Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly peptides restore thymus morphology in hypophysectomized young and old chickens

The thymus is a primary lymphoid organ critical for T-cell development and immune function, which naturally involutes with age. The pituitary gland plays a crucial role in regulating thymic activity, with its hormones influencing thymocyte proliferation and differentiation. Hypophysectomy, the surgical removal of the pituitary, leads to severe thymic atrophy and immune deficiency, particularly in younger individuals. Current strategies to restore thymic function often involve complex hormonal therapies or growth factors. This study explores novel short peptides, derived from pituitary complexes, as potential agents to counteract hypophysectomy-induced thymic damage and support immune system recovery.

Researchers investigated the effects of two synthetic peptides, Lys-Glu-Asp-Gly (derived from the anterior pituitary) and Ala-Glu-Asp-Gly (derived from the posterior pituitary), on thymic morphology. The study utilized chicks of different ages (young and old) that underwent hypophysectomy. The peptides were administered to these hypophysectomized birds, though specific doses, routes, or frequencies were not detailed in the abstract. The primary endpoint was the recovery of the morphological structures of the thymus, assessed via histological examination to observe changes in thymic architecture and cellular composition.

Hypophysectomy induced significant morphological changes in the thymus, with the most pronounced alterations observed in neonatal hypophysectomy models. These changes were comparatively less severe in old chicks. Administration of both Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly peptides to hypophysectomized birds, irrespective of their age, consistently promoted the recovery of the thymus's morphological structures. This indicates a restorative capacity for both peptides on thymic integrity. Notably, the anterior pituitary-derived peptide, Lys-Glu-Asp-Gly, demonstrated a more pronounced and robust effect on the recovery of thymic structure compared to the posterior pituitary-derived peptide, Ala-Glu-Asp-Gly. This suggests a differential efficacy linked to their origin or specific amino acid sequence. The study qualitatively highlights the ability of these peptides to mitigate the severe thymic atrophy induced by pituitary removal.

Lys-Glu-Asp-Gly had a more pronounced effect on the recovery of thymic structure than Ala-Glu-Asp-Gly.