Hyperprolactinemia and sexual function in men

Hyperprolactinemia and male sexual function: focus on erectile dysfunction and sexual desire

The present paper aims to analyze and discuss the available evidence supporting the relationship between male sexual function and elevated prolactin (PRL) levels (HPRL). Two different sources of data were analyzed. Clinical data were derived from a series of patients seeking medical care for sexual dysfunction at our Unit. Out of 418 studies, 25 papers were used with a meta-analytic approach to evaluate the overall prevalence of HPRL in patients with erectile dysfunction (ED) and to study the influence of HPRL and its treatment on male sexual function. Among 4215 patients (mean age 51.6 ± 13.1 years) consulting for sexual dysfunction at our Unit, 176 (4.2%) showed PRL levels above the normal range. Meta-analytic data showed that HPRL is a rare condition among patients with ED (2 [1;3]%). Either clinical and meta-analytic data confirm a stepwise negative influence of PRL on male sexual desire (S = 0.00004 [0.00003; 0.00006]; I = -0.58915 [-0.78438; -0.39392]; both p < 0.0001 from meta-regression analysis). Normalization of PRL levels is able to improve libido. The role of HPRL in ED remains inconclusive. Data from a meta-analytic approach showed that either HPRL or reduced T levels were independently associated with ED rates. The normalization of PRL levels only partially restored ED. HPRL did not significantly contribute to ED severity, in our clinical setting. In conclusion, treating HPRL can restore normal sexual desire, whereas its effect on erection is limited.

Proton pump inhibitors therapy and risk of hyperprolactinemia with associated sexual disorders

Proton pump inhibitors (PPIs) are the most widely prescribed medications in the world. According to numerous studies, PPIs have been linked to hyperprolactinemia, which can lead to a variety of sexual and reproductive issues. This review summarizes the effects of numerous PPIs on the blood prolactin levels and associated sexual dysfunctions, which have an effect on the patient's life quality and fertility. The study is taken into account all the available resources till January 31, 2021. Out of total 364, only 27 relevant resources were involved in this review. In certain studies, short-term PPIs use has been shown to have little or no effect on the blood prolactin and other reproductive hormones levels. PPIs have been linked to the development of hyperprolactinemia in several case studies with varying degrees of the blood prolactin levels increase seen in individuals taking PPI alone or in combination with medications, like prokinetics. The relative risk of the sexual consequences development, such as gynecomastia, has been documented using lansoprazole and omeprazole in various cohort studies. On the other hand, other bits of data are insufficient to establish a definite relationship that can turn a possibility into certainty. The majority of the literature data is comprising of double-blind, randomized, crossover studies, case reports, and adverse drug reaction incidents reported to various pharmacovigilance centers. To investigate this link, high-quality studies in patients taking PPIs for a longer time period are needed. We conclude this article with a comprehensive discussion of the hyperprolactinemia clinical implications and the PPIs' function.

Delayed ejaculation in men with depressive disorders

Delayed ejaculation belongs to the group of sexual disorders in men. The causes of delayed ejaculation or anejaculation are not exactly known. It is assumed that it can be caused by psychogenic or organic influences or their combinations. One of the causes of delayed ejaculation may be elevated prolactin levels, which may be increased by psychosocial stress, pituitary disorders or also treatment with selective serotonin reuptake inhibitors in the treatment of depression. We tested a selected group of 50 men who were diagnosed with a depressive disorder and whose antidepressant treatment lasted for at least 24 weeks. These patients reported long-term delayed ejaculation or, in some cases, anejaculation as comorbidity. The results showed significant Spearman's correlation between elevated prolactin levels and intravaginal ejaculation latency values (R = 0.45), as well as between Beck's Depression-II inventory and intravaginal ejaculation latency and latency values (R = 0.48).

Impaired prolactin transport into the brain and functional responses to prolactin in aged male mice

Ageing is related to changes in a number of endocrine systems that impact on the central actions of hormones. The anterior pituitary hormone prolactin is present in the circulation in both males and females, with widespread expression of the prolactin receptor throughout the forebrain. We aimed to investigate prolactin transport into the brain, as well as circulating levels of prolactin and functional responses to prolactin, in aged male mice (23 months). Transport of ¹²⁵ I-labelled prolactin (¹²⁵ I-prolactin) from the peripheral circulation into the brain was suppressed in aged compared to young adult (4 months) male mice, with no significant transport into the brain occurring in aged males. We subsequently investigated changes in the negative-feedback regulation of prolactin secretion and prolactin-induced suppression of luteinising hormone (LH) pulsatile secretion in aged male mice. Feedback regulation of prolactin secretion appeared to be unaffected in aged males, with no change in levels of circulating prolactin, and normal prolactin-induced phosphorylated signal transducer and activator of transcription 5(pSTAT5) immunoreactivity in tuberoinfundibular dopaminergic (TIDA) neurones in the arcuate nucleus. There were, however, significant impairments in the ability of prolactin to suppress LH pulsatile secretion in aged males. In young adult males, acute prolactin administration significantly decreased LH pulses from 1.5 ± 0.19 pulses of LH in 4 hours to 0.5 ± 0.27 pulses. In contrast, prolactin did not suppress LH pulse frequency in aged males, with prolactin leading to an increase in mean LH concentration. These data demonstrate the emergence of impairments in prolactin transport into the brain and deficits in specific functional responses to prolactin with ageing.

