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Clinically asymptomatic hypothyroidism secondary to hypercortisolism in Wistar rats (911.3)
Author(s) -
Novais Renata,
Fonseca Fabrícia,
LaureanoMelo Roberto,
Araújo Iracema,
Seara Fernando,
Mecawi Andre,
Silva Alba,
Reis Luis
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.911.3
Subject(s) - medicine , endocrinology , hormone , triiodothyronine , adrenocorticotropic hormone , thyroid , asymptomatic , corticosterone , deiodinase , thyroid stimulating hormone
Hypothyroidism is the result of inadequate production of thyroid hormone or inadequate action of thyroid hormone in target tissues. Hypothyroidism can be seen secondary to hyperadrenocorticism with an overlapping clinical signs. We intend to demonstrate that clinical symptoms of hypothyroidism secondary to hyperadrenocorticism can be undetectable even if there is already evidence of hormonal disease. Male Wistar rats (~ 280g, n = 7) were submitted to daily subcutaneous administration of 200µg of adrenocorticotropic hormone (0.2ml ACTH 1‐24 synthetic 1mg/ml) or vehicle (NaCl 0,9% 0.2ml) for 7 days. At the end of the experiment, were obtained the values of plasmatic thyroid hormones (TH): T3 (Triiodothyronine) and T4 (Thyroxine) by chemiluminescence method; serum corticosterone, TSH (Thyroid Stimulating Hormone) and hypothalamic and pituitary type 2 deiodinase (D2) by radioimmunoassay technique. ACTH group obtained significant elevated level of corticosterone (p < 0.05) and low levels of HT (p < 0.0001). Despite, TSH levels showed no significant difference between groups, ie, compatible with hypothyroidism secondary to hypercortisolism. Additionally, D2 levels showed no significant differences between groups, demonstrating that those tissues did not represent important sources of reducing HT in our protocol. Although it has been demonstrated hormonal difference between the groups, no clinical signs were detected in ACTH group. These data suggest that the lack of symptoms of hypothyroidism and hyperadrenocorticism in this protocol can be attributed to early of the syndrome, once hormone values could be able to confirm both diseases. Grant Funding Source : Supported by FAPERJ, CNPq and CAPES