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BMC Urology May 2018Penile erection is a complex reflex under spinal control and modulated by the brain. The hemodynamic events under autonomic control and the perineal muscles somatic...
BACKGROUND
Penile erection is a complex reflex under spinal control and modulated by the brain. The hemodynamic events under autonomic control and the perineal muscles somatic activity are interconnected during the reflex erection at the spinal level, however if the afferent feedback on the corpus cavernosum pressure during an erection affects the somatic activity (perineal muscles contractions) and vice versa is not known. This study was aimed to test this hypothesis using a rat model.
METHODS
Intracavernous pressure (ICP) and bulbocavernosus (BC) muscle EMG were recorded during reflex erections elicited with dorsal penile nerve (DNP) electrical stimulation in anaesthetized acutely spinalized SD rats with surgically (bilateral cavernous nerve section, CnX, n = 8) and pharmacologically (trimetaphan infusion, TMPh, n = 8) abolished pressor response, or with surgically (bilateral section of the motor branch of the pudendal nerve, PnX, n = 7) and pharmacologically (1 mg/kg d-tubocurarine, n = 8) blocked perineal muscles contractions, or with interrupted afferent input from the penis (bilateral crush of the dorsal penile nerve, DPnX, n = 7). Control rats (n = 8) received no intervention.
RESULTS
Moderate positive correlations were found between net parameters of pressor and somatic activity during DNP-stimulation induced reflex erection in spinal rats, particularly the speed of pressor response development was positively correlated to EMG parameters. No changes of EMG activity were found in CnX rats, while the decrease of BC EMG in TMPh-treated males can be attributed to direct inhibitory action of TMPh on neuromuscular transmission. Pressor response latency was increased and ICP front slope decreased in dTK and PnX rats, indicating that perineal muscles contraction augment pressor response. DPN crush had little effect on ICP and EMG.
CONCLUSION
Afferent input on the level of intracavernous pressure and the perineal muscles activity has minimal impact on, correspondingly, the somatic and the autonomic components of the reflex erection in spinal males, once the reflex has been initiated.
Topics: Animals; Electric Stimulation; Electromyography; Hemodynamics; Male; Muscle, Skeletal; Penile Erection; Random Allocation; Rats; Rats, Sprague-Dawley; Reflex
PubMed: 29739451
DOI: 10.1186/s12894-018-0352-5 -
Japanese Journal of Pharmacology Sep 1994The neural mechanisms underlying the penile erection induced by serotonergic, cholinergic and dopaminergic stimulants were comparatively investigated. Fenfluramine...
The neural mechanisms underlying the penile erection induced by serotonergic, cholinergic and dopaminergic stimulants were comparatively investigated. Fenfluramine (0.1-10 mg/kg, i.p.), pilocarpine (0.032-3.2 mg/kg) and apomorphine (0.01-1 mg/kg) induced penile erection in rats with bell-shaped dose-response curves. The penile erection induced by fenfluramine (1 mg/kg) was dose-dependently antagonized by pindolol (0.1-3.2 mg/kg), a 5-HT1 antagonist, or scopolamine (0.032-1 mg/kg), a muscarinic antagonist, but not by sulpiride (1-32 mg/kg), a dopaminergic antagonist. The penile erection induced by pilocarpine (0.32 mg/kg) was countered by pindolol or scopolamine but not by sulpiride, while that induced by apomorphine (0.032 mg/kg) was countered by all three antagonists. Septo-hippocampal cholinergic deafferentations by medial septum lesioning or fimbria-fornix transection also significantly attenuated the penile erection induced by fenfluramine or apomorphine, but scarcely affected that induced by pilocarpine. Raphe lesion by injections of 5,7-dihydroxytryptamine, a serotonergic neurotoxin, into the median- and dorsal-raphe nuclei significantly attenuated the penile erections induced by fenfluramine and apomorphine but not that by pilocarpine. These results suggest that a neuronal link between the dopaminergic, serotonergic and cholinergic systems plays a crucial role in the expression of penile erection; dopaminergic stimulation causes an activation of the raphe serotonergic neurons which in turn enhances the septo-hippocampal cholinergic pathway and results in expression of penile erection.
