The study's objective is to evaluate the enhanced effect of the ghrelin on the body weight and thyroid hormones in male rats after inducing hyperthyroidism by L–thyroxin. The rats (95 males) were split into two groups. The first group consisted of 25 male rats that were given normal saline for 30 days S.C and set as a control group. While the remainder of the animals were given levothyroxine 500g/kg subcutaneously for 30 days to induce hyperthyroidism. after induction the divided into 4 groups as followe ,the first one was the control group that mentioned previously, the second group was male rats were given normal saline for 30 days S.C, the third group was male rats were given ghrelin at a dose of (0.5nmol/100μl saline) for 30 days S.C, and the fourth group was male rats (1nmol/100μl saline) for 30 days S.C.   The fifth group consisted of hyperthyroidism male rats that was given ghrelin at a dosage of (2nmol/100μl saline) for 30 days S.C. The results of final weight and weight gain are presented showed no significant difference in initial weight within all groups that were observed, while a significant decrease in final body weight in hyperthyroidism group compared with control group. On the other hand, the results revealed a significant decrease in body weight gain in male rats have hyperthyroidism compared with the control group. While the results observed a significant increase final body weight and body weight gain in all treated rats with ghrelin as compared with hyperthyroidism group. On other hand, the effect of hyperthyroidism on serum TSH, T3, and T4 concentrations revealed that the hyperthyroidism group had a significant rise in serum T3 and T4 concentrations when compared to the control group. While no significant drop in serum TSH concentration was observed in all hyperthyroidism groups handled with ghrelin (0.5, 1 and 2 nmol) as compared to the hyperthyroidism group, a significant decrease in serum T3 and T4 level was observed in all hyperthyroidism groups treated with ghrelin in comparison to the group of hyperthyroidism. Ghrelin peptide hormone and it has been shown to have potential effects on the body weight and thyroid hormone.

This study was carried out in Veterinary Medicine College / University of Basrah to investigate the effect of Bisphenol A on thyroid, liver and testicular functions. A total of 24 adult male rats were randomly divided into four equal groups, six animals in each group. Animal of group (1) served as control and received a daily oral administration of corn oil throughout the experimental protocol. Animals of group 2, 3 and 4 were administered orally 50,100 and 200 mg/kg body weight of BPA respectively dissolved in corn oil, the experiment extended for 30 days. The results of the present study showed a significant decrease in serum thyroxin (T4) concentration and a significant increase in serum aspartate aminotransferase ( AST) and alanine aminotransferase ( ALT) concentration in bisphenol A treated groups. A significant decrease in serum testosterone and LH concentrations in all BPA-treated groups compared with control. On other hand non significant decrease in serum concentrations of FSH were observed in BPA-treated groups compared with control. A significant decrease in epididymal sperm count and sperms motility in all BPA treated groups. However no significant differences were noted in sperms viability between all BPA treatment groups and control. Histopathological changes were found in thyroid glands of male rats with different doses of BPA, also central vein dilation, enlarged nuclei, vacuolation of hepatocytes were observed in the liver of BPA treated groups and different degrees of histological changes include depression of spermatogenesis, decrease of leydig cells in dose dependent manner were found in testicular tissues of BPA treated groups.

Animals affected with Trypanosoma evansi show rare serum hormonal disturbances. One of the important hormones for livestock is thyroxin, and the level of thyroxin may be reduced during the T. evansi infection. The objective of the study was to investigate thyroxin level during experimentally induced T. evansi infection in Wister albino rats. Wistar albino white rats (n=12) were challenged with the local strain of T. evansi (at 5x105 trypanosomes/animal subcutaneously). At the high parasitemia, blood was collected from the rats, and serum was separated, which was subjected for biochemical evaluation. Decreased total serum thyroxin (2.91 ±0.04 µg/dL) and free thyroxin (1.30 ±0.05 ng/dL) levels (p<0.01) were recorded in T. evansi infected rats as compared to the control group of rats. Along with lowered thyroxin levels, decreased levels of total erythrocyte count, packed cell volume, hemoglobin, total leucocyte count, total serum proteins, albumin and glucose levels were recorded. On the other hand, significant increase (p<0.01) in cholesterol, blood urea nitrogen, serum alkaline phosphatase, serum aspartate aminotransferase, and serum alanine aminotransferase levels were observed. Thus, it is concluded that trypanosomiasis induces stress on rat, which have direct effect on thyroid hormone.