The Effect of Humic Acid Substances on the Thyroid Function and Structure in Lead Poisoning

Abstract

KeywordsLead poisoning, humic acid substances, thyroid gland, chicken.Submitted: April/2016 Approved: August/2016 ABSTRACT Lead (Pb) is a heavy metal, which adversely affects thyroid gland function and structure. Due to its high molecular weight and abundant functional groups, humic acid substances (HAS) can form chelates with heavy metals. The experiment was conducted to evaluate the prophylactic effect of HAS on thyroid hormone levels and histopathological lesions of laying hens exposed to lead (Pb) poisoning. After a week of adaptation, 192 Lohmann White laying hens (25 weeks of age) were fed one of four diets: a basal diet (BD) or the BD with HAS (0.15%), with Pb (0.3 g/kg), or with both. Experimental groups were replicated in 12 cages, with four hens each. Pb poisoning did not alter triiodothyronine (FT 3 ; 3.22 ± 0.20 ng/dL) or thyroxine (FT 4 ; 0.71 ± 0.08 ng/dL) concentrations, but caused a 167% increase in thyroid stimulating hormone (TSH) concentration. HAS supplementation returned the high TSH levels of hens exposed to Pb poisoning to normal values. Degenerative changes in the epithelial cells of the thyroid gland of the hens exposed to Pb poisoning were evidenced. Connective tissue cells in the interfollicular area and total amount of colloids with partially atrophic follicles were observed. These histopathological findings were less severe when HAS was added to the diet. In conclusion, HAS alleviates the effects of Pb poisoning on thyroid gland function and structure, possibly preventing its internalization by the tissue by forming chelates and exerting antiinflammatory effects.

The Consequences of Heavy Metals Resulting from Terrorist Operations in Three Regions of Baghdad, Iraq on Thyroid Function

“…in concurrence with existing study, Thyrotropin blood elevated in the levels of workers expos-ed to Pb -and source-of-lead. (11). (2) shows the means, standarddeviation, maximum and minimum of thyroxine (T4), Thyrotropin (TSH) triiodothyronine (T3), and Thyroglobulin-Ab (Tg-Ab) for the three studied groups.…”

Impact of humate substances and Bacillus subtilis PB6 on thyroid activity and histomorphometry, iron profile and blood haematology of quail

“…Laurberg et al (2003) stated that HS might be goitrogenic because it releases substances during intestinal degradation which inhibit one or more enzymes and transporters involved in thyroid hormone production. Sahin et al (2016) illustrated that feeding 0.15% HS may bind heavy metals and play a role in the recovery of thyroid gland structure and function. In the present study, addition of HS alone did not improve the thyroid activity, whereas the administration of HS in combination with B .…”

Association between blood lead levels and metabolic syndrome considering the effect of the thyroid-stimulating hormone based on the 2013 Korea National health and nutrition examination survey

“…KNHANES data also include the data on serum levels of fT4, which are also widely used as a measure of thyroid function, but we did not determine the effect of fT4 on the association between blood lead and MetS. However, TSH is independently affected by lead exposure regardless of other thyroid hormones [9,29,41], whereas the effect on other thyroid hormones is associated with the duration of exposure to lead [9]. Since KNHANES does not provide relevant data on the duration of exposure to environmental risk factors, it would be inappropriate to use fT4 as an indicator of thyroid function.…”