Patterns of prolactin secretion

Prolactin is pleotropic in nature affecting multiple tissues throughout the body. As a consequence of the broad range of functions, regulation of anterior pituitary prolactin secretion is complex and atypical as compared to other pituitary hormones. Many studies have provided insight into the complex hypothalamic-pituitary networks controlling prolactin secretion patterns in different species using a range of techniques. Here, we review prolactin secretion in both males and females; and consider the different patterns of prolactin secretion across the reproductive cycle in representative female mammals with short versus long luteal phases and in seasonal breeders. Additionally, we highlight changes in the pattern of secretion during pregnancy and lactation, and discuss the wide range of adaptive functions that prolactin may have in these important physiological states.

Controversial issues in the management of hyperprolactinemia and prolactinomas - An overview by the Neuroendocrinology Department of the Brazilian Society of Endocrinology and Metabolism

Prolactinomas are the most common pituitary adenomas (approximately 40% of cases), and they represent an important cause of hypogonadism and infertility in both sexes. The magnitude of prolactin (PRL) elevation can be useful in determining the etiology of hyperprolactinemia. Indeed, PRL levels > 250 ng/mL are highly suggestive of the presence of a prolactinoma. In contrast, most patients with stalk dysfunction, drug-induced hyperprolactinemia or systemic diseases present with PRL levels < 100 ng/mL. However, exceptions to these rules are not rare. On the other hand, among patients with macroprolactinomas (MACs), artificially low PRL levels may result from the so-called "hook effect". Patients harboring cystic MACs may also present with a mild PRL elevation. The screening for macroprolactin is mostly indicated for asymptomatic patients and those with apparent idiopathic hyperprolactinemia. Dopamine agonists (DAs) are the treatment of choice for prolactinomas, particularly cabergoline, which is more effective and better tolerated than bromocriptine. After 2 years of successful treatment, DA withdrawal should be considered in all cases of microprolactinomas and in selected cases of MACs. In this publication, the goal of the Neuroendocrinology Department of the Brazilian Society of Endocrinology and Metabolism (SBEM) is to provide a review of the diagnosis and treatment of hyperprolactinemia and prolactinomas, emphasizing controversial issues regarding these topics. This review is based on data published in the literature and the authors' experience.

Melatonin prevents and ameliorates lead-induced gonadotoxicity through antioxidative and hormonal mechanisms

We investigated the effects of melatonin on sperm parameters and some biochemical markers in lead-exposed male Wistar rats. Lead (50 mg/kg bw/day) and/or melatonin (4 mg/kg or 10 mg/kg bw/day) was administered for 4 weeks, while 2-week lead exposure was preceded by or followed by 2-week treatment with both doses of melatonin in other groups. Lead reduced glutathione, catalase, adjusted testes weight, semen parameters but did not change malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase, and total antioxidant capacity. Though independent of prolactin, lead-induced gonadotoxicity was both centrally and peripherally mediated, as it reduced gonadotropin-releasing hormone and testosterone levels, while gonadotropin levels did not change significantly probably due to negative feedback by elevated estradiol. However, pre-, simultaneous, or posttreatment of lead-exposed rats with melatonin reduced MDA, SOD, and estradiol but dose-dependently increased other parameters. Conclusively, lead causes male gonadotoxicity through oxidative stress and endocrine mechanisms, and these could be dose-dependently prevented and ameliorated by melatonin.

Serotonin and Antidepressant SSRIs Inhibit Rat Neuroendocrine Dopamine Neurons: Parallel Actions in the Lactotrophic Axis

Selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed for depression, but sexual side effects often compromise compliance. These reproductive dysfunctions are likely mediated by elevations of the hormone prolactin. Yet, how serotonin (5-HT) and SSRIs cause changes in prolactin secretion is not known. Here, using in vitro whole-cell patch-clamp recordings, we show that 5-HT hyperpolarizes and abolishes phasic discharge in rat neuroendocrine tuberoinfundibular dopamine (TIDA) neurons, the main inhibitor of prolactin secretion. This process is underpinned by 5-HT1A receptor-mediated activation of G-protein-coupled inwardly rectifying K(+)-like currents. We further demonstrate that the SSRIs, fluoxetine and sertraline, directly suppress TIDA neuron activity through parallel effects, independent of 5-HT transmission. This inhibition involves decreased intrinsic excitability and a slowing of TIDA network rhythms. These findings indicate that SSRIs may inhibit neuroendocrine dopamine release through both 5-HT-dependent and -independent actions, providing a mechanistic explanation for, and potential molecular targets for the amelioration of, the hyperprolactinemia and sexual dysfunction associated with these drugs.

SIGNIFICANCE STATEMENT

Depression affects approximately one-tenth of the population and is commonly treated with selective serotonin reuptake inhibitors (SSRIs; e.g., Prozac). Yet, many patients withdraw from SSRI therapy due to sexual side effects (e.g., infertility, menstrual disturbances, and impotence). Although it is generally accepted that sexual side effects are due to the ability of these drugs to elevate blood levels of the hormone prolactin, the mechanism for this hormonal imbalance is not known. Here, we show that SSRIs can inhibit hypothalamic dopamine neurons that normally suppress the secretion of prolactin. Intriguingly this inhibition can be explained both by increased serotonin activity and also by parallel serotonin-independent actions.

Testosterone replacement therapy: role of pituitary and thyroid in diagnosis and treatment

Crosstalk among hormones characterizes endocrine function, and assessment of the hypogonadal man should take that into consideration. In men for whom testosterone deficiency is a concern, initial evaluation should include a thorough history and physical exam in which other endocrinopathies are being considered. Hypogonadism can be associated with both pituitary and thyroid dysfunction, for which appropriate biochemical evaluation should be undertaken in certain clinical scenarios. If low serum testosterone is confirmed measurement of luteinizing and follicle stimulating hormones (LH and FSH respectively) is essential to establish whether the hypogonadism is primary or secondary. In secondary hypogonadism measurement of prolactin is always necessary, and measurement of other pituitary hormones, along with pituitary imaging, may be indicated. Checking thyroid function may also be enlightening, and can raise additional therapeutic considerations. Correction of other pituitary axes may attenuate the need for testosterone replacement therapy in some cases.

