Periodic movements of Dictyostelium discoideum sorocarps

We report periodic movements during erection of Dictyostelium discoideum (Dd) sorocarps. Our observations lead to the working hypothesis that Dd sorocarp erection occurs by two superimposed processes: one periodic, with a modal period of 6 1/2 min, and one continuous. We tentatively identify the periodic process with cell movement into the apex of the Dd stalk, and the continuous process with cell vacuolation, together with stalk sheath extension.     

Les injections intracaverneuses de prostaglandine E1: un reel progres dans l’efficacite et la securite des injections intracaverneuses

Intracavernosal injections of vaso-active agents were a major breakthrough in the investigation and treatment of impotence. However the first generation agents (papaverine ± phentolamine, phenoxybenzamine) result in a too high rate of complications (prolonged erection, priapism, corporeal fibrosis,), what requires strict precautions, making their use cumbersome and even stressing. A tremendous development of the pharmacological research arises in order to find agents not resulting in those risks. This article reviews the litterature concerning one of them, Prostaglandin E1 (PGE1), and compares its effects in near 4000 patients to those of papaverine ±phentolamine in over 5000. Experimental data suggests that PGE1 might act in normal erection, and its local tolerance might be better than that of Papaverine, specially as regards the risk of fibrosis. The studies without intraindividual comparison done in men tend to confirm this better tolerance: during the workup period, PGE1 induces prolonged erection in 2.7% of men (requiring treatment in only 0.3%) compared to 9.5% with papaverine and 5.3 % with papaverine + phentolamine (p<0.001); during auto-intracavernosal therapy, the rate of prolonged erections is 0.8% with PGE1 compared to 8.7% with papaverine, and the rate of fibrosis is 0.4% versus 3.5 to 5.4% with papaverine (p<0.001). PGE1 induces slightly more erections compatible with penetration than papaverine ± phentolamine (77% vs 73 %). However it induces pain in 23% of the cases, either at the time of injection, or, more specifically, during erection. This pain is intense in only 3.9% of the cases. General tolerance is excellent. The studies with intra-individual comparison confirm the statistically significant reduction of the risk of prolonged erection requiring treatment (1.7% with PGE1 versus 4.3% with papaverine and 6% with the combination, p<0.05) and the increase in efficacy (75% versus 64% with the combination), though papaverine is superior to PGE1 in a minority of the cases. By reducing the risks, PGE1 allows directly using the effective dosage as regards the diagnostic injections. Its higher effectiveness reduces the false-negative rate in the psychogenic patients, and widens the possibilities of the intracavernosal therapy.     

Impotence: treatment by autoinjection of vasoactive drugs.

One hundred and twenty five men with psychogenic or organic impotence used autoinjection of the penile corpora cavernosa with either papaverine or papaverine and phentolamine for a mean period of 10.5 months (range 1-24 months) to achieve penile erection for sexual intercourse. Prolonged (over four hours) painless erection resulted from 34 of the 3513 self administered injections. This seems to be a highly effective approach to treating impotence irrespective of the aetiology.     

Lack of central nitric oxide triggers erectile dysfunction in diabetes

Erectile dysfunction is a serious and common complication of diabetes mellitus. The proposed mechanisms for erectile dysfunction in diabetes include central and autonomic neuropathy, endothelial dysfunction, and smooth muscle dysfunction. The paraventricular nucleus (PVN) of the hypothalamus is known to be involved in centrally mediated penile erection. This study was designed to examine the role of nitric oxide (NO) within the central nervous system component of the behavioral responses including erection in diabetic rats. N-methyl-D-aspartic acid (NMDA)-induced erection, yawning, and stretch through the PVN can be blocked by prior administration of NO synthase (NOS) blocker, L-NMMA, in freely moving, conscious male normal rats. Four weeks after streptozotocin (STZ) and vehicle injections, NMDA-induced erection, yawning, and stretch responses through the PVN are significantly blunted in diabetic rats compared with control rats. Examination of neuronal NOS (nNOS) protein by Western blot analysis indicated a reduced amount of nNOS protein in the PVN of rats with diabetes compared with control rats. Furthermore, restoring nNOS within the PVN by gene transfer using adenoviral transfection significantly restored the erectile and yawning responses to NMDA in diabetic rats. These data demonstrate that a blunted NO mechanism within the PVN may contribute to NMDA-induced erectile dysfunction observed in diabetes mellitus.     

