Innervation of the ventral prostate of the rat

Use of beta-blocker types and risk of incident prostate cancer in a multiethnic population

PURPOSE

Increased adrenergic innervation is observed in prostate cancer (CaP) and is associated with aggressive disease. Emerging evidence suggests that beta-adrenergic blockade inhibits CaP progression. However, the association between type of beta-blocker use and risk of incident CaP on initial prostate biopsy has not been investigated in multiethnic populations.

MATERIALS AND METHODS

A retrospective study of racially/ethnically diverse men (64% African-American and Hispanic), who underwent initial prostate biopsy between 2006 and 2016 in a large healthcare system was performed. Oral use of beta-blocker type was assessed by reviewing active prescriptions within the 5-year period preceding initial biopsy. Patient demographics and clinical factors were collected.

RESULTS

Of 4,607 men who underwent initial prostate biopsy, 4,516 met criteria and 2,128 had a biopsy positive for CaP; 20% high-risk, 41% intermediate-risk, and 39% low or very-low risk (National Comprehensive Cancer Network classification). Overall, 15% of patients were taking a beta-blocker prior to initial biopsy, with Metoprolol, Atenolol, and Carvedilol accounting for the majority. Of beta-blocker types, Atenolol alone was associated with a 38% reduction in odds of incident CaP (P= 0.01), with a 40% and 54% reduction in risks of National Comprehensive Cancer Network intermediate and high-risk CaP (P = 0.03 and P = 0.03, respectively) compared to men not taking a beta-blocker. Furthermore, longer duration of Atenolol use (3-5 years) was associated with a 54% and 72% reduction in intermediate and high-risk disease, (P = 0.03 and P = 0.03, respectively).

CONCLUSIONS

Among beta blocker types, long-term Atenolol use is associated with a significant reduction in incident CaP risk on initial prostate biopsy for clinically-significant intermediate and high-risk disease compared to men not taking a beta-blocker.

Does length of prostate biopsy cores have an impact on diagnosis of prostate cancer?

OBJECTIVE

To investigate whether core length is a significant biopsy parameter in the detection of prostate cancer.

MATERIAL AND METHODS

We retrospectively analyzed pathology reports of the specimens of 188 patients diagnosed with prostate cancer who had undergone initial transrectal ultrasound (TRUS) guided prostate biopsy, and compared biopsy core lengths of the patients with, and without prostate cancer. The biopsy specimens of prostate cancer patients were divided into 3 groups according to core length, and the data obtained were compared (Group 1; total core length <10 mm, Group 2; total core length 10 mm-19 mm, and Group 3; total core length >20 mm). Biopsy core lengths of the patients diagnosed as prostate cancer, and benign prostatic hyperplasia were compared, and a certain cut-off value for core length with optimal diagnostic sensitivity and specificity for prostate cancer was calculated.

RESULTS

Mean age, PSA and total length of cores were 65.08±7.41 years, 9.82±6.34 ng/mL and 11.2±0.2 mm, respectively. Assessment of biopsy core lengths showed that cores with cancer (n=993, median length 12.5 mm) were significantly longer than benign cores (n=1185, median length=11.3 mm) (p<0.001). Core length analysis yielded 12 mm cores have an optimal sensitivity (41.9%) and specificity (62%) for detection of cancer (odds ratio: 1.08).

CONCLUSION

Biopsy core length is one of the most important parameter that determines the quality of biopsy and detection of prostate cancer. A median sample length of 12 mm is ideal lower limit for cancer detection, and biopsy procedures which yield shorter biopsy cores should be repeated.

The effects of retropubic and perineal radical prostatectomy techniques on postoperative urinary continence after surgery: Results of 196 patients

OBJECTIVE

The aim of this study was to examine the effects of the retropubic and perineal radical prostatectomy techniques on postoperative urinary continence.

MATERIAL AND METHODS

This study included patients who had undergone radical retropubic (RRP) (n=54) or radical perineal prostatectomies (RPP) (n=142) in our clinic between December 2006 and December 2010 with the indication of localized prostate cancer. Preoperative, and postoperative continence levels of the patients were evaluated on the day of catheter removal, and at 3., 6. or 12. months using University of California-Los Angeles (UCLA) prostate cancer index query forms completed by the patients themselves in outpatient clinics.

RESULTS

Mean ages of the perineal, and retropubic groups were 62.3 (48-77), and 62.5 (50-74) years, respectively. The absolute urinary control rates of the RPP patients on the first days, and the first, third, sixth, and twelfth months were 44.3, 63.6, 76.2, 79.5, and 86.1%, respectively. The same rates were 51.4, 75.7, 78.4, 89.2, and 91.9% for the RRP group, respectively.

CONCLUSION

There was no significant difference between RRP groups as for the frequency of urinary incontinence.

