In one of the first studies to explore the interrelationships between hormones from different hypothalamic-pituitary-target gland axes over 24 hours, there was evidence of interaction between distinct hormonal axes in healthy older adults, according to study results published in The Journal of Clinical Endocrinology & Metabolism.
The interplay between central and peripheral feedback signals dictates the pituitary hormone secretion pattern, which depends on the changing needs of the organism, aiming to maintain homeostasis in the body. Furthermore, anterior pituitary cells share the same embryonic origin. For these reasons, researchers have theorized that changes in these hormones might be synchronized with each other.
As limited data are available on the interplay of hormones from different hypothalamic-pituitary-target gland axes, the goal of the current study was to explore the interrelationships between growth hormone [GH], thyroid stimulating hormone [TSH], adrenocorticotropic hormone [ACTH], and cortisol in healthy older men and women.
The researchers analyzed 24-hour hormone concentrations series at intervals of 10 minutes from 38 healthy older people (aged 52-76 years; 20 men and 18 women) who participated in the Leiden Longevity Study in The Netherlands. They examined whether there were differences in the interrelationships between hormones in the offspring of long-lived families and their partners or between the sexes.
Cross-correlation analyses were completed to assess the relative strength between two 24-hour hormone concentration series for all possible time shifts. The researchers also performed cross-approximate entropy analyses to assess pattern synchronicity between the different 24-hour series.
ACTH was positively correlated with cortisol, with a mean maximal correlation coefficient of 0.78 (95% CI, 0.74-0.81) at lag time 10, which indicated that cortisol concentrations followed ACTH concentrations with a delay of 10 minutes. The cross-correlation between ACTH and cortisol was stronger during the night hours. No significant cross-correlations were found between cortisol and GH or between ACTH and GH.
Cortisol and TSH concentrations were negatively cross-correlated, as TSH followed cortisol concentrations with a delay of 170 minutes, with a mean correlation coefficient of -0.30 (95% CI, -0.36 to -0.25). Also between lag times 90 and 180, cortisol and TSH were significantly negatively correlated, which indicated that cortisol concentrations were negatively followed by TSH with a delay of 90 to 180 minutes. The researchers also found a positive mean correlation coefficient of 0.29 (95% CI, 0.22-0.37) between TSH and GH concentrations without any delay.
The cross-approximate entropy analyses showed that GH and cortisol were synchronized in serum concentration patterns. As there were notable differences in cross-approximate entropy values between lights-on and light-off periods, the researchers stated that “the pattern synchronicity between the hormones is dependent on the time of the day.”
There were no major sex differences in cross-correlations, except a positive correlation without any delay between cortisol and TSH concentrations found in women but not in men. In addition, the researchers noted no major differences in interrelationships between hormones in the offspring of long-lived families and partners.
The researchers noted that due to the innovative approach of this study, there are no similar studies to support the findings, adding that this is a more descriptive than conclusive study.
“More research is needed to determine the biological meaning and clinical consequences of these interrelationships between pituitary hormones,” concluded the researchers.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
van der Spoel E, Roelfsema F, Akintola AA, et al. Interrelationships between pituitary hormones as assessed from 24-h serum concentrations in healthy older subjects [published online December 19, 2019]. J Clin Endocrinol Metab. doi:10.1210/clinem/dgz253