PMID: 645902May 1, 1978

Mutual influence of rats having different circadian rhythm of adrenocortical activity

The American Journal of Physiology
K TakahashiY Takahashi


The possibility of a mutual influence between male adult rats having different circadian adrenocortical rhythms was studied under two different lighting conditions. Intact and optic-enucleated rats were housed together in the same cage in various ratios of intact to blinded rats. Twenty-four- or forty-eight-hour patterns of plasma corticosterone levels were determined individually at 4-h intervals. Under diurnal light-dark alternation, the circadian periodicity of the intact rats always synchronized with light, whereas single blinded rats in cages with three intact rats demonstrated free-running rhythms throughout the experimental period of 15 wk. Under constant light the circadian rhythm free-ran in both intact and blinded rats for the first 2 wk. A phase reversal of the rhythm was observed in the intact rats at the end of the 2nd wk, and between 5 and 8 wk after binding in the blinded rats. These results indicate that the circadian adrenocortical rhythms in intact and blinded rats are not entrained to each other, even when the two types of rats live together in the same cage.


Jan 1, 1977·Proceedings of the Society for Experimental Biology and Medicine·M M Wilson, M A Greer
Apr 1, 1969·The Journal of Clinical Endocrinology and Metabolism·D N Orth, D P Island
Nov 1, 1954·The American Journal of Physiology·F HALBERGJ J BITTNER

Related Concepts

Blindness, Transient
Circadian Rhythms
Social Ecology

Trending Feeds


Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Neural Activity: Imaging

Imaging of neural activity in vivo has developed rapidly recently with the advancement of fluorescence microscopy, including new applications using miniaturized microscopes (miniscopes). This feed follows the progress in this growing field.

The Tendon Seed Network

Tendons are rich in the extracellular matrix and are abundant throughout the body providing essential roles including structure and mobility. The transcriptome of tendons is being compiled to understand the micro-anatomical functioning of tendons. Discover the latest research pertaining to the Tendon Seed Network here.

Myocardial Stunning

Myocardial stunning is a mechanical dysfunction that persists after reperfusion of previously ischemic tissue in the absence of irreversible damage including myocardial necrosis. Here is the latest research.

Chronic Fatigue Syndrome

Chronic fatigue syndrome is a disease characterized by unexplained disabling fatigue; the pathology of which is incompletely understood. Discover the latest research on chronic fatigue syndrome here.


Incretins are metabolic hormones that stimulate a decrease in glucose levels in the blood and they have been implicated in glycemic regulation in the remission phase of type 1 diabetes. Here is the latest research.

Chromatin Regulation and Circadian Clocks

The circadian clock plays an important role in regulating transcriptional dynamics through changes in chromatin folding and remodelling. Discover the latest research on Chromatin Regulation and Circadian Clocks here.

Long COVID-19

“Long Covid-19” describes illness in patients who are reporting long-lasting effects of the SARS-CoV-19 infection, often long after they have recovered from acute Covid-19. Ongoing health issues often reported include low exercise tolerance and breathing difficulties, chronic tiredness, and mental health problems such as post-traumatic stress disorder and depression. This feed follows the latest research into Long Covid.

Spatio-Temporal Regulation of DNA Repair

DNA repair is a complex process regulated by several different classes of enzymes, including ligases, endonucleases, and polymerases. This feed focuses on the spatial and temporal regulation that accompanies DNA damage signaling and repair enzymes and processes.