Pig Prostate Research Articles

Involvement of prostatic interstitial cells of Cajal in inflammatory cytokines-elicited catecholamines production: Implications for the pathophysiology of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS)

In a previous work using guinea pig prostate, we have identified a novel interstitial cells of Cajal (ICCs) which possess close contacts between sympathetic nerve bundles and smooth muscle cells. The ability of prostatic ICCs in mediating excitatory neural inputs was therefore studied using isolated murine prostate ICCs by collagenase digestion combined with FACS method. RT-PCR and Western blotting analyses revealed that prostatic ICCs under a quiescent state expressed abundantly the rate-limiting enzymes essential for catecholamine synthesis. Moreover, distinct proinflammatory cytokines (e.g. IL-1β, IL-8, ICAM-1 and TNF-α) could significantly stimulate the expression levels of the rate-limiting enzymes of catecholamine production in prostate ICCs. Mechanistically, the above-mentioned stimulatory effects of proinflammatory cytokines appeared to be mediated via activation of NF-κB, HIF-1α and HDACs signaling pathways. Considering that prostatic catecholamine overactivity serves as an essential etiology of pelvic pain by indirectly stimulating the smooth muscle cell proliferation, or by directly causing muscular spasm, our results collectively suggest that targeting the NF-κB, HIF-1α and HDACs pathways in prostate ICCs be considered as a new strategy for treatment of chronic pelvic pain syndrome (CPPS) induced by chronic prostatitis (CP). Overall, the current study should shed novel light on the biology of this unique prostate ICCs.

Epigenetic effects of prenatal estradiol-17β exposure on the reproductive system of pigs

There is growing evidence that early life exposure to endocrine disrupting chemicals might increase the risk for certain adult onset diseases, in particular reproductive health problems and hormone dependent cancers. Studies in rodents suggest that perinatal exposure to even low doses of estrogenic substances can cause adverse effects, including epigenetic reprogramming of the prostate and increased formation of precancerous lesions. We analyzed the effects of an in utero exposure to the strongest natural estrogen, estradiol-17β, in a pig model. Two different low and one high dose of estradiol-17β (0.05, 10 and 1000 μg/kg body weight/day) were orally applied to gilts during pregnancy and potential effects on the reproductive system of the offspring were analyzed. No significant effects on sperm vitality parameters and testes size were observed in adult boars. However, prenatal exposure to the high dose decreased absolute, but not relative weight of the testes in prepubertal piglets. RNA sequencing revealed significantly regulated genes of the prepubertal prostate, while testes and uteri were not affected. Notably, we found an increased prostate expression of CCDC80 and a decreased ADH1C expression in the low dose treatment groups. BGN and SPARC, two genes associated with prostate tumor progression, were as well more abundant in exposed animals. Strikingly, the gene body DNA methylation level of BGN was accordingly increased in the high dose group. Thus, while only prenatal exposure to a high dose of estrogen altered testes development and local DNA methylation of the prostate, even low dose exposure had significant effects on gene expression in the prostate of prepubertal piglet offspring. The relevance of these distinct, but subtle transcriptional changes following low dose treatment lacking a clear phenotype calls for further long-term investigations. An epigenetic reprogramming of the pig prostate due to prenatal estrogen cannot be neglected.

This Month in Investigative Urology

No AccessJournal of UrologyThis Month in Investigative Urology1 Oct 2014This Month in Investigative Urology Karl-Erik Andersson Karl-Erik AnderssonKarl-Erik Andersson More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.07.006AboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "This Month in Investigative Urology." The Journal of Urology, 192(4), pp. 1011–1012 References 1 : Voltage dependence of slow wave frequency in the guinea pig prostate. J Urol2014; 192: 1286. Link, Google Scholar 2 : Shock wave lithotripsy targeting of the kidney and pancreas does not increase the severity of metabolic syndrome in a porcine model. J Urol2014; 192: 1257. Link, Google Scholar 3 : Elevated serum IgE may be associated with development of ketamine cystitis. J Urol2014; 192: 1249. Link, Google Scholar © 2014 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 192Issue 4October 2014Page: 1011-1012 Advertisement Copyright & Permissions© 2014 by American Urological Association Education and Research, Inc.MetricsAuthor Information Karl-Erik Andersson More articles by this author Expand All Advertisement PDF downloadLoading ...

