Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly Peptides Normalize Thyroid Morphology, Immunity, and Hemostasis in Hypophysectomized Chickens

The pituitary gland plays a critical role in regulating numerous physiological processes, including thyroid function, immune responses, and hemostasis. Pituitary insufficiency, often modeled by hypophysectomy, leads to widespread systemic dysregulation. In particular, the absence of pituitary hormones can cause significant thyroid gland morphological changes, impair the body's immune defenses, and disrupt the delicate balance of blood coagulation, leading to hypercoagulation and depressed fibrinolysis. Current therapeutic approaches for pituitary dysfunction often involve hormone replacement, but novel, targeted peptide interventions could offer more precise or complementary strategies to restore specific organ functions and systemic balance.

Researchers investigated the effects of two synthetic tetrapeptides, Lys-Glu-Asp-Gly (derived from the anterior pituitary) and Ala-Glu-Asp-Gly (derived from the posterior pituitary), in hypophysectomized chickens. The study utilized two models: chickens subjected to neonatal hypophysectomy, which induces severe and pronounced impairments, and one-year-old birds hypophysectomized, exhibiting less severe but still significant disruptions. Peptides were administered via injection to the hypophysectomized birds. The primary endpoints included assessing changes in thyroid gland morphology (e.g., follicle size, colloid accumulation, thyrocyte nucleus-cytoplasm ratio), immune parameters, and hemostatic markers (e.g., coagulation and fibrinolysis). Control groups consisted of hypophysectomized birds that did not receive peptide treatment.

Neonatal hypophysectomy in chickens induced significant systemic dysregulation. Specifically, the thyroid gland exhibited enlarged follicles, substantial colloid accumulation, impressed follicular epithelium, an increased nucleus-cytoplasm ratio in thyrocytes, and atrophied inter-follicular epithelium. These morphological changes were accompanied by depressed immunity, a shift towards hypercoagulation, and depressed fibrinolysis. In one-year-old birds, similar impairments in thyroid morphology, immunity, and hemostasis were observed, though these were less pronounced compared to the neonatally hypophysectomized group. > Administration of Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly peptides to hypophysectomized birds effectively prevented the atrophic changes in the thyroid gland, restoring a more normal morphology. Furthermore, both peptides successfully normalized the previously depressed immune parameters and corrected the hemostatic imbalances, shifting them away from hypercoagulation and restoring fibrinolytic activity. The study demonstrated that these peptides could counteract the multi-systemic consequences of pituitary removal.