Nonpharmacologic treatment of erectile dysfunction

Nonpharmacologic treatment for erectile dysfunction (ED) includes sex therapy, the use of vacuum erection devices, penile prosthesis implantation, and penile vascular surgery. Sex therapy is indicated for psychogenic ED and is at times a useful adjunct for other treatments in men with mixed psychogenic and organic ED. Vacuum erection devices produce usable erections in over 90% of patients; however, patient and partner acceptability is an issue. Three-piece inflatable penile prostheses create flaccidity and an erection that comes close to that which occurs naturally. Penile vascular surgery has shown greatest efficacy in young men with vasculogenic ED resulting from pelvic or perineal trauma.     

Proerectile effects of apomorphine in mice

Dopaminergic pathways play a key role in the central control of sexual behavior. Stimulation of central dopaminergic receptors elicits penile erection in a variety of species and has been proposed as a treatment option for erectile dysfunction in humans. The present study investigated the proerectile effects of apomorphine in mice. In this species, subcutaneous injection of apomorphine (range: 0.11-110 microg/kg sc) elicited three different behavioral responses: erection, erection-like responses and genital grooming. Proerectile effects of apomorphine were dose-dependent. More than 50% of mice displayed erections after administration of 1.1-11 microg/kg of apomorphine sc. Proerectile effects of apomorphine were blocked by haloperidol, a central D2 antagonist, but not by domperidone, a peripherally active dopaminergic antagonist. We conclude that apomorphine elicits erection in mice. This effect is dose-dependent and due to activation of central D2 dopaminergic receptors. The mouse model may be useful for pharmacological approaches designed to provide a better understanding of the central mechanisms of penile erection and sexual behavior.     

PGF(2α), LH, testosterone, oestrone sulphate, and cortisol plasma concentrations around sexual stimulation in jackass

Many hormones are involved in the regulation of male reproductive functions, controlling sexual behavior, and influencing sexual arousal, the onset of erection and ejaculation, and the post-ejaculatory detumescence. The aims of this study were to analyze the plasma concentrations of 15-ketodihydro-PGF_2α (PGFM), LH, testosterone (T), oestrone sulphate (OS), and cortisol (C) in relation to sexual stimulation and to evaluate the possible correlations among circulating hormones and between hormones and semen characteristics in the donkey stallion. Thirteen sexually experienced Martina Franca jackass of proven fertility were enrolled and semen was collected through an artificial vagina. Plasma samples were collected at 12, 9, 6 and 3 min before oestrous jenny exposure, at the first erection in the mating arena in the presence of an oestrous jenny, during ejaculation, at dismounting, 3, 6, 9 and 12 min after ejaculation in box, and then every 10 min during the following 50 min. PGFM showed an increasing trend with significant differences between the pre-ejaculatory and post-ejaculatory period, suggesting a role of this hormone in the control of ejaculation. LH showed a significantly higher concentration at ejaculation compared to last samples, while T showed significantly higher levels at erection, ejaculation and dismounting, probably for its influence on these processes and on sexual behavior. Finally, OS did not show any difference in the period of observation, while C presented a significant increase only 22 minutes after erection. The only hormonal correlation found was a positive one between LH and T at erection and dismounting, while T and OS were positively correlated with total and progressive motility, respectively.     