The epidemiology of hyperprolactinaemia over 20 years in the Tayside region of Scotland: the Prolactin Epidemiology, Audit and Research Study (PROLEARS)

OBJECTIVE

To estimate the prevalence and incidence of hyperprolactinaemia. Hyperprolactinaemia is a common problem in endocrine practice, but its epidemiology has not been accurately established.

STUDY DESIGN

A population-based retrospective follow-up study in Tayside, Scotland (population 400,000), from 1993 to 2013.

PATIENTS

Record linkage technology (biochemistry, prescribing, hospital admissions, radiology, mortality and maternity data) was used to identify all patients with a serum prolactin measurement. From these, cases were defined as those with a prolactin greater than 1000 mU/L (47·2 ng/ml) or at least three prescriptions for a dopamine agonist.

MEASUREMENTS

Number of prevalent and incident cases of hyperprolactinaemia per calendar year by age, sex and cause of hyperprolactinaemia.

RESULTS

A total of 32289 patients had a serum prolactin assay undertaken, of which 1301 had hyperprolactinaemia not related to pregnancy: 25·6% patients had pituitary disorder, 45·9% were drug-induced, 7·5% had macroprolactin and 6·1% had hypothyroidism, leaving 15·0% idiopathic. Over the 20 years, there was a fourfold increase in the number of prolactin assays performed, and prevalence of hyperprolactinaemia was initially 0·02%, but rose to 0·23% by 2013. Overall incidence was 13·8 cases per 100000 person-years (20·6 in 2008-13) and was 3·5 times higher in women than in men. The highest rates were found in women aged 25-44 years. Drug-induced causes tripled during the 20 years.

CONCLUSIONS

Rising prevalence of hyperprolactinaemia is probably due to an increased ascertainment and increased incidence of psychoactive drug-related causes. Rates are higher in women than in men but only before the age of 65 years.

Epidemiology of delayed ejaculation

A large body of literature on diminished ejaculatory disorders has been generated without the use of a clear diagnostic definition. Many studies have not distinguished between the orgasm and ejaculation disorders leading to doubtful results. Delayed ejaculation (DE) is one of the diminished ejaculatory disorders, which range from varying delays in ejaculatory latency to a complete inability to ejaculate. The present review is aimed at providing a comprehensive overview of the current knowledge on the definition and epidemiology of diminished ejaculatory disorders. We focus on the acquired diseases, such as benign prostatic hyperplasia (BPH) and specific drug regimens that may cause an iatrogenic form of ejaculatory disorder. In addition, the impact of aging is discussed since the prevalence of DE appears to be moderately but positively related to age. Finally, we also focus on the importance of the hormonal milieu on male ejaculation. To date, evidence on the endocrine control of ejaculation is derived from small clinical trials, but the evidence suggests that hormones modulate the ejaculatory process by altering its overall latency.

Challenges and pitfalls in the diagnosis of hyperprolactinemia

The definition of the etiology of hyperprolactinemia often represents a great challenge and an accurate diagnosis is paramount before treatment. Although prolactin levels > 200-250 ng/mL are highly suggestive of prolactinomas, they can occasionally be found in other conditions. Moreover, as much as 25% of patients with microprolactinomas may present prolactin levels < 100 ng/mL, which are found in most patients with pseudoprolactinomas, drug-induced hyperprolactinemia, or systemic diseases. On the other hand, some conditions may lead to falsely low PRL levels, particularly the so-called hook effect, that is an assay artifact caused by an extremely high level of PRL, and can be confirmed by repeating assay after a 1:100 serum sample dilution. The hook effect must be considered in all patients with large pituitary adenomas and PRL levels within the normal range or only modestly elevated (e.g., < 200 ng/mL). An overlooked hook effect may lead to incorrect diagnosis and unnecessary surgical intervention in patients with prolactinomas. Another important challenge is macroprolactinemia, a common finding that needs to be identified, as it usually requires no treatment. Although most macroprolactinemic patients are asymptomatic, many of them may present galactorrhea or menstrual disorders, as well as neuroradiological abnormalities, due to the concomitance of other diseases. Finally, physicians should be aware that pituitary incidentalomas are found in at least 10% of adult population.

TIDAL WAVES: Network mechanisms in the neuroendocrine control of prolactin release

Neuroendocrine tuberoinfundibular dopamine (TIDA) neurons tonically inhibit pituitary release of the hormone, prolactin. Through the powerful actions of prolactin in promoting lactation and maternal behaviour while suppressing sexual drive and fertility, TIDA neurons play a key role in reproduction. We summarize insights from recent in vitro studies into the membrane properties and network behaviour of TIDA neurons including the observations that TIDA neurons exhibit a robust oscillation that is synchronized between cells and depends on intact gap junction communication. Comparisons are made with phasic firing patterns in other neuronal populations. Modulators involved in the control of lactation - including serotonin, thyrotropin-releasing hormone and prolactin itself - have been shown to change the electrical behaviour of TIDA cells. We propose that TIDA discharge mode may play a central role in tuning the amount of dopamine delivered to the pituitary and hence circulating prolactin concentrations in different reproductive states and pathological conditions.