Voltage Dependence of Slow Wave Frequency in the Guinea Pig Prostate

Spontaneous phasic contractions of the guinea pig prostate stroma result from the generation of slow waves that appear to primarily rely on spontaneous Ca(2+) release from the endoplasmic/sarcoplasmic reticulum and subsequent opening of Ca(2+) activated chloride channels. We investigated voltage dependent mechanisms in the regulation of slow wave frequency. Changes in membrane potential were recorded using conventional intracellular recording techniques while simultaneously measuring the isometric tension of guinea pig prostate lobes. Fluorescence immunohistochemistry was done to determine the cellular composition of the prostate stroma. Depolarization induced by high K(+) solution, K(+) free solution or outward current injection was associated with increased slow wave frequency. In contrast, hyperpolarization induced by the re-addition of K(+), adenosine triphosphate sensitive K(+) channel openers or inward current injection prevented slow wave generation. K(+) channel openers induced hyperpolarization and thecessation of slow waves was reversed by glibenclamide (10 μM). Nifedipine (1to 10 μM) shortened the duration of slow waves and pacemaker potentials butoften failed to prevent their generation and associated contractions. Subsequently Ni(2+) (100 μM) or mibefradil (1 μM) largely suppressed slow waves and abolished residual contractions. Immunohistochemistry revealed small interconnected smooth muscle bundles as well as vimentin positive interstitial cells but failed to show a network of Kit positive interstitial cells. Prostate slow wave frequency is voltage dependent due to the significant contribution of L-type and T-type Ca(2+) channels. Prostate slow waves may arise from cooperation between spontaneous Ca(2+) release from internal stores and plasmalemmal voltage dependent Ca(2+) channels.

Tamsulosin modulates, but does not abolish the spontaneous activity in the guinea pig prostate gland

To examine the effects of the α1A -adrenoceptor antagonist, tamsulosin, on spontaneous contractile and electrical activity in the guinea-pig prostate gland. The effects of tamsulosin (0.1 and 0.3 nM) were investigated in adult and ageing male guinea pig prostate glands using conventional tension recording and electrophysiological intracellular microelectrode recording techniques. Tamsulosin reduced spontaneous activity, and had different age-dependent effects on adult and ageing guinea pigs at different concentrations. 0.1 nM tamsulosin caused a significantly greater reduction of spontaneous contractile and electrical activity in ageing guinea pigs in comparison to adult guinea pigs. In contrast, 0.3 nM tamsulosin had a significantly greater reduction of spontaneous contractile and electrical activity in adult guinea pigs in comparison to ageing guinea pigs. This study demonstrates that tamsulosin can modulate spontaneous myogenic stromal contractility and the underlying spontaneous electrical activity; tamsulosin does not block spontaneous activity. This reduction in spontaneous activity suggests that downstream cellular mechanisms underlying smooth muscle tone are being targeted, and these may represent novel therapeutic targets to better treat benign prostatic hyperplasia.

Interstitial cells of Cajal mediate excitatory sympathetic neurotransmission in guinea pig prostate

