Selective inhibition of the 5 alpha-reductase of the rat epididymis

The effect of several synthetic steroids belonging either to the 4-aza-3-oxo-steroid family or to androstene and androstane derivatives was investigated "in vitro" on the epididymal as well as prostatic 5 alpha-reductase activity. For this purpose rat caput epididymis and prostate were incubated with the different steroidal compounds at molar concentrations of 10(-7), 10(-6), and 10(-5) in the presence of labelled testosterone as substrate. The steroids 4-MA (17 beta, N,N-diethyl-carbamoyl-4-aza-5 alpha-androstan-3-one) and 4-OH-A (4-hydroxy-androstenedione), already known to be effective 5 alpha-reductase inhibitors at the level of the prostate, have been used as reference molecules. The 5 alpha-reductase activity was evaluated by measuring pg of dihydrotestosterone (DHT) formed in 2 h of incubation by mg of tissue. The steroids A, B, C, F, G and I inhibit the formation of DHT in the rat epididymis although to different extents; they are also equally effective on the formation of DHT in the rat prostate. The steroids D, E, H and L are devoid of any inhibitory property on the formation of DHT in both the rat epididymis and prostate. The most interesting results were obtained with compound M which exhibits a dose-dependent and significant inhibitory effect on the formation of DHT in the epididymis, but it is inactive at the level of the prostate. These findings suggest that it is possible (a) to selectively interfere with the 5 alpha-reductase of the epididymis without affecting that present in the prostate, and (b) consequently to envisage new ways to regulate male fertility.

Intertubular capillary changes in kidney allografts: a morphologic investigation on 61 renal specimens

A total of 61 kidney allograft specimens (51 biopsies and 10 nephrectomies) from 44 patients were investigated. Transplant glomerulopathy (TGP) was found in 38 specimens. Electron microscopy disclosed peculiar intertubular capillary changes (ITCC) in 47 specimens (all those showing TGP and nine without TGP). They were characterized by splitting and multilayering of the basement membranes. TGP and ITCC were graded and found mild (in 23 and 22 specimens), moderate (in 11 and 16 specimens), and severe (in four and nine specimens). Both worsened with time lapse from transplantation. When both were compared in single specimens, their grading was similar or, with a few exceptions, more severe for ITCC. TGP and ITCC were more frequent in biopsies with morphologic evidence of rejection and less frequent in patients treated with Cyclosporine A. Repeated biopsies and nephrectomies were studied in 10 patients and a somewhat more precocious appearance of ITCC than of TGP was found. Earlier and more severe ITCC were found in two patients who had had two transplants as compared to those with one. Morphologic similarities between TGP and ITCC suggest a common pathogenetic mechanism related to endothelial damage. The association to the histological evidence of rejection as well as the apparently protective activity of Cyclosporine A could support the involvement of an immune-mediated mechanism in agreement with what is reported in literature. The constant association of ITCC and TGP and its possible more precocious appearance enforce the diagnostic value of the former, which allows to infer the presence or the subsequent development of TGP even in biopsies where glomeruli are lacking.

Treatment of pre-menopausal advanced breast cancer with goserelin--a long-acting luteinizing hormone releasing hormone agonist

Twenty-two pre-menopausal evaluable patients with advanced breast cancer (median age 39 years; ER positive 19, unknown three; prior adjuvant chemotherapy 16) were treated with the LHRH agonist goserelin depot (Zoladex). Serum levels of 17 beta-estradiol and progesterone were suppressed by goserelin within 3-4 weeks of therapy, while serum leuteinizing hormone and follicle stimulating hormone titers remained in the low level of the normal range. Complete or partial response was documented in seven of 22 cases (32%) and occurred in all major sites of disease. Tumor response was documented in women regularly menstruating at the start of therapy. Median time to disease progression was 23 weeks; median duration of response was 64 weeks; overall survival was 141 weeks. Zoladex was well tolerated: only hot flushes in 82% and reversible cutaneous pigmentation in the site of injection in 45% of the patients were observed. In our experience the activity of Zoladex was comparable to that of oophorectomy, without the psychological trauma and the morbidity related to surgical castration.