Caenorhabditis elegans male sensory-motor neurons and dopaminergic support cells couple ejaculation and post-ejaculatory behaviors

The circuit structure and function underlying post-coital male behaviors remain poorly understood. Using mutant analysis, laser ablation, optogenetics, and Ca²⁺ imaging, we observed that following C. elegans male copulation, the duration of post-coital lethargy is coupled to cellular events involved in ejaculation. We show that the SPV and SPD spicule-associated sensory neurons and the spicule socket neuronal support cells function with intromission circuit components, including the cholinergic SPC and PCB and the glutamatergic PCA sensory-motor neurons, to coordinate sex muscle contractions with initiation and continuation of sperm movement. Our observations suggest that the SPV and SPD and their associated dopamine-containing socket cells sense the intrauterine environment through cellular endings exposed at the spicule tips and regulate both sperm release into the hermaphrodite and the recovery from post-coital lethargy.

DOI:http://dx.doi.org/10.7554/eLife.02938.001

The nematode worm, C. elegans, is roughly 1 mm long, made up of around 1000 cells and has two sexes: male and hermaphrodite. Hermaphrodite worms produce both eggs and sperm and can self-fertilize to generate around 300 offspring each time. Fertilization by a male, on the other hand, results in three times as many progeny and introduces genetic diversity into the population. However, it also reduces the lifespan of the hermaphrodite.

Mating also incurs a cost for males: it requires a lot of energy, which prevents male works from engaging in other activities, such as feeding, and it also increases their risk of predation. In many species, including C. elegans, the frequency with which a male can mate is limited by a period of reduced mating drive and ability that follows each instance of successful mating. However, the molecular and cellular basis of this ‘refractory period’ remains largely unclear.

Using a range of techniques, LeBoeuf et al. have now identified the circuits that regulate male mating behavior in C. elegans. When male worms were introduced into a Petri dish containing 15 hermaphrodites, most males initiated mating within about 2 min. The length of the refractory period varied between worms, but averaged roughly 12 min. This consisted of a period of disinterest, in which males did not approach hermaphrodites, followed by a period in which males attempted mating but were slower and less efficient, suggesting that the neural circuits controlling mating behaviors had yet to recover completely.

Males with longer refractory periods produced more progeny in their second mating than those with shorter refractory periods, suggesting that the interval also enables males to replenish their sperm levels. Further experiments revealed that a chemical transmitter called dopamine promotes ejaculation and then immediately reduces the worm's activity levels, giving rise to the refractory period.

By enforcing a delay between matings, the refractory period may also increase the likelihood that successive matings will be with different hermaphrodites, helping to maximize the number and diversity of offspring. Some aspects of the neural circuitry that controls the refractory period in C. elegans resemble those seen in mammals, suggesting that insights gained from an animal with 1000 cells could also be relevant to more complex species.

DOI:http://dx.doi.org/10.7554/eLife.02938.002

A systematic review of the correlates and management of nonpremature ejaculatory dysfunction in heterosexual men

INTRODUCTION

A better understanding of ejaculatory disorders has led to an increasing interest in nonpremature ejaculatory dysfunction (non-PE EjD). Current reviews on the subject use a symptom-based classification to describe ejaculatory dysfunction even when it is a single case report. While these reviews provide important information on the disorder, a clearer picture of the prevalence of non-PE EjD in relation to the community and various pathophysiologic states is needed.

OBJECTIVES

The objective of this study was to provide a systematic review of studies of non-PE EjD excluding single case reports.

METHODS

A systematic review of Medline for terms including ejaculation, orgasm or hematospermia. Association with terms delay, pain or headache was made. The search was restricted to male gender and articles written in English. Abstracts were reviewed and those mainly concerned with premature ejaculation were excluded.

RESULTS

A total of 333 articles on non-PE EjD were identified. The condition was reported in community-based studies. In certain patient populations, non-PE EjD was commonly reported in association with antidepressant and antipsychotic treatments, in patients with chronic prostatitis/chronic pelvic pain syndrome, patients with lower urinary tract symptoms particularly in association with medical or surgical treatment, patients with retroperitoneal surgery and in patients with neurological diseases. Few articles were concerned with treatment options.

CONCLUSION

There is a significant prevalence of non-PE EjD in the community and in association with particular disease states or as a side effect of medical or surgical interventions. There is a need to direct efforts to prevent and treat these conditions.

Evolving ideas about the male refractory period

The male refractory period (MRP) continues to be a topic of discussion and debate within the field of sexual medicine. To date explanations rely on central descending (efferent) influences involving specific neurotransmitter systems. Herein we explore the issue of the male refractory period, identifying problems with current explanations, specifying the parameters of an adequate model, and suggesting possible mechanisms mediating this phenomenon. We review the literature regarding existing explanations for the MRP and look to other systems of physiological regulation that might provide a model for the conceptualization of the MRP. Our approach differs from traditional explanations in that it emphasizes the possible roles of various peripheral, rather than central, feedback (afferent) systems that affect peripheral autonomic functioning and response. Yet our approach is consistent with other peripheral regulatory feedback systems controlling autonomic response related to such processes as heart rate, respiration, and gut motility. Although direct empirical research supporting our approach is lacking, sufficient evidence exists to support the idea that such processes are not only possible but likely with respect to the male refractory period. We suggest several lines of research that might provide empirical support for this approach.

