title: Morphological and biochemical changes in the Harderian gland of hypothyroid rats.
abstract: The secretory activity of the Harderian gland (HG) is influenced by both exogenous (such as light and temperature) and endogenous (such as prolactin, thyroid hormones and steroid hormones) factors, which vary among species. In the present study, the effects of hypothyroidism on the rat HG were examined at morphological and biochemical levels. The decrease in cytoplasmic lipoproteic vacuoles and the increase in mucosubstance secretion in the acinar lumina were the most notable histological effects elicited by hypothyroidism. The release of all granules with nuclei and cellular debris suggested the occurrence of holocrine secretion. Electron microscopy revealed in the glandular cells of hypothyroid rat an increased condensation of chromatin in the nuclei, mitochondria with decreased cristae and vacuolisation, decreased glycogen granules, autophagic vacuoles, and lipofuscins in the cytoplasm. TUNEL reaction indicated DNA fragmentation in hypothyroid HG, indicative of an underlying apoptotic process. Translocation of cytochrome c from mitochondria to cytosol strongly supported this hypothesis. In conclusion, these findings indicate that thyroid hormones play a pivotal role in preserving the structural integrity of the rat HG and, hence, its secretory activity.
authors.affiliation: Dipartimento di Scienze della Vita, Seconda Università degli Studi di Napoli, via Vivaldi, 43, 81100-Caserta, Italy.
authors.forename: Rossella
authors.initials: R
authors.lastname: Monteforte
authors.forename: Alessandra
authors.initials: A
authors.lastname: Santillo
authors.forename: Antonia
authors.initials: A
authors.lastname: Lanni
authors.forename: Salvatore
authors.initials: S
authors.lastname: D'Aniello
authors.forename: Gabriella Chieffi
authors.initials: GC
authors.lastname: Baccari
mesh_terms: D000818:Animals; D013956:Antithyroid Agents / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D005786:Gene Expression Regulation; D006243:Harderian Gland / Q000033:anatomy & histology* / Q000378:metabolism / Q000648:ultrastructure*; D007037:Hypothyroidism / Q000139:chemically induced / Q000378:metabolism*; D007480:Iopanoic Acid / Q000494:pharmacology; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D011441:Propylthiouracil / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D013956:Antithyroid Agents; D011441:Propylthiouracil; D045304:Cytochromes c; D007480:Iopanoic Acid