finasteride, Propecia
Stress-induced deoxycorticosterone-derived neurosteroids modulate GABA(A) receptor function and seizure susceptibility.

Reddy DS, Rogawski MA.

Epilepsy Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.

Stress affects seizure susceptibility in animals and humans, but the underlying mechanisms are obscure. Here, we provide evidence that GABA(A) receptor-modulating neurosteroids derived from deoxycorticosterone (DOC) play a role in stress-related changes in seizure control. DOC, an adrenal steroid whose synthesis is enhanced during stress, undergoes sequential metabolic reduction by 5alpha-reductase and 3alpha-hydroxysteroid oxidoreductase to form 5alpha-dihydrodeoxycorticosterone (DHDOC) and allotetrahydrodeoxycorticosterone (THDOC), a GABA(A) receptor-modulating neurosteroid with anticonvulsant properties. Acute swim stress in rats significantly elevated plasma THDOC concentrations and raised the pentylenetetrazol (PTZ) seizure threshold. Small systemic doses of DOC produced comparable increases in THDOC and PTZ seizure threshold. Pretreatment with finasteride, a 5alpha-reductase inhibitor that blocks the conversion of DOC to DHDOC, reversed the antiseizure effects of stress. DOC also elevated plasma THDOC levels and protected mice against PTZ, methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate, picrotoxin, and amygdala-kindled seizures in mice (ED50 values, 84-97 mg/kg). Finasteride reversed the antiseizure activity of DOC (ED50, 7.2 mg/kg); partial antagonism was also obtained with indomethacin (100 mg/kg), an inhibitor of 3alpha-hydroxysteroid oxidoreductase. Finasteride had no effect on seizure protection by DHDOC and THDOC, whereas indomethacin partially reversed DHDOC but not THDOC. DHDOC, like THDOC, potentiated GABA-activated Cl- currents in cultured hippocampal neurons (< or =1 microm) and directly activated GABA(A) receptor currents (> or =1 microm), compatible with a role for DHDOC in the antiseizure activity of DOC. DOC is a mediator of the physiological effects of acute stress that could contribute to stress-induced changes in seizure susceptibility through its conversion to neurosteroids with modulatory actions on GABA(A) receptors including THDOC and possibly also DHDOC.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11978855&dopt=Abstract finasteride Propecia



finasteride, Propecia
[Finasteride (Proscar) for benign prostatic hypertrophy]

[Article in Hebrew]

Matzkin H, Chen J, Braf Z.

Urology Dept., Ichilov Hospital, Tel Aviv Medical Center.

Several alternatives to surgery for benign prostatic hypertrophy (BPH) were studied during the past few years. Finasteride (Proscar), a 4-azosteroid, is an inhibitor of the enzyme 5-alpha reductase, which is responsible for the conversion of testosterone to the biologically more active dihydrotestosterone (DHT). We report 3 years of experience with the drug in 23 men. Persistent significant decreases in serum DHT and prostate-specific antigen (PSA) were documented. Prostatic volume decreased by about 25% after 1 year, and remained fairly constant thereafter. Urination improved, as evidenced by increased maximal flow rate and decreased volume of residual urine. Symptoms were affected favorably, but only mildly. One of the main advantages of the drug is its lack of side-effects. More data on a larger number of patients with a longer follow-up are needed before finasteride can be established as having a role as an alternative treatment for BPH.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7509305&dopt=Abstract finasteride Propecia



finasteride, Propecia
Qualitative and quantitative evaluation of prostatic histomorphology in rats following chronic treatment with finasteride, a 5-alpha reductase inhibitor.

Prahalada SR, Keenan KP, Hertzog PR, Gordon LR, Peter CP, Soper KA, van Zwieten MJ, Bokelman DL.

Merck Research Laboratories, Department of Safety Assessment, West Point, Pennsylvania 19486.