Morphological and functional studies have confirmed that interstitial cells of Cajal (ICCs) are involved in many enteric motor neurotransmission pathways. Recent investigations have demonstrated that human and guinea pig prostate glands possess a distinct cell type with morphological and immunological similarities to ICCs. These prostate ICCs have a close relationship with nerve bundles and smooth muscle cells. Prostate smooth muscle tone is largely induced by stimulation from the sympathetic nervous system, which releases excitatory norepinephrine (NE) to act on the α1-adrenoceptor. We have performed morphological and functional experiments to determine the role of ICCs in sympathetic neurotransmission in the guinea pig prostate based on the hypothesis that prostate ICCs act as mediators of sympathetic neurotransmission. Immunohistochemistry revealed many close points of contact between ICCs and sympathetic nerve bundles and smooth muscle cells. Double-labeled sections revealed that α1-adrenoceptor and the gap junction protein connexin 43 were expressed in prostate ICCs. Surprisingly, prostate ICCs co-expressed tyrosine hydroxylase and dopamine β-hydroxylase, two markers of sympathetic neurons. Functionally, the application of NE evoked a large single inward current in isolated prostate ICCs in a dose-dependent manner. The inward current evoked by NE was mediated via the activation of α1-adrenoceptors, because it was abolished by the non-specific α-adrenoceptor antagonist, phentolamine and the specific α1-adrenoceptor antagonist, prazosin. Thus, ICCs in the guinea pig prostate are target cells for prostate sympathetic nerves and possess the morphological and functional characteristics required to mediate sympathetic signals.

Involvement of Rho-Kinase Signaling Pathways in Nerve Evoked and Spontaneous Contractions of the Guinea Pig Prostate

Men with benign prostatic hyperplasia commonly experience irritative lower urinary tract symptoms, which are due at least in part to enhanced prostatic smooth muscle tone. To provide some insight into the changes that occur in prostatic contractility with age, we examined the contribution of rho-kinase dependent Ca(2+) sensitization in neurogenic and spontaneous contractions of young and aging guinea pig prostates. We used conventional tension recording and electrophysiological intracellular microelectrode recording techniques. The Rho-kinase inhibitor Y-27632 (10 and 100 μM) significantly inhibited electrical field stimulated evoked (neurogenic) contractions in the guinea pig prostate in a dose dependent manner. In addition, Y-27632 (1 and 10 μM) similarly suppressed tetrodotoxin insensitive spontaneous contractions in dose dependent fashion. While Y-27632 at 10 μM decreased spontaneous contractions of young and aging guinea pig prostates, as evidenced by a significant decrease in the AUC, there was no significant difference in the degree of inhibition between the 2 age groups. In contrast to contractile activity, Y-27632 did not affect the generation or modulation of spontaneous slow wave electrical activity, which underlies spontaneous contractions. There are strong indicators that Rho-kinase signaling pathways have a significant role in prostatic smooth muscle contractility, most likely independent of cytosolic Ca(2+) levels. Features of the rho-kinase pathway may well represent alternative, novel future therapeutic targets to reduce prostatic contractility, thereby alleviating the lower urinary tract symptoms arising from benign prostatic hyperplasia.

Nitric Oxide Signaling Pathways Involved in the Inhibition of Spontaneous Activity in the Guinea Pig Prostate

We investigated nitric oxide mediated inhibition of spontaneous activity recorded in young and aging guinea pig prostates. Conventional intracellular microelectrode and tension recording techniques were used. The nitric oxide donor sodium nitroprusside (10 μM) abolished spontaneous contractions and slow wave activity in 5 young and 5 aging prostates. Upon adding the nitric oxide synthase inhibitor L-NAME (10 μM) the frequency of spontaneous contractile and electrical activity was significantly increased in each age group. This increase was significantly larger in 4 to 8 preparations of younger vs aging prostates (about 40% to 50% vs about 10% to 20%, 2-way ANOVA p<0.01). Other measured parameters, including the duration, amplitude and membrane potential of spontaneous electrical and contractile activity, were not altered from control values. The guanylate cyclase inhibitor ODQ (10 μM) significantly increased the frequency of spontaneous activity by 10% to 30% in 6 young guinea pig prostates (Student paired t test p<0.05). However, it had no effect on aging prostates. The cGMP analogue 8-Br-GMP (1 μM) and the PDE5 inhibitor dipyridamole (1 μM) significantly decreased the frequency of contractile activity by about 70% in 4 to 9 young and older prostates (Student paired t test p<0.05). The decrease in the response to L-NAME in spontaneous contractile and slow wave activity in aging prostate tissue compared to that in young prostates suggests that with age there is a decrease in nitric oxide production. This may further explain the increase in prostatic smooth muscle tone observed in age related prostate specific conditions, such as benign prostatic hyperplasia.