Topics: Animals; Denervation; Dopamine; Dose-Response Relationship, Drug; Drug Interactions; Hippocampus; Male; Neurons, Afferent; Parasympathetic Nervous System; Penile Erection; Pindolol; Raphe Nuclei; Rats; Rats, Inbred F344; Scopolamine; Serotonin; Sulpiride
PubMed: 7861668
DOI: 10.1254/jjp.66.59 -
Biomedical Research (Tokyo, Japan) Apr 2009It has been suggested that dopamine (DA) and serotonin (5-HT) and their receptors, particularly D(2)-like and 5-HT(2C) receptors, may play a significant role in the...
It has been suggested that dopamine (DA) and serotonin (5-HT) and their receptors, particularly D(2)-like and 5-HT(2C) receptors, may play a significant role in the control of male sexual function. The purpose of this study was to investigate whether the combination of a dopamine receptor agonist apomorphine and a 5-HT(2) receptor agonist m-CPP would potentiate penile erection and ejaculation in male rats. Systemic administration of either apomorphine (0.01-0.1 mg/kg, s.c.) or m-CPP (0.01-0.3 mg/kg, i.p.) dose-dependently elicited penile erections, but did not induce ejaculation. When combined, there was a drastic increase in both the incidence of ejaculation and the amount of ejaculated seminal materials, while the proerectile effect induced by each drug was not potentiated. The proejaculatory effect induced by the combination of apomorphine (0.1 mg/kg, s.c.) and m-CPP (0.3 mg/kg, i.p.) was completely blocked by pretreatment with the D(2)-like receptor antagonists haloperidol and sulpiride, but not by the D(1)-like receptor antagonist SCH-23390. The synergistic action for ejaculation was also blocked by domperidone, the D(2)-like receptor antagonist that dose not cross the blood-brain barrier. The rats pretreated with the 5-HT(2C) receptor antagonist SB242084 did not show the synergistic action by the combination of apomorphine and m-CPP, whereas the rats pretreated with the 5-HT(2A) receptor antagonist ketanserin and the 5-HT(2B) receptor antagonist SB204741 showed the combination-induced synergistic action. These results suggest that the combination of a small dose of apomorphine and m-CPP potently and selectively facilitates the ejaculatory response through the activation of D(2)-like and 5-HT(2C) receptors, respectively. The D(2)-like receptors involved in the synergistic action may be, at least in part, located in the peripheral sites.
Topics: Animals; Apomorphine; Dopamine Agonists; Dose-Response Relationship, Drug; Drug Synergism; Ejaculation; Male; Penile Erection; Piperazines; Rats; Rats, Wistar; Receptor, Serotonin, 5-HT2C; Receptors, Dopamine D2; Serotonin 5-HT2 Receptor Agonists; Serotonin Receptor Agonists
PubMed: 19420729
DOI: 10.2220/biomedres.30.71 -
Asian Journal of Andrology Jan 2006Erectile response is centrally and peripherally regulated by androgens. The original insights into the mechanisms of action of androgens were that androgens particularly... (Review)
Review
Erectile response is centrally and peripherally regulated by androgens. The original insights into the mechanisms of action of androgens were that androgens particularly exert effects on libido and that erections in response to erotic stimuli were relatively androgen-independent. It was shown that sexual functions in men required androgen levels at the low end of reference values of testosterone. So it seemed that testosterone was not useful treatment for men with erectile difficulties, particularly following the advent of the phosphodiesterase type 5 (PDE5) inhibitors. However, approximately 50% of those treated with PDE5 inhibitors discontinue their treatment. A number of recent developments shed new light on testosterone treatment of erectile dysfunction (ED) in aging men. (1) A recent insight is that, in contrast to younger men, elderly men might require higher levels of testosterone for normal sexual functioning. (2) Several studies have indicated that PDE5 inhibitors are not always sufficient to restore erectile potency in men, and that testosterone improves the therapeutical response to PDE5 inhibitors considerably. (3) There is growing insight that testosterone has profound effects on tissues of the penis involved in the mechanism of erection and that testosterone deficiency impairs the anatomical and physiological substrate of erectile capacity, reversible upon androgen replacement. The synthesis of PDE5 is upregulated by androgens, and the arterial inflow into the penis is improved by giving androgen. The above invites a re-examination of the merits of giving testosterone to aging men with ED. The beneficial effects of PDE5 inhibitors may only be optimally expressed in a eugonadal environment.
