Steroid 5α-reductase Inhibitors Research Articles

PD02-07 ALTERNATE ANDROGEN-INDEPENDENT PATHWAYS FOR PROSTATE GROWTH IN THE ABSENCE OF SRD5A2

You have accessJournal of UrologyCME1 Apr 2023PD02-07 ALTERNATE ANDROGEN-INDEPENDENT PATHWAYS FOR PROSTATE GROWTH IN THE ABSENCE OF SRD5A2 Christina Sharkey, Xingbo Long, Ra'ad Al-Faouri, Aria F. Olumi, and Zongwei Wang Christina SharkeyChristina Sharkey More articles by this author , Xingbo LongXingbo Long More articles by this author , Ra'ad Al-FaouriRa'ad Al-Faouri More articles by this author , Aria F. OlumiAria F. Olumi More articles by this author , and Zongwei WangZongwei Wang More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003219.07AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Benign prostatic hyperplasia (BPH) is a heterogeneous disease that results from the nonmalignant proliferation of both the prostate epithelial and stromal compartments. Steroid 5α reductase 2 (SRD5A2) is the predominant enzyme responsible for prostatic development and growth. Despite the introduction of steroid 5α-reductase inhibitors (5ARI) for benign prostatic hyperplasia (BPH), the progression of LUTS is only slowed by 34% with 5ARI-response. Therefore, we hypothesize that there are alternative pathways driving prostate growth and development when SRD5A2 is absent. To address this question we generated SRD5A2 null (Srd5a2-/-) mouse model and demonstrated that luminal cells with lineage signature and progenitor signature diminished, whereas luminal cells with estrogen response genetic signature stably survived when SRD5A2 is absent. Here we further aim to identify whether the cell-cell interactions between stromal cells and luminal cells with WNT5A are the critical modulators in absence of SRD5A2. METHODS: Single cell RNA sequencing (scRNA seq) and bulk RNA seq was performed with prostate tissues from Srd5a2-/- and Srd5a2+/- littermate control mice. Unbiased scRNA seq with 10x genomics platform, followed by unsupervised clustering, was utilized to generate cell clusters based on differentially expressed (DE) gene profiles. The heterotypic cell-cell communication was analyzed using CellphoneDB2. Identified ligand-receptor pairs were validated by qPCR in BHPrS1 human prostatic stromal cell line and human prostatic tissues with BPH. RNAscope was performed to identify the transcription expression of target genes. RESULTS: The expression of SRD5A2 was exclusively identified in fibroblasts and myofibroblasts. The absence of SRD5A2 induced the increase of stromal cells (11.3% vs. 18.0%) but decrease of luminal cells (53.2% vs. 31.8%). Analysis of ligand-receptor pairs indicated that stromal cells were the most prolific interactors, and myofibroblasts were the most "outbound" cells. Meanwhile, in Srd5a2-/- mice the fibroblasts had the most significantly increased weighted value (366 vs. 493), and LE1, one subset of luminal cells had most significantly decreased weighted value (205 vs. 96). Myofibroblast and muscle system processes were most significantly upregulated in Srd5a2-/- mice as assessed by bulk RNA-seq analysis. Nine highly significant interactions were identified which regulate stromal–luminal cell communication, including WNT5A/PTPRK, TGFB2/TGFBR1, and (NRP1, NRP2, FLT1)/VEGFA. RNAscope data showed a significant upregulation of WNT5A in the anterior prostate of Srd5a2-/- mice (p<0.0001). CONCLUSIONS: Our data suggest that the heterotypic cell-cell communication is substantially changed in the absence of SRD5A2. The stroma-niched signaling, particularly WNT5A and WNT signaling pathway might serve as a therapeutic target for managing BPH patients who lack SRD5A2 expression and may be unresponsive to 5ARI therapies. Source of Funding: NIH/R01 DK124502 © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e71 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Christina Sharkey More articles by this author Xingbo Long More articles by this author Ra'ad Al-Faouri More articles by this author Aria F. Olumi More articles by this author Zongwei Wang More articles by this author Expand All Advertisement PDF downloadLoading ...

