The effects of cigarette or waterpipe smoke and immobilization on serum levels of TSH, T3 or T4 in male rats

The results of different studies have shown smoking can influence functions of thyroid gland. The aim of this study was to determine the effects of cigarette or water pipe smoking and immobilization on serum levels of TSH، T3 and T4 in male rats.

In this laboratory experimental study، male Wistar rats were randomly divided into the following groups: control،rats exposed to cigarette smoke، rats exposed to waterpipe smoke، chronically immobilized rats، and chronically immobilized rats exposed to cigarette or waterpipe smoke. Each group consisted of 5 rats. After 6 weeks blood samples were collected by cardiac puncture method. After obtaining serum، levels of TSH، T3 or T4 were measured by radioimmunoassay method. Data were statistically analyzed and compared among the groups by means of one way ANOVA.

Serum TSH levels were not significantly changed in experimental groups comaperd to control animals. Serum T3 and T4 levels were significantly increased in rats exposed to waterpipe smoke as compared to control animals (P<0. 01). There were also a significant increase in T3 and T4 levels in the rats exposed to cigarette smoke compared to control rats (P<0. 001 and P<0. 01، respectively). Serum levels of T3 or T4 showed no significant alterations in immobilized rats، but significantly increased in immobilized rats exposed to cigarette or waterpipe smoke in comparison to control or immobilized animals (P<0. 01).

Our findings showed that exposure to cigarette and water pipe smoke can increase serum levels of T3 or T4 and may be a predisposing factor in the development of hyperthyroidism.