Topics: 3',5'-Cyclic-GMP Phosphodiesterases; Aging; Animals; Cyclic Nucleotide Phosphodiesterases, Type 5; Humans; Male; Middle Aged; Penile Erection; Penis; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Piperazines; Purines; Sildenafil Citrate; Sulfones; Testosterone
PubMed: 16372114
DOI: 10.1111/j.1745-7262.2006.00105.x -
Journal of Anatomy Mar 2015The baculum (os penis) has been extensively studied as a taxon-specific character in bats and other mammals but its mechanical function is still unclear. There is a wide...
The baculum (os penis) has been extensively studied as a taxon-specific character in bats and other mammals but its mechanical function is still unclear. There is a wide consensus in the literature that the baculum is probably a sexually selected character. Using a novel approach combining postmortem manipulation and three-dimensional (3D) imaging, we tested two functional hypotheses in the common noctule bat Nyctalus noctula, the common pipistrelle Pipistrellus pipistrellus, and Nathusius' pipistrelle Pipistrellus nathusii: (i) whether the baculum can protect the distal urethra and urethral opening from compression during erection and copulation; and (ii) whether the baculum and corpora cavernosa form a functional unit to support both the penile shaft and the more distal glans tip. In freshly dead or frozen and thawed bats, we compared flaccid penises with artificially 'erect' penises that were inflated with 10% formalin. Penises were stained with alcoholic iodine and imaged with a lab-based high-resolution x-ray microtomography system. Analysis of the 3D images enabled us to compare the changes in relative positions of the baculum, corpora cavernosa, urethra, and corpus spongiosum with one another between flaccid and 'erect' penises. Our results support both functional hypotheses, indicating that the baculum probably performs two different roles during erection. Our approach should prove valuable for comparing and testing the functions of different baculum morphologies in bats and other mammals. Moreover, we have validated an essential component of the groundwork necessary to extend this approach with finite element analysis for quantitative 3D biomechanical modeling of penis function.
Topics: Animals; Chiroptera; Imaging, Three-Dimensional; Male; Penile Erection; Penis; X-Ray Microtomography
PubMed: 25655647
DOI: 10.1111/joa.12274 -
Biological & Pharmaceutical Bulletin Jul 2006SA1 is a mixture of 9 Oriental herbs (Korean red ginseng, fermented soybean, Tribulus terrestris, Fructus Rubi, Fructus Lycii, Semen Cuscutae, Dioscorea Rhizome, Fructus...
SA1 is a mixture of 9 Oriental herbs (Korean red ginseng, fermented soybean, Tribulus terrestris, Fructus Rubi, Fructus Lycii, Semen Cuscutae, Dioscorea Rhizome, Fructus Corni and Fructus Crataegi) that are widely used as energizers and vitalizers in the indigenous system of medicine and have been alleged to improve the sexual functions in men. This study evaluated SA1 using both in vitro and in vivo experiments on laboratory animals in order to determine its effect on the sexual behavior and penile erection. The male rats used to examine the copulatory behavior were administered either the vehicle or SA1 (30, 100, 300, 600 mg/kg) orally for 2 weeks. The intracavernous pressure and systemic blood pressure were recorded in anesthetized rats. The responses to acetylcholine and SA1 of rabbit corpus cavernosum strips were also examined. There was an overall increase in the copulatory behavior parameters in the SA1-treated rats, which was reflected by a decrease in the mount and intromission latencies and an increase in the ejaculation latency and mount frequency. SA1 significantly increased the ratio of the intracavernous pressure to mean arterial pressure. In vitro, SA1 significantly enhanced the relaxation responses to acetylcholine. These results suggest that SA1 improves the sexual activity and erectile function.
Topics: Animals; Copulation; Drugs, Chinese Herbal; Ejaculation; Female; Korea; Male; Ovariectomy; Penile Erection; Plant Extracts; Rats; Rats, Sprague-Dawley; Sexual Behavior, Animal
PubMed: 16819173
DOI: 10.1248/bpb.29.1383 -
PloS One 2022Male mice with homozygous loss of function mutations of the transcription factor gene Pea3 (Pea3 null) are infertile due to their inability to inseminate females,...
