It has been known that the cold stress inducts the adrenergic system and increases tyrosin hydroxylase (TH) enzyme activity which has a key role on the catecholamine synthesis. In this study, the effects of epinephrine and cold stress on TH enzyme activity and total RNA level of rat adrenal medulla, heart and hypothalamus were examined comparatively. It was found that there was clear increase of TH enzyme activities and total RNA concentrations in three tissues with administration of epinephrine. It was also observed that there was an increase in TH enzyme activity at the end of the 48-hour cold stress treatment. Similarly, total RNA concentration was increased in heart and hypothalamus except adrenal medulla.
Key words: Epinephrine, Cold Stress, Tyrosine Hydroxylase, Rat
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