OBJECTIVE. To determine any potential direct and/or indirect effects of elevated intraprostatic T levels on the prostates of rats chronically (1-2 years) exposed to high doses (160 mg/kg/day) of finasteride, a selective inhibitor of 5-alpha reductase. METHODS. Sprague-Dawley male rats were administered daily finasteride by oral gavage. Prostates from all rats were weighed, fixed in 10% neutral buffered formalin, and processed for light microscopic examination. The volume fractions of the prostatic glandular and stromal compartments were quantitated by morphometric analysis. RESULTS. Administration of finasteride at doses of 20, 40, and 80 mg/kg/day for one year resulted in a significant (P < or = 0.05) decrease in prostatic weight; prostatic atrophy was evident by light microscopy. Morphometric analysis of the prostate showed that chronic finasteride administration resulted in a significant (P < or = 0.001) decrease in the absolute volume of both glandular (-65.2%) and stromal (-57.1%) compartments of the prostate. Furthermore, the total number of epithelial and stromal cells per gland were significantly (P < or = 0.002) decreased in finasteride-treated rats compared with vehicle controls; the magnitude of mean decrease was 69.8 percent and 50.6 percent of controls in epithelial and stromal cells, respectively. In addition, prostates from all two hundred fifty rats in a two-year study were qualitatively evaluated by light microscopy. Administration of finasteride at doses ranging from 2.5 mg/kg/day to 160 mg/kg/day for two years did not result in an increase over the background incidence of prostatic focal hyperplasia or adenoma. No malignant tumors of the prostate were seen in any of the groups. CONCLUSIONS. These studies have demonstrated that the expected pharmacologic effects of finasteride on the prostate are maintained following chronic treatment and that there was no evidence of a direct and/or an indirect effect of elevated intraprostatic T on prostatic morphology in rats.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7513109&dopt=Abstract finasteride Propecia



finasteride, Propecia
Clinical predictors in the use of finasteride for control of gross hematuria due to benign prostatic hyperplasia.

Kearney MC, Bingham JB, Bergland R, Meade-D'Alisera P, Puchner PJ.

Squier Urological Clinic, New York-Presbyterian Hospital, Columbia College of Physicians and Surgeons, New York, NY, USA.

PURPOSE: We identify predictors of clinical response as well as response time in patients treated with finasteride for gross hematuria due to benign prostatic hyperplasia. MATERIALS AND METHODS: A retrospective chart review was preformed of 53 patients who had been given 5 mg. finasteride daily for the treatment of active bleeding or a recent history of recurrent bleeding. Urological evaluations were negative for tumor in all patients. A history of prostatectomy, anticoagulant status and prostate size was determined. The degree of hematuria was then graded before and after finasteride treatment according to our previously described system. Of the 53 patients who were actively bleeding at initial evaluation 16 were followed to determine time required for complete resolution of hematuria. RESULTS: Hematuria grade improved after finasteride in 50 (94%) patients. Overall 77% of patients (41 of 53) experienced no further bleeding while taking finasteride. Mean followup was 38 months (range 3 to 86). Of the patients 86% (12 of 14) taking coumadin, 77% (10 of 13) taking aspirin and 73% (19 of 26) on no anticoagulants had no further bleeding once on finasteride. Of the patients who had undergone prior transurethral prostatectomy 84% (26 of 31) experienced no further bleeding versus 68% (15 of 22) of those who had not undergone previous surgery. In the 16 patients who began finasteride while actively bleeding the average time to clear urine was 12 days (range 2 to 45). Prostatic volume correlated with the average time needed for resolution of hematuria, which was 2.7 days or longer for small (less than 40 gm.), 10.3 days or longer for large (40 to 100), 19 days or longer for extra large (100 to 150) and 45 days or longer for extra extra large (greater than 150) glands. Hematuria resolved an average of 5.5 days versus 18.6 days in those who had or had not undergone previous prostatectomy, respectively. CONCLUSIONS: Our long-term followup demonstrates finasteride as a useful treatment for benign prostatic hyperplasia related gross hematuria, which is effective in patients who are on anticoagulants. In patients with larger prostatic volumes a longer time to response and higher incidence of recurrent but lower grade bleeding should be anticipated compared to those who have undergone prior prostatectomy or have a smaller prostate.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11992064&dopt=Abstract finasteride Propecia



finasteride, Propecia
Dihydrotestosterone is the active androgen in the maintenance of nitric oxide-mediated penile erection in the rat.