Slimmer or fertile? Pharmacological mechanisms involved in reduced sperm quality and fertility in rats exposed to the anorexigen sibutramine

Sperm acquire motility and fertility capacity during epididymal transit, under the control of androgens and sympathetic innervations. It is already known that the acceleration of epididymal sperm transit time can lead to lower sperm quality. In a previous work we showed that rats exposed to the anorexigen sibutramine, a non-selective serotonin-norepinephrine reuptake inhibitor, presented faster sperm transit time, lower epididymal sperm reserves and potentiation of the tension of epididymal duct to norepinephrine exposed acutely in vitro to sibutramine. In the present work we aimed to further investigate pharmacological mechanisms involved in these alterations and the impact on rat sperm quality. For this, adult male Wistar rats were treated with sibutramine (10 mg/kg/day) or vehicle for 30 days. Sibutramine decreased final body, seminal vesicle, ventral prostate and epididymal weights, as well as sperm transit time in the epididymal cauda. On the contrary of the in vitro pharmacological assays, in which sibutramine was added directly to the bath containing strips of distal epididymal cauda, the ductal tension was not altered after in vivo sub-chronic exposure to sibutramine. However, there is pharmacological evidence that the endogenous epididymal norepinephrine reserves were reduced in these animals. It was also shown that the decrease in prostate weight can be related to increased tension developed of the gland, due to sibutramine sympathomimetic effects. In addition, our results showed reduced sperm quality after in utero artificial insemination, a more sensitive procedure to assess fertility in rodents. The epididymal norepinephrine depletion exerted by sibutramine, associated with decreases in sperm transit time, quantity and quality, leading to reduced fertility in this experimental model, reinforces the concerns about the possible impact on fertility of man taking sibutramine as well as other non-selective serotonin-norepinephrine reuptake inhibitors, especially considering the lower reproductive efficiency of humans compared to males of other species.

Evidence for increased tissue androgen sensitivity in neurturin knockout mice

Neurturin (NTN) is a member of the glial cell line-derived neurotrophic factor (GDNF) family and signals through GDNF family receptor alpha 2 (GFRα2). We hypothesised that epithelial atrophy reported in the reproductive organs of Ntn (Nrtn)- and Gfrα2 (Gfra2)-deficient mice could be due to NTN affecting the hormonal environment. To investigate this, we compared the reproductive organs of Ntn- and Gfrα2-deficient male mice in parallel with an analysis of their circulating reproductive hormone levels. There were no significant structural changes within the organs of the knockout mice; however, serum and intratesticular testosterone and serum LH levels were very low. To reconcile these observations, we tested androgen sensitivity by creating a dihydrotestosterone (DHT) clamp (castration plus DHT implant) to create fixed circulating levels of androgens, allowing the evaluation of androgen-sensitive endpoints. At the same serum DHT levels, serum LH levels were lower and prostate and seminal vesicle weights were higher in the Ntn knockout (NTNKO) mice than in the wild-type mice, suggesting an increased response to androgens in the accessory glands and hypothalamus and pituitary of the NTNKO mice. Testicular and pituitary responsiveness was unaffected in the NTNKO males, as determined by the response to the human chorionic gonadotrophin or GNRH analogue, leuprolide, respectively. In conclusion, our results suggest that NTN inactivation enhances androgen sensitivity in reproductive and neuroendocrine tissues, revealing a novel mechanism to influence reproductive function and the activity of other androgen-dependent tissues.

Fibrosis-related gene expression in the prostate is modulated by doxazosin treatment

AIMS

To gain new insights into the molecular mechanisms of action of doxazosin, we investigated the prostatic stroma ultrastructure and the expression of genes involved with fibrosis, such as collagen type I and III (COL1A1 and COL3A1, respectively) and TGF-beta 1, in the rat ventral prostate.

MAIN METHODS

Adult Wistar rats were treated with doxazosin (25mg/kg/day), and the ventral prostates were excised at 7 and 30days after treatment. Untreated rats were controls. Ventral prostates were subjected to ultrastructural, immunohistochemical, biochemical and molecular analyses.

KEY FINDINGS

Doxazosin-treated prostates showed thickened bundles of collagen fibrils, activated fibroblasts, enlarged neurotransmitter vesicles and increased tissue immunostaining for collagen type I and type III when compared to untreated prostates. After 7 and 30days of doxazosin treatment mRNA expression of COL1A1 and COL3A1 was significantly increased and reduced, respectively, compared to the control group. TGF-beta 1 mRNA and protein levels were increased after 7days of doxazosin treatment, whereas only mRNA levels remained increased after 30days of treatment.

SIGNIFICANCE

Our data suggest that relaxation of smooth muscle cells by alpha-blockers interferes with the mechanical dynamics of the prostatic stroma extracellular matrix components, generating a pro-fibrotic effect probably via the TGF-beta 1 signaling pathway. Long term treatment with doxazosin may also lead to a reduced turnover of extracellular matrix components. Our results add to a better understanding of the molecular mechanisms behind the effects of alpha-blockade on prostatic histoarchitecture and the response to treatment for benign prostatic hyperplasia.

Amikacin: A Novel Modulator of Vesical and Prostate Efferences. An in vitro Experimental Study

The autonomic efferent neurotransmission to the bladder and prostate smooth muscle is a potential target for drug therapy of specific low urinary tract disfunction (LUTD). Since amikacin and other amynoglicosides were reported to affect neurotransmission by a pre-junctional mechanism, we investigated the effect of amikacin on isolated rat and human detrusor smooth muscle contraction and on isolated rat and human prostate contraction, to further evaluate its potential relaxant properties.

Materials and Methods

Samples of detrusor smooth muscle and prostate tissue, obtained from 97 rats and 16 patients undergoing surgery, were studied through the measurement of isometric contraction induced by electrical field stimulation (EFS) and other pharmacological stimuli in the presence or absence of 1mM amikacin in a low-Ca medium.

Results

Amikacin 1 mM significantly reduced contraction of isolated rat and human detrusor muscle and prostate, achieved with pre-junctional stimulation, while no significant effect was observed on contraction induced by pharmacological post-junctional stimulators. EFS contraction inhibited by amikacin was restored after addition of calcium chloride. The amikacin effect was comparable to the effect of magnesium ions, which are known to exert a pre-junctional inhibition of neurotransmitter release.