Physiological changes governing the onset of sexual receptivity in male mosquitoes

The effectors which erect antennal hairs in male mosquitoes are shown to be unresponsive to the neurotransmitter that triggers antennal hair erection until 12–24 hr after emergence.The unresponsive period can be prolonged by transfusion of haemolymph from newly-emerged males, or by injection of 20-hydroxyecdysone. This suggests that the hormone persisting after the metamorphosis from pupa to adult, affects the duration of the post-emergence delay in antennal hair erection and is indirectly responsible for timing the onset of sexual receptivity in male mosquitoes.     

Penile erection and micturition events triggered by electrical stimulation of the mesopontine tegmental area

The cholinergic neurons in the laterodorsal tegmental nucleus (LDT) play a crucial role in the regulation of rapid eye movement (REM) sleep. Because penile erection occurs during REM sleep, the involvement of the LDT in penile erection was examined in unanesthetized head-restrained rats. To detect penile erection, corpus spongiosum of the penis (CSP) pressure was measured through a telemetric device with simultaneous bulbospongiosum (BS) muscle EMG recording through stainless wires. Electrical stimulation in and around the LDT induced the following three CSP pressure patterns: 1) a full erection pattern indistinguishable from the nonevoked or spontaneous erection, characterized by a slow increase in CSP pressure with additional sharp CSP peaks associated with BS muscle bursts, 2) a muscular pattern characterized by sharp CSP pressure peaks but in the absence of a vascular component, i.e., without an increase in baseline CSP pressure, and 3) a mixed-type response characterized by high-frequency CSP pressure peaks followed by a full erection response. Full erections were evoked in and around the LDT, including more medially and ventrally. The sites for inducing mixed-type events were intermingled with the sites that triggered full erections in the anterior half of the LDT, whereas they were separated in the posterior half. The sites for muscular responses were lateral to the sites for full erections. Finally, a CSP pressure response identical to micturition was evoked in and around the Barrington's nucleus and in the dorsal raphe nucleus. These results suggest that the LDT and surrounding region are involved in the regulation of penile erection. Moreover, different anatomical areas in the mesopontine tegmentum may have specific roles in the regulation of penile erection and micturition.     

Molecular phylogeny,taxonomy, and evolution of Geosiphon pyriformis and arbuscular mycorrhizal fungi

Geosiphon pyriformis(Kütz.) v. Wettstein is the only known example of a fungus living in endocytobiotic association with a cyanobacterium. The close phylogenetic relationship of Geosiphonwith some arbuscular mycorrhizal fungi (AMF) and the phylogenetic position of Geosiphonare shown in detail. Comprehensive small subunit (SSU) rRNA sequence analyses allow the erection of a new, molecular phylogeny-based taxonomic system for the AMF, including Geosiphon (Geosiphonaceae). Within the recently described phylum Glomeromycota (with one class, Glomeromycetes), a system including four orders was proposed. The erection of several new families will also be necessary. Evolutionary implications are discussed, referring to different possibilities of the influence of AMF on the colonization of the terrestrial habitat by plants.     

Nitric oxide-dependent penile erection in mice lacking neuronal nitric oxide synthase.

BACKGROUND: Nitric oxide (NO) has been implicated as a mediator of penile erection, because the neuronal isoform of NO synthase (NOS) is localized to the penile innervation and NOS inhibitors selectively block erections. NO can also be formed by two other NOS isoforms derived from distinct genes, inducible NOS (iNOS) and endothelial NOS (eNOS). To clarify the source of NO in penile function, we have examined mice with targeted deletion of the nNOS gene (nNOS- mice). MATERIALS AND METHODS: Mating behavior, electrophysiologically induced penile erection, isolated erectile tissue isometric tension, and eNOS localization by immunohistochemistry and Western blot were performed on nNOS- mice and wild-type controls. RESULTS: Both intact animal penile erections and isolated erectile tissue function are maintained in nNOS mice, in agreement with demonstrated normal sexual behaviors, but is stereospecifically blocked by the NOS inhibitor, L-nitroarginine methyl ester (L-NAME). eNOS is abundantly present in endothelium of penile vasculature and sinusoidal endothelium within the corpora cavemosa, with levels that are significantly higher in nNOS- mice than in wild-type controls. CONCLUSIONS: eNOS mediates NO-dependent penile erection in nNOS- animals and normal penile erection. These data clarify the role of nitric oxide in penile erection and may have implications for therapeutic agents with selective effects on NOS isoforms.     

