oxytocin and Erectile-Dysfunction

A continuously increasing amount of research shows that oxytocin is involved in numerous central functions. Among the functions in which oxytocin is thought to be involved are those that play a role in social and sexual behaviors, and the involvement of central oxytocin in erectile function and sexual behavior was indeed one of the first to be discovered in laboratory animals in the 1980s. The first part of this review summarizes the results of studies done in laboratory animals that support a facilitatory role of oxytocin in male and female sexual behavior and reveal mechanisms through which this ancient neuropeptide participates in concert with other neurotransmitters and neuropeptides in this complex function, which is fundamental for the species reproduction. The second part summarizes the results of studies done mainly with intranasal oxytocin in men and women with the aim to translate the results found in laboratory animals to humans. Unexpectedly, the results of these studies do not appear to confirm the facilitatory role of oxytocin found in male and female sexual behavior in animals, both in men and women. Possible explanations for the failure of oxytocin to improve sexual behavior in men and women and strategies to attempt to overcome this impasse are considered.

Topics: Animals; Erectile Dysfunction; Female; Humans; Male; Oxytocin; Penile Erection; Sexual Behavior

Significant scientific advances during the past 3 decades have deepened our understanding of the physiology and pathophysiology of penile erection. A critical evaluation of the current state of knowledge is essential to provide perspective for future research and development of new therapies.. To develop an evidence-based, state-of-the-art consensus report on the anatomy, physiology, and pathophysiology of erectile dysfunction (ED).. Consensus process over a period of 16 months, representing the opinions of 12 experts from seven countries.. Expert opinion was based on the grading of scientific and evidence-based medical literature, internal committee discussion, public presentation, and debate.. ED occurs from multifaceted, complex mechanisms that can involve disruptions in neural, vascular, and hormonal signaling. Research on central neural regulation of penile erection is progressing rapidly with the identification of key neurotransmitters and the association of neural structures with both spinal and supraspinal pathways that regulate sexual function. In parallel to advances in cardiovascular physiology, the most extensive efforts in the physiology of penile erection have focused on elucidating mechanisms that regulate the functions of the endothelium and vascular smooth muscle of the corpus cavernosum. Major health concerns such as atherosclerosis, hyperlipidemia, hypertension, diabetes, and metabolic syndrome (MetS) have become well integrated into the investigation of ED.. Despite the efficacy of current therapies, they remain insufficient to address growing patient populations, such as those with diabetes and MetS. In addition, increasing awareness of the adverse side effects of commonly prescribed medications on sexual function provides a rationale for developing new treatment strategies that minimize the likelihood of causing sexual dysfunction. Many basic questions with regard to erectile function remain unanswered and further laboratory and clinical studies are necessary.

Topics: Adrenocorticotropic Hormone; Diabetes Complications; Erectile Dysfunction; Humans; Hypertension; Male; Muscle, Smooth; N-Methylaspartate; Oxytocin; Penis; Phosphodiesterase Inhibitors

Selective serotonin reuptake inhibitors (SSRIs) differ in the severity of induced ejaculation delay. Various studies indicate that oxytocin is involved in sexual behavior.. To review and evaluate the involvement of oxytocin in SSRI-induced ejaculation delay.. Oxytocine release, 5-hydroxytryptamine (5-HT) neurotransmission, and desensitization of 5-HT(1A) receptors.. A review and critical analysis of animal studies investigating the interaction of serotonergic and oxytocinergic neurotransmission in relation to the ejaculation process.. Although acute treatment with the SSRIs fluoxetine and paroxetine immediately causes increased serotonin levels, delayed ejaculation does not occur. The increased serotonin levels induce oxytocin release via activation of 5-HT(1A) receptors, and this might compensate for the inhibitory actions of serotonin on sexual behavior. Chronic treatment with fluoxetine and paroxetine desensitizes 5-HT(1A) receptors on oxytocin neurons, and that might in part determine the onset of delayed ejaculation. Desensitization of 5-HT(1A) receptors is less strong following chronic treatment with the SSRIs fluvoxamine or citalopram, which may attenuate the degree of delayed ejaculation.. Preliminary data suggest that the severity of chronic SSRI treatment-induced delayed ejaculation and the differences between the various SSRIs in inducing ejaculation delay is related to gradual desensitization of 5-HT(1A) receptors on oxytocin neurons.