Conclusions

Amikacin significantly inhibited rat and human detrusor and prostate contraction evoked by pre-junctional stimulation in vitro, suggesting a depressant effect on autonomic efferent neurotransmission. Further pharmacokinetics studies and researches on related compounds may hold potential for future development in the treatment of specific low urinary tract disfunction (LUTD).

Prostate-specific antigen and prostate volume in Korean men with spinal cord injury: a case–control study

STUDY DESIGN

Prospective, cross-sectional, case-control study.

SETTING

Outpatient department in Seoul, Korea.

OBJECTIVES

To assess prostate volume and serum prostate-specific antigen (PSA) levels in Korean men with spinal cord injury (SCI).

METHODS

A total of 31 SCI patients with ages ranging between 45 and 81 years old (median age, 58 years) were studied. Thirty-one age-matched individuals without SCI were enrolled in the study as controls. We tested PSA levels and performed transrectal ultrasonographies on all enrolled patients. Of the patients with SCI, 20 were evaluated for testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels.

RESULTS

Serum PSA levels and prostate volume parameters in the two groups had similar values: the median (5th-95th percentiles) serum PSA level was 1.56 ng/ml (0.12-9.77) for SCI patients and 1.04 ng/ml (0.50-2.98) for controls (P=0.481), whereas the median (5th-95th percentiles) prostate volume was 18.33 ml (10.16-76.78) for SCI patients and 20.80 ml (14.23-41.22) for controls (P=0.072). No significant differences were found when serum PSA levels and prostate volumes were compared according to SCI patient injury characteristics. Testosterone levels were lower than the normal range in 7 SCI patients (35%), LH was higher than the normal range in 10 SCI patients (20%), and FSH was higher than the normal range in eight SCI patients (40%). We observed an age-related increase in FSH levels (r=0.634, P=0.004), although hormone levels did not correlate with serum PSA levels and prostate volume parameters.

CONCLUSIONS

According to our results, serum PSA levels and prostate volume in Korean SCI patients are not different from those in uninjured men and are not affected by injury characteristics.

Morphometric and ultrastructure features of the ventral prostate of rats (Rattus norvegicus) submitted to long-term nicotine treatment

The harmful effects of nicotine on male genital system fertility have been reported in experimental and clinical studies. However, its effects on prostatic cells and glandular pathogenesis remain unclear. The aim of the present study was to analyse the histological, histochemical and ultrastructural alterations, in addition to stereology, of the ventral lobe of the prostate of rats, submitted to chronic nicotine administration, as well as to establish the relationship between these changes and prostate diseases. Twelve male Wistar rats (Rattus norvegicus) were divided into two experimental groups: group I (nicotine) and group II (control). Samples of the ventral prostate were collected, processed and submitted to histological analysis, acid phosphatase histochemistry and ultrastructural analysis by transmission and scanning electron microscopies. The results showed that in the nicotine group, the secretory epithelial cells of the ventral lobe of the prostate were atrophied, and prostatic intraepithelial neoplasia occurred and reduced the expression of acid phosphatase. The disorganisation of organelles involved in the glandular secretory process, accompanied by biomembrane destructuring, was also observed. In conclusion, nicotine causes drastic alterations in the secretory epithelium of the ventral prostate, compromising its function. Furthermore, nicotine also induces premalignant lesions in the prostate gland, thus representing a risk factor in the development of prostate diseases.

Prostate activity and prostate cancer in spinal cord injury

In addition to androgen, autonomic nerves may be involved in prostatic function. As patients with spinal cord injury (SCI) have impaired innervation of the prostate, the prostate volume and prostate-specific antigen (PSA) level in patients with SCI may be different from those of healthy men. Experiments in rats with SCI indicate that neurogenic factors play an important role in prostate growth and function but the same phenomena may not occur in men with SCI because the current animal models differ from clinical results in humans in several respects. Although many of studies indicate the importance of intact peripheral innervation on the secretory function of the prostate, the effect of more central denervation such as occurs in complete SCI at the cervical, thoracic, or lumbar levels on prostatic function is unclear. In addition, the impact of central nervous system injury on prostatic secretory activity, and consequently on serum PSA levels, is also not clear. Furthermore, the impact of hormonal changes on prostate cancer development and prognosis observed in patients with SCI may also be affected by the level of injury and patient age at the time of injury, which have not been studied. In this article, we review prostate activity and prostate cancer in SCI and discuss how they may relate to neurogenic factors.

Noradrenergic and cholinergic innervation of the accessory sexual glands in male sheep

Immunohistochemistry was applied to determine the distribution patterns of nerve fibres containing tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DbetaH), neuropeptide Y (NPY), vasoactive intestinal peptide (VIP) and vesicular acetylcholine transporter (VAChT) in the prostate, seminal vesicle (SV) and bulbourethral glands (BU) of male sheep. In all organs studied, cholinergic innervation was more developed than noradrenergic innervation. Numerous VAChT-immunoreactive (IR) nerve fibres were found in the muscular layer and mucosa of the SV and BU as well as in the prostate. A similar abundance of noradrenergic nerve fibres (showing immunoreactivity both to TH and DbetaH) was also found in both layers of the SV and BU (but not in the prostate). In the prostate a moderate density of VIP-IR nerve fibres was present but only very scarce NPY-IR nerve fibres were shown. All the studied accessory sexual glands (ASG) of male sheep contained VIP-IR nerve fibres in a similar frequency. Double immunohistochemistry revealed that the vast majority of noradrenergic nerve fibres also contained NPY. None of the noradrenergic nerve fibres showed the presence of VAChT or VIP. The possible functional significance of these findings is discussed.