Persistence to Medications for Benign Prostatic Hyperplasia/Benign Prostatic Obstruction-Associated Lower Urinary Tract Symptoms in the ASL TO4 Regione Piemonte (Italy).

Pharmacological treatment of benign prostatic hyperplasia (BPH)/benign prostatic obstruction (BPO)-associated lower urinary tract symptoms (LUTS) aims at improving patients' quality of life by managing urinary symptoms and preventing complications and disease progression. However, continuous use of drugs to treat BPH/BPO-associated LUTS decreases over time. The aim of this retrospective observational study was to describe use of α1-adrenoceptor antagonists (ABs) and steroid 5α-reductase inhibitors (5ARIs) by adult (age ≥ 40 years) men in the ASL TO4, a Local Health Authority in the northern area of the city of Turin (Italy). Persistence measures were adopted as a robust, informative, and feasible way to understand medication-taking behavior and to assess patient compliance. A total of 4309 men (median age 71 years) were enrolled. Monotherapy was the treatment option prescribed to the largest part of the study population. However, ≥two drugs were prescribed to a substantial proportion of men (23%). Men prescribed alfuzosin or dutasteride had significantly greater persistence, which decreased over time. Unmet needs and areas of intervention for healthcare systems aimed at improving the use of drugs for BHP/BPO-associated LUTS in the ASL TO4 Regione Piemonte were identified.

Impact of sex, androgens, and prostate size on C57BL/6J mouse urinary physiology: urethral histology.

The National Institutes of Health leveled new focus on sex as a biological variable with the goal of understanding sex-specific differences in health and physiology. We previously published a functional assessment of the impact of sex, androgens, and prostate size on C57BL/6J mouse urinary physiology (Ruetten H, Wegner KA, Zhang HL, Wang P, Sandhu J, Sandhu S, Mueller B, Wang Z, Macoska J, Peterson RE, Bjorling DE, Ricke WA, Marker PC, Vezina CM. Am J Physiol Renal Physiol 317: F996-F1009, 2019). Here, we measured and compared five characteristics of urethral histology (urethral lumen diameter and area, epithelial cell count, epithelial and rhabdosphincter thickness, epithelial cell area, and total urethral area) in male and female 9-wk-old C57BL/6J mice using hematoxylin and eosin staining. We also compared male mice with castrated male mice, male and female mice treated with the steroid 5α-reductase inhibitor finasteride or testosterone, or male mice harboring alleles (Pbsn4cre/+; R26RDta/+) that reduce prostate lobe mass. The three methods used to reduce prostate mass (castration, finasteride, and Pbsn4cre/+; R26RDta/+) changed urethral histology, but none feminized male urethral histology (increased urethral epithelial area). Exogenous testosterone caused increased epithelial cell count in intact females but did not masculinize female urethral histology (decrease epithelial area). Our results lay a critical foundation for future studies as we begin to parse out the influence of hormones and cellular morphology on male and female urinary function.

The Steroidogenesis Inhibitor Finasteride Reduces the Response to Both Stressful and Rewarding Stimuli.

Finasteride (FIN) is the prototypical inhibitor of steroid 5α-reductase (5αR), the enzyme that catalyzes the rate-limiting step of the conversion of progesterone and testosterone into their main neuroactive metabolites. FIN is clinically approved for the treatment of benign prostatic hyperplasia and male baldness; while often well-tolerated, FIN has also been shown to cause or exacerbate psychological problems in vulnerable subjects. Evidence on the psychological effects of FIN, however, remains controversial, in view of inconsistent clinical reports. Here, we tested the effects of FIN in a battery of tests aimed at capturing complementary aspects of mood regulation and stress reactivity in rats. FIN reduced exploratory, incentive, prosocial, and risk-taking behavior; furthermore, it decreased stress coping, as revealed by increased immobility in the forced-swim test (FST). This last effect was also observed in female and orchiectomized male rats, suggesting that the mechanism of action of FIN does not primarily reflect changes in gonadal steroids. The effects of FIN on FST responses were associated with a dramatic decrease in corticotropin release hormone (CRH) mRNA and adrenocorticotropic hormone (ACTH) levels. These results suggest that FIN impairs stress reactivity and reduces behavioral activation and impulsive behavior by altering the function of the hypothalamus–pituitary–adrenal (HPA) axis.

