Influence of thyroid hormone on thyroid hormone receptor beta-1 expression and lacrimal gland and ocular surface morphology.
OBJECTIVE
Hormone diseases induce changes in the lacrimal gland (LG) and ocular surface (OS). Thyroid hormone (TH) induces cell proliferation and lipid metabolism through the activation of TH receptors. The aim of the present study was to evaluate the location and comparative expression of TH receptor beta-1 (Thrb) in LG of rats with hypothyroidism and in controls and to evaluate the impact of this disease on LG and OS structure and function.


METHODS
Hypothyroidism was induced in Wistar male rats by the long-term use of tiamazole. Ten weeks later corneal cells were collected for impression cytology (IC). Rats were humanely killed, and tissues were evaluated by immunoperoxidase staining and Western blot for Thrb. The content of malondialdehyde (MDA) and acetylcholine (ACh) in LG was determined by spectrophotometry (n = 5/group in all experiments).


RESULTS
LG weight was significantly lower in hypothyroid rats (P < 0.05). Western blot analysis indicated that LGs express Thrb and that hypothyroidism induces a higher expression of this receptor. IC was significantly different and ACh was significantly lower in hypothyroid rats (P < 0.05).


CONCLUSIONS
Chronically reduced levels of TH lead to biochemical and structural changes and modulate the levels of Thrb in LG. These events confirm that LG is a target organ for TH and may facilitate understanding of the mechanism related to dry eye in hypothyroidism.
Dias
Ana Carolina
AC
Departamento de Oftalmologia, Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil.
Módulo
Carolina Maria
CM
Jorge
Angélica Gobbi
AG
Braz
Alexandre Martins
AM
Jordão
Alceu A
AA
Filho
Rubens Bertazolli
RB
de Paula
Jayter Silva
JS
Rocha
Eduardo Melani
EM
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D003228:Conjunctiva / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D007037:Hypothyroidism / Q000139:chemically induced / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D007765:Lacrimal Apparatus / Q000378:metabolism*; D015227:Lipid Peroxidation; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D008713:Methimazole; D018384:Oxidative Stress; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D037042:Thyroid Hormone Receptors beta / Q000378:metabolism*; D013963:Thyroid Hormones / Q000502:physiology*
D037042:Thyroid Hormone Receptors beta; D013963:Thyroid Hormones; D008315:Malondialdehyde; D008713:Methimazole; D009195:Peroxidase; D005978:Glutathione; D000109:Acetylcholine