Current models of human prostate contractility

1. The human prostate is a compact gland contributing to seminal fluid. With increasing age, most humans will develop benign prostatic hyperplasia, a condition of prostatic enlargement and contractility that leads to occlusion of the urethra. Over many years, investigators have used a variety of animal and cell culture models to elucidate some of the contractile and proliferative mechanisms that may be associated with the development of this condition. 2. This review briefly assesses the current state of knowledge of the mechanisms underlying human prostatic contractility and compares it with that of animal and cell culture models. It is not intended as a comprehensive methodological review, nor is it intended to indicate our preferences for either model. Our aim is to correlate findings from animal and cell culture models with the current understanding of human prostate contractility. 3. We hope that the present review will increase awareness of the suitability of the current models in developing our understanding of benign prostatic hyperplasia.

Supraspinal connections of the reproductive organs: structural and functional aspects

Gonadal functions are governed by the hypothalamo-hypophyseal system. Other organs of the reproduction tract are under the regulatory action of gonadal steroids. In the past two decades several data have been accumulated on the involvement of fine-tuning control mechanisms which include autocrine and paracrine effects of biologically active substances produced locally and the regulatory action of nerves innervating the organs of the system. Recent studies using the viral transsynaptic technique have revealed cell groups in the central nervous system that are transneuronally connected with the male and female reproductive organs. This review summarizes neuromorphological data on the supraspinal innervation of reproductive organs and the functional significance of these brain areas in the control of reproduction.

Origin of the primary efferent neurons projecting to the prostate of the dog

The retrograde tracing technique of neuronal tracer Fast Blue was used to determine sources of origin of efferent nerve fibers supplying the prostate of the dog. After injection of Fast Blue into the canine prostate retrogradely labelled neurons were found in bilateral L3-S3 sympathetic chain ganglia, bilateral caudal mesenteric ganglion and in bilateral pelvic plexus ganglia. No Fast Blue-positive neurons were present in bilateral L1-L2 sympathetic chain ganglia and in coeliac-mesenteric ganglion complex. The vast majority of Fast Blue-positive efferent prostate-projecting neurons (56.2% +/- 1.7) were located in bilateral caudal mesenteric ganglion, whereas 28.7% +/- 1.5 of them were located in bilateral pelvic plexus ganglia and 14.9% +/- 0.5 in bilateral L3-S3 sympathetic chain ganglia. Immunohistochemical staining for tyrosine hydroxylase and dopamine beta-hydroxylase was applied to determine the neurochemical character of Fast Blue-positive efferent neurons. Immunohistochemistry revealed that in all tyrosine hydroxylase immunoreactive Fast Blue-positive neurons immunoreactivity for dopamine beta-hydroxylase was also found (noradrenergic neurons) while all tyrosine hydroxylase-negative Fast Blue-positive neurons did not express dopamine beta-hydroxylase (non-noradrenergic neurons). In bilateral sympathetic chain ganglia, 96.4% +/- 2.1 of the prostate-projecting neurons were adrenergic and in bilateral caudal mesenteric ganglion this frequency amounted to 95.6% +/- 1.6. In bilateral pelvic plexus ganglia, 26.7% +/- 1.5 of the prostate-supplying efferent neurons did not express either tyrosine hydroxylase or dopamine beta-hydroxylase immunoreactivity which makes discussion of their cholinergic character possible.

Mechanistic investigation of the adrenergic induction of ventral prostate hyperplasia in mice

BACKGROUND

The norepinephrine (NE) analog phenylephrine has previously been shown to induce atypical prostate hyperplasia in rats. The objective of the present study was to provide further insight into the mechanism of phenylephrine-induced prostate growth.

METHODS

Adult male C57/BL6 mice were given daily subcutaneous injection of phenylephrine, isoproterenol, or phenylephrine in combination with BMY7378, cyclazosin, RS100329, or yohimbine, and the effects on ventral prostate histology, and proliferative and apoptotic indices determined. Phenylephrine was also administered in combination with testosterone in castrated mice.

RESULTS

Atypical prostatic hyperplasia characterized by piling up and/or papillary infolding of epithelial cells with concomitant stromal smooth muscle hyperplasia was seen in adult mice given subcutaneous injection of phenylephrine daily for 26 days. Phenylephrine induced hyperplasia was more severe proximally and was associated with significantly reduced rates of apoptosis (but no change in cell proliferation) in both stromal and epithelial compartments. Only the alpha(1A)-adrenoceptor selective subtype antagonist RS100329 abrogated the phenylephrine-induced hyperplasia. Using selective antibodies, the alpha(1A-1)-adrenoceptor subtype was predominantly localized to the stromal compartments of the mouse and rat ventral prostates. The effects of phenylephrine were mediated independent of testicular androgens.

CONCLUSIONS

Prostatic hyperplasia in mice occurs as a consequence of subchronic administration of the sympathomimetic phenylephrine. Response to phenylephrine is mediated by the alpha(1A)-adrenoceptor, which predominates in the stroma of the rodent ventral prostate. Conceivably, therefore, phenylephrine could directly modulate prostate stromal growth, and indirectly modulate epithelial growth in a paracrine fashion. We cannot, however, rule out the contribution of other indirect effects such as hypoxia/reperfusion or effects on intermediary metabolism.