Growth hormone, prolactin, and sexuality

GH and PRL, although not considered as 'classi cal' sexual hormones, could play a role in the endocrine control of sexual function both in men and women. Physiologically, PRL seems to be involved in the central control of sexual behavior and activity, by modulating mainly the effects of dopaminergic and serotoninergic systems on sexual function. Indeed, circulating PRL levels increase after orgasm and may potentially play a role in the acute regulation of further sexual arousal following orgasm both in men and women. On the other hand, either short-term or long-term PRL in crease can modulate central nervous system areas involved in the control of sexual function and, peripherally, can directly influence mechanisms of penile erection in men, and presently only as an hypothesis, mechanisms related to the sexual response of genitalia in women. Furthermore, chronic hyperprolactinemia is classically associated with hypogonadotropic hypogonadism and sexual dysfunction in both sexes. Successful treatment of chronic hyperprolactinemia generally restores normal sexual function both in men and women although this effect is not only related to relapse of gonadal function. Hypoprolactinemia is recently recognised as a possible risk factor of arteriogenic erectile dysfunction while a possible role on female sexual function is not known. The physiological role of GH on sexual function is not fully elucidated. GH is an important regulator of hypothalamus-pituitary-gonadal axis and seems to participate in the regulation of the sexual response of genitalia in men, and potentially also in women. Sexual function in men and women with GH deficiency (GHD) and GH excess, particularly in acromegaly, is scantily studied and GH- or IGF-I-dependent effects are difficult to quantify. Nevertheless, a decrease of desire and arousability both in men and women, together with an impairment of erectile function in men, have been described both in patients with GHD and acromegaly, although it is not clear whether they are dependent directly on the hormone defect or excess or they are consequence of the hypogonadism or the different clinical complications or the physical disfigurement and psychological imbalance, which are associated with the diseases, and are potentially affecting sexual function. Data on beneficial effects of GH replacement therapy and specific surgical or pharmacological approach for acromegaly are far to be fully elucidated although restoring normal GH/IGF-I levels have been associated to improvement of sexual function.

Plasma concentration of prolactin, testosterone might be associated with brain response to visual erotic stimuli in healthy heterosexual males

OBJECTIVE

Many studies have showed that excess or lack of sexual hormones, such as prolactin and testosterone, induced the sexual dysfunction in humans. Little, however, is known about the role of sexual hormones showing normal range in, especially, the basal state unexposed to any sexual stimulation. We hypothesized sexual hormones in the basal state may affect sexual behavior.

METHODS

We investigated the association of the sexual hormones level in the basal hormonal state before visual sexual stimulation with the sexual response-related brain activity during the stimulation. Twelve heterosexual men were recorded the functional MRI signals of their brain activation elicited by passive viewing erotic (ERO), happy-faced (HA) couple, food and nature pictures. Both plasma prolacitn and testosterone concentrations were measured before functional MR scanning. A voxel wise regression analyses were performed to investigate the relationship between the concentration of sexual hormones in basal state and brain activity elicited by ERO minus HA, not food minus nature, contrast.

RESULTS

The plasma concentration of prolactin in basal state showed positive association with the activity of the brain involving cognitive component of sexual behavior including the left middle frontal gyrus, paracingulate/superior frontal/anterior cingulate gyri, bilateral parietal lobule, right angular, bilateral precuneus and right cerebellum. Testosterone in basal state was positively associated with the brain activity of the bilateral supplementary motor area which related with motivational component of sexual behavior.

CONCLUSION

Our results suggested sexual hormones in basal state may have their specific target regions or network associated with sexual response.

Sexual dysfunction in patients with schizophrenia treated with conventional antipsychotics or risperidone

OBJECTIVE

To better understand sexual dysfunction in patients with schizophrenia and its associations with prolactin and reproductive hormones.

METHODS

This was a secondary analysis of an open-label, one-day study (N = 402). The primary objective of the study was to assess the prevalence of hyperprolactinemia in patients with schizophrenia who had been treated with conventional antipsychotics or risperidone. Other atypical antipsychotics available at the time of the study were not included due to a more favorable prolactin profile.

RESULTS

The majority of patients (59% of females and 60% of males) reported impairment of sexual function. In postmenopausal females, risk of impaired sexual interest was increased by 31% for every 10 ng/ml increase in prolactin (p = 0.035). In males, lower testosterone was associated with higher prolactin (p < 0.001) and with orgasmic (p = 0.004) and ejaculatory dysfunction (p = 0.028).

CONCLUSION

These findings suggest that hyperprolactinemia may be associated with sexual dysfunction. They also provide more information on the relationships between prolactin, reproductive hormones, and sexual dysfunction. Sexual dysfunction is an understudied yet important consideration in the treatment of schizophrenia. More attention is warranted in this area as it may provide opportunities for improved quality of life and adherence to treatment for patients.

Hyperprolactinaemia due to hypothalamic-pituitary disease or drug-induced in patients with erectile dysfunction

One hundred and sixty-five patients with erectile dysfunction were assessed at the Athens Medical Sex Institute: 60 men (36.4%) considered their condition as organic, 52 (31.5%) rated it as mostly psychogenic, 45 (27.2%) thought it could be of mixed aetiology and 8 (4.8%) could not comment at all as to the aetiology. Initial psychologic evaluation rated the condition in the majority of cases as psychogenic (130 patients, 84.8%). No psychologist considered the erectile dysfunction as purely (100%) organic. After the urological and endocrine evaluation, vascular disorder was considered in 30 patients (18.2%), endocrine dysfunction in 16 patients (9.7%) and psychogenic in 109 patients (66.1%). Sixteen of the above patients had definite hyperprolactinaemia, two had large-sized prolactinomas as revealed by magnetic resonance imaging (MRI) and pituitary function tests. Four had nonfunctioning pituitary tumours, which was also based on MRI and pituitary tests. Four had small prolactin (PRL) adenomas. Drug-induced hyperprolactinaemia was suspected in six patients who used medications affecting PRL secretion and had no evidence of tumour on radiological evaluation. In conclusion, hyperprolactinaemia in men with erectile dysfunction needs to be evaluated before considering any other treatment.

