The haemostatic efficacy and foreign body reaction of epinephrine-Impregnated polyurethane foam in osseous defects.

The objective of this study was to compare the haemostatic efficacy and foreign body reaction of epinephrine-impregnated cotton pellets with those of epinephrine-impregnated polyurethane (PU) foam cubes in osseous defects created in guinea pigs. Initially, these substances were randomly applied to the osseous defects in guinea pigs for 2 min and blood loss was measured. The animals were then sacrificed 7 weeks later and the degree of foreign body reaction was scored. The data were analysed by the independent-samples Kruskal-Wallis test. Epinephrine-impregnated PU foam cubes showed significantly better haemostatic effect compared to epinephrine-impregnated cotton pellets. The PU foam containing epinephrine specimens elicited significantly less foreign body reaction compared to epinephrine cotton pellets (P < 0.05). Based on the results of this study, it is concluded that epinephrine-impregnated PU foam cubes are a good alternative to epinephrine-impregnated cotton pellets as a local haemostatic agent in endodontic surgery.

Relationship between serum testosterone and nocturia in men without benign prostate enlargement.

Recent studies have focused on the relationship between nocturia and serum testosterone because testosterone is thought to be an important factor of prostate growth. However, it remains unclear whether altered serum concentrations of testosterone is associated with an increased risk of nocturia because patients who were taking diuretics or who had a large prostate, which may precipitate nocturia, were not excluded from most previous studies. We analyzed the clinical records of 596 non-benign prostatic enlargement (BPE) male patients to explore the relationship between serum total testosterone and nocturia. All patients were evaluated using a serum prostate-specific antigen (PSA) assay, measurement of serum total testosterone, transrectal ultrasonography, uroflowmetry, and a compilation of the International Prostate Symptom Score (IPSS) and International Index of Erectile Function (IIEF) questionnaires. Nocturia was defined as ≥2 nocturnal voiding episodes. The number of nocturia episodes was assessed using IPSS question 7. To evaluate the effect of serum testosterone on nocturia, multivariate regression analysis was performed including the covariates of age, IPSS, IIEF score, body mass index, PSA, prostate volume, and maximal urine flow rate. Based on multivariate linear analysis, serum testosterone level was not significantly associated with the severity of nocturia. However, with regard to the relationship between prevalence of nocturia and serum testosterone, prevalence of nocturia was significantly positively associated with age (OR = 1.048, p = 0.005), total IPSS (OR = 1.217, p < 0.001), and testosterone level (OR = 1.150, p = 0.041). Therefore, in men without an enlarged prostate, testosterone may play an opposing role in the etiology of nocturia.

Effect of levitra on sustenance of erection (EROS): an open-label, prospective, multicenter, single-arm study to investigate erection duration measured by stopwatch with flexible dose vardenafil administered for 8 weeks in subjects with erectile dysfunction.

To investigate the change of erection duration measured by stopwatch with flexible dose vardenafil administered for 8 weeks in subjects with erectile dysfunction (ED). Effect of levitra on sustenance of erection was an open-label, prospective, multicenter and single-arm study designed to measure the duration of erection in men with ED receiving a flexible dose of vardenafil over an 8-week treatment period. Patients were instructed to take vardenafil 10 mg 60 min before attempting the intercourse. Vardenfil could be increased to 20 mg or decreased to 5 mg concerning patients' efficacy and safety. Following the initial screening, patients entered a 4-week treatment-free run-in phase and 8-week treatment period, during which they were instructed to attempt intercourse at least four times on four separate days. A total of 95 men were enrolled in 10 centers. After the 8 weeks treatment, the mean duration of erection leading to successful intercourse was statistically superior when patients were treated with vardenafil. After an 8-week treatment, the duration of erection leading to successful intercourse was 9.39 min. There were significant benefits with vardenafil in all domains of International Index of Erectile Function. Secondary efficacy end points included success rate of penetration, maintaining erection, ejaculation and satisfaction were superior when patients were treated with vardenafil. There was a significant correlation between duration of erection with other sexual factors. Also partner's sexual satisfaction was increased with vardenafil. Most adverse events were mild or moderate in severity. Vardenafil was safe and well tolerated. Vardenafil therapy provided a statistically superior duration of erection leading to successful intercourse in men with ED with female partner.

Impact of erectile function and age in men with lower urinary tract symptoms on ejaculatory dysfunction and premature ejaculation.