Prostate innervation and local anesthesia in prostate procedures

The nerve supply of the human prostate is very abundant, and knowledge of the anatomy contributes to successful administration of local anesthesia. However, the exact anatomy of extrinsic neuronal cell bodies of the autonomic and sensory innervation of the prostate is not clear, except in other animals. Branches of pelvic ganglia composed of pelvic (parasympathetic) and hypogastric (sympathetic) nerves innervate the prostate. The autonomic nervous system plays an important role in the growth, maturation, and secretory function of this gland. Prostate procedures under local anesthesia, such as transurethral prostatic resections or transrectal ultrasound-guided prostatic biopsy, are safe, simple, and effective. Local anesthesia can be feasible for many special conditions including uncomplicated prostate surgery and may be particularly useful for the high-risk group of patients for whom inhalation or spinal anesthesia is inadvisable.

Ultrastructural study of the ventral lobe of the prostate of mice with streptozotocin induced diabetes (C57BL/6J)

Morphological and functional changes caused by diabetes in the accessory sex organs and especially the prostate have been reported by several investigators. The aim of the present study was to examine the possible deleterious effects of experimentally induced diabetes on the secretory epithelium of the ventral prostate of mice. Sixteen adult male C57BL/6J mice were divided into two groups. The diabetic group received a streptozotocin injection of 75 mg/kg, while the control group received only 0.1 ml citrate buffer, i.p. After 30 days, the diabetic state was ascertained, the animals were sacrificed and the ventral lobe of the prostate was collected for histological and ultrastructural examination. The results showed reduction in glandular epithelium cell height, increased numbers of cytoplasmic vacuoles and thickening of the extracellular matrix. In conclusion, experimental diabetes has harmful effects on the secretory epithelial cells of the ventral lobe of the prostate of mice.

The autonomic and sensory innervation of the smooth muscle of the prostate gland: a review of pharmacological and histological studies

1. We review literature demonstrating (a) the presence and (b) the actions of substances that mediate or modify neuroeffector transmission to the smooth muscle of the prostrate stroma of a number of species including man. 2. In all species studied prostatic stroma, but not secretory acini, receives rich noradrenergic innervation. Stimulation of these nerves causes contractions of prostate smooth muscle that are inhibited by guanethidine and by alpha1-adrenoceptor antagonists that probably act at the alpha1L-adrenoceptor. Such actions underlie the clinical use of alpha1-adrenoceptor antagonists in benign prostatic hyperplasia (BPH). 3. Acetylcholinesterase-positive nerves innervate prostatic stroma as well as epithelium. Atropine reduces nerve-mediated contractions of stromal muscle in the rat, guinea-pig and rabbit. M1, M2 and M3 muscarinic receptors have been implicated in eliciting or facilitating contraction in the prostate from guinea-pig, dog and rat, respectively. 4. Adenine nucleotides and nucleosides, nitric oxide (NO), opioids, neuropeptide Y (NPY) and vasoactive intestinal peptide (VIP) may act as co-transmitters or modulators in autonomic effector nerves supplying prostate stroma. Adenosine inhibits neurotransmission to the rat prostate, and NO is inhibitory in prostate from human, rat, rabbit, pig and dog. The activity of peptides present in the relatively sparse sensory innervation of the prostate exhibits species variation, but, when effective, calcitonin gene-related peptide is inhibitory while tachykinins are stimulant. The roles of NPY and VIP in modulating stromal contractility remain unclear. 5. Taken together the current literature indicates that, in addition to noradrenaline, other neurotransmitters and neuromodulators may regulate the tone of prostatic smooth muscle. Whether drugs that mimic or modify their actions might be useful in providing symptomatic relief of the urinary symptoms associated with BPH remains to be established.

[Effect of sacral roots block in the prostatic structure of the rat]

OBJECTIVE

To validate a simplified model of neural manipulation of the lower urinary tract of the rat, by means of alcoholic blockade of sacral roots.

MATERIAL AND METHODS

Twenty Sprague-Dawle rats (aged 3 months) underwent alcohol sacral root blockade under total anesthesia with previous needle placement monitoring (electrostimulation). After 28-30 days, ipsilateral ventral prostatic lobe (VL) was obtained. Macroscopic and light microscopy (LM) studies were performed (computerized image analysis). Results were compared with 20 LV from non manipulated rats.

RESULTS

A slight non significant decrease of LV weight in the blockade group was notice. LM study showed a reduced epithelial height after manipulation. Gland compartment mean proportions were: control group: 28.1% (epithelial), 29.8% (stromal), y 70.2% (glandular -lumen plus epithelium-); study group: 30.5% (not significant), 37.4% y 62.3% (both p < 0.05) respectively. Epithelium area did not suffer any variation. A reduced vascular overall count was noted in the study group. Ipsilateral diffusion of blockade solution was shown in 9 rats (45%), and bilateral in 11 (55%).

CONCLUSIONS

Alcoholic sacral root blockade produces an atrophy of the glandular component (due to luminal shrinkage, without epithelial change). No differences were found after the macroscopic study. This study could not reproduce the changes produced after standard surgical denervation, therefore we cannot recommend this method to be used in future models.

