Interplay Between Thyrotroph Morphometry and Circulating Thyroid Hormones in Lactating and Non-Lactating Female Camels (Camelus dromedarius).

Abstract

This study investigated the morphometric characteristics of adenohypophyseal thyrotrophs and circulating thyroid hormone profiles in dromedary camels (Camelus dromedarius) in relation to age and lactation status. Clinically healthy Brela breed camels were divided into lactating female, and non-lactating female groups across two age categories (5-10 years and ≥11 years), with fifty animals per group. Blood samples were collected before slaughter and pituitary glands were collected post-slaughter and processed for immunohistochemical detection of thyroid-stimulating hormone (TSH) using anti-porcine TSHβ antibody, while morphometric measurements of thyrotrophs were conducted through image analysis. Plasma concentrations of TSH, triiodothyronine (T₃), and thyroxine (T₄) were quantified using validated ELISA and enzyme immunoassay kits. Group differences were analyzed using one-way ANOVA followed by post hoc comparisons, with statistical significance set at p < 0.05. Morphometric analysis revealed that lactating female camels exhibited significantly higher thyrotroph counts compared with non-lactating counterparts, whereas non-lactating females displayed larger cell and nuclear dimensions. Age influenced these patterns, with older camels showing hypertrophied thyrotrophs but reduced functional plasticity compared to younger animals. Plasma hormone assays demonstrated that non-lactating camels had higher TSH and T₄ concentrations, while lactating camels maintained elevated T₃ levels, suggesting enhanced peripheral conversion of T₄ to T₃ during milk production. Additionally, younger camels exhibited higher T₃ concentrations than older animals, indicating age-related decline in thyroidal activity. These findings highlight the dynamic regulation of the hypothalamic-pituitary-thyroid axis in camels, demonstrating how lactation and age shape thyroidal morphology and function to meet diverse physiological demands. These findings not only broaden the comparative endocrinology of underexplored species but also provide physiopathological insights relevant to farm animal management, lactation efficiency, and adaptive metabolism in harsh environments.