[The prevalence of serum anti-hepatitis C virus antibodies in hemodialyzed patients]

Hepatitis C virus (HCV) is responsible for a high percentage of cases of transfusional hepatitis and is often considered the etiological agent of numerous cases of non-A, non-B hepatitis in which parenteral transmission has not been documented. Patients undergoing hemodialysis are at risk for HCV infection. We used an immunoenzymatic method and confirmatory test (neutralization test) to determine serum anti-HCV antibody positivity in order to identify the factors associated with increased risk of HCV infection. We studied 63 hemodialyzed patients from eastern Sicily and compared the mean dialytic age and transfusion case history in positive and negative groups. 17.4 percent of the patients were anti-HCV positive. Mean dialytic age was significantly higher in the anti-HCV positive group. On the contrary no significant differences regarding transfusion case history or number of units of blood transfused were seen in the two groups. Our study confirms that hemodialyzed patients are at risk for HCV infection. This risk seems to increase with dialytic age. The lack of correlation between HCV and transfusion case history suggests that it may be a hospital-acquired infection.

Effect of unilateral vagotomy on serum gonadotropin concentration in rats with two testes and in hemicastrates

The effect of right- or left-sided vagotomy on serum gonadotropin secretion was studied in rats with two testes and in hemicastrates. Right-sided vagotomy in animals with two testes in situ induced a very marked rise in serum LH levels. Left-sided vagotomy was also accompanied with a slight increase in LH secretion. The difference in serum LH levels between right-and left-sided vagotomized animals was significant. FSH levels were unaffected by either right- or left-sided vagotomy. Removal of the right or of the left testis resulted in a significant increase in serum gonadotropin levels. Unilateral vagotomy in hemicastrates did not alter the hemicastration-induced changes in serum gonadotropin hormone levels. These data indicate that the vagus nerve might have a modulatory role in the control of LH secretion in rats with two testes but not in hemicastrates. The different response in LH levels after right-sided and left-sided vagotomy suggests a functional asymmetry of the vagus nerve in the regulation of LH secretion.

AgNOR distribution in normal and dysplastic laryngeal mucosa and in laryngeal epidermoid carcinomas

Samples of normal and dysplastic laryngeal mucosa and of laryngeal epidermoid carcinomas were submitted to the AgNOR silver staining technique. AgNORs were subdivided in large (LN) and small (SN) and counted separately along their sum (TN). Overlap of values is great between normal and mildly dysplastic mucosa and between moderate and severe dysplasia. Grouping together normal with mildly dysplastic mucosa, and moderate with severe dysplasia, their mean values show minimal overlap and the differences between them are highly significant. Plotting the mean values of these two groups and of carcinomas, the linear interpolations show a clearcut increase of values.

Diabetes in the elderly: remarks from an epidemiological study carried out in a town in south-eastern Sicily (Militello V.C.)

Longer mean life span and life expectancy of diabetics and increased factors that favor onset of type II diabetes have determined greater prevalence of diabetes in the elderly population. According to HANES II, it is 17% in the elderly in U.S.A. We carried out an epidemiological study on the over 65 year olds in Militello V.C. and examined 910 elderly subjects (72.05% of the total elderly population). All were tested for peripheral fasting blood glucose, body weight and height and filled out a questionnaire with general and diabetological questions. The values recommended by the NDDG were used to diagnose diabetes. One hundred and sixty-one diabetics (25 newly diagnosed) were observed (17.69%). Onset had occurred before age 65 (aged diabetics) in 72 cases and after 65 in 89 (senile diabetics). Mean blood glucose was 152.91 +/- 55.56 mg/dl. Our results indicated that sulfonylureas and/or biguanides are first choice treatment. By grouping the diabetics on the basis of age at onset and duration of disease, a fall in the number of cases treated with diet alone and hypoglycemic drugs and an increase in patients on insulin were seen in aged diabetics as the disease evolves. On the contrary, there was a rise in the number of senile diabetics on hypoglycemic drugs.

[Cutaneous tuberculosis with multifocal visceral involvement]

The case of a young Senegalese man who developed a form of cutaneous tuberculosis associated with a disseminated disease, successfully treated with appropriate antitubercular chemotherapy is reported. We found Mycobacterium Microti in the cutaneous ulcers, the only organism isolated after many cultural and microscopical examinations of different exudates and tissues. This mycobacterium was considered up to now to be pathogenic to rodents, but not man. Its possible pathogenicity to man (under certain situations) is also suggested, and it is expected that this possibility will be supported by other reports in the near future. In addition, stress is laid on the problems of diagnosis and classification of the cutaneous tuberculosis, so uncommon in the Western Hemisphere, and its possible association with leprosy.