Re: Incidence of Type 2 Diabetes Mellitus in Men Receiving Steroid 5α-Reductase Inhibitors: Population Based Cohort Study.

Re: Incidence of Type 2 Diabetes Mellitus in Men Receiving Steroid 5α-Reductase Inhibitors: Population Based Cohort Study.

Impact of sex, androgens, and prostate size on C57BL/6J mouse urinary physiology: functional assessment.

Laboratory mice are used to identify causes of urinary dysfunction including prostate-related mechanisms of lower urinary tract symptoms. Effective use of mice for this purpose requires a clear understanding of molecular, cellular, anatomic, and endocrine contributions to voiding function. Whether the prostate influences baseline voiding function has not been specifically evaluated, in part because most methods that alter prostate mass also change circulating testosterone concentrations. We performed void spot assay and cystometry to establish a multiparameter "baseline" of voiding function in intact male and female 9-wk-old (adult) C57BL/6J mice. We then compared voiding function in intact male mice to that of castrated male mice, male (and female) mice treated with the steroid 5α-reductase inhibitor finasteride, or male mice harboring alleles (Pbsn4cre/+; R26RDta/+) that significantly reduce prostate lobe mass by depleting prostatic luminal epithelial cells. We evaluated aging-related changes in male urinary voiding. We also treated intact male, castrate male, and female mice with exogenous testosterone to determine the influence of androgen on voiding function. The three methods used to reduce prostate mass (castration, finasteride, and Pbsn4cre/+; R26RDta/+) changed voiding function from baseline but in a nonuniform manner. Castration feminized some aspects of male urinary physiology (making them more like intact female mice) while exogenous testosterone masculinized some aspects of female urinary physiology (making them more like intact male mice). Our results provide evidence that circulating testosterone is responsible in part for baseline sex differences in C57BL/6J mouse voiding function while prostate lobe mass in young, healthy adult mice has a lesser influence.

5α-Reductase Inhibitors Might Increase Risk for Diabetes

Previous studies have shown that dutasteride, a steroid 5α-reductase inhibitor used to treat patients with benign prostatic hyperplasia (BPH), induced

Incidence of type 2 diabetes mellitus in men receiving steroid 5α-reductase inhibitors: population based cohort study

ObjectiveTo investigate the incidence of new onset type 2 diabetes mellitus in men receiving steroid 5α-reductase inhibitors (dutasteride or finasteride) for long term treatment of benign prostatic hyperplasia.DesignPopulation based cohort...

Synthesis, Biological Evaluation and Molecular Docking of Avicequinone C Analogues as Potential Steroid 5α-Reductase Inhibitors.

Avicequinone C (5a), a furanonaphthoquinone isolated from the Thai mangrove Avicennia marina has been shown previously to have interesting steroid 5α-reductase type 1 inhibitory activity. In this study, a series of avicequinone C analogues containing furanonaphthoquinone with different degrees of saturation and substituents at the furan ring were synthesized. The resulting synthetic avicequinone C and analogues (5a-f) along with some related compounds including 2,5-dihydroxy-1,4-benzoquinone (6) and natural naphthoquinones such as lawsone (7a) and lapachol (7b) were evaluated for their in vitro cell viability and steroid 5α-reductase type 1 inhibitory activities using the cultured cell line of human keratinocytes (HaCaT). This cell-based bioassay was performed based on a direct detection of the enzymatic product dihydrotestosterone (2) by using a non-radioactive high performance thin layer chromatography (HPTLC) method. Among the furanonaphthoquinones in this series, 5e having a propionic substituent at furan ring possessed approximately 22-fold more potent than the original isolated compound 5a. However, the compounds without furan motif such as 6, 7a and b could not inhibit the activity of steroid 5α-reductase. Molecular docking results of the in silico three-dimensional steroid 5α-reductase type 1-reduced nicotinamide adenine dinucleotide phosphate (NADPH) binary complex was performed via AutoDock Vina and it illustrated that the furanonaphthoquinone moiety and the substituent at furan ring might play a key role as pharmacophores for the steroid 5α-reductase inhibitory activity.