Male mice with homozygous loss of function mutations of the transcription factor gene Pea3 (Pea3 null) are infertile due to their inability to inseminate females, however the specific deficits in male sexual behaviors that drive this phenotype are unknown. Here, the copulatory behavior of male mice (Pea3 null and control) with hormonally primed ovariectomized females was monitored via high-speed and high-resolution digital videography to assess for differences in female-directed social behaviors, gross sexual behaviors (mounting, thrusting), and erectile and ejaculatory function. Pea3 null male mice exhibit greatly reduced erectile function, with 44% of males displaying no visible erections during copulation, and 0% achieving sustained erections. As such, Pea3 null males are incapable of intromission and copulatory plug deposition, despite displaying largely normal female-directed social behaviors, mounting behaviors, and ejaculatory grasping behavior. Additionally, the organization and timing of thrusting behaviors is impaired in Pea3 null males. Our results show that the transcription factor gene Pea3 regulates the ability to achieve and maintain erections during copulation in mice.
Topics: Animals; Female; Male; Mice; Copulation; Ejaculation; Erectile Dysfunction; Penile Erection; Transcription Factors
PubMed: 36301850
DOI: 10.1371/journal.pone.0276069 -
Long-Term Functional, Cosmetic and Sexual Outcomes of Hypospadias Correction Performed in Childhood.Urologia Internationalis 2015Hypospadias surgery, especially when performed early in life, may have a significant impact on the urinary and sexual functions in an adult. Because the literature is...
OBJECTIVE
Hypospadias surgery, especially when performed early in life, may have a significant impact on the urinary and sexual functions in an adult. Because the literature is still limited, this paper assesses long-term functional, cosmetic and sexual results of hypospadias repair performed in childhood.
PATIENTS AND METHODS
The study includes 275 patients older than 12 years treated for a hypospadias by an Onlay, Mathieu, Duplay, or Duckett's technique between January 1990 and December 2000. Flowmetry results were retrospectively obtained from patients' charts. The Paediatric Penile Perception Score (PPPS), the Hypospadias Objective Scoring Evaluation (HOSE) and the IIEF-5 score (when older than 16 years old) questionnaires were used to assess cosmetic and sexual results. The PPPS is designed to assess both penile self-perception with regard to meatus, glans, skin and general appearance. The HOSE is a five-point scoring system designed to allow an objective appraisal of the outcome of hypospadias repair, based on evaluating meatal location, meatal shape, urinary stream, straightness of erection, and the presence and complexity of any complicating urethral fistula.
RESULTS
Qmax were within age-adjusted references, independent of the surgical technique, with median (range) Qmax of 18.8 ml/s (range 3-45, n = 136). Patients expressed a high satisfaction for every single item of the penile perception scale (PPPS), with mean values between 2 (satisfied) and 3 (very satisfied). Eighty-two percent were satisfied or very satisfied of the overall evaluation of penile appearance. Eighty-one percent of patients had a normal erectile function (IIEF-5 >22; n = 35/43).
CONCLUSIONS
Taking into account the limitation of a small number of patients resulting from a low 21% questionnaire's response rate, the results of this study align with previous reports from the literature and confirms that hypospadias repair using standard techniques results in acceptable functional, cosmetic and sexual outcomes. This study highlights the need of developing a set of standard approved outcomes assessments tools for evaluating the long-term impact of hypospadias repair performed in infancy.
Topics: Adolescent; Adult; Child; Child, Preschool; Databases, Factual; Fistula; Follow-Up Studies; Humans; Hypospadias; Male; Patient Satisfaction; Penile Erection; Penis; Plastic Surgery Procedures; Retrospective Studies; Rheology; Self Concept; Sexual Behavior; Surveys and Questionnaires; Treatment Outcome; Urethra; Urologic Surgical Procedures, Male; Young Adult
PubMed: 26201846
DOI: 10.1159/000430500 -
The Journal of Sexual Medicine Jan 2014Investigating the ways in which barrier methods such as condoms may affect penile sensory thresholds has potential relevance to the development of interventions in men...