[Evaluation of the risk of hepatitis delta virus (HDV) infection in a population of hemodialyzed patients: significance of the determination of anti-delta antibodies in the blood]

Hepatitis delta virus (HDV) is a defective virus which requires the helper function of hepatitis B virus (HBV) for replication. HDV infection occurs only during or after HDV infection. Viral infection spreads parenterally in both cases. However, it has been reported that the risk of HDV infection is limited to hemodialysed patients, unlike the risk of HBV infection. In order to verify these findings the Authors studied 108 patients undergoing periodical hemodialytic treatment in order to study the delta antibodies present in their blood. Sixty-one of these subjects had received previous blood transfusions, 15 were HBsAg positive and 7 positive for other serological markers of the hepatitis B virus. None of the subjects examined was positive for anti HDV. Our results agreed with the literature reporting an incidence of positive HDV serological markers limited to hemodialyzed patients. The Authors observed that the behaviour of the HDV serological markers can vary from patient to patient and that it is impossible to furnish diagnosis of HDV infection after HBV and HDV clearance. Since these factors can lead to underestimation of the real incidence of HDV infection in hemodialyzed patients, the Authors underline the need to perform long term epidemiological studies and to investigate all the HDV serological markers.

Substance P-like immunoreactive nerve fibers of the human laryngeal mucosa--preliminary report

Substance P (SP) is considered a primary sensory transmitter and is widely distributed within the autonomic nervous system. This study is concerned with the distribution of SP-like immunoreactive nerve fibers in the human larynx. Individual SP-like immunoreactive nerve fibers were detected in the subepithelial connective tissue of the laryngeal mucosa, in the ventricular and subglottic glandular regions and in a few nervous ganglia in the deep connective tissue. No intraepithelial SP-like immunoreactive fibers were present in our material.

Synergistic effect of testosterone and of a luteinizing hormone-releasing hormone agonist on androgen receptor content in the ventral prostate of castrated rats

The aim of the present experiment was that of studying the effect of an LHRH agonist analog on the prostatic content of cytosol and nuclear salt-extractable and salt-resistant androgen receptors (AR). Castrated rats were treated for six days with the LHRH agonist WY 40972 (A), with testosterone enanthate (T) or with A plus T. Intact adult male rats and castrated rats treated with the vehicle served as controls. The animals were sacrificed 18 h after the last subcutaneous injection. The ventral prostates were quickly removed and submitted to subcellular fractionation for the determination of cytosol and nuclear AR content. In addition, the weights of the prostates and of the seminal vesicles were recorded, and serum levels of LH and FSH were evaluated by radioimmunoassay. The dissociation constants (Kd) of cytosol and nuclear AR, on the order of 1 x 10(-9) M, were not affected by the various treatments. Conversely, the combined treatment with T and A induced a significant increase of nuclear AR in the prostatic tissue, when compared to the levels found in castrated rats treated with T alone and in intact rats. The treatment with T was able to restore the reproductive organs to their normal weights. The treatment with A inhibited the hypersecretion of gonadotropins induced by castration. The results show that, under the conditions of the present experiment, A exhibits a synergistic effect with T on nuclear AR content in the rat ventral prostate. The results also suggest that A acts directly on this androgen-dependent structure.

