|
This study examined the effect of alcohol(AL) and/or paraquat(PQ) on serum TSH, thyroid hormones and enzyme activities, and the protective effect of selenium(SE) against alcohol and/or paraquat-induced thyroid toxicity in guinea pigs. The experimental group consisted of control, 15% alcohol(AL), 4ppm sodium selenite(SE), 200ppm paraquat(PQ), AL+PQ, AL+SE, PQ+SE and AL+PQ+SE mixed in drinking water-fed guinea pigs for 4 weeks. The morphological changes of thyroid gland were studied on paraffin-embedded sections stained with H-E stain. Body weight losses, high serum concentration in TSH and cholesterol, and low values in triiodothyronine(T₃), thyroxine(T₄), free T₄ and alkaline phosphatase(ALP) were produced in the groups fed AL and/or PQ. We also noted that AL+PQ-fed group was marked increase in serum TSH. In AL or AL+PQ-fed groups when compared to control group had increased the ratio of thyroid weight to body weight(ratio Twt/Bwt), whereas the ratio Twt/Bwt was decreased in SE or PQ-fed groups. However, the serum TSH, T₃, T₄, free T₄ and cholesterol values, and the ratio Twt/Bwt were reversed in groups given the combination of SE, compared with AL and/or Pq-fed groups, also ALP values were reversed in groups given the combination of SE, comparted with AL or AL+PQ-fed groups. In microscope, morphological changes showed a remarkable between the AL or PQ-fed group and controls. In AL+PQ+SE-fed guinea pig, follicular colloid is high density in thyroid follicle and iincreased in connective tissue around the thyroid cells, and thyroidal epithelia were composed of cuboidal or columnar epithelium. This indicated that the morphological changes of thyroid were direct action in the thyroid cell. The results of this study confirmed that the toxic effect of AL or PQ on thyroid occur independently of changes in liver function. and that SE confers marked protection against AL or PQ-induced thyroid toxicity.
|