Efficacy and safety of two dosing regimens of tadalafil and patterns of sexual activity in men with diabetes mellitus and erectile dysfunction: Scheduled use vs. on-demand regimen evaluation (SURE) study in 14 European countries

AIM

The aim of this article is to evaluate the efficacy and safety of 20-mg tadalafil taken on demand or three times per week and its effect on the sexual activity of patients with diabetes mellitus and erectile dysfunction (ED).

METHODS

The scheduled use vs. on-demand regimen evaluation (SURE) was a randomized, crossover, open-label study with 4,262 patients in 14 European countries. The efficacy measures for the 762 patients with diabetes and ED included changes from baseline in the erectile function (EF) domain of the International Index of Erectile Function (IIEF), and the proportion of "yes" responses to patient Sexual Encounter Profile (SEP) questions 2 (SEP2) and 3 (SEP3). The treatment satisfaction was measured with responses to SEP question 4 (SEP4) and SEP question 5 (SEP5), and sexual attempts data were collected. Patient preference for either regimen was determined by the treatment preference question (TPQ).

RESULTS

At end point on both regimens, the mean IIEF EF domain score was 22, and >40% of the patients had a normal EF domain score (> or =26). The proportion of "yes" responses was > or =73% for SEP2 (penetration), > or =58% for SEP3 (successful intercourse), >46% for SEP4 (hardness of erection), and > or =45% for SEP5 (overall satisfaction). Efficacy was maintained up to 36 hours post-dosing. More than 70% of sexual attempts while on the three-times-per-week regimen and approximately 50% of the attempts on the on-demand treatment occurred >4 hours post-dosing. Tadalafil was well tolerated, with dyspepsia and headache as the most frequent adverse events reported. Treatment preference was 57.2% for on demand and 42.8% for three times per week.

CONCLUSIONS

Tadalafil, when taken on demand or three times per week, is efficacious and safe in men with diabetes and ED.

Endocrine causes of erectile dysfunction

Erectile dysfunction (ED) is one of the commonest disorders of male sexual function. Penile erection depends on a complex interaction of psychological, neural, vascular and endocrine factors. Testosterone has an important role in both central and peripheral domains of this process. In this article we discuss the role of testosterone in male sexual function and endocrine causes of ED.

Gene transfer of vasoactive intestinal polypeptide into the penis improves erectile response in the diabetic rat

OBJECTIVES

To determine the feasibility of transfecting penile corpora cavernosa with pcDNA3/vasoactive intestinal polypeptide (VIP) cDNA, which encodes for VIP in streptozotocin (STZ)-diabetic rats, to clarify whether transfection of VIP cDNA into the cavernosum affects the physiological response to cavernosal nerve stimulation, and whether this process would affect other organs in the diabetic rat model in vivo.

MATERIALS AND METHODS

pcDNA3/VIP cDNA was injected into the corpus cavernosum of STZ-induced diabetic Sprague-Dawley rats. The intracavernosal pressure (ICP) and response to electrical stimulation of the cavernosal nerve (15 Hz, 1.5 ms, 20 V, 1 min) were measured in subsamples of rats at 1, 3, 7 and 14 days after injection; after measuring the ICP the animals were killed, and penile, hepatic, renal artery and abdominal aorta tissue samples were frozen in liquid nitrogen and stored at -80 degrees C. The gene expression of VIP in all samples, assessed as the expression of VIP mRNA, was estimated using a semiquantitative reverse-transcription polymerase chain reaction.

RESULTS

The mean amplitude of ICP and expression of VIP mRNA in the cavernosa of the VIP-treated rats was greater at 1, 3, 7 and 14 days after injection (P < 0.05) than in the control animals. There were no changes in the expression of VIP mRNA in hepatic, renal and abdominal aorta samples after injection (P > 0.05).

CONCLUSIONS

VIP cDNA is easily incorporated into corpus cavernosum, and the expression is sustained for > or = 2 weeks in the penis in vivo. The transfer of VIP is capable of altering the physiologically relevant erectile response, as measured by an increase in the ICP after stimulating the cavernosal nerve. The intracorporal micro-injection of pcDNA3/VIP cDNA had little effect on the expression of VIP mRNA in other important organs.

Prolactinergic and dopaminergic mechanisms underlying sexual arousal and orgasm in humans

Dopaminergic mechanisms play a major role in modulating sexual behavior in humans and animals. Animal data demonstrate important interactions between the dopaminergic and prolactinergic system. As recently demonstrated, dopamine agonists have facilitatory properties for penile erection but may also enhance sexual drive and orgasmic quality. In contrast, chronic elevations of prolactin inhibit appetitive as well as consummatory parameters of sexual behavior. Recent human studies show a marked increase in prolactin after orgasm in males and females. Concerning the biological relevance of acute prolactin alterations after orgasm, prolactin might serve as a neuroendocrine reproductive reflex for peripheral reproductive organs. Alternatively, prolactin may feedback to dopaminergic neurons in the central nervous system and thereby modulate sexual drive and satiation. Here, we provide a brief overview of the physiology of dopamine and prolactin in regulating sexual behavior. In addition, recent experimental and clinical evidence for a postulated feedback mechanism for prolactin and its implications for orgasmic disorders are discussed.

