Quantitation of mRNA levels of steroid 5alpha-reductase isozymes: a novel method that combines quantitative RT-PCR and capillary electrophoresis

Bisphenol A modifies the regulation exerted by testosterone on 5 α -reductase isozymes in ventral prostate of adult rats

The development, growth, and function of the prostate gland depend on androgen stimulation. The primary androgen in prostate is 5α-dihydrotestosterone (DHT) which is synthesized from circulating testosterone (T) through the action of 5α-reductase (5α-R). Although 5α-R occurs as five isozymes, only 5α-R1 and 5α-R2 are physiologically involved in steroidogenesis. The endocrine disruptor bisphenol A (BPA) alters sexual organs, including the prostate. Our previous findings indicated that BPA decreased the expression of 5α-R1 and 5α-R2 in rat prostate but also circulating T. Thus, it is unclear whether BPA exerts this effect on 5α-R isozymes by reducing circulating T or by any other mechanism. In this study, we examine the effects of short-term exposure to BPA at doses below 25 μg/Kg/d and above 300 μg/Kg/d of the TDI on mRNA levels of 5α-R1 and 5α-R2 in prostate of adult castrated rats supplemented with T to achieve constant circulating T levels. mRNA levels were measured by absolute quantitative RT-PCR, T levels by RIA, and DHT levels by ELISA. Our results indicated that in castrated rats treated with T BPA at the two doses studied significantly decreased the mRNA levels of both 5α-R isozymes in a dose-dependent manner without modifications in circulating T.

Steroid 5α-reductase in adult rat brain after neonatal dihydrotestosterone administration

Testosterone (T) is known to play an important masculinizing role in the developing brain of rat, including the regulation of 5α-reductase (5α-R) isozymes. However, the effects of dihydrotesterone (DHT), a more potent androgen than T, have not been elucidated. In this study, DHT was administered from day 5 through day 20 of postnatal life (period of postnatal sexual differentiation of the central nervous system) at doses of: 12 mg/kg/d on days 5, 6, 7, 8, 19, and 20; 15 mg/kg/d on days 9, 10, 11, 12, 16, 17, and 18; and 18 mg/kg/d on days 13, 14, and 15. In adulthood, quantitative RT-PCR was used to measure mRNA levels of 5α-R1 and 5α-R2 isozymes in the prefrontal cortex (PFC) of male and female rats with varied androgenic status. Under our study conditions, neonatal DHT administration influenced on adult PFC 5α-R isozymes levels and their regulation pattern by androgens, and this pattern was the inverse of that reported in adult neonatally T-treated rats.

Effects of environmental stress on mRNA and protein expression levels of steroid 5alpha-Reductase isozymes in adult rat brain

Environmental stress conditions are important factors in human health and should be considered in the development of appropriate health policies, since they have been associated with psychological disorders and even with death. A link between stress and changes in 3alpha,5alpha-reduced neurosteroids has been reported. Steroid 5alpha-Reductase (5alpha-R) is the rate-limiting enzyme in the biosynthesis of 3alpha,5alpha-reduced neurosteroids. Using reverse transcription-polymerase chain reaction and immunohistochemistry, 5alpha-R isozymes (5alpha-R1 and 5alpha-R2) mRNA and protein levels were detected in prefrontal cortex of male and female rats after they underwent environmental stresses, i.e., excessive heat, artificial light, and the sensation of immobility in a small space, similar to those found in common workplace situations. Results showed significantly higher 5alpha-R2 mRNA and protein levels in environmentally-stressed versus control rats. Interestingly, a sexual dimorphism in 5alpha-R1 mRNA and protein levels was observed after environmental stress, with an increase in males and a decrease in females. This fact might explain gender differences in the incidence of some type of minor depression.

Effects of swim stress on mRNA and protein levels of steroid 5α-reductase isozymes in prefrontal cortex of adult male rats

The metabolite of progesterone, allopregnanolone, is among the most potent known ligands of the gamma-aminobutyric acid receptor complex (GABA(A)-R) in the central nervous system. This neuroactive steroid is markedly increased in an animal model of acute stress. Allopregnanolone is synthesized from progesterone by steroidogenic enzymes 5alpha-reductase (5alpha-R) and 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD), with the former being the rate-limiting enzyme in this reaction sequence. In this paper, a quantitative RT-PCR method coupled to laser-induced fluorescence capillary electrophoresis (LIF-CE) and Western blot were used to measure both mRNA and protein levels of 5alpha-R type 1 (5alpha-R1) and 5alpha-R type 2 (5alpha-R2) isozymes in prefrontal cortex of male rats after acute swim stress situations. Our results demonstrate that both 5alpha-R isozymes are significantly higher in prefrontal cortex of male rats after acute swim stress in comparison with control rats. These data may open up a new research line that could improve our understanding of the role of 5alpha-R isozymes in processes that accompany stress situations.

Effects of dihydrotestosterone on brain mRNA levels of steroid 5alpha-reductase isozymes in early postnatal life of rat

We studied the expression of type 1 (5alpha-R1) and type 2 (5alpha-R2) 5alpha-reductase isozymes (5alpha-R) and their regulation by dihydrotestosterone (DHT) in the prefrontal cortex of male and female rats during postnatal sexual differentiation of the central nervous system (CNS), using one-step quantitative RT-PCR coupled with laser-induced fluorescence capillary electrophoresis. We found a higher expression of 5alpha-R2, which is considered a masculinizing enzyme, in the female versus male CNS, and observed sexual dimorphism in the regulation of both 5alpha-R isozymes by DHT. These results open up a new research line that could improve understanding of the role of 5alpha-R isozymes in the physiology of the CNS.