INTRODUCTION
Investigating the ways in which barrier methods such as condoms may affect penile sensory thresholds has potential relevance to the development of interventions in men who experience negative effects of condoms on sexual response and sensation. A quantitative, psychophysiological investigation examining the degree to which sensations are altered by condoms has, to date, not been conducted.
AIM
The objective of this study was to examine penile vibrotactile sensitivity thresholds in both flaccid and erect penises with and without a condom while comparing men who do and those who do not report condom-associated erection problems (CAEP).
METHODS
Penile vibrotactile sensitivity thresholds were assessed among a total of 141 young, heterosexual men using biothesiometry. An incremental two-step staircase method was used and repeated three times for each of four conditions. Intra-class correlation coefficients (ICCs) were calculated for all vibratory assessments. Penile vibratory thresholds were compared using a mixed-model analysis of variance.
MAIN OUTCOME MEASURES
Penile vibrotactile sensitivity thresholds with and without a condom, erectile function measured by International Index of Erectile Function Questionnaire, and self-reported degree of erection.
RESULTS
Significant main effects of condoms (yes/no) and erection (yes/no) were found. No main or interaction effects of CAEP were found. Condoms were associated with higher penile vibrotactile sensitivity thresholds (F[1,124] = 17.11, P < 0.001). Penile vibrotactile thresholds were higher with an erect penis than with a flaccid penis (F[1,124] = 4.21, P = 0.042).
CONCLUSION
The current study demonstrates the feasibility of measuring penile vibratory thresholds with and without a condom in both erect and flaccid experimental conditions. As might be expected, condoms increased penile vibrotactile sensitivity thresholds. Interestingly, erections were associated with the highest thresholds. Thus, this study was the first to document that erect penises are less sensitive to vibrotactile stimulation than flaccid penises.
Topics: Adolescent; Adult; Condoms; Heterosexuality; Humans; Male; Penile Erection; Penis; Sensation; Sensory Thresholds; Sexual Behavior; Vibration; Young Adult
PubMed: 24168347
DOI: 10.1111/jsm.12362 -
Journal of Pediatric Urology Feb 2016Congenital ventral penile curvature without hypospadias is often treated surgically in childhood. The history of untreated ventral curvature is unknown.
INTRODUCTION
Congenital ventral penile curvature without hypospadias is often treated surgically in childhood. The history of untreated ventral curvature is unknown.
OBJECTIVE
This study's aim was to examine the association of untreated ventral penile curvature with various sexual and psychosexual outcomes.
STUDY DESIGN
An electronic survey was advertised to men older than 18 years on Facebook. Men with possible ventral penile curvature identified themselves by choosing sketches that most closely represented their anatomy. Outcomes assessed included: Sexual Health Inventory for Men, difficulty of intercourse because of curvature, International Prostate Symptom Score, Penile Perception Score, psychosexual milestones, paternity, infertility, sitting to urinate, and the CDC HRQOL-4 module.
RESULTS
Among participants, 81 out of 684 men (11.8%) reported untreated ventral penile curvature. Participants with self-reported curvature noted more difficulty with intercourse because of curvature (4.5 vs 4.9, p < 0.001), more unhealthy mental days (8.6 vs 6.2, p = 0.02), and increased dissatisfaction with penile self-perception compared with men without reported curvature (8.6 vs 9.5, p < 0.001).
DISCUSSION
Men with possible untreated ventral curvature reported worse penile perception scores, more mentally unhealthy days, and increased difficulty with intercourse secondary to curvature compared with men without curvature. A limitation to this study is selection bias; responses collected were self-reported from survey volunteers. Additionally, the question identifying ventral penile curvature is not validated but performed well in pretesting. Most questions were from validated surveys, but some were modeled after validated surveys and/or contained high face validity types of questions.
CONCLUSION
Men with possible untreated ventral penile curvature reported more dissatisfaction with penile appearance, increased difficulty with intercourse, and more unhealthy mental days. Given high success rates, low complications, and improved outcomes after surgical correction of penile curvature reported in the literature, our results support correction of congenital penile curvature in childhood.
Topics: Adult; Female; Follow-Up Studies; Humans; Hypospadias; Male; Penile Erection; Penis; Retrospective Studies; Self Concept; Self Report; Sexuality; Surveys and Questionnaires
PubMed: 26776946
DOI: 10.1016/j.jpurol.2015.09.009