Pharmacology of neurotransmission to the smooth muscle of the rat and the guinea-pig prostate glands

Histochemical studies carried out on sections of rat and guinea-pig prostate glands revealed the presence of acetylcholinesterase- and noradrenaline-containing nerve fibres in the fibromuscular stroma. Positive staining for acetylcholinesterase but not for noradrenaline was also seen in the epithelium. Electrical field stimulation with trains of 0.5 ms pulses, dial setting of 60 V, delivered at 1-30 Hz for 10 s at 5 min intervals, was applied to nerve terminals within the rat and guinea-pig isolated prostate glands. The evoked contractions were frequency-dependent. Tetrodotoxin (1 microM) abolished contractions evoked by short pulse repetitive stimulation (trains of 20 0.5 ms pulses at 10 Hz every 100 s) in tissues from both species. The field stimulation-induced contractions of the prostatic smooth muscle were markedly attenuated by guanethidine (10 microM) and prazosin (0.1 and 1 microM) indicating that neurotransmission to the prostatic smooth muscle in both species is predominantly sympathetic and noradrenergic, and that noradrenaline released during field stimulation acts at postjunctional alpha1-adrenoceptors. Atropine (0.1 and 1 microM) caused a slight but significant reduction of the field stimulation-induced contractions of prostate smooth muscle from both the rat and the guinea-pig. In the guinea-pig, cholinesterase inhibition by physostigmine and neostigmine, both at 10 microM, enhanced the field stimulation-induced contractions of the prostatic smooth muscle. This enhancement was reversed by atropine (0.1 microM) but not by hexamethonium (0.1 mM). These data are compatible with some participation of acetylcholine, acting at muscarinic receptors, in neurotransmission to prostatic smooth muscle.

Identification of CNS neurons innervating the rat prostate: a transneuronal tracing study using pseudorabies virus

The spinal and brain neurons that innervate the rat prostate were identified using the transneuronal tracing technique. Three groups of rats were prepared: (1) nerve intact, (2) bilateral pelvic nerve cut and right hypogastric nerve cut and (3) bilateral hypogastric nerve cut and right pelvic nerve cut. Pseudorabies virus (PRV) was injected into the ventral prostate on the left side. After 2-4 days, the rats were perfused transcardially under deep anesthesia and the spinal cord and brain removed. PRV-labelled cells were identified using immunohistochemistry. After 3 days survival, sympathetic and parasympathetic preganglionic neurons were labelled with PRV. In addition, spinal interneurons were found in the dorsal gray commissure (DGC) of T13-S1. Rats with only one hypogastric nerve intact resulted in spinal labelling of sympathetic preganglionic neurons in the DGC and ipsilateral intermediolateral cell column (IML). In addition, many spinal interneurons were found from L1 to L6 in the medial gray. Rats with only one pelvic nerve intact displayed PRV-labelled cells in the parasympathetic preganglionic nucleus ipsilateral to the injection site. Spinal interneurons were present in the region of the IML and in the medial cord. In the brain, areas predominately labelled with PRV included the nucleus gigantocellularis and paragigantocellularis, raphe magnus, raphe pallidus, A5, Barrington's nucleus, central gray, ventral tegmental area, the paraventricular nucleus of the hypothalamus, lateral hypothalamus and medial preoptic area. These data demonstrate the sympathetic and parasympathetic spinal circuits and demonstrate the overlap of supraspinal innervation of the spinal interneurons.

Muscarinic receptor subtypes in the rat prostate gland

Muscarinic receptor subtypes mediating carbachol-induced contractions of the rat prostatic smooth muscle were determined. The rank order of potency of muscarinic receptor antagonists in blocking the effects of carbachol was (mean pKB estimates in parentheses): atropine (8.90) >> para-fluorohexahydrosiladifenidol (7.75) > or = hexahydrosiladifenidol (7.62) > methoctramine (6.89) > or = pirenzepine (6.68) > or = himbacine (6.67). The specific binding of [3H]quinuclidinyl benzilate to the rat prostatic homogenates was competitively inhibited by (mean pKi values in parentheses): atropine (8.89) >> hexahydrosiladifenidol (7.86) > para-fluorohexahydrosiladifenidol (7.28) > or = himbacine (7.22) > pirenzepine (6.63) > or = methoctramine (6.38). These profiles, whilst different, indicate the probable involvement of muscarinic M3 receptors in the carbachol-induced contraction.

Characterization of muscarinic cholinergic receptor subtypes in rat prostate

The purpose of this study was to characterize the muscarinic receptor subtypes in the individual lobes of the rat prostate. Immunoprecipitation was performed on homogenates of these 3 lobes using antibodies to the m1-m4 muscarinic receptor subtypes. Reverse transcriptase polymerase chain reaction assays (RT-PCR) were also performed using primers specific for each of the five muscarinic receptor subtypes (m1-m5). The susceptibility of the receptors to degradation by endogenous prostate proteases was assessed by mixing rat ventral prostate with rat heart (m2) and rat parotid (m3) prior to immunoprecipitation. In the ventral lobe, transcripts for the m1-m4 subtypes were amplified whereas in the dorsal and lateral lobes only the m2 and m3 sets of primers amplified PCR products of the predicted size. Immunoprecipitation of the ventral lobe resulted in predominantly m3 receptors, while the majority of receptors immunoprecipitated from lateral and dorsal lobes were the m2 subtype. The m3 muscarinic subtype was apparently susceptible to degradation by prostate proteases whereas the m2 subtype was not. These results demonstrate a regional distribution in the subtypes of muscarinic receptors in the rat prostate, and a greater susceptibility of the m3 receptor to degradation during immunoprecipitation than the m2 subtype.