Lower urinary tract symptoms (LUTSs) and ED are clearly correlated, but to date no correlation with ejaculatory dysfunction (EjD) has been identified. Therefore, this study evaluated the impact of erectile function in men with LUTS on EjD and premature ejaculation (PE). Erectile function, PE and EjD of 239 men (mean age, 53.0 ± 10.65 years), International Prostate Symptom Score (IPSS), International Index of Erection Function (IIEF), intravaginal ejaculatory latency time (IELT) and the seven-item Male Sexual Health questionnaire (MSHQ)-EjD were used to compare with the degree of LUTS. Ages were divided into five groups (<40, 40-49, 50-59, 60-69 and >70 years). The IPSS categorized patients into three symptom groups: mild, 1-7; moderate, 8-19; and severe, >19. ED was classified into five categories based on IIEF-EF scores: severe (0-6), moderate (7-12), mild-to-moderate (13-18), mild (19-24) and normal (25-30). The correlations among age, IIEF-EF, IELT and the MSHQ-EjD domain were studied through regression and cross-tabulation analyses. The results revealed that aging significantly affected each item of the MSHQ-EjD (P<0.05). The IIEF-EF domain was also correlated with each question on the MSHQ-EjD (P<0.05). PE (IELT <1 min) increased in incidence as patients got older but was not linked to IIEF-EF (P>0.05). These results indicate that EjD is closely related to age and erectile function, and that PE is closely related to age, although PE is not related to erectile function.

The relaxation effect and mechanism of action of higenamine in the rat corpus cavernosum.

Higenamine mediates cardiotonic, vascular relaxation and bronchodilator effects. The relaxation effects and the mechanism of action of higenamine on the rat corpus cavernosum (CC) were assessed to investigate the effect of higenamine on penile erection. Strips of CC and aorta were used in organ baths for isometric tension studies. Tension was measured with isometric force transducers, and muscle relaxation was expressed as the percent decrease in precontraction induced by phenylephrine (PE). The relaxation reactions were investigated in an endothelial-denuded group and groups pretreated with N(G)-nitro-L-arginine methyl ester (NO synthesis inhibitor), propranolol (ß-receptor blocker), indomethacin (COX inhibitor), glibenclamide (K(+)(ATP) channel inhibitor), 4-aminopyridine (membrane potential-dependent potassium channel inhibitor) and methylene blue (guanylyl cyclase inhibitor) for 30 min. Intracavernous pressure (ICP) was assessed in rats after the intravenous administration of higenamine, and changes in guanosine 3',5'-cyclic monophosphate and adenosine 3',5'-cyclic monophosphate (cAMP) concentrations were measured on the basis of the higenamine concentration. Also, the combined reaction of higenamine and the phosphodiesterase type-5 (PDE-5) inhibitors was assessed. Higenamine induced relaxation of the CC and the aortic strips precontracted with PE in a dose-dependent manner. The CC was significantly more relaxed than the aortic rings in response to the same higenamine concentration (P<0.05). The CC relaxation reaction was suppressed by the ß-receptor blocker propranolol. The cAMP concentration increased gradually with increased higenamine concentration (P<0.05). The ICP also increased with increased higenamine concentration in vivo (P<0.05). In the group pretreated with 10(-7) M higenamine, the relaxation reaction of CC induced by the PDE-5 inhibitor increased significantly, compared with CC exposed to the PDE-5 inhibitor but not pretreated with higenamine (P<0.05). In conclusion, higenamine induced relaxation of the rat CC in a dose-dependent manner. The effect may be mediated through ß-adrenoceptors. The results suggest that higenamine may be valuable as a new lead compound for treating erectile dysfunction.

Effects of sertraline on brain current source of the high beta frequency band: analysis of electroencephalography during audiovisual erotic stimulation in males with premature ejaculation.

