiO 3 and Li 2 ZrO 3 , known as advanced breeder materials for a fusion reactor, D-T neutron benchmark experiments have been conducted at fusion neutronics source (FNS) of Japan Atomic Energy Research Institute (JAERI), Japan, to validate five nuclear data files, i.e. JENDL-3.2, JENDL fusion file, ENDF/B-VI, FENDL/E-1.0 and FENDL/E-2.0. From the result, all the nuclear data files were confirmed to be fairly reliable with respect to the prediction of neutron spectrum in the use of LiAlO 2 and Li 2 TiO 3 . However, it was recommended that the inelastic scattering neutron spectra of oxygen, lithium and aluminium in the five nuclear data files had to be re-examined. As for zirconium, it was pointed out that the nat Zr(n, 2n) cross section could be overestimated for the five nuclear data files.

Fusion Neutronics Benchmark Experiment on Structural and Advanced Blanket Materials - Leakage Neutron Spectrum Measurement -

Fusion neutronics benchmark experiments for copper and tungsten and advanced breeder materials of LiAlO2, Li2TiO3 and Li2ZrO3 have been conducted at FNS of JAERI to validate five nuclear data files, i.e., JENDL-3.2, JENDL Fusion File, ENDF/B-VI, FENDL/E-1.0 and FENDL/E-2.0. From the result, all the nuclear data files were confirmed to be fairly reliable with respect to the prediction of neutron spectrum. However, some problems were pointed out. Especially for Zr, the discrepancy between the experimental and calculated spectra is remarkably large.

(n, 2n) Reaction Cross Section Measurement with A Beam DT Neutron Source

The method has been established to measure (n,2n) reaction cross section with the coincidence detection technique using a newly developed pencil beam DT neutron source at FNS of JAERI. A cylindrical manganese, the (n,2n) cross section of which was measured precisely with the foil activation method, was used to check the experimental method. It was confirmed from the experimental results that the present new method was basically functioning to measure only two neutrons emitted through (n,2n) reaction. Considering the not so strong angular dependence for Mn, by adoption of the TOF measurement the cross sections especially for medium heavy elements can be accurately determined. Consequently, by the present method, it is expected that complete (n,2n) reaction cross section measurements for stable-isotope producing elements by (n,2n) reaction would become possible with the coincidence detection and TOF methods.