Antihormonal activities of 5 alpha-reductase and aromatase inhibitors

The problem of developing androgen antagonists has been tackled so far only by synthesizing steroids able to displace testosterone and other androgens from their specific receptor sites. The observation that testosterone has to be converted intracellularly either to 5 alpha-reduced metabolites (DHT, 3 alpha-diol, etc.) or to estrogens, in order to become fully active on androgen-dependent structures (both central and peripheral), has opened the possibility of creating molecules which prevent these conversions, and which could then block the actions of testosterone. The availability of these new compounds has allowed a better understanding of the selective physiological role of each of the metabolites of testosterone, and to provide the basis for the development of new hormone antagonists to be used in those clinical conditions for which an inhibition of the actions of testosterone is foreseen. The usefulness of these enzyme inhibitors is underlined by some examples described in this paper. The results obtained may permit the formulation of the following conclusions: (1) The conversion of testosterone to its 5 alpha-reduced metabolites occurring in the neuroendocrine structures may represent an essential step for the appearance of the inhibitory feedback effect testosterone exerts on LH secretion; (2) Testosterone exhibits its negative feedback effect on FSH secretion as such and not following the local aromatization to estrogens; (3) Testosterone exerts its effect on the intrahypothalamic stores of LHRH acting as such and not following its local conversion either to 5 alpha-reduced metabolites or to estrogenic molecules; (4) Some of the new enzyme inhibitors (e.g. 4-OH-A) may represent an interesting tool for the treatment and/or the prevention of BPH and possibly of other androgen-dependent diseases (prostate carcinoma, acne etc.), as shown by their ability to prevent the in vitro conversion of testosterone to its 5 alpha-reduced metabolites both in the normal prostate of the rat and in the human BPH tissue.

Testosterone and the control of hypothalamic GnRH

The aim of the present study was to test the hypothesis that the restoring effect of testosterone on hypothalamic GnRH stores in orchidectomized rats might be linked to the intrahypothalamic transformation of the hormone into estrogenic metabolites. To this purpose, advantage has been taken of the availability of the potent antiestrogen, tamoxifen (TMX). Different groups of adult male rats castrated since 4 weeks were submitted to a 6-day treatment with testosterone propionate (TP, 2 mg/rat daily); TMX (50 or 200 micrograms/rat daily); or TP (2 mg/rat daily) plus TMX (50 or 200 micrograms/rat daily). The animals were sacrificed 24 h after the last injection, and hypothalamic GnRH content was measured by radioimmunoassay. The results have confirmed the ability of TP to counteract the decreasing effect of orchidectomy on hypothalamic GnRH stores, and have shown that TMX does not have any intrinsic activity on this parameter. Furthermore, TMX at either dose used in the present experiments, was found not to be able to abolish the restoring effect of TP on MBH-GnRH stores. It is concluded that the action of testosterone on hypothalamic GnRH does not require the conversion of the hormone into estrogens.

Ultrashort feedback control of luteinizing hormone-releasing hormone secretion in vitro

The present experiments were performed to clarify whether LHRH might inhibit its own secretion via an ultrashort feedback mechanism acting directly on the hypothalamus. Using an in vitro system, mediobasal hypothalami (MBHs) of adult male rats were perifused in either the presence or absence of a LHRH agonistic analog [D-Ser(TBU)6,Des-Gly10] LHRH ethylamide shown not to cross-react in the LHRH RIA. In the first series of experiments, six MBHs per chamber were initially perifused with control medium and submitted to two K+ stimulations (110 mM) for 5 min every 30 min; the control medium was then replaced by medium containing the LHRH analog (5 microM), and three additional K+ pulses were applied. In the second series of experiments, a single MBH per chamber was exposed for the duration of the experiments to either control medium or medium containing the LHRH analog (5 microM). In both cases, pulses of K+ were applied to the tissue. The amounts of endogenous LHRH released both under basal conditions and after K+ stimulation were measured in the effluent (1 ml every 5 min) with a specific RIA. The results show that the LHRH analog inhibits basal secretion of endogenous LHRH from the MBH, and diminishes or abolishes the response to K+ stimulations. The specificity of the inhibitory effect exerted by the LHRH analog on LHRH secretion was shown by the inability of TRH to mimic the effect of the LHRH analog. The data are consistent with the hypothesis that LHRH, acting at a hypothalamic level, might participate in the control of its own release via an ultrashort feedback mechanism.

Evaluation of factor VII antigen in factor VII congenital deficiencies with a new ELISA assay

An evaluation of a new Enzyme Linked Immunosorbent Assay (ELISA) factor VII:Ag assay in factor VII congenital deficiencies was carried out. This assay was compared to factor VII:C assay and the Inhibitor Neutralization Assay (INA) for factor VII:Ag, both in normals and F VII-deficient patients. The correlations between ELISA F VII:Ag and VII:C, as well as the one between INA F VII:Ag and VII:C, were good (r = .86 and .81, respectively). The correlation between the two immunologic methods of assay in normals was fairly good (r = 0.73, P less than 0.001); whereas in mild F VII deficiencies (heterozygotes for F VII deficiencies), the two methods correlated very well (r = .96). In the severe deficiencies, ELISA F VII:Ag assay allowed the evaluation of F VII protein levels below 1 u/dl. The sensitivities of the INA and ELISA assays were evaluated by creating artificially prepared plasmas containing serial amounts of purified F VII: INA was unable to pick up F VII protein levels lower than 75 ng/ml, whereas the ELISA assay could detect up to 5 ng of F VII.