Spontaneous Ca 2+ Signaling of Interstitial Cells in the Guinea Pig Prostate

We investigated whether prostate interstitial cells generate spontaneous Ca(2+) oscillation, a proposed mechanism underlying pacemaker potentials to drive spontaneous activity in stromal smooth muscle cells. Intracellular free Ca(2+) in portions of guinea pig prostate and freshly isolated, single prostate interstitial cells were visualized using fluo-4 Ca(2+) fluorescence. Spontaneous electrical activity was recorded in situ with intracellular microelectrodes. In whole tissue preparations spontaneous Ca(2+) flashes firing synchronously across all smooth muscle cells within the field of view resulted in muscle wall contractions. Nonpropagating Ca(2+) waves were also recorded in individual smooth muscle cells. Nifedipine (Sigma®) (1 μM) largely decreased or abolished these Ca(2+) flashes and suppressed slow wave discharge upon blockade of their superimposed action potentials. Isolated prostate interstitial cells were readily distinguished from smooth muscle cells by their spiky processes and lack of contraction during intracellular Ca(2+) increases. Prostate interstitial cells generated spontaneous Ca(2+) transients in the form of whole cell flashes, intracellular Ca(2+) waves or localized Ca(2+) sparks. All 3 Ca(2+) signals were abolished by nicardipine (1 μM), cyclopiazonic acid (10 μM), caffeine (Sigma) (10 mM) or extracellular Ca(2+) removal. Prostate interstitial cells generate spontaneous Ca(2+) transients that occur at a frequency comparable to Ca(2+) flashes in situ or slow waves relying on functional internal Ca(2+) stores. However, unlike other interstitial cells in the urinary tract, Ca(2+) influx through L-type Ca(2+) channels is fundamental to Ca(2+) transient firings in prostate interstitial cells. Thus, it is not possible to conclude that prostate interstitial cells are responsible for pacemaker potential generation.

Role of connexin 43 in the maintenance of spontaneous activity in the guinea pig prostate gland

To investigate the role of connexin 43 in the maintenance of spontaneous activity in prostate tissue from young and old guinea pigs. Conventional intracellular microelectrode and tension recording techniques, coupled with Western blot analysis and immunohistochemistry for connexin 43 (CX43) were used. The effects of three gap junction uncouplers, 18β glycyrrhetinic acid (10 µM, 40 µM), carbenoxolone (10 µM, 50 µM) and octanol (0.5 mM, 1 mM), were studied in cells displaying slow wave activity and on spontaneously contracting tissue from prostate glands of young (2-5 months) and old (9-16 months) guinea pigs. 18β Glycyrrhetinic acid (40 µM), carbenoxolone (50 µM) or octanol (0.5 mM) abolished slow wave activity in prostate tissue from young and old guinea pigs and depolarized membrane potential by approximately 5 mV. These treatments also abolished all contractions in both sets of prostate tissue. These effects were reversed upon washout. Western blot analysis and CX43 immunohistochemistry showed that there was no age-related difference in the expression and distribution of CX43 in prostate tissues. When gap junctional communication via CX43 was disrupted, spontaneous activity was abolished at a cellular and whole tissue level; CX43 is therefore essential for the maintenance of spontaneous slow wave activity and subsequent contractile activity in the guinea pig prostate gland.