Innervation of accessory sex glands in the adult male golden hamster and quantitative changes of nerve densities with age

Enzyme histochemistry and immunohistochemistry were used to determine the types of nerves supplying the ampullary gland, coagulating gland, dorsolateral prostate, ventral prostate and seminal vesicle of the male golden hamster. Quantitative change of dopamine beta-hydroxylase (DbetaH), and neuropeptide Y (NPY) immunoreactive and acetylcholinesterase-stained (AChE-stained) nerves with age was also determined. Using an antibody against protein gene product 9.5, nerves were seen to distribute in subepithelial connective tissues, smooth muscles and adventitial connective tissues. Presumptive catecholaminergic nerves immunoreactive for DbetaH and tyrosine hydroxylase were found mainly in periacinar smooth muscles, while AChE-stained nerves predominantly ramified subepithelial connective tissues. In addition, nerves immunoreactive to NPY, calcitonin gene-related peptide, leu-enkephalin, galanin, substance P, and vasoactive intestinal peptide were also detected. Quantitative estimation at 10, 52 and 78 weeks of age showed that densities of DbetaH and NPY nerves were halved by 52 weeks of age. This level was maintained in older animals. The density of AChE-stained nerves in all glands did not change with age. The ampullary gland appeared to have more AChE-stained nerves. These results were discussed from a comparative viewpoint and with regard to possible implications of aging of peripheral nerves on functioning of the male accessory sex glands.

Propranolol treatment affects ventral prostate blood vessels and serum testosterone concentrations in adult rats

The influence of prolonged beta-adrenergic receptor blockade on stereologic parameters of the ventral prostate and serum testosterone concentrations was examined in adult rats injected with propranolol (0.1 or 0.4 mg kg-1/day) for 15 or 30 consecutive days. Both doses of propranolol reduced the relative and absolute volume of the ventral prostate blood vessels. This effect was prevented by simultaneous administration of urapidil, an alpha 1-adrenergic receptor antagonist, indicating that a compensatory vasoconstriction took place as a consequence of propranolol treatment. Serum testosterone concentration was significantly increased following the 30-day application of the lower dose of the drug. These results show that prolonged administration of propranolol, although not affecting the epithelial component of the gland, may indirectly influence prostatic function by reducing the blood flow to the gland.

The pelvic plexus: innervation of pelvic and extrapelvic visceral tissues

The pelvic plexus is an association of neurons that govern visceral tissues involved in eliminative and reproductive functions. It is the singular site in the autonomic nervous system where sympathetic and parasympathetic neurons occur in the same ganglia. Within the plexus, ganglia are not randomly positioned; sympathetic neurons tend to occur more ventrally while parasympathetic neurons are located more dorsally, both in accordance with the location of their target tissues and the entry point of their corresponding preganglionic nerve tracts. For example, the vas deferens and seminal vesicle are ventral in position and thus are innervated by more ventrally located pelvic neurons. Neurochemical studies of pelvic ganglia indicate that there are some characteristic associations of putative neurotransmitters which are based on target organ distribution and in part, dictated by the variety of target tissues within each organ. Penile neurons comprise a uniform population in that they are cholinergic and also may release vasoactive intestinal polypeptide (VIP) and nitric oxide. In contrast, target tissues of the internal genitalia are more diverse, requiring adrenergic and nonadrenergic innervation and a complementary neuropeptide. Preganglionic innervation may also be coded and although sympathetic and parasympathetic fibers are cholinergic, they may differ in respect to neuropeptides and nitric oxide. Sensory neuron collaterals may also influence principal neurons as do intrinsic neurons such as small intensely fluorescent cells. Transmission through pelvic ganglia may be simple as is apparent in penile innervation, or shows a greater integrative capacity, as exemplified by the innervation of the urinary bladder. The extent of interaction of sympathetic and parasympathetic pathways at the level of the pelvic plexus remains largely unknown.

Immunohistochemical properties and spinal connections of pelvic autonomic neurons that innervate the rat prostate gland

Autonomic innervation of the prostate gland supplies the acini, and non-vascular and vascular smooth muscle. The activity of each of these tissues is enhanced by sympathetic outflow, whereas the role of the parasympathetic nervous system in this organ is unclear. In the present study, a range of methods was applied in rats to determine the location of autonomic neurons supplying this gland, the immunohistochemical properties of these neurons, the spinal connections made with the postganglionic pathways and the distribution of various axon types within the gland. Injection of the retrograde tracer, FluoroGold, into the ventral gland visualised neurons within the major pelvic ganglion and sympathetic chain. Fluorescence immunohistochemical studies on the labelled pelvic neurons showed that most were nonadrenergic (also containing neuropeptide Y, NPY), the others being non-noradrenergic and containing either vasoactive intestinal peptide (VIP) or NPY. Sympathetic dye-labelled neurons were identified by the presence of varicose nerve terminals stained for synaptophysin on their somata following lesion of sacral inputs. Parasympathetic innervation of dye-labelled neurons was identified by continued innervation after hypogastric nerve lesion. Most noradrenergic prostate-projecting neurons were sympathetic, as were many of the non-noradrenergic VIP neurons. Parasympathetic prostate-projecting neurons were largely non-noradrenergic and contained either VIP or NPY. All substances found in retrogradely labelled somata were located in axons within the prostate gland but had slightly different patterns of distribution. The studies have shown that there are a significant number of non-noradrenergic sympathetic prostate-projecting neurons, which contain VIP.

Neuroendocrine peptides in the prostate

Circulating androgens are required for normal growth and maintenance of function of the prostate. However, the prostate also contains neuroendocrine peptides, found either in nerve terminals or in prostatic neuroendocrine cells, which are likely to regulate prostate growth or function. The neuronal peptides are likely to participate in the regulation of the synthesis and secretion of prostatic secretory products. While the function of the neuroendocrine cells is undefined, there is evidence for growth-regulating effects of several neuroendocrine cell peptides. Since neuroendocrine differentiation has been correlated with tumor grade and poor prognosis in prostate cancer, the peptide products of the neuroendocrine cells may influence cancer cell replication as well. Recent evidence in other tissues suggests that peptide hormone receptor second-messenger systems may interact with steroid receptors to modulate their actions. These findings raise the possibility that prostatic neuroendocrine peptides may modulate the response of prostate to androgens.