Effect of oestrus cyclicity on the number of brain opioid mu receptors in the rat

The present experiments have been performed in order to analyse whether the binding characteristics of brain opioid receptors of the mu type vary during the different phases of the oestrous cycle in the female rat. To this purpose different groups of females with a regular 4-day oestrous cycle were killed by decapitation in different phases of their oestrous cycle, i.e. at 10.00 and 16.00 h of the first and second day of dioestrus, at 10.00, 12.00, 14.00, 16.00 18.00 and 20.00 of the day of pro-oestrus, and at 10.00, 12.00 14.00, 16.00 and 18.00 of the day of oestrus. The total brains, after discarding the cerebellum, were homogenized and crude membrane preparations were obtained. On these preparations the maximal binding capacity (Bmax, index of the number of receptors) and the constant of affinity (Ka) for dihydromorphine, a typical ligand of mu opioid receptors were evaluated. Serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin were measured by specific radioimmunoassays in order to exactly ascertain the different phases of the oestrous cycle. The results obtained show that the number of mu opioid receptors in the whole brain presents significant changes during the different phases of the oestrous cycle. In particular, an increase in the concentration of these receptors was observed at 12.00 h of the day of pro-oestrus and at 18.00 h of the day of oestrus; these fluctuations of the number of mu receptors were not accompanied by any change of their affinity for the ligand.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging and the hypothalamo-pituitary-testicular axis in the rat

Several experiments have been performed in order to clarify the mechanisms through which aging in male rats brings about profound modifications of the neuroendocrine system (reduced pulsatile secretion of LH and FSH, decreased serum levels of gonadotropins and testosterone, etc.). (1) It has been found that the number of mu opioid receptors decreases significantly in the hypothalami of old male rats; the substitution therapy with testosterone is ineffective in increasing the number of mu opioid receptors. These data suggest that the decrease of hypothalamic mu opioid receptors is not due to a decline of serum testosterone levels, but appears to be an independent phenomenon. (2) K opioid receptors increase significantly in the amygdala and in the thalamus of old male rats. These results show that aging, in addition to mu receptors, affects also the number of K receptors in selected areas of the brain. The increase of the number of K receptors in the amygdala might have some bearing on the decrease of serum gonadotropins observed in aged rats, since the amygdala is involved in the nervous circuitry influencing the hypothalamo-pituitary-gonadal axis. (3) The study of the release of LHRH from the hypothalamus of old male rats with an in vitro perfusion system shows that the release of the hormone is comparable in young and old animals, both in basal and in K+ stimulated conditions. These results indicate that the hypothalamus of old male rats retains the capacity of releasing LHRH both in basal and in stimulated conditions. (4) It has been observed that the number of LHRH receptors at the level of the anterior pituitary is significantly reduced in old male rats. This finding might explain the low serum levels of gonadotropins and testosterone in aged rats, due to a lack of an adequate response of the pituitary to hypothalamic LHRH.

New approaches for the treatment of prostatic hypertrophy and cancer

The present study reports the effects exerted by 4-hydroxy-4-androstene-3,17-dione (4-OH-A) on the in vitro metabolism of labelled testosterone, dihydrotestosterone (DHT) and androstenedione (delta-4-A) in the prostate of adult male rats and in human benign prostatic hypertrophic (BPH) tissue. It has been found that 4-OH-A decreases the formation of DHT and of the diols. When testosterone is used as the substrate, the presence in the medium of 4-OH-A enhances the formation of delta-4-A and of 5-alpha-androstanedione (5-alpha-A); 4-OH-A does not inhibit the conversion of labelled DHT into the diols. Also, the transformation of labelled delta-4-A into 5-alpha-A is not modified by 4-OH-A. On the basis of these findings, it is suggested that 4-OH-A might represent a potential new agent for the prevention and/or treatment of human BPH.