To identify the effects of sertraline, a selective serotonin reuptake inhibitor, for the treatment of premature ejaculation (PE), changes in brain current-source density (CSD) of the high beta frequency band (22-30 Hz) induced by sertraline administration were investigated during audiovisual erotic stimulation. Eleven patients with PE (36.9±7.8 yrs) and 11 male volunteers (24.2±1.9 years) were enrolled. Scalp electroencephalography (EEG) was conducted twice: once before sertraline administration and then again 4 h after the administration of 50 mg sertraline. Statistical non-parametric maps were obtained using the EEG segments to detect the current-density differences in the high beta frequency bands (beta-3, 22-30 Hz) between the EEGs before and after sertraline administration in the patient group and between the patient group and controls after the administration of sertraline during the erotic video sessions. Comparing between before and after sertraline administration in the patients with PE, the CSD of the high beta frequency band at 4 h after sertraline administration increased significantly in both superior frontal gyri and the right medial frontal gyrus (P<0.01). The CSD of the beta-3 band of the patients with PE were less activated significantly in the middle and superior temporal gyrus, lingual and fusiform gyrus, inferior occipital gyrus and cuneus of the right cerebral hemisphere compared with the normal volunteers 4 h after sertraline administration (P<0.01). In conclusion, sertraline administration increased the CSD in both the superior frontal and right middle temporal gyrus in patients with PE. The results suggest that the increased neural activity in these particular cerebral regions after sertraline administration may be associated with inhibitory effects on ejaculation in patients with PE.

Cubic SiC nano-thin films and nano-wires: high vacuum metal-organic chemical vapor deposition, surface characterization, and application tests.

Single-crystalline and epitaxial cubic silicon carbide (beta-SiC) nano-thin films have been deposited on Si(100) substrates at a sample temperature of approximately 900 degrees C using single source precursors by the thermal metal-organic chemical vapor deposition (MOCVD) method. Diethylmethylsilane and 1,3-disilabutane, which contain Si and C atoms in the same molecule, were used as precursors without any carrier or bubbler gas. Upon increasing the deposition temperature from 900 to 950 degrees C, beta-SiC nano-thin films with relatively small crystals and smoother surfaces were created on Si(100) substrates. Moreover, beta-SiC nano-wires with 40 approximately 100 nm in diameter have also been grown selectively on nickel catalyzed Si(100) substrates with dichloromethylvinylsilane by the MOCVD method. The deposition temperature in this case was as low as 800 degrees C under the pressure of 5.0 x 10(-2) Torr. It is worth noting that the initial growth rates of deposited beta-SiC nano-thin films and nano-wires strongly depend on the deposition temperature rather than the time. In order to test the possibility of applications of these materials for electronic components such as field emitter, MEMS, and high-power transistor, we fabricated the nanoelectronic devices using both beta-SiC nano-wires and nano-thin films. With these preliminary application tests, it is expected that SiC nanowires can be used as field emitter and nanoelectronic high-power transistor, and application of the SiC nano-thin films to MEMS is promising as well.

Comparison of cadaveric pericardial, dermal, vein, and synthetic grafts for tunica albuginea substitution using a rat model.

OBJECTIVE: To evaluate in an animal model the intermediate and long-term efficacy of cadaveric pericardium, dermis, vein and Gore-Tex per thousand as grafting materials for tunica albuginea substitution after plaque excision for Peyronie's disease. MATERIALS AND METHODS: The study comprised 100 male Sprague-Dawley rats (300-325 g) divided into five equal groups: group 1, sham-operated controls; and groups 2-5 which underwent wedge excision of the tunica albuginea and replacement with either cadaveric pericardium, dermis, vein or Gore-Tex grafts. Ten rats in each group had the cavernosal nerve stimulated electrically to assess erectile function at 4 months, and the remaining 10 rats at 6 months. After death the sampled tissues were fixed in 10% formalin, paraffin-embedded, and stained with Masson's trichrome and Verhoff's van Giesen for collagen and elastic fibres. RESULTS: Erectile function, assessed by cavernosal nerve stimulation, did not differ significantly in any of the groups (P > 0.05). The histological assessment of penile cross-sections showed minimal fibrosis surrounding the patch in the dermal and vein grafts, and moderate to severe fibrosis in the Gore-Tex graft at 4 and 6 months. In the pericardial graft there was a moderate degree of fibrosis at 4 months with only minimal fibrosis at 6 months. CONCLUSIONS: These results show that cadaveric pericardium allows complete penile expansion and is strong enough to withstand normal intracorporal pressures. There was minimal fibrosis in the pericardial, dermal and vein grafts, and moderate fibrosis in the Gore-Tex graft at 6 months. The pericardial graft is a satisfactory grafting material when used for tunica albuginea substitution, including the surgical management of Peyronie's disease.

Antimicrobial activity of antibiotic-soaked, Resist-coated Bioflex.