Inositol trisphosphate‐dependent Ca2+ stores and mitochondria modulate slow wave activity arising from the smooth muscle cells of the guinea pig prostate gland

Changes in smooth muscle tone of the prostate gland are involved in aetiology of symptomatic prostatic hyperplasia, however the control mechanisms of prostatic smooth muscle are not well understood. Here, we have examined the role of internal Ca(2+) compartments in regulating slow wave activity in the guinea pig prostate. Standard intracellular membrane potential recording techniques were used. The majority (89%) of impaled cells displayed 'slow wave' activity. Cyclopiazonic acid (10 micromol.L(-1)) transiently depolarized (3-9 mV) the membrane potential of the prostatic stroma and transiently increased slow wave frequency. Thereafter, slow wave frequency slowly decreased over 20-30 min. Ryanodine transiently increased slow wave frequency, although after 30 min exposure slow wave frequency and time course returned to near control values. Caffeine (1 mmol.L(-1)) reduced slow wave frequency, accompanied by membrane depolarization of about 8 mV. Blockade of inositol trisphosphate receptor (IP(3)R)-mediated Ca(2+) release with 2-aminoethoxy-diphenylborate (60 micromol.L(-1)) or Xestospongin C (3 micromol.L(-1)) or inhibiting phospholipase C and IP(3) formation using U73122 (5 micromol.L(-1)) or neomycin (1 and 4 mmol.L(-1)) reduced slow wave frequency, amplitude and duration. The mitochondrial uncouplers, p-trifluoromethoxy carbonyl cyanide phenyl hydrazone (1-10 micromol.L(-1)), carbonyl cyanide m-chlorophenylhydrazone (1-3 micromol.L(-1)) or rotenone (10 micromol.L(-1)), depolarized the membrane (8-10 mV) before abolishing electrical activity. These results suggest that slow wave activity was dependent on the cyclical release of Ca(2+) from IP(3)-controlled internal stores and mitochondria. This implies that intracellular compartments were essential in the initiation and/or maintenance of the regenerative contractile activity in the guinea pig prostate gland.

Prostatic Interstitial Cells in Ageing Guinea Pig Prostates

Objective: Prostatic interstitial cells (PIC) have been previously identified in the young guinea pig and human prostates and have been suggested to be a potential new therapeutic target for diseases of the prostate gland. In this study we have established the presence of PIC and their intercellular communication via connexin 43, in the ageing guinea pig prostate. Materials and Methods: Immunohistochemical and electrophysiological techniques were used. Results: Microscopic examination of preparations of guinea pig pros-tate revealed the presence of c-Kit immunoreactive cells in the region between the smooth muscle (SM) and glandular layers in ageing guinea pigs. Connexin 43 immunoreactive cells were observed within the border between the glandu-lar layer and SM layer but not within SM layer itself. Three distinct types of electrical activity were recorded in the ageing guinea pig prostate gland: slow waves, spontaneous transient depolarisations and spike potentials. Pacemaker potentials were not recorded. Conclusion: C-Kit immuno-reactive cells are present in the ageing guinea pig prostate gland and appear to communicate to each other, but not to SM cells via connexin 43 protein. Ageing prostates do not appear to exhibit pacemaker activity, although PIC are pres-ent, indicating that the characteristics of the PIC may change with age. These results have implications in better under-standing and treating prostate-specific conditions such as benign prostatic hyperplasia.

Spontaneous slow wave activity in aging guinea pig prostates

Spontaneous slow wave activity in aging guinea pig prostates

Changes in steroid receptors and proteoglycan expression in the guinea pig prostate stroma during puberty and hormone manipulation

