The thymus-adrenal connection: thymosin has corticotropin-releasing activity in primates.
Healy. D L DL; Hodgen. G D GD; Schulte. H M HM; Chrousos. G P GP; Loriaux. D L DL; Hall. N R NR; Goldstein. A L AL
Key Findings
- Thymosin fraction 5 caused dose‑ and time‑dependent increases in ACTH, cortisol, and beta‑endorphin in prepubertal cynomolgus monkeys.
- Synthetic component peptides of the fraction, such as thymosin‑α1, showed no acute impact on pituitary hormone release.
- Total thymectomy in juvenile macaques reduced plasma levels of cortisol, ACTH, and beta‑endorphin, indicating a thymus‑derived corticotropin‑releasing activity.
Practical Outcomes
- For biohackers, this study suggests that whole thymus extracts may affect stress‑hormone pathways, but isolated thymosin‑α1 likely does not. Using thymosin‑α1 for HPA‑axis modulation is probably ineffective, and any protocol aiming to boost cortisol or ACTH should consider whole‑extract products rather than the single peptide.
Summary
In young monkeys, a mixture called thymosin fraction 5 raised stress hormones (ACTH, cortisol) and beta‑endorphin when given by IV, but the individual synthetic pieces, including thymosin‑α1, did not have this effect. Removing the thymus lowered those hormones, suggesting the thymus itself can influence the pituitary‑adrenal system during development.
Abstract
Endotoxin-free thymosin fraction 5 elevated corticotropin, beta-endorphin, and cortisol in a dose- and time-dependent fashion when administered intravenously to prepubertal cynomolgus monkeys. Two synthetic component peptides of thymosin fraction 5 had no acute effects on pituitary function, suggesting that some other peptides in thymosin fraction 5 were responsible for its corticotropin-releasing activity. In agreement with these observations, total thymectomy of juvenile macaques was associated with decreases in plasma cortisol, corticotropin, and beta-endorphin. These findings indicate that the prepubertal primate thymus contains corticotropin-releasing activity that may contribute to a physiological immunoregulatory circuit between the developing immunological and pituitary-adrenal systems.
Study Information
pubmed
1983
1983-12-23T00:00:00.000Z
10.1126/science.6318312