Topics: Animals; Disease Models, Animal; Drug Administration Schedule; Ejaculation; Erectile Dysfunction; Male; Oxytocin; Rats; Receptors, Serotonin; Selective Serotonin Reuptake Inhibitors; Sexual Behavior, Animal

A group of oxytocinergic neurons originating in the paraventricular nucleus of the hypothalamus and projecting to extrahypothalamic brain areas (e.g. hippocampus, medulla oblongata and spinal cord) control penile erection. Activation of these neurons by dopamine and dopamine agonists, excitatory amino acids (N-methyl-D-aspartic acid) or oxytocin itself, or by electrical stimulation leads to penile erection, while their inhibition by GABA and GABA agonists or by opioid peptides and opiate-like drugs inhibits this sexual response. The activation of oxytocinergic neurons in the paraventricular nucleus by dopamine, oxytocin and excitatory amino acids is apparently secondary to the activation of nitric oxide (NO) synthase. NO in turn activates, by a mechanism that is as yet unidentified, the release of oxytocin from oxytocinergic neurons in extrahypothalamic brain areas. Several peptide analogues of hexarelin, a growth hormone releasing peptide, also induce penile erection when injected into the paraventricular nucleus and, to a lesser extent, systemically, apparently by acting on a specific receptor to activate oxytocinergic neurons as shown for the above drugs and oxytocin. Paraventricular oxytocinergic neurons and mechanisms similar to those reported above are also involved in the expression of penile erection in physiological contexts, namely when penile erection is induced in the male by the presence of an inaccessible receptive female, which is considered a model for psychogenic impotence in man, as well as during copulation. These findings show that paraventricular oxytocinergic neurons projecting to extra-hypothalamic brain areas and to the spinal cord are a likely target for the treatment of erectile dysfunction of central origin.

Topics: Animals; Dopamine Agonists; Erectile Dysfunction; Excitatory Amino Acid Agonists; GABA Agonists; Growth Substances; Humans; Male; Narcotics; Neurons; Neurotransmitter Agents; Nitric Oxide; Oxytocin; Paraventricular Hypothalamic Nucleus

What drives the human sexual response cycle? The human sexual response cycle is a highly complex phenomenon that encompasses many transmitters and transmitter systems centrally and peripherally. The endocrine system is also intricately involved in the brain and in the periphery organs. Integration of these systems is a function of the nervous system that ultimately produces a vast array of cognitive, emotional, physiological, and behavioral responses. Therefore, it is not surprising that a disturbance in even a single system will lead to dysfunction in one or more phases of the sexual response cycle. This article highlights the complex roles the aminergic system plays along with key hormones that are equally involved. The article also points out how rudimentary and fragmented our knowledge is in this field and how few controlled studies are available. The potential for development of specific agents that target selective sexual dysfunctions is exemplified in sildenafil, the first such agent ever to be brought to market.

Topics: Brain; Dopamine; Erectile Dysfunction; Female; Gonadal Steroid Hormones; Humans; Libido; Male; Nitric Oxide; Oxytocin; Prolactin; Serotonin; Sexual Behavior

Topics: Animals; Apomorphine; Biogenic Monoamines; Brain; Dopamine; Dopamine Agonists; Erectile Dysfunction; Humans; Male; Oxytocin; Penile Erection; Penis; Rats

The influence of oraly administered synthetic oxytocin (Syntocinon, Sandoz) on the impotentia erectionis has been studied in a double-blind trial in comparison to placebo. Twenty-nine out-patients divided into 3 groups were treated for a minimum of 7 weeks. Nine patients were given 300 IU daily, ten patients 600 IU daily and further 10 patients placebo. The treatment with 300 IU of oxytocin daily has shown the best therapeutic results. The difference between this group and the placebo group was statistically significant regarding the overall parameters sexual interest and sexual capability (P less than 0.05) and P less than 0.10 respectively). The daily oral dose of 600 IU produced no significant therapeutic effect. Oxytocin in both dosage schedules was well tolerated and no untoward side effects were observed.

Topics: Coitus; Drug Evaluation; Erectile Dysfunction; Female; Humans; Male; Muscle, Smooth; Oxytocin; Time Factors

Topics: Animals; Calcineurin; Convulsants; Erectile Dysfunction; Humans; Male; Nitric Oxide; Oxytocin; Phosphodiesterase 5 Inhibitors; Receptors, Opioid; Sildenafil Citrate

Oxytocin is released by the posterior pituitary gland during male orgasm. Additionally, the presence of an oxytocin receptor gene and protein expression in human corpus cavernosum is demonstrated, and it has contractile activity on the smooth muscle of the animal and human corpus cavernosum in vitro. The aim of this study was to investigate the immunoreactivity of oxytocin in corpus cavernosum of patients with organic erectile dysfunction and to compare it with healthy controls.. Cavernous biopsies were obtained from 31 patients with erectile dysfunction and 11 patients without erectile dysfunction. Oxytocin immunohistochemistry was performed using the streptavidin-biotin immunoperoxidase staining on all cases. Intensity and proportion of stained cells were added for the immunoreactivity score.. The mean ages of patients with erectile dysfunction and controls were 41.47 ± 2.08 and 36.50 ± 3.35 years, respectively (p > 0.05). Oxytocin expression was detected in smooth muscle as well as in endothelial cells in both groups. The mean oxytocin immunoreactivity score values of patients with erectile dysfunction and controls were also 2.16 ± 0.12 and 2.30 ± 0.21, respectively (p > 0.05). There was no significant difference in immunoreactivity scores both in arterial and cavernosal failure and also in smoker and nonsmoker groups (p > 0.05). Immunoreactivity scores were not statistically significantly different between patients with concomitant medical disorders and patients with no other medical disorder (p > 0.05).. We detected oxytocin immunoreactivity in male corpus cavernosum, but staining was not different between patients with erectile dysfunction and controls. However, further studies are necessary to reach a final conclusion regarding the effects of oxytocin on corpus cavernosum.