Determination of prostatic secretion in rats: effect of neurotransmitters and testosterone

To study the neuronal and hormonal control of prostatic secretion, the prostatic urethra was cannulated in urethane anesthetized rats. The volume of prostatic secretion was measured following infusion of cholinergic and adrenergic agonists intact animals. Prostatic secretion was elicited by norepinephrine, phenylephrine and carbachol; but not by clonidine, isoproterenol, pilocarpine, or acetylcholine. Phenylephrine and norepinephrine infusions caused a high initial rate of secretion, which then declined rapidly. Carbachol infusion, in contrast, produced a low but constant rate of secretion that was maintained for up to 1 hour. Histological examination of the prostate revealed contraction of smooth muscle surrounding prostatic ducts after infusion of phenylephrine and norepinephrine, but not carbachol. Prostatic secretion was also measured in castrated rats supplemented with various doses of testosterone. Testosterone exerted a dose dependent control of prostatic weight and secretory volume. These results indicate 1) alpha 1 receptor agonists can cause contraction of smooth muscle to expel fluid from the rat prostate, 2) carbachol induces prostatic secretion through a mechanism other than contraction of gland, and 3) testosterone has a primary role in controlling prostatic size.

Morphologic and regulatory aspects of prostatic function

Current concepts of the structural and functional organization of the human prostate are presented and are related to endocrine principles which have been studied in experimental animals. Based on embryological and histological studies, the internal structure of the human prostate gland is divided into four subdivisions: 1. the anterior nonglandular fibromuscular stroma. 2. the periurethral portion, 3. the peripheral zone, and 4. the central zone. The central zone which accounts for 25% of the gland, is formed by a wedge-shaped group of ducts, arising close to the orifices of the ejaculatory ducts and is surrounded by the peripheral zone (75% of the gland). The functional interdependence and relationship between the stroma and the epithelium observed during embryological development, postnatal maturation and under certain pathological conditions, has led to the concept of a functional prostatic unit, which is useful for the explanation of prostatic growth and the expression of specific genes. There is growing evidence of a functional heterogeneity within the prostatic secretory duct system, with a concentration of estrogen-sensitive cells close to the urethra, and a relatively long persistence of undifferentiated nonsecretory acini at the peripheral tips of the gland ducts close to the dorsal capsule until late puberty. Secretory and proliferative activities of the gland are strictly androgen-dependent. Of particular importance with respect to glandular and stromal proliferation are the recent reports on the presence of different growth factors in the prostate. Hormonally induced imbalances in the system of growth factor production, androgen- and estrogen-dependence and general ageing of the cells have to be taken into consideration in understanding various prostatic pathologies such as benign prostatic hyperplasia and prostate cancer.

The effect of sympathetic denervation with 6-hydroxydopamine on the ventral prostate of the rat

The effect of chemical sympathectomy with 6-hydroxydopamine (6-OHDA) on the ventral prostate of the rat was studied. A dose of 50 mg/kg i.v., which was repeated after 1 week, was effective enough to produce total disappearance of sympathetic nerves. Reappearance of nerve fibres was evident 2 weeks after treatment. Dilation of prostatic alveoli was noted 1 week after denervation. It is concluded that the absence of normal sympathetic innervation prevents the emptying of the rat prostate.

The histochemistry of complex carbohydrates in the epithelium lining the ventral prostate of the rat

In the epithelium lining the ventral prostate of the rat, complex carbohydrate-containing structures have been studied by means of both light and electron microscopic histochemical methods. According to light microscopy, the free surface and granules of different sizes in the distal cytoplasm of the epithelial cells were found to exhibit positive reactions for complex carbohydrates with 1,2-glycol and acidic groups and sialic acid residues. In addition, secretory substances within the glandular lumen were shown to exhibit positive reactions for similar groups and saccharide residues of complex carbohydrates. In electron microscopy, the surface coat of the plasma membrane, certain elements of the Golgi apparatus and lysosomal dense bodies were found to exhibit positive reactions for glycoproteins with 1,2-glycol groupings. The histophysiological significances of the carbohydrate-containing structures have been discussed with special reference to the known physiological functions of the prostate in the rat.

Nerve endings in the human prostate

The ultrastructure of nerve endings in the human prostate was studied using glutaraldehyde-OsO4 and KMnO4 fixation. The nerve endings were classified into three categories according to the size of the vesicles and the contents of the synaptic profiles. In addition to the conventional adrenergic and cholinergic axons, a third type of axon profile containing a predominance of large granular vesicles was constantly found. Synaptic contacts were found only on smooth muscle cells. No epithelial innervation could be demonstrated. The functions and possible transmitters of the various types of axon terminals are discussed.

Immunohistochemical demonstration of VIP, [Met5]-and [Leu5]-enkephalin immunoreactive nerve fibres in the human prostate and seminal vesicles

The distribution of nerves containing immunoreactivity for the VIP and enkephalins has been demonstrated in the human prostate and seminal vesicles using the immunoperoxidase bridge. VIP-containing nerves were detected in both organs studied mainly in association with the epithelium, while nerves containing ELI seemed to be related to smooth muscle. Compared with the distribution of adrenergic and cholinergic nerves in the prostate marked differences in the density of the innervation were detected. The possible nature of these peptide-containing nerves is discussed.