A new label-free screen for steroid 5α-reductase inhibitors using LC-MS

Steroid 5α-reductase (S5αR) plays an important role in metabolizing testosterone into active androgen dihydrotestosterone (DHT) which is involved in many androgen dependent disorders, such as androgenic alopecia, benign prostatic hyperplasia and acne. The method for screening for S5αR inhibition is key in finding new antagonists. In this study, the label-free S5αR inhibitory assay using LC-MS was developed. S5αR type 1 enzyme was obtained from LNCaP prostate cancer cells. The enzymatic assay was optimised for enzyme-substrate (testosterone) concentration, NADPH-cofactor concentration, solvent tolerance, enzyme activity stability and incubation time. The developed assay was validated by measuring the signal to background ratio (S/B), the signal to noise ratio (S/N), the signal window (SW) and the zeta factor Z′ in accordance with published bioassay guidelines. The enzymatic reaction was performed in 96-well plates and DHT formation was determined by LC-MS. S/B, S/N, SW and Z′ factor were well above acceptable criteria and the reproducibility was good using Z′ factor other 3days and further validated by dutasteride and finasteride inhibition. The method was successfully applied to quantify S5αR inhibitory activity of some Thai herbal extracts. Two plant extracts, Impatiens balsamina L. and Curcuma longa L. showed IC50 at 5.4±0.2 and 9.0±1.2μgmL−1 and are therefore promising sources of new S5αR inhibitors. The assay has high selectability and reproducibility and suited to medium throughput screening required by phytochemistry.

Transcriptomic profiling in Silurana tropicalis testes exposed to finasteride

Investigations of endocrine disrupting chemicals found in aquatic ecosystems with estrogenic and androgenic modes of action have increased over the past two decades due to a surge of evidence of adverse effects in wildlife. Chemicals that disrupt androgen signalling and steroidogenesis can result in an imbalanced conversion of testosterone (T) into 17β-estradiol (E2) and other androgens such as 5α-dihydrotestosterone (5α-DHT). Therefore, a better understanding of how chemicals perturb these pathways is warranted. In this study, the brain, liver, and testes of Silurana tropicalis were exposed ex vivo to the human drug finasteride, a potent steroid 5α-reductase inhibitor and a model compound to study the inhibition of the conversion of T into 5α-DHT. These experiments were conducted (1) to determine organ specific changes in sex steroid production after treatment, and (2) to elucidate the transcriptomic response to finasteride in testicular tissue. Enzyme-linked immunosorbent assays were used to measure hormone levels in media following finasteride incubation for 6h. Finasteride significantly increased T levels in the media of liver and testis tissue, but did not induce any changes in E2 and 5α-DHT production. Gene expression analysis was performed in frog testes and data revealed that finasteride treatment significantly altered 1,434 gene probes. Gene networks associated with male reproduction such as meiosis, hormone biosynthesis, sperm entry, gonadotropin releasing hormone were affected by finasteride exposure as well as other pathways such as oxysterol synthesis, apoptosis, and epigenetic regulation. For example, this study suggests that the mode of action by which finasteride induces cellular damage in testicular tissue as reported by others, is via oxidative stress in testes. This data also suggests that 5-reductase inhibition disrupts the expression of genes related to reproduction. It is proposed that androgen–disrupting chemicals may mediate their action via 5-reductases and that the effects of environmental pollutants are not limited to the androgen receptor signalling.

Steroid 5α-reductase inhibition by polymethoxyflavones

Steroid 5α-reductase inhibition was studied using eleven polymethoxyflavones (PMFs). Homologous eleven PMFs showed wide range of steroid 5α-reductase inhibitory effects. Among the tested PMFs, 5-hydroxy-7,4′-dimethoxyflavone (5) was found to be the most potent inhibitor of steroid 5α-reductase with the IC50 of 20 μM. These results showed PMFs could be used as a nonsteroidal steroid 5α-reductase for the treatment of benign prostatic hyperplasia.

