Epitalon extended maximum survival and preserved estrous cycles in senescence-accelerated mice

Accelerated aging and spontaneous carcinogenesis represent intertwined biological processes where disruption of neuroendocrine signaling — particularly pineal-derived signals — is thought to accelerate both somatic decline and malignant transformation. The senescence-accelerated mouse (SAM) model offers a genetically defined substrate for studying these trajectories, with SAMP-1 (prone) and SAMR-1 (resistant) substrains diverging in aging rate and mortality kinetics. Standard interventions have not reliably separated lifespan extension from tumor suppression in this model. The tetrapeptide epitalon (Ala-Glu-Asp-Gly), a synthetic pineal gland-derived peptide, and melatonin are both being investigated as modulators of the neuroendocrine-aging axis, with particular interest in their capacity to preserve reproductive cyclicity and slow mortality doubling time as functional aging biomarkers.

Female SAMP-1 (prone) and SAMR-1 (resistant) senescence-accelerated mice received either melatonin 20 mg/ml in drinking water during nighttime hours 5 times per week monthly, or subcutaneous injections of epitalon (Ala-Glu-Asp-Gly) 1 mcg/mouse on the same schedule. Control groups were either intact or received 0.1 ml normal saline s.c. Primary endpoints included mean and maximum lifespan (10% last survivors), tumor incidence, estrous cycle regularity, body weight, body temperature, and food consumption monitored longitudinally across the animals' lifetimes.

As animals aged, body weight increased in both substrains while food consumption and body temperature remained stable; neither epitalon nor melatonin significantly altered these physiological parameters. Age-related irregular estrous cycles increased progressively in both SAMP-1 and SAMR-1, but treatment with both melatonin and epitalon prevented these disturbances. SAMP-1 showed features of accelerated aging relative to SAMR-1, including increased aging rate and decreased mortality doubling time. A direct correlation was observed between body mass at 3 and 12 months and longer lifespan across both substrains.

Epitalon treatment was followed by longer mean and maximum survival in the 10% of last survivors among SAMP-1, and extended tumor-free survival, though it did not significantly alter overall tumor incidence or time to tumor detection.

Melatonin additionally produced a decreased aging rate and increased mortality doubling time in SAMP-1. Malignant lymphomas predominated across both SAM substrains with no significant frequency difference between them. Neither melatonin nor epitalon affected tumor incidence or detection timing in SAMP-1; no link between either treatment and carcinogenesis was found in SAMR-1.

Written by TitrateLab, separately from the study summarized above.