Etude de l’erection chez le rat: un nouveau modele physiologique

Penile erection is a muscular and vascular event mediated by the autonomic nervous system. The neurophysiology of erection remains poorly understood and controversial, requiring a suitable model for in-vitro studies of erectile function. Such a model, based in the rat whose penile innervation is very similar to man, is described here. The first study using this model considers the influence of systemic blodd pressure (BP) on penile erection. In 33 anaesthetized rats the pelvic and cavernosal nerves were identified and dissected. Supra maximal electrical stimulation was delivered over 1 minute by a train of 1 ms pulses onto the pelvic nerve (10 V, 15 Hz) or the cavernosal nerve (6 V, 10 Hz). Systemic blood pressure and intracavernosal pressure (ICP) were monitored and stored on a computer. As in previous animal models (dog, monkey), four phases of the cavernosal response to neural electrical stimulation were observed: latency, tumescence, full erection, and détumescence. In all rats electrical stimulation of either the pelvic or cavernosal nerves significantly increased intracavernosal pressure. Complete erectile response (rigidity and unfolding of the penis) was only seen with intracavernosal pressures > 95 mm Hg. Intracavernosal pressure increased proportionally with blood preessure during the full erection phase according to the equation ICP=0.94 BP ? 31 mm Hg (r=0.94 BP ? 31 mm Hg (r=0.94) for electrical stimulation of the cavernosal nerve, or the alternative aquation ICP=0.76 BP ? 21 mm Hg (r=0.73) for electrical stimulation of the pelvic nerve. The rat is a readily available model for the study of erection and present obvious advantages over existing models such as the dog, cat and monkey. Cavernosal repsonse to neural stimulation was closely related to arterial blood pressure and the two linear equations presented above should be considered further in studies modifying autonomic neurotransmission as well as in relation to the effects of pharmacological compounds with vasomotor actions on erectile function.     

Erectile function outcomes in the current era of anatomic nerve-sparing radical prostatectomy

The contemporary use of anatomic nerve-sparing radical prostatectomy, which entails preserving the autonomic nerve supply to the penis required for penile erection, has led to improved erectile function outcomes compared with what has been seen historically. However, delay of postoperative recovery of erection for as long as 2 years is common, such that dysfunctional erection status lingers as a major postoperative problem. Several possible strategies to improve overall recovery rates and to hasten postoperative recovery of erectile function are currently being advanced. These include pharmacologic rehabilitation therapy and neuromodulatory therapy. Rigorous basic scientific investigation and clinical assessment of these new strategic approaches are critically important to establish their actual therapeutic benefits.     

DA-8159 has erectile potentials much longer than the plasma half-life in a conscious rabbit model

