title: Effect of acute hexavalent chromium exposure on pituitary-thyroid axis of a freshwater fish, Channa punctatus (Bloch).
abstract: Acute exposure to hexavalent chromium (10 mg L(-1) , 20 mg L(-1) , and 40 mg L(-1) potassium dichromate for 96 h) dose-dependently affected the pituitary-thyroid axis of teleost, Channa punctatus. Significant hypertrophy of the thyroid follicle was observed in 20 mg L(-1) and 40 mg L(-1) groups; the follicular epithelium was however hypertrophied only in 40 mg L(-1) group. The colloid depletion in the lumen of thyroid follicle was evident in 20 mg L(-1) and 40 mg L(-1) groups. Serum thyroid hormones (thyroxine/T4 and triiodothyronine/T3) level increased significantly at both the higher doses. Increased immunointensity and significant hypertrophy of the pituitary thyrotrophs (anti TSHβ-immunoreactive cells) was observed in both 20 mg L(-1) and 40 mg L(-1) chromium-exposed fish. The increased thyroid hormones secretion observed in this study might be an adaptive response of the pituitary-thyroid axis under acute chromium-induced stress condition to maintain homeostasis. The long-term Cr(VI) exposures, however, may lead to attenuation/exhaustion of the pituitary-thyroid axis and pose serious threat to fish health and affect their population.
authors.affiliation: Department of Zoology, University of Allahabad, Allahabad, 211002, Uttar Pradesh, India.
authors.forename: Ashish K
authors.initials: AK
authors.lastname: Mishra
authors.affiliation: Department of Zoology, University of Allahabad, Allahabad, 211002, Uttar Pradesh, India.
authors.forename: Banalata
authors.initials: B
authors.lastname: Mohanty
mesh_terms: D000818:Animals; D002857:Chromium / Q000633:toxicity*; D007150:Immunohistochemistry; D010473:Perciformes / Q000502:physiology*; D010902:Pituitary Gland / Q000187:drug effects* / Q000473:pathology; D010907:Pituitary Hormones / Q000097:blood; D013961:Thyroid Gland / Q000187:drug effects* / Q000473:pathology; D013963:Thyroid Hormones / Q000097:blood
chemical_list: D010907:Pituitary Hormones; D013963:Thyroid Hormones; D002857:Chromium; C074702:chromium hexavalent ion
keywords: Channa punctatus; acute exposure; hexavalent chromium; histopathology; hormone assay; immunocytochemistry; pituitary-thyroid axis