This study investigates whether a hydrophilic coating (Resist), designed to inhibit bacterial adherence, applied to inflatable penile prostheses can prolong the effect of intraoperative antibiotics. The activity of antibiotic-soaked Bioflex (penile prosthetic substrate material) discs with and without Resist was examined by measuring the zone of inhibition following in vivo exposure in four groups of rabbits: 1, 2, 3 and 5 days' duration of disc implantation. Coated and uncoated discs were soaked in an aqueous solution of gentamicin and bacitracin. The implanted antibiotic-soaked discs were extracted, and the zone of inhibition against four microorganisms in vitro demonstrated that the Resist coating was especially effective against Staphylococcus epidermidis, and statistically significant improvements were observed for the coated over the uncoated substrate up to 3 days following implantation. This effect, and the anti-adherence properties of Resist, may prevent adhesion and colonization of some microorganisms to penile implants and reduce chances for infection.

Localization of peripheral dopamine D1 and D2 receptors in rat corpus cavernosum.

OBJECTIVE: To detect and locate anatomically peripheral dopamine D1 and D2 receptors in rat cavernosa, as dopamine is important in sexual drive and penile erection through receptors located in the central nervous system. MATERIALS AND METHODS: Corpora cavernosa were obtained from Sprague-Dawley rats; total RNA and membrane proteins were extracted and cryostat sections prepared. The rat brain hypothalamus was used as a control for dopamine D1 and D2 receptors. The presence and expression of peripheral dopamine D1 and D2 receptor mRNAs in rat corpus cavernosa was assessed using reverse transcription and polymerase chain reaction (RT-PCR), and Northern blot hybridization using (32)P-UTP-labelled RNA probes. Concurrently, corresponding proteins from D1 and D2 receptors were assayed and detected by a Western blotting technique. The anatomical location of dopamine D1 and D2 receptor mRNAs in rat penile tissues was identified by in situ hybridization using (35)S-UTP-labelled RNA probes in cryostat sections. Immunohistochemical staining was used to locate peripheral dopamine D1 and D2 receptor proteins in rat corpora cavernosa. RESULTS: Dopamine D1 and D2 receptor gene expression was detected in rat corpora cavernosa. In situ hybridization signals for dopamine D1 and D2 receptor mRNAs were localized to corpus cavernosal tissues and dorsal vessels in the rat penis. Western blot analyses showed peripheral dopamine D1 and D2 receptor proteins in rat corpora cavernosa. Immunohistochemically, peripheral dopamine D1 and D2 receptor proteins were detected in dorsal nerves, dorsal vessels and corpus cavernosal smooth muscle of the rat penile tissues. CONCLUSIONS: Peripheral dopamine D1 and D2 receptors are present in the corpora cavernosa of rats. The functional significance of these receptors and signal transduction pathways in modulating the vascular tone of the penis warrants further investigation.

Evaluation of nitric oxide synthase and arginase in the induction of a Peyronie's-like condition in the rat.

Peyronie's disease is an idiopathic, localized connective tissue disorder of the penis, involving the tunica albuginea of the corpus cavernosum and adjacent areolar space. Current proposals as to the origin of Peyronie's disease suggest that fibrosis and collagen changes of the tunica are the result of an inflammatory process following vascular trauma. Our laboratory and other investigators have recently proposed an animal model for the study of Peyronie's disease. When transforming growth factor-beta1 (TGF-beta1) was injected into the rat tunica albuginea, tissue fibrosis was observed at 6 weeks. Therefore, our aim was to assess arginase II, endothelial and inducible nitric oxide synthase isoforms, and nitrotyrosine levels--all factors involved in inflammatory reactions--in the cavernosal tissue of saline-injected and TGF-beta1-injected rats after 6 weeks in order to evaluate the roles these enzymes may play in the induction of a Peyronie's-like condition in the rat. To examine the expression of endothelial nitric oxide synthase (eNOS), iNOS, and arginase II protein, and mRNA in the corpus cavernosum, immunoblot analysis, and reverse transcriptase-polymerase chain reaction were performed. We also determined immunohistochemically the expression of nitrotyrosine, a marker of peroxynitrite formation, in the rat penis. After 6 weeks, iNOS protein and gene expression was up-regulated and eNOS protein and gene expression was down-regulated in the corpora cavernosa of the TGF-beta1-injected penises. Furthermore, arginase II protein expression as well as immunohistochemical localization of nitrotyrosine was significantly higher in the TGF-beta1-injected corpora cavernosa. These results suggest that iNOS is the key control element for peroxynitrite formation, arginase II expression, and eNOS down-regulation in the induction of a Peyronie's-like condition in the rat.

