[Effects of simulated space rhythm (L:D = 0.75h:0.75h) on circadian rhythm in tree shrews (Tupaia belangeri chinensis)].
Li. H Y HY; Liu. S Y SY
Key Findings
- A simulated space light‑dark cycle (0.75 h:0.75 h) dramatically disturbs the circadian rhythm of tree shrews.
- Morning motor activity (06:00‑12:00) drops, while an exaggerated activity peak appears in the evening (18:00‑24:00).
- Repeated doses of Asp5‑alpha‑DSIP (30 µg/kg, i.p.) do not prevent the rhythm disturbance, but they prevent a drop in total 24‑hour activity and may even increase it.
Practical Outcomes
- For biohackers, this study suggests that DSIP is not effective at protecting the body’s internal clock against extreme or irregular light schedules. However, DSIP might help maintain overall activity levels when circadian rhythms are challenged, though the relevance to human sleep or performance is uncertain.
Summary
Researchers put tree shrews on a super‑fast light‑dark schedule (45 min light, 45 min dark) to mimic a space‑station rhythm. This messed up the animals' natural daily activity patterns, cutting morning movement and creating a huge evening spike, while overall 24‑hour activity dropped. Giving the sleep‑peptide Asp5‑alpha‑DSIP for a few days didn’t stop the disruption, but it did keep the total daily activity from falling and even slightly boosted it in some cases.
Abstract
It is known that contemporary space station revolves at the altitude of 400-500 km in the outer space. The present study was undertaken to investigate the effects of simulated space rhythm (L:D = 0.75 h:0.75 h) at this altitude on circadian rhythm in tree shrews (Tupaia belangeri chinensis) and the effects of endogenous sleep inducing neuropeptide Asp5-alpha-DSIP on the space-rhythm-entrained circadian rhythm. This primitive stock serves as one species of Tupaiidae and is a unique native of South China. Our previous studies have shown that this species showed striking differences in natural circadian rhythm between day and night (e.g. 3.03 degrees C of rectal temperature). Results showed that the above mentioned space rhythm (L:D = 0.75h:0.75h) could drastically disturb the inherent circadian rhythm of Tupaia belangeri chinensis. The maximal peak of motor activity dropped significantly in the morning (0600-1200) and a new enhanced peak (more than 20 times greater than that of the control) was found between 1800-2400, whereas the maximal trough of motor activity (2400-0600) remained basically unchanged. Concurrently, the total amount of 24-h motor activity was significantly decreased and the recovery after the cessation of space rhythm was slow. Experimental results also demonstrated that consecutive administration of Asp5-alpha-DSIP (30 micrograms/kg, i.p.) for 5 days (2 days before and 3 days during space rhythm) did not prevent the basic disturbance of circadian rhythm of Tupaia belangeri chinensis caused by the space rhythm (L:D = 0.75h:0.75h). Nevertheless, no decrease or even some enhancement of the total amount of 24th motor activity was observed during space rhythm or after its cessation.
Study Information
pubmed
1990