Quantitation of mRNA levels of steroid 5alpha-reductase isozymes in the rat brain by "one-step" RT-PCR and capillary electrophoresis

The enzyme 5alpha-reductase (5alpha-R) is present in many mammalian tissues, including the brain. The physiological importance of 5alpha-R in the brain derives from its capability to convert testosterone (T) to a more potent androgen, dihydrotestosterone (DHT), and to convert progesterone to its 5alpha-reduced derivative, precursors of allopregnanolone, potent allosteric modulator of the gamma-aminobutyric acid receptor (GABA(A)-R). 5alpha-R occurs as two isoforms, 5alpha-R type 1 (5alpha-R1) and 5alpha-R type 2 (5alpha-R2). We present an accurate, rapid, and modestly labor-intensive method to precisely quantitate 5alpha-R mRNA species in the cerebral cortex of the rat. This approach combines the high specificity of "one-step" reverse transcription-polymerase chain reaction (RT-PCR) with the sensitivity of laser-induced fluorescence capillary electrophoresis (LIF-CE). Both cDNA synthesis and PCR amplification are performed with the same enzyme and site-specific primers, improving the efficiency of cDNA synthesis. The specific target mRNA and a mimic DNA fragment, used as a competitive internal standard, were co-amplified in a single reaction in which the same primers are used. The method presented in this paper enables a more efficient quantitative determination of 5alpha-R mRNA isozymes, and may lead to a better understanding of the role of 5alpha-R isozymes in the physiology of the central nervous system.

Quantitation of mRNA levels of steroid 5α-reductase isozymes in the rat brain by “one-step” RT-PCR and capillary electrophoresis

The enzyme 5alpha-reductase (5alpha-R) is present in many mammalian tissues, including the brain. The physiological importance of 5alpha-R in the brain derives from its capability to convert testosterone (T) to a more potent androgen, dihydrotestosterone (DHT), and to convert progesterone to its 5alpha-reduced derivative, precursors of allopregnanolone, potent allosteric modulator of the gamma-aminobutyric acid receptor (GABA(A)-R). 5alpha-R occurs as two isoforms, 5alpha-R type 1 (5alpha-R1) and 5alpha-R type 2 (5alpha-R2). We present an accurate, rapid, and modestly labor-intensive method to precisely quantitate 5alpha-R mRNA species in the cerebral cortex of the rat. This approach combines the high specificity of "one-step" reverse transcription-polymerase chain reaction (RT-PCR) with the sensitivity of laser-induced fluorescence capillary electrophoresis (LIF-CE). Both cDNA synthesis and PCR amplification are performed with the same enzyme and site-specific primers, improving the efficiency of cDNA synthesis. The specific target mRNA and a mimic DNA fragment, used as a competitive internal standard, were co-amplified in a single reaction in which the same primers are used. The method presented in this paper enables a more efficient quantitative determination of 5alpha-R mRNA isozymes, and may lead to a better understanding of the role of 5alpha-R isozymes in the physiology of the central nervous system.

Precise quantitation of steroid 5alpha lambda pi eta alpha-reductase type 1 mRNA levels by RT-PCR in female rat liver

The liver is a multifunctional organ capable of steroid hormone catabolism. The steroid metabolizing enzyme activities have been identified in the liver and it has been demonstrated that neonatal testicular androgens irreversibly program several hepatic enzyme activities in the rat including 5alpha-reductase (5alpha-R). In this paper we have applied a quantitative RT-PCR method coupled to laser-induced fluorescence capillary electrophoresis (LIF-CE) to measure the mRNA levels of 5alpha-R type 1 isozyme (5alpha-R1) in the liver of female intact and ovariectomized rats. Both groups were treated with testosterone (T) to study the possible regulation of 5alpha-R1 by androgens in females and to allow comparison with our previous findings in the liver of male rats. Our results demonstrate that the 5alpha-R1 mRNA isozyme is higher in the liver of female rats than in males and that the regulation of 5alpha-R1 mRNA by T is different in the liver of female than in male rats. Finally, our results could point to hepatic 5alpha-Reductase participation in the female not only in the catabolism of steroids with delta4,5 double bond, but also in other physiological functions such as the production of 3alpha,5alpha-reduced metabolites of progesterone and deoxycorticosterone (DOC), potent allosteric modulators of GABA(A) receptors.

Testosterone's Analgesic, Anxiolytic, and Cognitive-Enhancing Effects May Be Due in Part to Actions of Its 5α-Reduced Metabolites in the Hippocampus

Although testosterone (T) may decrease anxiety and enhance cognitive performance, its mechanisms are not well understood. The authors hypothesized that if T's effects are mediated in part through actions of its 5alpha-reduced, nonaromatizable metabolite dihydrotestosterone (DHT) and/or its 3alpha-hydroxysteroid dehydrogenase reduced metabolite 3alpha-androstanediol (3alpha-diol) in the hippocampus, then T, DHT, and 3alpha-diol administration should produce similar behavioral effects concomitant with elevating T metabolites in the hippocampus. Gonadectomized male rats administered T, DHT, or 3alpha-diol via Silastic capsules or intrahippocampal infusions had greater analgesia (tail flick, paw lick), less anxiety behavior (plus-maze, open field, defensive freezing), and better learning (inhibitory avoidance) compared with vehicle control rats. Only 3alpha-diol levels in the hippocampus were consistently elevated in conjunction with these behavioral effects.