Lugg JA, Rajfer J, Gonzalez-Cadavid NF.

Department of Surgery, University of California at Los Angeles (UCLA) School of Medicine, Harbor-UCLA Medical Center, Torrance 90509.

Androgens are essential for the expression of normal libido in the male, but their role in the maintenance of the erectile response in humans is controversial. It has been shown previously in the rat that castration induces 1) loss of penile reflexes; and 2) considerable reduction in the erectile response to electric field stimulation (EFS) of the cavernosal nerve. Both of these effects can be reversed by testosterone replacement. The current study was performed to determine whether these testosterone effects are mediated via its conversion to dihydrotestosterone (DHT), and to what extent the synthesis of the mediator of penile erection, nitric oxide, is affected by castration and androgen replacement. Five-month-old rats were either castrated or left intact. The orchiectomized rats were implanted with SILASTIC brand silicon tubing (Dow Corning) containing testosterone or DHT with or without daily injections of the 5 alpha-reductase inhibitor finasteride. After 7 days, rats were submitted to EFS and the intracavernosal pressure was recorded. Castration reduced the EFS-induced erectile response by 50% in comparison with intact rats and testosterone restored this decrease to normal. When finasteride was given to these testosterone-treated castrate rats, erectile response was not restored. DHT was as effective as testosterone in restoring response to EFS in castrates and this effect was not decreased by finasteride. Nitric oxide synthase activity in the penile cytosol was measured by the arginine-citrulline conversion and was found to correlate with the EFS determinations. These results show that DHT is the active androgen in the prevention of erectile failure seen in castrated rats, and suggest that this effect may be mediated, at least partially, by changes in nitric oxide synthase levels in the penis.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7534702&dopt=Abstract finasteride Propecia



finasteride, Propecia
5 alpha-reductase inhibition by finasteride (Proscar) in epithelium and stroma of human benign prostatic hyperplasia.

Weisser H, Tunn S, Debus M, Krieg M.

Institute of Clinical Chemistry and Laboratory Medicine, University Clinic Bergmannsheil, Bochum, Germany.

Finasteride is a specific 5 alpha-reductase inhibitor that has been shown to reduce the size of human benign prostatic hyperplasia (BPH) by inhibiting the intraprostatic conversion of testosterone to 5 alpha-dihydrotestosterone. The aim of the present in vitro study was to describe in more detail the inhibitory effect of finasteride on 5 alpha-reductase in epithelium and stroma of human BPH. 5 alpha-Reductase activity in epithelium and stroma was inhibited dose-dependently by finasteride. The mean IC50 (50% inhibitory concentration) values, determined in the presence of various testosterone concentrations, were generally 2- to 4-fold lower in epithelium than in stroma. With finasteride concentrations greater than 5 nM, competitive inhibition of 5 alpha-reductase occurred both in epithelium and stroma. The mean inhibition constant Ki[nM +/- SEM] was 7 +/- 3 and 31 +/- 3 in epithelium and stroma, respectively. In the presence of finasteride concentrations < or = 5 nM, the epithelial 5 alpha-reductase seems to be inhibited in an uncompetitive manner, whereas such low finasteride concentrations cause either no inhibition (1-2 nM) or competitive inhibition (5 nM) in stroma. Our present study provides evidence that the inhibitory effect of finasteride on 5 alpha-reductase is much stronger in epithelium than in stroma. Therefore, it is conceivable that the global size-reduction of BPH under finasteride treatment is primarily due to the regression of BPH epithelium.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7535480&dopt=Abstract finasteride Propecia