Related Experiment Video
Updated: Aug 18, 2026

Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures
Published on: November 11, 2016
Twenty-four hour profiles of four hormones under constant routine
M Uchiyama1, K Ishibashi, T Enomoto
1Department of Psychophysiology, National Institute of Mental Health, Ichikawa, Japan.
Abstract:
We studied the circadian features of melatonin, cortisol, thyroid stimulating hormone (TSH), and growth hormone (GH) together with rectal temperature during 36 h continuous forced wakefulness without physical exercise under dim light condition (constant routine). Subjects consisted of four healthy men aged 22-24 years. Blood sampling was conducted hourly, and food and water were supplied bi-hourly during the constant routine. Melatonin, TSH and cortisol displayed clear circadian rhythms under constant routine condition. While GH secretion was unlikely to be driven solely by the circadian pacemaker, its suppression round BT nadir may indicate that GH secretion was modulated to some extent by circadian rhythm.
Related Concept Videos
Feedback Loops
Types of Hormones
An Overview of the Endocrine System
The endocrine system collaborates...
Types of Hormones
Steroids and eicosanoids fall under the category of lipid-soluble hormones. Steroids are derived from cholesterol and feature four interconnected carbon rings with variable side chains. Notable examples include estradiol from ovaries and testosterone from testes, exemplifying the critical roles of these lipid-soluble hormones in reproductive physiology. Eicosanoids, derived...
Target Cell Response to Hormones
Notably, the cellular response can be regulated by altering the number of receptors expressed in the cell. For example, prolonged exposure to elevated hormone levels results in a gradual decline or down-regulation in the number of receptors for that specific hormone on the cell surface. Conversely, in response to low hormone levels, cells may use up-regulation, producing an...
Regulation of Hormone Secretion
Humoral stimuli,...

