MOTS-c primes adrenal cortex metabolism without directly driving steroidogenesis.
This animal study investigated whether MOTS-c, a 16-amino acid mitochondrial-derived peptide, influences adrenal gland physiology in adult male Wistar rats. Sixteen rats received either continuous subcutaneous MOTS-c or saline for 24 hours via micro-osmotic pumps. The researchers used qRT-PCR, immunohistochemistry, ELISA, and RNA sequencing to assess adrenal tissue responses. The study first confirmed that endogenous MOTS-c expression was higher in the zona fasciculata/reticularis compared to the zona glomerulosa. MOTS-c treatment did not alter classical steroidogenic gene expression or circulating corticosterone and aldosterone levels. However, RNA sequencing identified 39 differentially expressed genes, most notably a 4.3-fold upregulation of the purinergic receptor P2ry4. The authors interpreted these findings as evidence that MOTS-c "primes" adrenocortical cells for steroidogenic responsiveness—via calcium signaling, lipid metabolism modulation, stress-response protein downregulation, and mitophagy inhibition—without directly stimulating basal hormone synthesis. Key limitations include the exclusive use of male rats, the short 24-hour treatment window, small sample size (n=16), and the absence of functional stimulation challenges (e.g., ACTH) to test the proposed "readiness" hypothesis.
Why this grade: All experimental work was conducted exclusively in male Wistar rats (n=16) with no human subjects or human-derived tissue, providing no direct evidence of effects in humans.
Introduction Mitochondrial open reading frame of the 12S rRNA type-c (MOTS-c), a 16-amino acid mitochondrial-derived peptide, regulates cellular metabolism through AMPK and mTOR signaling and exerts protective effects across multiple endocrine tissues. However, its role in adrenal physiology remains unexplored. We hypothesized that MOTS-c establishes "steroidogenic readiness" by priming metabolic pathways rather than directly activating hormone synthesis. Material and methods Adult male Wistar rats (n = 16) received continuous MOTS-c (0.1 μmol/24 h) or saline via subcutaneous micro-osmotic pumps for 24 hours. Adrenal tissues were analyzed using qRT-PCR, immunohistochemistry, ELISA, and RNA-sequencing. Results MOTS-c showed significantly higher expression in ZF/ZR vs. ZG. MOTS-c treatment did not alter classical steroidogenic genes or circulating corticosterone and aldosterone levels. RNA-seq identified 39 differentially expressed genes, notably upregulation of purinergic receptor P2ry4 (4.3-fold, P Conclusions MOTS-c functions as a metabolic conductor that primes adrenocortical cells for enhanced steroidogenic responsiveness without stimulating basal hormone synthesis. By upregulating calcium signaling, modulating lipid metabolism, downregulating stress-response proteins, and inhibiting mitophagy, MOTS-c establishes a preparatory metabolic state optimized for subsequent ACTH or stress stimulation. These findings reveal a novel preparatory mechanism in adrenal physiology and identify MOTS-c as a potential therapeutic target for HPA axis disorders requiring enhanced adrenal reserve capacity without basal hypercortisolemia.
Educational summary of published research — not medical advice. Full text is shown only where licensing permits.