Proteoglycans are structural and informational molecules important during embryogenesis and organ maturation. Maturation of the prostate is influenced by androgens and estrogens, but changes in the relative spatiotemporal expression of steroid receptors and proteoglycans during hormonal change are unexplored. Guinea pig prostate was used to define hormone-induced changes in the expression of androgen (AR) and estrogen (ER(alpha)) receptors, chondroitin sulfate (CS) glycosaminoglycan and core proteins of versican and syndecan-1. Tissue locations of AR, ER(alpha), CS and the proteoglycans versican and syndecan-1 were determined by immunohistochemistry. Cellular content of ER(alpha) and syndecan-1 was assessed visually. Versican, CS56 epitope, and AR were quantified by image analysis. AR expression within prostate epithelial and stromal cell nuclei decreased following castration and increased following treatment of castrate animals with dihydrotestosterone (DHT). ER(alpha) expression was restricted to prostate stromal cell nuclei and decreased during puberty, and following treatment of castrate animals with DHT. Versican was present in periacinar stroma immediately peripheral to basal epithelial cells, fibromuscular stromal tissue bands surrounding acinar units, and loose fibrovascular connective tissue interspersed between individual acini. Versican and native CS expression decreased (>10-fold) in periacinar stroma during puberty and following administration of DHT to castrated animals. Expression of syndecan-1 was restricted to fibromuscular cells of prostate stroma, and remained constant during puberty and hormone manipulation. ER(alpha), versican core protein and CS side chain epitopes are negatively regulated in prostate stromal tissue by DHT, whilst AR levels are positively regulated.

Characterization of Spontaneous Depolarizations in Smooth Muscle Cells of the Guinea Pig Prostate

Characterization of Spontaneous Depolarizations in Smooth Muscle Cells of the Guinea Pig Prostate

Characterization of Spontaneous Depolarizations in Smooth Muscle Cells of the Guinea Pig Prostate

We characterized the electrical events recorded in small segments of the dorsal lobe of the prostate of immature male guinea pigs and examined some mechanisms underlying their generation. Membrane potential recordings were made in the stroma of the guinea pig prostate using conventional single microelectrode techniques. Three distinct, spontaneously occurring electrical events were recorded in guinea pig prostate, namely slow waves, consisting of a depolarizing transient 14 mV in amplitude with 1 to 6 nifedipine sensitive spikes superimposed, pacemaker potentials, consisting of a larger depolarization 40 mV in amplitude, and STDs 1 to 10 mV in amplitude. Only spikes on slow waves were inhibited by nifedipine. The depolarizing transient of slow waves, pacemaker potentials and STDs were abolished by cyclopiazonic acid, a blocker of the SERCA pump, and the mitochondrial uncoupler cyanide m-chlorophenyl hydrazone as well as upon exposure to Ca(2+)-free saline or the Cl(-) channel blockers niflumic acid and anthracene-9-carboxylic acid (Sigma Chemical Co., St. Louis, Missouri). Examination of the stochastic properties of STDs revealed that they were not well modeled by Poisson statistics, but rather they occurred in a clustered manner, such they may well underlie pacemaker potential generation. Guinea pig prostate shows STD and pacemaker potentials that arise from the release of Ca(2+) from intracellular stores and the activation of Ca(2+) activated Cl(-) channels. We speculate that the depolarizing transient of prostatic slow waves is the propagated response of pacemaker potentials evoked at sites electrically distant from the recording electrode.

Tissue remodeling in Guinea pig lateral prostate at different ages after estradiol treatment

Estrogen seems to have an essential role in the fibromuscular growth characteristic of benign prostatic hyperplasia (BPH). This paper describes the effects of chronic estradiol treatment on Guinea pig prostatic stroma at different ages. Tissues from experimental animals were studied by histological and histochemical procedures, morphometric-stereological analysis and transmission electron microscopy (TEM). Marked fibromuscular hypertrophy was observed after estradiol treatment in animals of pre-pubertal and adult ages. Increases in the density and thickness of the collagen and elastic fibers were observed by histochemistry. TEM revealed wide distributions of collagen fibrils and large elastic fibers adjacent to the epithelial basal lamina and between the stromal cells, establishing contacts between them. These results indicate that the Guinea pig prostate simulates the stromal modifications observed in BPH in some aged animals after estrogen treatment at different ages, making it a good model for this disease.