Psycho-biological correlates of hypoactive sexual desire in patients with erectile dysfunction

We studied the psychological and biological correlates of hypoactive sexual desire (HSD) in a consecutive series of 428 patients with erectile dysfunction (ED), by using the structured interview SIEDY. A complete physical examination and a series of biochemical, hormonal, psychometric, and penile vascular tests were also performed. Among the patients studied, 22.8% reported a mild, 12.9% a moderate, and 4.6% a complete loss of sexual interest. Patients reporting HSD showed significantly lower testosterone (T) levels than the rest of the sample, although the prevalence of hypogonadism (T<10 nM) was comparable in the two groups. Only a minority (<2%) had severe hyperprolactinemia (>700 mU/l), which, nonetheless, was closely associated with a relevant HSD. Both mental disorders and use of medication interfering with sexual function were significantly associated with HSD, as well as depressive and anxiety symptoms. HSD patients showed significantly higher scores in SIEDY scale 2, which explores the relational component of ED. In particular, perceived partner's libido and climax were crucially associated with an impairment of patients' sexual desire. In conclusion, HSD in ED is associated with several biological, psychological, and relational factors that can be simultaneously identified and quantified using the SIEDY structured interview.

Hyperprolactinemia and sexual function in men: a short review

Erectile dysfunction (ED), generally associated with reduced sexual desire and sometimes with orgasmic or ejaculatory dysfunction, is the major revealing symptom of hyperprolactinemia (HPRL) in men, a condition that should not be neglected since many cases result from pituitary tumors, likely to result in serious complications. It is generally believed that the mechanism of the prolactin (PRL)-induced sexual dysfunctions is a decrease in testosterone secretion. In fact, serum testosterone is normal in many hyperprolactinemic males and there are also testosterone-independent mechanisms, probably mainly set at the level of the brain's neurotransmitter systems. Systematic determinations of serum PRL found very low prevalences of marked HPRL (>35 ng/ml) in ED patients (0.76% in a compilation of over 3200 patients) as well as of pituitary adenomas (0.4%). In addition, the association of HPRL with ED may have been coincidental in some of these cases, since 10% of the HPRLs diagnosed by the usual immunological assays are composed of macroprolactins, which are biologically inactive or little active variants of PRL. Their identification requires a PRL chromatography that is restricted to some specialized laboratories. There is presently no consensus with regards to the screening for HPRL in ED: systematic determination of serum PRL may be justified since HPRL is a serious but reversible disease, while there is presently no reliable clinical, psychometric or hormonal criteria (including serum testosterone level) allowing to restrict its determination to certain categories of the ED patients without risk of neglecting some HPRLs. In case of consistent HPRL, searching for a hypothalamic or pituitary tumor is mandatory. Dopamine-agonist therapy is the first choice treatment for the PRL-induced sexual dysfunctions. Additional sexual counselling may be necessary for certain patients.

Endocrine Aspects of Sexual Dysfunction in Men

INTRODUCTION

Endocrine disorders of sex steroid hormones may adversely affect men's sexual function. Aim. To provide expert opinions/recommendations concerning state-of-the-art knowledge for the pathophysiology, diagnosis and treatment of endocrinologic sexual medicine disorders.

METHODS

An International Consultation in collaboration with the major urology and sexual medicine associations assembled over 200 multidisciplinary experts from 60 countries into 17 committees. Committee members established specific objectives and scopes for various male and female sexual medicine topics. The recommendations concerning state-of-the-art knowledge in the respective sexual medicine topic represent the opinion of experts from five continents developed in a scientific and debate process. Concerning the Endocrine committee, there were eight experts from seven countries.

MAIN OUTCOME MEASURE

Expert opinions/recommendations are based on grading of evidence-based medical literature, extensive internal committee discussion over 2 years, public presentation and deliberation.

RESULTS

Hypogonadism is a clinical and biochemical syndrome characterized by a deficiency in serum androgen levels which may decrease sexual interest, quality of erections and quality of life. Biochemical investigations include testosterone and either bioavailable or calculated free testosterone; prolactin should be considered when hypogonadism has been documented. If clinically indicated, androgen therapy should maintain testosterone within the physiological range avoiding supraphysiologic values. Digital rectal examination and determination of serum prostate specific antigen values are mandatory prior to therapy and regularly thereafter. Androgen therapy is usually long-term requiring regular follow-up, frequent monitoring of blood levels and beneficial and adverse therapeutic responses.

CONCLUSIONS

Safe and effective treatments for endocrinologic sexual medicine disorders examined by prospective, placebo-controlled, multi-institutional clinical trials are needed.

Acute neuroendocrine response to sexual stimulation in sexual offenders

BACKGROUND

Several pharmacotherapeutic approaches have confirmed the influence of neuroendocrine parameters on sexual desire, function, and fantasies in men; however, the relevance of acute neuroendocrine changes in mediating heightened sexual drive remains unknown. We recently demonstrated that plasma prolactin substantially increases following orgasm in healthy men, suggesting a feedback mechanism for peripheral prolactin in the control of acute sexual arousal. Because prolactin appears to play a regulatory role in acute sexual drive, we initiated this study to see whether sexual offenders with a high sexual drive have a different neuroendocrine response to sexual arousal. This study compares the prolactin response to orgasm of sexual offenders with high sexual drive and that of healthy subjects with average sexual drive.

METHODS

From a subject pool of 150 inpatients held because of sexual crimes, we recruited 10 volunteers, based on their high sexual drive according to an intensive, semistructured clinical interview. We defined sexual drive by a short refractory period and strong sexualization, or a high frequency of sexual stimulation. We analyzed the acute psychoneuroendocrine response to sexual arousal and orgasm continuously before, during, and after masturbation-induced orgasm in patients and control subjects.

RESULTS

Sexual offenders demonstrated higher sexual desire (P < 0.001) and function (P < 0.001) and a more positively perceived refractory period (P < 0.05). Both groups displayed a prolonged, significant increase in prolactin plasma levels after orgasm (P < 0.001). Sexual offenders did not differ from control subjects in neuroendocrine response to sexual arousal and orgasm.

