Setsuo Usui

Circadian behavioral rhythms during various light-intensity cycles in rats.

Sleep, ambulation and drinking were recorded on 5 kinds of light-intensity cycles fluctuating between 300 lux and 0 lux with a 24-hr period in rats. The waveforms of the cycles were rectangular wave (RA), sinusoidal wave (SO), triangular wave (TA), descending saw-tooth wave (ST-d) and ascending saw-tooth wave (ST-a). Each condition was maintained for 28 days. Thereafter, the rats were released into constant darkness (DD) for 20 days. The circadian behavioral rhythms clearly entrained to RA, SO, TA and ST-a, but not to ST-d. The waveforms of the behavioral rhythms varied depending on those of the fluctuating light-intensity cycles, and were quite different from those in RA and DD. Daily amounts of slow wave sleep and paradoxical sleep were hardly affected by the lighting conditions, while those of ambulation and drinking were decreased on the other light-intensity cycles than RA. These results present new aspects of entrainment and masking of circadian rhythm by light.

High Fos expression during the active phase in orexin neurons of a diurnal rodent, Tamias sibiricus barberi

To investigate whether a diurnal animal possesses the orexinergic system implicating vigilance and behavior, we examined Fos immunoreactivity (IR) in orexinergic neurons of Korean chipmunks raised under 12h light-dark cycles. Brain tissue, collected at four different zeitgeber times (ZT), was double-labeled with Fos and orexin-A antibodies. There was no difference in the number of orexin-IR neurons in the hypothalamus across all ZTs. However, more orexin-IR neurons expressing Fos-IR were found at ZTs 3 and 9 than ZTs 15 and 21. The results demonstrate circadian variations in the activation of orexin neurons corresponding with locomotor cycles, similarly seen in nocturnal rodents.

Multivariate Correlation Analysis Suggested High Ubiquinol and Low Ubiquinone in Plasma Promoted PrimateâÂÂs Social Motivation and IR Detected Lower Body Temperature

Mental problems caused by various kinds of stress induce neurotoxic damage through biological mechanisms like oxidation or metabolic unbalancing. We evaluated the dietary supplementation of antioxidant and nutrition, ubiquinol with milk in normal isolated adult common marmoset (Callithrix jacchus) as a preliminary preclinical study. The primates were fed with milk with or without ubiquinol every day for three months and after a two-month-interval, the treatment conditions were alternated. Psycho-physiological state was evaluated by video-recording of social behavior, body temperature detection by a simple IR thermal camera and a blood glucose chip-sensor. Furthermore, social behavior data were information-processed by technology to integrate multiple factors, ‘Behavior output analysis for quantification of emotional state translation’ abbreviated as BOUQUET, which visualized a statistical partial space where the status of high ubiquinol and low ubiquinone in plasma strongly correlated with high frequency of social approaching behavior and lower body temperatures in a social meeting context. This analysis also suggested that high frequency of face direction to a peer correlated with the high ubiquinol-low ubiquinone and high variation of body temperature. Blood glucose seemed weakly relevant to alert behavior in this multiple correlation. These results imply that unbiquinol supplementation promotes social motivation. Finally, the result that the BOUQUET and the sensor systems revealed the implicit psycho-physiological information suggests its applicability in various toxico-psychopathological studies as quantitative manner.

Susceptible period of socio-emotional development affected by constant exposure to daylight

As a diurnal experimental primate, the common marmoset (Callithrix jacchus) has recently contributed to numerous kinds of studies of neurobiological psychiatry as an essential pre-clinical model. The marmoset matures sexually within one or two years after birth. Thus, we can observe how the primate learns and develops psycho-cognitive functions through experiences in experimental environment for a much shorter period compared to that of humans. Longer daylight exposure may affect psychological development of children. In our research, we focus on raising marmosets under constant daylight from birth until various ages. In order to quantitatively evaluate the development of higher-ordered psychological functions, we designed a system of socio-behavioral tests and multivariate correlation analysis methods based on principal component analysis. With reference to the call and typical body movement expressed during a particular social context, we statistically inferred the emotional features of the subjects. In the current literature, we review our published results showing increased alert behaviors by constant light, and then, attempted to extend our additional analysis to seek age-dependent susceptibility to constant light. We then present the neurobiological mechanisms with reference to previous research reports. The current review suggests possible existence of a susceptible period earlier than three to five month-old in the environment-induced developmental disorder model, supposedly like attention deficit hyperactive disorders (ADHD) or oppositional defiant disorder (ODD).

The lower entrainable limit of rat circadian rhythm to sinusoidal light intensity cycles: A preliminary study

The lower entrainable limit of the circadian behavioral rhythm was examined in rats exposed to sinusoidal light intensity cycles with maximum illuminance of 20 lux and the minimum of 0.01 lux. The period (T) of the light intensity cycle was initially kept at 23.5 h for 20 cycles, and then shortened to 23 h for 33 cycles. Thereafter the rats were released into constant darkness. Five out of 10 rats entrained their circadian rhythms to T = 23.5‐h cycle, and they also entrained to the T = 23‐h cycle. The phase angle of entrainment was almost unchanged when T was shortened from 23.5 h to 23 h. These results suggest that the T = 23‐h cycle was close to the lower limit of entrainment.

Sleep-promoting effect following intracerebroventricular injection of a phosphorylated analogue of delta sleep-inducing peptide (DSIP-P) in rats

The effect of phosphorylated delta sleep-inducing peptide (DSIP-P) on sleep of rats was studied. DSIP-P (20 or 200 pmol/kg) was injected into the third cerebroventricle of male rats immediately before the onset of the dark period of a 12:12 h light-dark cycle. DSIP-P resulted in increases of slow-wave sleep (SWS) (17.3%, P less than 0.01) and paradoxical sleep (PS) (32.3%, P less than 0.05) during the subsequent dark period without shortening sleep latency in the dose of 200 pmol/kg. The SWS-promoting effect was carried over to the next light period. These changes returned to control levels on the second day. These results indicate that DSIP-P is a long-lasting sleep-promoting substance in rats.

Loss of circadian behavioural rhythms in rats kept in constant darkness

Abstract Ten male Sprague–Dawley rats were exposed to 1‐h light and 1‐h dark (LD 1 : 1) cycles for 50 days. They were then released into constant darkness (DD) for 104 days. Exposure to LD 1 : 1 caused gradual disruption of circadian rhythms in their ambulatory and drinking activities until, finally, all the animals lost their circadian behavioural rhythms. After their release into DD, eight rats showed free‐running circadian behavioural rhythms, whereas the remaining two rats showed circadian arrhythmicity for approximately 50 days in DD before they restored their free‐running rhythms spontaneously.

Non-contact behavioral/physiological measuring system for quantitativepsychiatric diagnosis - from animal model to human social disorder

O2-7-2-4 The establishment and analysis of 26S proteasome conditional knockout mice for the mechanisms of neurodegenerative diseases Yoshitaka Tashiro 1 , Haruhisa Inoue 2, Maya Yamazaki 3, Manabu Abe 3, Hidehumi Ito 1, Hidemi Misawa 4, Kenji Sakimura 3, Ryosuke Takahashi 1,5 1 Department of Neurology, Kyoto University Graduate School of Medicine 2 Center for iPS Cell Research and Application, Institute for integrated Cell-Material Sciences. Kyoto University 3 Basic Neuroscience Branch, Niigata University Brain Research 4 Department of Pharmacology, School of Medicine, Keio University 5 JST-CREST