CHARACTERIZATION OF THE ION CHANNEL CURRENTS IN SINGLE MYOCYTES OF THE GUINEA PIG PROSTATE

We characterized membrane ionic currents underlying the action potential in single myocytes freshly isolated from the stroma of the guinea pig prostate. Whole cell and single channel currents were recorded in single stromal smooth muscle cells using standard patch clamp techniques. : A rapidly activating, nifedipine (1 microM) sensitive Ca current was recorded in CsCl (130 mM) filled myocytes at potentials positive to -50 mV This current was half maximally activated at -22 mV and half maximally inactivated at -53 mV. In KCl (130 mM) filled myocytes membrane depolarization evoked a complex set of K selective outward currents, consisting of a rapidly activating transient outward current (IKto) followed by a more slowly developing transient outward current (IP2), which decayed to a steady state current (ISS). Tetraethylammonium (1 mM), a blocker of large conductance, Ca activated K channels, substantially blocked IP2 and ISS. Initial IKto was half maximally activated at -5 mV, half maximally inactivated at -65 mV and blocked by 4-aminopyridine (IC50 0.8 mM). IP2 and ISS were decreased by ryanodine (10 microM) or cyclopiazonic acid (10 microM) and increased by caffeine (1 mM), suggesting that Ca release from internal stores participates in the activation of these large conductance, Ca activated K channel currents. We speculate that membrane currents characterized in stromal myocytes underlie the generation of simple action potentials triggered during the slow wave recorded in the intact guinea pig prostate and pharmacological manipulation of IKto and IP2 may well provide a selective avenue of modulating stromal excitability and muscle tone.

Adenosine 5′-triphosphate and noradrenaline are excitatory cotransmitters to the fibromuscular stroma of the guinea pig prostate gland

Immunohistochemical studies demonstrated abundant P2X 1-receptor immunoreactivity colocalized with α-actin within the fibromuscular stroma of the guinea pig prostate. P2X 2-, P2X 3- and P2X 4-receptor immunoreactivity was absent. αβmethylene Adenosine 5′-triphosphate (ATP) attenuated contractile responses to electrical field stimulation (50 V, 0.5 ms, 5–20 Hz) in the absence and presence of prazosin (0.3 μM). Responses to 1–2 Hz were unaffected. ARL 67156 (6- N, N-Diethyl-β-γ-dibromomethylene- d-adenosine-5-triphosphate; 100 μM) enhanced contractile responses to electrical field stimulation (50 V, 0.5 ms, 10–20 Hz). Concentration–response curves to exogenously applied ATP analogues on unstimulated preparations elicited concentration-dependent suramin (100 μM)-sensitive contractions. The rank order of potency was: αβmethylene ATP>2methylthio ATP=βγmethylene ATP>adenosine 5′-diphosphate (ADP)=ATP. Adenosine and adenosine 5′-monophosphate (AMP) did not produce contractile responses. These results demonstrate the presence of functional P2X 1-receptors within the fibromuscular stroma of the guinea pig prostate and suggest a cotransmitter role for ATP with noradrenaline during high-frequency stimulation.

Interstitial cells in the human prostate: A new therapeutic target?

Interstitial cells have been described in different human organs, including gut and bladder. In the gut they function as pacemaker cells, generating slow wave potentials. Absence or defects in these cells result in motility disorders. In the bladder these cells express the vanilloid receptor and may contribute to the working mechanism of vanilloid therapy. Recently, slow wave potentials and interstitial cells were described in the guinea-pig prostate. In this study we describe the presence of interstitial cells in the human prostate gland. We performed immunohistochemical staining for c-kit, vanilloid receptor (VR1), cannabinoid receptor (CB1) connexin43, and neurofilament on fresh frozen tissue from 14 prostatectomy specimens. A large number of cells with a stellate aspect were noticed under the basal layer of the prostatic duct system and in between the smooth muscle cells. They were immunoreactive for c-kit, VR1, and connexin43 but not to CB1 or neurofilament. There is evidence for interstitial cells in the human prostate. Taken together their topography and immunohistochemical characterization, the discovery of slow wave potentials in guinea pig prostate and the knowledge of interstitial cells in other organs, interstitial cells are likely to be involved in normal prostate physiology.