Multicenter study of the treatment of erectile dysfunction with transurethral alprostadil (MUSE) in Korea.

A Korean multicenter study was conducted to assess the effectiveness of transurethral alprostadil with MUSE in 334 subjects with chronic erectile dysfunction (ED) who were enrolled in 21 clinical centers. Patients with psychogenic impotence comprised about 30% of subjects. Intraurethral alprostadil was titrated in a stepwise fashion in the clinics from 250 to 500 or 1000 mcg based on erectile response and tolerability. The erectile responses were evaluated using an erection assessment scale (score of 1-5). The dose that produced a maximal penile response of score 5 (full rigid erection) or 4 (full tumescence, partial rigidity) was selected for home treatment. Patients who showed partial erection (score of 3) with 1000 mcg were also included in the home-treatment group. In-clinic phase: 198 men (59.3%) had maximal penile responses of score 4 or 5. The rate of maximal responses was not related to patient age, etiology or duration of the ED. A total of 228 (68.3%) men progressed to home treatment. The overall level of comfort of the transurethral alprostadil was rated as uncomfortable or very uncomfortable in 12%. Home phase: During the two-month period of home treatment, 178 (78.1%) men had successful sexual intercourse at least once, and 78.2% of administrations (1976) resulted in successful intercourse. The main causes of drop-out were insufficient erectile response in 27 men (11.8%), adverse reactions (mostly penile or urethral pain) in 7 (3.1%) or both in 7 (3.1%). In conclusion, transurethral alprostadil could be a suitable treatment option for patients with ED regardless of age and etiology of ED. Efficacy in an Asian population (Korea) is comparable to that reported previously in Caucasians.

Concentration of ofloxacin in canine prostate tissue and prostate fluid after intraprostatic injection of biodegradable sustained-releasing microspheres containing ofloxacin.

PURPOSE: Excellent treatment results in chronic prostatitis by direct intra-prostatic injection of antibiotic were reported several decades ago with only minimal scientific background. We examined the distribution, in prostatic tissue and fluid, of the antibiotic in canines after intra-prostatic injection of biodegradable sustained-releasing microspheres containing 12 mg. of ofloxacin. MATERIALS AND METHODS: A total of 36 male dogs, 12 controls and 24 experimental, older than 2 years, were used. Experimental dogs were given biodegradable sustained releasing microspheres containing ofloxacin 12 mg. and poly(D,L-lactic) acid 28 mg., designed to release over more than a 4 week period. The 12 control animals were divided into 2 groups, and oral ofloxacin 100 mg. was given twice a day for 2 and 4 weeks. The 24 experimental animals were divided into 4 subgroups of 6 dogs each, 4 for prostatic tissue and 2 for prostatic fluid level of ofloxacin determination. Anesthesia was initiated with ketamine HCl and xylazine, and maintained with intermittent ketamine HCl. In the experimental groups, 1 ml. of resolved formula was injected into one lobe of surgically exposed prostates. The concentration of ofloxacin was measured by high performance liquid chromatography (HPLC) of blood, prostatic tissue and prostatic fluid. Pilocarpine 0.5 mg./kg. was used for the collection of the prostatic fluid. RESULTS: The total ofloxacin of controls were 2,800 (2 weeks) and 5,600 (4 weeks) mg. In control groups, tissue concentrations of ofloxacin were relatively even at all segments of prostate, 7.4 +/- 0.8 (2 weeks) and 9.2 +/- 1.1 microg./ml. (4 weeks). The blood level ranged between 3.6 to 5.1 microg./ml. The prostatic fluid level ranged from 3.1 to 5.7 microg. /ml. In the experimental groups, the tissue levels of ofloxacin were 10.5 +/- 3.0 (1 week), 13.8 +/- 4.5 (2 weeks), 7.1 +/- 0.9 (3 weeks) and 7.7 +/- 3.0 microg./ml. (4 weeks) in the injected lobe. The opposite lobes were 8.0 +/- 1.1 (1 week), 10.2 +/- 4.2 (2 weeks), 5. 1 +/- 1.4 (3 weeks) and 7.6 +/- 0.8 (4 weeks) microg./ml. The blood level in the experimental groups ranged between 0.16 to 0.59 microg./ml. The prostate fluid level ranged from 2.9 to 6.1 microg./ml. in 8 dogs. Upon pathologic examination, the microspheres were interposed between prostate stroma and their size was reduced over time. CONCLUSIONS: Our study indicates that there is communication between the right and left prostate lobes. Direct injection of biodegradable sustained releasing ofloxacin formula into the prostate may be a substitute for long term antibiotic medication in humans for chronic prostatitis in the future without hurting the minimal inhibitory concentration(MIC)90.