DA-8159 is a pyrazolopyrimidinone derivative which is a potent and selective phosphodiesterase type 5 inhibitor. The efficacy of oral DA-8159 has been demonstrated in conscious and spinalized rabbits by its enhancement of nitric oxide-induced erections. The aim of this study was to investigate the time dependency of this efficacy on its plasma concentration in rabbits. DA-8159 was given orally to normal rabbits at a dose of 10 or 30 mg/kg in order to determine its pharmacokinetic parameters. After then, to investigate the relationship between penile erectile activity and plasma half-life, a dose of 10 mg/kg DA-8159 was administered and the erectile response was examined in a time-course manner by measuring the length of the uncovered penile mucosa after the intravenous administration of sodium nitroprusside, which was administered 1, 3, 6, 8, 24 hours after administering DA-8159. DA-8159 was absorbed rapidly with a Tmax of 0.6 hours in 30 mg/kg and 1.0 hour in the 10 mg/kg group, and T1/2 of 1.23 hours in 30 mg/kg and 1.17 hours in 10 mg/kg, respectively. DA-8159 was not detected in the blood plasma 3 hours (10 mg/kg) or 6 hours (30 mg/kg) after administration. In an erection test, DA-8159 alone (10 mg/kg) induced a penile erection for approximately 2 hours but there was no significant erection thereafter. Although the DA-8159-induced penile erection disappeared, an intravenous injection of sodium nitroprusside significantly induced a penile erection for 6 hours, when the plasma drug concentration was below the detection limit and a no longer visible erection was noted. These results demonstrate that DA-8159 is absorbed and rapidly cleared in rabbits. In addition, it can enhance a sodium nitroprusside-induced penile erection even after 6 hours, which is approximately five times longer than the plasma half-life in the rabbits. These results suggest that DA-8159 may have an erectile potential for much longer than its measured half-life.     

去势大鼠阴茎海绵体胱硫醚γ裂解酶与硫化氢的表达

目的观察去势大鼠阴茎海绵体胱硫醚γ裂解酶（Cystathionine-γ-lyase,CSE）/硫化氢（Hydrogen sulphide,H2S）的变化,进一步探讨勃起功能障碍的发病机制。方法雄性SD大鼠72只分4组：对照组、假手术组,去势组和去势炔丙基甘氨酸（PAG,CSE阻断剂）组,检测基础条件下和阿扑吗啡（Apomorphine,APO）刺激后的海绵体内压（Intracavernous pressure,ICP）及勃起率;激光共聚焦显微镜检测CSE在大鼠勃起不同时期阴茎海绵体组织中的表达,敏感硫电极测定H2S在勃起不同时期的含量。结果与假手术组比较,去势组和去势PAG组ICP与勃起率下降（P〈0.01）;且去势PAG组较去势组ICP明显下降（P〈0.01）;阿朴吗啡刺激后,与假手术组比较,勃起前去势组和去势PAG组CSE蛋白表达降低（P〈0.01）,勃起中去势各组较假手术组CSE蛋白表达降低（P〈0.01）,且去势PAG组较去势组CSE蛋白表达明显降低（P〈0.01）;勃起后各组间CSE蛋白表达变化无差异。勃起前和勃起中去势各组较假手术组H2S含量下降（P〈0.05）,且勃起中去势PAG组较去势组H2S含量明显下降（P〈0.01）：勃起后去势组和去势PAG组较假手术组H2S含量下降（P〈0.01）。结论去势大鼠勃起功能障碍与CSE和H2S表达下降有关。     

L’erection et l’ejaculation psychogenes: Mythe ou realite? Intérêt de leur recherche chez le blessé médullaire

Erection and ejaculation can be induced by two forms of stimulation. The first is mechanical: touching of the penis, scrotum and anus stimulates the pudendal nerves and a reflex erection appears via the parasympathetic pathway. The second form of sexual stimulation is psychological: erotic pictures and fantasies stimulate the splanchnic nerves and the hypogastric plexus, via the orthosympathetic dorso-lumbar pathway, and induce a psychogenic erection. Spinal injury can destroy a part of these neurological routes and cause impotence and/or failures of ejaculation. We have studied 35 patients reporting a sexual dysfunction after a spinal injury, and have tried to generate an erection and ejaculation first with mechanical stimulation, and then with erotic pictures without mechanical genital stimulation. Tumescence was registered using a plethysmograph and semen was collected in order to study spermatogenesis. The spinal cord was destroyed in 12 patients, but orthosympathetic stimulation produced a psychogenic erection in 15 cases, followed by ejaculation in six cases. This form of stimulation seems to be better than prostaglandin or electrical stimulation.     