Prostate cancer cells differ in testosterone accumulation, dihydrotestosterone conversion, and androgen receptor signaling response to steroid 5α-reductase inhibitors

Blocking 5α-reductase-mediated testosterone conversion to dihydrotestosterone (DHT) with finasteride or dutasteride is the driving hypothesis behind two prostate cancer prevention trials. Factors affecting intracellular androgen levels and the androgen receptor (AR) signaling axis need to be examined systematically in order to fully understand the outcome of interventions using these drugs. The expression of three 5α-reductase isozymes, as determined by immunohistochemistry and qRT-PCR, was studied in five human prostate cancer cell lines. Intracellular testosterone and DHT were analyzed using mass spectrometry. A luciferase reporter assay and AR-regulated genes were used to evaluate the modulation of AR activity. Prostate cancer cells were capable of accumulating testosterone to a level 15-50 times higher than that in the medium. The profile and expression of 5α-reductase isozymes did not predict the capacity to convert testosterone to DHT. Finasteride and dutasteride were able to depress testosterone uptake in addition to lowering intracellular DHT. The inhibition of AR activity following drug treatment often exceeded the expected response due to reduced availability of DHT. The ability to maintain high intracellular testosterone might compensate for the shortage of DHT. The biological effect of finasteride or dutasteride appears to be complex and may depend on the interplay of several factors, which include testosterone turnover, enzymology of DHT production, ability to use testosterone and DHT interchangeably, and propensity of cells for off-target AR inhibitory effect.

Design of potent human steroid 5α-reductase inhibitors: 3D-QSAR CoMFA, CoMSIA and docking studies

3D-QSAR CoMFA, CoMSIA and docking studies were performed on a set of 4-azasteroidal human steroid 5α-reductase inhibitors. The models developed using maximal common substructure-based alignment was found to be reliable and significant with good predictive r2 value. CoMSIA model developed using combination of steric, electrostatic, hydrophobic, hydrogen bond donor and hydrogen bond acceptor features has shown rcv2 = 0.564 with six optimum components, rncv2 = 0.945, F value = 101.196, rPred2 = 0.693 and SEE = 0.209. The contour plots obtained has shown a favourable effect of bulkier groups at C-17 position. Docking studies indicates the importance of bulkier groups at C-17 position for favourable activity. The study further helps in design of potent inhibitors of the enzyme.

Inhibition of 5α-reductase attenuates behavioral effects of D1-, but not D2-like receptor agonists in C57BL/6 mice

Converging lines of evidence point to the involvement of neurosteroids in the regulation of dopamine (DA) neurotransmission and signaling, yet the neurobiological bases of this link remain poorly understood. We previously showed that inhibition of steroid 5α-reductase (5αR), the key rate-limiting enzyme in neurosteroidogenesis, attenuates the behavioral effects of non-selective DA receptor agonists in rats, including stereotyped responses and sensorimotor gating deficits, as measured by the prepulse inhibition (PPI) of the acoustic startle reflex. Since previous findings suggested that the role of DA D(1)- and D(2)-like receptor families in behavioral regulation may exhibit broad interspecies and interstrain variations, we assessed the impact of 5αR blockade on the behavioral effects of DAergic agonists in C57BL/6 mice. The prototypical 5αR inhibitor finasteride (FIN; 25-50 mg/kg, intraperitoneally, IP) dose-dependently countered the PPI deficits and the enhancement of rearing responses induced by the full D(1)-like receptor agonist SKF-82958 (0.3 mg/kg, IP); however, FIN did not significantly affect the hyperlocomotive and startle-attenuating effects of SKF-82958. Whereas the D(2)-like receptor agonist quinpirole (QUIN; 0.5 mg/kg, IP) did not induce significant changes in PPI, the combination of this agent and FIN surprisingly produced marked gating and startle deficits. In contrast with previous data on rats, FIN did not affect the reductions of startle reflex and PPI produced by the non-selective DAergic agonist apomorphine (APO; 0.5 mg/kg, IP). These findings collectively indicate that, in C57BL/6 mice, 5αR differentially modulates the effects of D(1)- and D(2)-like receptor agonists in behavioral regulation.