Expression of gonadotropin-releasing hormone (GnRH) and GnRH receptor mRNA in prostate cancer cells and effect of GnRH on the proliferation of prostate cancer cells.

The purpose of this study was to determine the production of gonadotropin-releasing hormone (GnRH), the co-occurrence of GnRH receptors in prostate cancer cells, and the effect of GnRH on prostate cancer cell proliferation. Four human prostate cancer cell lines were studied. LNCaP is an androgen sensitive prostate cancer cell line, DU-145 and PC-3 are androgen resistant, and TSU-Pr1 is uncharacterized. The expression of GnRH and GnRH receptor mRNAs were assessed by in situ hybridization and the effect of exogenous GnRH on proliferation of prostate cancer cells was measured by thymidine incorporation assay. GnRH mRNA expression, determined by in situ hybridization, was found in 83.48% of the LNCaP, 89.7% of the TSU-Pr1, 86.2% of the PC-3 and 95.3% of the DU-145. Signals of GnRH receptor mRNA were detected in more than 95% of the cells of all four cell lines. The proliferation of the prostate cancer cells grown in media supplemented with peptide hormone lacking charcoal-stripped serum was significantly (P < 0.05) suppressed. No significant effect of GnRH on the proliferation of all four prostate cancer cells was observed. In summary, prostate cancer cells produced GnRH and its receptors, and exogenous GnRH treatment did not affect the prostate cancer cell proliferation. The existence of GnRH and GnRH receptor mRNA in the same cell suggests that the role of GnRH produced by prostate cancer cells would be autocrine.

Changes in erectile response to repeated audiovisual sexual stimulation.

OBJECTIVES: To determine changes in erectile response to repeated audiovisual sexual stimulation in patients with psychogenic impotence and normal men. METHODS: The same erotic video was shown to 45 men (20 patients with psychogenic impotence and 25 normal men) for 3 consecutive days. Their erectile responses during the audiovisual stimulation were monitored using RigiScan (Dacomed, Minneapolis, Minn., USA), and the maximal rigidity of erection, sustained for more than 5 min, was measured. The rigidities on the first, second and third days were comparatively analyzed. Whether previous multiple viewings of the erotic movie and previous exposure to the same or a similar movie influenced the erectile response were also evaluated. RESULTS: Rigidity on the third day was significantly decreased compared to that on the first day in both patients with psychogenic impotence and normal controls (p < 0.05), regardless of the frequency of previous viewings and the previous exposure to a similar movie. Rigidity on the first day was significantly lower in the group with multiple viewings than in the group with fewer viewings (p < 0.05). CONCLUSIONS: Real-time monitoring of penile erection during audiovisual sexual stimulation may result in false-negative responses when patients are repeatedly exposed to the stimulation.

Stage specific identification of the expression of GnRH mRNA and localization of the GnRH receptor in mature rat and adult human testis.

PURPOSE: To identify the expression of gonadotropin-releasing hormone (GnRH) messenger ribonuclueic acid (mRNA) and localize GnRH receptors in mature rat and adult human testes. MATERIALS AND METHODS: In situ hybridization and enzymatic receptor binding localization were performed. RESULTS: GnRH mRNA was expressed within the seminiferous tubules in both mature rat and adult human testis. In rats, expression of GnRH mRNA was identified in the Sertoli cells and spermatogenic cells of some seminiferous tubules, but the other tubules did not express any hybridization signal. In humans, expression of GnRH mRNA was identified only in some spermatogenic cells in some seminiferous tubules. The receptors for GnRH were localized to cells in the interstitial tissues of the testis, probably Leydig cells. CONCLUSION: The authors believe that the mature rat and adult human seminiferous tubular cells produce GnRH at the same specific stage of the spermatogenic cycle and that GnRH produced within seminiferous tubules, including Sertoli cells and spermatogenic cells, reacts with neighboring GnRH receptors in interstitial cells, including Leydig cells. The GnRH produced from the Sertoli cells in seminiferous tubules would react with GnRH receptors in interstitial cells as a paracrine hormone.