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The neonicotinoid pesticide imidacloprid and the dithiocarbamate fungicide mancozeb disrupt the pituitary-thyroid axis of a wildlife bird.
- Source :
-
Chemosphere [Chemosphere] 2015 Mar; Vol. 122, pp. 227-234. Date of Electronic Publication: 2014 Dec 12. - Publication Year :
- 2015
-
Abstract
- Thyroid is an important homeostatic regulator of metabolic activities as well as endocrine mechanisms including those of reproduction. Present investigation elucidated the thyroid disrupting potential of a neonicotinoid imidacloprid and a dithiocarbamate mancozeb in a seasonally breeding wildlife bird, Red Munia (Amandava amandava) who is vulnerable to these two pesticides through diet (seed grains and small insects). Adult male birds were exposed to 0.5% LD50 mgkg(-1)bwd(-1) of both the pesticides through food for 30days during the preparatory and breeding phases. Weight, volume and histopathology of thyroid gland were distinctly altered. Disruption of thyroid follicles reflected in nucleus-to-cytoplasm ratio (N/C) in epithelial and stromal cells, epithelial cell hypertrophy and altered colloid volume. Impairment of thyroid axis was pesticide and phase specific as evident from the plasma levels of thyroid (T4 and T3) and pituitary (TSH) hormones. In preparatory phase, plasma TSH was increased in response to decrease of T4 on mancozeb exposure showing responsiveness of the hypothalamic-pituitary-thyroid (HPT) axis to feedback regulation. On imidacloprid exposure, however, plasma levels of both T4 and TSH were decreased indicating non-functioning of negative feedback mechanism. Increased plasma T3 in response to both the pesticides exposure might be due to synthesis from non-thyroidal source(s) in a compensatory response to decrease level of T4. In breeding phase, impairment of HPT axis was more pronounced as plasma T4, T3 and TSH were significantly decreased in response to both mancozeb and imidacloprid. Thus, low dose pesticide exposure could affect the thyroid homeostasis and reproduction.<br /> (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Subjects :
- Animals
Body Weight drug effects
Cell Nucleus Size drug effects
Environmental Exposure adverse effects
Environmental Monitoring
Epithelial Cells cytology
Epithelial Cells drug effects
Male
Neonicotinoids
Organ Size drug effects
Passeriformes anatomy & histology
Passeriformes metabolism
Pituitary Gland anatomy & histology
Pituitary Gland cytology
Pituitary Gland physiology
Stromal Cells cytology
Stromal Cells drug effects
Thyroid Gland anatomy & histology
Thyroid Gland cytology
Thyroid Gland physiology
Thyroid Hormones blood
Thyrotropin blood
Fungicides, Industrial toxicity
Imidazoles toxicity
Maneb toxicity
Nitro Compounds toxicity
Passeriformes physiology
Pituitary Gland drug effects
Thyroid Gland drug effects
Zineb toxicity
Subjects
Details
- Language :
- English
- ISSN :
- 1879-1298
- Volume :
- 122
- Database :
- MEDLINE
- Journal :
- Chemosphere
- Publication Type :
- Academic Journal
- Accession number :
- 25496744
- Full Text :
- https://doi.org/10.1016/j.chemosphere.2014.11.061