3D-QSAR CoMFA and CoMSIA studies for design of potent human steroid 5α-reductase inhibitors

3D-QSAR studies were performed on a set of sixty-one 6-azasteroidal human steroid 5α-reductase inhibitors. The models developed using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methodologies employing atom and centroid based alignment were reliable and significant having good predictive r 2 value. CoMSIA model developed by a combination of steric, electrostatic, hydrophobic and hydrogen bond donor showed good relative and predictive properties. The predictive power of the models was assessed using an external test set of 10 compounds. The best model had shown cross validation r 2 (0.702) with 7 optimum components, non-cross-validation r 2 (0.956), F value (86.158), predicted r 2 (0.704), standard error of estimate (0.165). Further the CoMFA/CoMSIA contour plots show a preference toward the C-17 substituents and indicate that bulky group at C-17 is an important requirement for exhibiting 5α-reductase inhibition. These developed models could be used to design and optimise the more potent 6-aza steroidal inhibitors of 5α-reductase enzyme. The 3D-QSAR studies involving comparative molecular field analysis and comparative molecular similarity indices analysis on a series of 6-azasteroids as 5α-reductase inhibitors is reported.

Effect of Testosterone Supplementation With and Without a Dual 5α-Reductase Inhibitor on Fat-Free Mass in Men With Suppressed Testosterone Production

Steroid 5α-reductase inhibitors are used to treat benign prostatic hyperplasia and androgenic alopecia, but the role of 5α-dihydrotestosterone (DHT) in mediating testosterone's effects on muscle, sexual function, erythropoiesis, and other androgen-dependent processes remains poorly understood. To determine whether testosterone's effects on muscle mass, strength, sexual function, hematocrit level, prostate volume, sebum production, and lipid levels are attenuated when its conversion to DHT is blocked by dutasteride (an inhibitor of 5α-reductase type 1 and 2). The 5α-Reductase Trial was a randomized controlled trial of healthy men aged 18 to 50 years comparing placebo plus testosterone enthanate with dutasteride plus testosterone enanthate from May 2005 through June 2010. Eight treatment groups received 50, 125, 300, or 600 mg/wk of testosterone enanthate for 20 weeks plus placebo (4 groups) or 2.5 mg/d of dutasteride (4 groups). The primary outcome was change in fat-free mass; secondary outcomes: changes in fat mass, muscle strength, sexual function, prostate volume, sebum production, and hematocrit and lipid levels. A total of 139 men were randomized; 102 completed the 20-week intervention. Men assigned to dutasteride were similar at baseline to those assigned to placebo. The mean fat-free mass gained by the dutasteride groups was 0.6 kg (95% CI, -0.1 to 1.2 kg) when receiving 50 mg/wk of testosterone enanthate, 2.6 kg (95% CI, 0.9 to 4.3 kg) for 125 mg/wk, 5.8 kg (95% CI, 4.8 to 6.9 kg) for 300 mg/wk, and 7.1 kg (95% CI, 6.0 to 8.2 kg) for 600 mg/wk. The mean fat-free mass gained by the placebo groups was 0.8 kg (95% CI, -0.1 to 1.7 kg) when receiving 50 mg/wk of testosterone enanthate, 3.5 kg (95% CI, 2.1 to 4.8 kg) for 125 mg/wk, 5.7 kg (95% CI, 4.8 to 6.5 kg) for 300 mg/wk, and 8.1 kg (95% CI, 6.7 to 9.5 kg) for 600 mg/wk. The dose-adjusted differences between the dutasteride and placebo groups for fat-free mass were not significant (P = .18). Changes in fat mass, muscle strength, sexual function, prostate volume, sebum production, and hematocrit and lipid levels did not differ between groups. Changes in fat-free mass in response to graded testosterone doses did not differ in men in whom DHT was suppressed by dutasteride from those treated with placebo, indicating that conversion of testosterone to DHT is not essential for mediating its anabolic effects on muscle. clinicaltrials.gov Identifier: NCT00493987.