The mechanism of frill erection in the bearded dragon Amphibolurus barbatus with comments on the jacky lizard A. muricatus (Agamidae)

Amphibolurus barbatus has a threat display which includes the erection of the gular regions as a frill and may also include wide opening of the mouth to display a yellow mouth lining. Frill erection involves protraction, depression, and lateral expansion of the hyoid apparatus. Electrical stimulation of the hyoid muscles and dissection of the hyoid apparatus were used to examine specializations for producing frill erection. Specializations of the hyoid skeleton include the absence of a ceratobranchial II, presence of a synovial joint between the ceratohyal and body of the hyoid, and combined shortening of the entoglossal process and lengthening of the posterior arches. The only apparent specialization of the hyoid musculature is the anterior displacement of the origin of m. hyomandibularis. All of the hyoid muscles are involved in some way in frill erection and the actions of each muscle is described. The characteristic frill erection in the threat display of Amphibolurus barbatus is possible because of the 1:2 ratio of the anterior and posterior parts of the apparatus and the absence of the ceratobrnchial II.     

Apomorphine, systèmes dopaminergiques centraux et contrôle de l’érection

Relaxation of penile erectile tissue and increased blood flow in the penile arteries are the two basic local mechanisms of erection. Relaxation is elicited by several agents released by the nerve terminals of sacral parasympathetic pathways (nitric oxide [NO] and vasoactive intestinal polypeptide [VIP]) and endothelial cells. The increased activity of sacral parasympathetic pathways leads to erection. Other molecules (e.g. noradrenaline) released by the nerve endings of sympathetic pathways contract the penile tissue and arteries. A decrease in sympathetic pathway activity can therefore lead to erection. A better understanding of the local mechanisms of penile erection has led to the production of compounds designed to treat erectile dysfunction via a peripheral target. Such compounds are recognised as initiators if they elicit erectionper se or as conditioners if they potentiate a mechanism already present. The central control of penile erection plays an important role in the optimal functioning of the erectile process. Sympathetic and parasympathetic nerves to the penis originate in the spinal cord. In a sexually relevant context, it is likely that a shift of the balance between sympathetic and parasympathetic activities causes erection. This shift is controlled at the spinal cord level by information from the periphery (reflex pathways) and from supraspinal nuclei. Recent experiments have focused on supraspinal nuclei present in the brainstem, pons, and hypothalamus that directly project onto the sacral spinal cord. Pharmacological approaches have revealed an important role for central dopamine in the control of sexual behavior and the genital tract in males. Central dopamine can therefore regulate both sympathetic and parasympathetic pathways. Levels of DA and its metabolites increase in several brain structures during sexual activity. DA agonists, e.g. the D₁/D₂ agonist apomorphine, affect the sexual behavior, erection and ejaculation in a variety of animal species and in humans. Recent clinical investigations have revealed the benefits of the use of apomorphine in patients suffering from erectile dysfunction. Compounds acting centrally, such as apomorphine, can contribute to reorganize the activity of sympathetic and parasympathetic outflows leading to an appropriate recruitment of the autonomic pathways to the genital tract.     

L’erection,ou le concept de l’eponge active: Données physiologiques et conséquences physiopathologiques

Until recently, the erectile tissues were considered a simple sponge, passively filled or emptied by an imbalance between arterial and venous flows. In reality, the erectile tissues themselves control eretion by virtue of their powerful smooth musculature. Anatomically and physiologicall the erectile tissues act a muscular sponge that is both independent and deformable. Flaccidity and detumescence are caused by a contraction of these muscles while erection is brought about their relaxation. However, the simple contractility of the erectile bodies is insufficient to fully explain erection. This complex hydraulic phenomenon also requires the involvement of vascular mechanisms (arterial dilation, occlusion of cavernosal drainage) as well as tissue mechanisms (compression by the striated erectile muscles, the specific deformation of each erectile structure) all under endocrine and psychoneurological control. By emphasizing the major role played by tissue mechanisms in erection, this concept of an active sponge hightlights the necessity of investigating the erectile tissues leading to a reevaluation of the pathophysiology and treatment of erectile problems.