Deiodinase type 1 activity is expressed in the prostate of pubescent rats and is modulated by thyroid hormones, prolactin and sex hormones

Abstract

The aim of this study was to characterize the type of 5 0 -deiodinase activity in the prostate of pubescent rats (7-8 weeks), to establish its distribution in the lobes (ventral, dorsolateral, and anterior), and to analyze its modulation by prolactin (PRL), testosterone, dihydrotestosterone (DHT), and 17b-estradiol (E 2 ). Our results showed that the enzymatic activity was highly susceptible to inhibition by 6-n-propyl-2-thiouracil and gold thioglucose, its preferential substrate was reverse tri-iodothyronine (rT 3 ), it exhibited a low dithiothreitol requirement (5 mM), and the apparent K m and V max values for substrate (rT 3 ) were approximately 0$25 mM and 9$0 pmol liberated/mg protein per hour, respectively. All these characteristics indicate the preferential expression of type 1 deiodinase (D1), which was corroborated by demonstrating the presence of D1 mRNA in prostate.D1 activity was detected in all lobes and was most abundant in the dorsolateral. Although we detected type 2 deiodinase (D2) mRNA expression, the D2 activity was almost undetectable. D1 activity was enhanced in animals with hyperthyroidism and hyperprolactinemia, in intact animals treated with finasteride (inhibitor of local DHT production), and in castrated animals with E 2 replacement. In contrast, activity diminished in castrated animals with testosterone replacement. Our results suggest that thyroid hormones, PRL, and E 2 exert a positive modulation on D1 activity, while testosterone and DHT exhibit an inhibitory effect. D1 activity may be associated with prostate maturation and/or function.

The Impact of Iodine Excess on Thyroid Hormone Biosynthesis and Metabolism in Rats

“…Recently, several methods have been used to detect tissue D1 activity [8,[32][33][34][35][36]. The method described here has been proved to be reliable, reproducible, and sensitive.…”

Postejaculatory Increase of Prostatic Triiodothyronine (T3) Depends on Sympathetic Innervation in the Rat1

“…However, studies from our laboratory have shown a strong association between D1 activity and local T 3 generation in tissues of the male reproductive system, such as the epididymis and prostate gland. In both tissues, D1 activity is present at the onset of puberty and sexual maturity [17,18]. In non-sexually active males, we have found that the prostate T 3 concentration decreases with age, but long-term (1 and 5 months) continuation of sexual activity prevents the age-related decline [19].…”

“…In non-sexually active males, we have found that the prostate T 3 concentration decreases with age, but long-term (1 and 5 months) continuation of sexual activity prevents the age-related decline [19]. It has been demonstrated that prostate D1 activity is under a complex endocrine control, mediated by inhibitory (androgens) and stimulatory (estrogens, prolactin, hyperthyroidism) factors [17]. During copulatory behavior, the emission/ ejaculation phases are accompanied by an acute trigger of the sympathetic and parasympathetic pathways [20,21]; however, a neural involvement in prostate D1 regulation has not been assessed.…”

Profile of Sex Steroids at Early Stages of Liver Metastasis From Sarcoma 45 in Male Rats

“…Известно, что ароматаза содержится преиму-щественно в клетках стромы ПЖ и обеспечивает локальный синтез эстрогенов (эстрадиола, эстрона, эстриола) из локальных форм андрогенов (5α-андро-стендиона, 5α-дигидротестостерона и 17-гидрокси-тестостерона) [8]. Оказывать влияние на функцио-нирование ПЖ могла не только гипо-Е 2 -емия, но и гипо-ПРЛ-емия и гипер-Тсв-емия, так как известно, что ПРЛ и Е 2 , наряду с гормонами щитовидной же-лезы, оказывают положительную модуляцию, а Т демонстрирует ингибирующий эффект на актив-ность дейодиназы 1 типа, расположенной в ПЖ [9].…”

“…Уменьшать продукцию Т в семенниках в этот пе-риод по механизму отрицательной обратной связи мог предшествующий (на 1-й неделе) рост Е 1 в ПЖ [9]. В ПЖ, напротив, значительно увеличивалась концентрация Тобщ, при этом уровень Тсв не изме-нялся, а ССГ -уменьшался.…”