Inhibition of 5α-reductase in the nucleus accumbens counters sensorimotor gating deficits induced by dopaminergic activation

Cogent evidence highlights a key role of neurosteroids and androgens in schizophrenia. We recently reported that inhibition of steroid 5α-reductase (5αR), the rate-limiting enzyme in neurosteroid synthesis and androgen metabolism, elicits antipsychotic-like effects in humans and animal models, without inducing extrapyramidal side effects. To elucidate the anatomical substrates mediating these effects, we investigated the contribution of peripheral and neural structures to the behavioral effects of the 5αR inhibitor finasteride (FIN) on the prepulse inhibition (PPI) of the acoustic startle reflex (ASR), a rat paradigm that dependably simulates the sensorimotor gating impairments observed in schizophrenia and other neuropsychiatric disorders. The potential effect of drug-induced ASR modifications on PPI was excluded by measuring this index both as percent (%PPI) and absolute values (ΔPPI). In both orchidectomized and sham-operated rats, FIN prevented the %PPI deficits induced by the dopamine (DA) receptor agonists apomorphine (APO, 0.25mg/kg, SC) and d-amphetamine (AMPH, 2.5mg/kg, SC), although the latter effect was not corroborated by ΔPPI analysis. Conversely, APO-induced PPI deficits were countered by FIN infusions in the brain ventricles (10μg/1μl) and in the nucleus accumbens (NAc) shell and core (0.5μg/0.5μl/side). No significant PPI-ameliorating effect was observed following FIN injections in other brain regions, including dorsal caudate, basolateral amygdala, ventral hippocampus and medial prefrontal cortex, although a statistical trend was observed for the latter region. The efflux of DA in NAc was increased by systemic, but not intracerebral FIN administration. Taken together, these findings suggest that the role of 5αR in gating regulation is based on post-synaptic mechanisms in the NAc, and is not directly related to alterations in DA efflux in this region.

Transdermal Delivery of Bioidentical Progesterone with a Steroid 5α-Reductase Inhibitor (Dutasteride): a Pilot Study

Bioavailability of transdermal progesterone is low and variable. This may be attributed to transdermal metabolism by the 5α-reductase enzymes or the direct transport to the saliva. The objective of the current study was to evaluate the effect of enzyme inhibition on the bioavailability of transdermal progesterone. Serum and salivary progesterone levels were evaluated to gain a better insight into the mechanism progesterone transport across the skin. Twenty postmenopausal women with a Follicle Stimulating Hormone > 40IU/L were recruited to take part in the study. The subjects were randomly allocated to either dutasteride (n=10) or placebo (n=10). Each group applied either 500 mg of non ionic cream or dutasteride cream (2mg/g) to the right arm for 2 weeks. This was followed by applying 500 mg of progesterone or progesterone dutasteride cream (equivalent to 40 mg of progesterone) for a further 2 weeks. On day 30 blood and saliva were collected for over 12 hours and progesterone concentration was measured. The baseline progesterone concentration on day zero was 0.1 ng/ml. On day 30 baseline progesterone levels increased significantly (p <0.05) to 1.40 ng/ml and 1.15 ng/ml in the progesterone and dutasteride groups, respectively. Salivary progesterone concentrations were increased by seven fold, from 0.40 ng/ml to 2.9 ng/ml. On average, salivary progesterone concentration was four times the serum levels. The average serum and salivary progesterone concentration, Cmax, and the AUC were slightly higher in the dutasteride group, but no significant difference could be noted. Metabolism by the 5α-reductase enzyme is unlikely to affect the bioavailability of progesterone.

Synthesis and structure–activity relationship of 3- O-acylated (–)-epigallocatechins as 5α-reductase inhibitors

A series of 3- O-acylated (–)-epigallocatechins were synthesized and their inhibition of steroid 5α-reductase was studied. They were prepared from the reaction of EGCG with tert-butyldimethylsilyl chloride followed by reductive cleavage of the ester bond. The resultant (–)-epigallocatechins penta- O- tert-butyldimethylsilyl ether was esterified with different fatty acids then desilylated to provide the corresponding products. The activity of 3- O-acylated (–)-epigallocatechins increased with the increasing carbon numbers of the fatty acid moiety, reaching maximum for 16 carbon atoms (compound 4h) with an IC 50 of 0.53 μM, which was ∼12-fold more potent than EGCG (IC 50 = 6.29 μM). Introduction of monounsaturated fatty acid provided the most potent compound 6 (IC 50 = 0.48 μM), which showed moderate anti-tumor activity in vivo.