Topics: Adult; Biopsy; Erectile Dysfunction; Humans; Immunohistochemistry; Male; Middle Aged; Models, Statistical; Orgasm; Oxytocin; Penile Erection; Penis; Pituitary Gland

Introduction. This is a case report on male anorgasmia that was successfully treated with oxytocin. Oxytocin is increased during arousal and peaks during orgasm. More recently, a study on humans published in Nature has shown its value in social bonding, increasing trust, and enhancing the sense of well-being. Aim. To test the effectiveness of administering oxytocin in a case of treatment-resistant anorgasmia. Methods. The patient underwent a biopsychosocial evaluation by a psychiatrist trained in sexual medicine and sex therapy for male orgasmic disorder, acquired type. Medical conditions, effect of substances, and psychological issues were ruled out. The patient was properly consented to using oxytocin as an off-label trial. Oxytocin was administered using a nasal spray intracoitally because of its ultra-short half-life. Results. Oxytocin was effective in restoring ejaculation. Conclusions. A case of treatment-resistant male anorgasmia was successfully treated with intracoital administration of intranasal oxytocin.

Topics: Aged; Ejaculation; Erectile Dysfunction; Humans; Male; Orgasm; Oxytocics; Oxytocin; Treatment Outcome

Topics: Drug Design; Erectile Dysfunction; Humans; Male; Oxytocin; Phosphodiesterase Inhibitors

Topics: Animals; Disease Models, Animal; Drug Administration Schedule; Ejaculation; Erectile Dysfunction; Male; Oxytocin; Rats; Receptors, Serotonin; Selective Serotonin Reuptake Inhibitors; Sexual Behavior, Animal

It is well established that transmitters of the nonadrenergic-noncholinergic (NANC) system are involved in the control of sexual arousal and penile erection in healthy males. The proerectile activity of dopamine D1/D2 receptor agonist apomorphine-HCl (IXENSE, UPRIMA) involves oxytocinergic pathways descending from the hypothalamus to the brain stem and spinal autonomic centers. Although it has been demonstrated that injection of oxytocin into the paraventricular nucleus and the hippocampus produces penile erection in rats, the significance of the peptide in the control of sexual arousal and penile erection in man has been, up until now, only poorly evaluated. The present study was undertaken to determine whether oxytocin (OT) plasma levels alter in the systemic and cavernous blood of healthy males under different penile conditions (flaccidity, tumescence, rigidity, detumescence). Twenty-five healthy adult males were exposed to visual and tactile erotic stimuli in order to elicit penile tumescence and rigid erection. Blood was taken from the corpus cavernosum (CC) and the cubital vein (CV) during penile flaccidity, tumescence, rigidity and detumescence. Following extraction from plasma aliqouts, oxytocin was measured by means of a radioimmunoassay. An increase was observed in the mean OT plasma levels in the systemic and cavernous blood when the flaccid penis became tumescent (CC: from 66.7+/-34 to 75+/-44 pg/ml; CV: from 71+/-41 to 79+/-49.5 pg/ml). From tumescence to rigidity, OT further rose in the cavernous blood (to 81+/-58 pg/ml), whereas it remained unaltered in the systemic circulation. During detumescence, oxytocin plasma levels dropped in the cavernous but again increased in the systemic blood (to 94+/-49 pg/ml). Our results support the hypothesis of a pivotal role of OT in the mechanism of male sexual arousal and penile erection and provide a rationale for the use of apomorphine in the treatment of erectile dysfunction.

Topics: Adult; Arousal; Erectile Dysfunction; Humans; Male; Muscle Contraction; Muscle, Smooth, Vascular; Oxytocin; Penile Erection; Penis; Reference Values

Oxytocin plays a physiological stimulatory role on sexual behavior. Conversely, opioid neuropeptides play a physiological inhibitory role. Here we show that in sexually impotent rats there is a reduced expression of oxytocin mRNA and an increased expression of proenkephalin and pro-dynorphin mRNA in the paraventricular nucleus of hypothalamus (PVN), a brain structure of key importance for sexual behavior. These data suggest that an imbalance in the production of oxytocin and of opioid peptides in the PVN, with prevalence of opioid peptides, may underlie a condition of sexual impotence.

Topics: Animals; Enkephalins; Erectile Dysfunction; Female; Male; Oxytocin; Paraventricular Hypothalamic Nucleus; Protein Precursors; Rats; Rats, Sprague-Dawley; Sexual Behavior, Animal

Topics: Alcohol Drinking; Alcoholism; Belgium; Erectile Dysfunction; Humans; Liver Cirrhosis, Alcoholic; Male; Neurophysins; Oxytocin; Prognosis