Evaluation of the nature of mildly prolonged prothrombin times

Twenty-one asymptomatic individuals with a mildly prolonged prothrombin time (greater than 2 SD from the prothrombin time of the reference plasma) were found to have a mild isolated factor VII (F VII) defect (mean 38.8 U/dl; SD 13.2). Factor VII antigen levels were also found to be reduced (mean 45.5 U/dl; SD 7.8) in 13 of them. These figures were compared with those of 50 normals and 28 obligatory heterozygotes for F VII deficiency. The phenotypical behaviors in the propositi were found to be equal to those of the F VII congenital deficiency heterozygotes: the discrepant one (VII+) and the nondiscrepant one (VII-/R). Fifteen families of the propositi could also be studied, totalling 55 additional individuals; in 25 of them (ten pedigrees) a mild F VII deficiency was found showing the same phenotypical features of the corresponding propositi. We therefore believe that these individuals with mild F VII deficiency can be considered as heterozygotes for the defect, since the other vitamin K-dependent clotting factors were normal; the defect is transmitted throughout the kindred with the same mode of inheritance as F VII congenital deficiency; and F VII:C and F VII:Ag levels are highly comparable with those of known obligatory heterozygotes for F VII deficiency. On the grounds of a careful statistical analysis we propose a formula which allows a discrimination between the two phenotypes of the heterozygotes for F VII congenital deficiency. In addition it is suggested that sensitive tissue thromboplastins should be used to pick up these mild defects.

Tamoxifen does not block the inhibitory effect of testosterone on FSH release in rats

The aim of the present experiments was to analyze whether the inhibitory effect exerted by testosterone on FSH release might be mediated by the intracerebral transformation of the hormone into oestrogenic metabolites. Advantage has been taken of the availability of the potent antioestrogen tamoxifen. Two series of experiments have been performed. In the first one, adult male rats have been castrated and submitted, beginning immediately after surgery, to a 6-day treatment with testosterone propionate (2 mg/rat/day), tamoxifen (50 or 200 micrograms/rat/day) or testosterone propionate (2 mg/rat/day) plus tamoxifen (either 50 or 200 micrograms/rat/day). In the second experiment, adult male rats have been castrated and submitted to the same 6-day treatments, beginning 4 weeks following orchidectomy. In both experiments, the animals were killed 24 h after the last injection, and serum levels of FSH and LH have been measured by radioimmunoassays. The results have clearly shown that, in both experiments, the administration of testosterone results in a significant decrease of serum FSH and in a total suppression of LH release. The administration of tamoxifen, in either dose, does not modify the elevated serum FSH and LH levels present in the orchidectomized animals, and does not antagonize the inhibitory effect on FSH and LH secretion exerted by the concomitant treatment with testosterone propionate. It is concluded that testosterone inhibits FSH secretion in orchidectomized rats acting as such, and not following aromatization to oestrogens.

In vitro metabolism of testosterone in the rat prostate: influence of aging

The in vitro metabolism of labelled testosterone has been studied in the ventral prostate of young (2 months) and old (15 and 22 months) male rats. It has been found that the prostate of 2-month old animals converts testosterone into dihydrotestosterone (5-alpha-androstane-17-beta-ol-3-one, DHT) and into the diols (5-alpha-androstane-3-alpha,-17-beta-diol and 5-alpha-androstane-3-beta,17-beta-diol) with considerable yields. The prostate of young animals is also able to convert testosterone into delta-4-androstenedione (delta-4-A), 5-alpha-androstanedione (5-alpha-A) and androsterone (A); however, the amount of these metabolites are lower than those of DHT and the diols. Aging induces major alterations in the prostatic metabolism of testosterone. In particular, a progressive and significant decrease in the formation of DHT and of the diols has been found in animals of 15 and 22 months of age. Advancing age induces, on the contrary, a progressive and significant increase of the formation of delta-4-A. The total amounts of 5-alpha-reduced metabolites of the 17-keto series (5-alpha-A + A) are higher at 15 and 22 months than at 2 months of age. This increase appears to result from an enhanced formation of 5-alpha-A at 15 months, and of A at 22 months. The present data show that aging exerts important effects on the metabolism of testosterone in the ventral prostate of the rat. The results may help explaining why the old rat does not develop spontaneously the syndrome of benign prostatic hypertrophy (BPH), as it occurs in other species (dogs and humans).