CONCLUSIONS

These data demonstrate that sexual offenders with a high sexual drive do not differ from control subjects in the postorgasmic neuroendocrine response, particularly in prolactin release. This study confirms that factors other than peripheral hormones influence deviant sexual behaviour.

Effects of tadalafil on erectile dysfunction in men with diabetes

OBJECTIVE

To evaluate the efficacy and safety of tadalafil taken as needed before sexual activity by men with diabetes and erectile dysfunction (ED).

RESEARCH DESIGN AND METHODS

Men with type 1 or type 2 diabetes and a minimum 3-month history of ED were randomly allocated to one of three groups: placebo (n = 71), tadalafil 10 mg (n = 73), or tadalafil 20 mg (n = 72) taken up to once daily for 12 weeks. Changes from baseline in mean scores on the erectile function domain of the International Index of Erectile Function (IIEF) and changes from baseline in the proportion of "yes" responses to question 2, "Were you able to penetrate?," and 3, "Were you able to complete intercourse?," of the Sexual Encounter Profile were coprimary outcome measures.

RESULTS

A total of 191 (88%) of 216 patients completed the study. Treatment with tadalafil significantly improved all primary efficacy variables, regardless of baseline HbA(1c) level. Therapy with tadalafil also significantly improved a number of secondary outcome measures, including changes in other IIEF domains, individual IIEF questions, and percentage of positive responses to a global assessment question measuring erection improvement. Treatment with tadalafil did not alter mean HbA(1c) levels. Tadalafil was well tolerated, with headache and dyspepsia being the most frequent adverse events with active treatment.

CONCLUSIONS

Tadalafil therapy significantly enhanced erectile function and was well tolerated by men with diabetes and ED.

Single- and multiple-dose pharmacokinetics of ziprasidone under non-fasting conditions in healthy male volunteers

AIMS

To evaluate the pharmacokinetics and tolerability of single and multiple oral doses of ziprasidone in healthy male volunteers, and to determine the influence of ziprasidone on serum prolactin levels.

METHODS

Single and multiple doses of ziprasidone were given orally (as two divided daily doses), at fixed dosages of 10 and 40 mg day(-1), and using titrated regimens of 40-80 and 40-120 mg day(-1), for 14 days. All dosages were taken immediately after food. The study adopted a randomized, double-blind, placebo-controlled design. Prolactin response, sedative properties, tolerability, and extrapyramidal symptoms were also investigated.

RESULTS

Steady-state exposure to ziprasidone was attained after 1 day of dosing. Mean Cmax and AUC(0,12 h) increased with increasing dose, with apparent dose-proportionality between the 20 and 60 mg dose levels. Trough-to-peak ratios at steady state ranged from 2 to 5. Accumulation ratios for the fixed-dose regimens were 1.49 and 1.48 at the 5 and 20 mg dose levels, respectively. Ziprasidone was associated with transient prolactin elevation but levels of prolactin returned to baseline within the dosing interval at steady state. There was a marginal, transient increase in serum prolactin levels which was not dose-related at the 80 and 120 mg day(-1) doses, and which was noted to attenuate with chronic dosing. Ziprasidone was generally well tolerated. The most frequent side-effect was mild or moderate headache. A minority of patients suffered first-dose postural hypotension. Ziprasidone was also associated with a mild sedative effect that became less pronounced as treatment continued. There were no drug-related changes in electrocardiogram or clinical laboratory variables that were of clinical importance.

CONCLUSIONS

Ziprasidone is characterized by a predictable pharmacokinetic profile resulting in symptoms that reflect its pharmacological action.

Endocrine screening in 1,022 men with erectile dysfunction: clinical significance and cost-effective strategy

PURPOSE

We reviewed the results of serum testosterone and prolactin determination in 1,022 patients referred because of erectile dysfunction and compared the data with history, results of physical examination, other etiological investigations and effects of endocrine therapy to refine the rules of cost-effective endocrine screening and to pinpoint actual responsibility for hormonal abnormalities.

MATERIALS AND METHODS

Testosterone and prolactin were determined by radioimmunoassay. Every patient was screened for testosterone and 451 were screened for prolactin on the basis of low sexual desire, gynecomastia or testosterone less than 4 ng./ml. Determination was repeated in case of abnormal first results. Prolactin results were compared with those of a previous personal cohort of 1,340 patients with erectile dysfunction and systematic prolactin determination. Main clinical criteria tested regarding efficiency in hormone determination were low sexual desire, small testes and gynecomastia. Endocrine therapy consisted of testosterone heptylate or human chorionic gonadotropin for hypogonadism and bromocriptine for hyperprolactinemia.

RESULTS

Testosterone was less than 3 ng./ml. in 107 patients but normal in 40% at repeat determination. The prevalence of repeatedly low testosterone increased with age (4% before age 50 years and 9% 50 years or older). Two pituitary tumors were discovered after testosterone determination. Most of the other low testosterone levels seemed to result from nonorganic hypothalamic dysfunction because of normal serum luteinizing hormone and prolactin and to have only a small role in erectile dysfunction (definite improvement in only 16 of 44 [36%] after androgen therapy, normal morning or nocturnal erections in 30% and definite vasculogenic contributions in 42%). Determining testosterone only in cases of low sexual desire or abnormal physical examination would have missed 40% of the cases with low testosterone, including 37% of those subsequently improved by androgen therapy. Prolactin exceeded 20 ng./ml. in 5 men and was normal in 2 at repeat determination. Only 1 prolactinoma was discovered. These data are lower than those we found during the last 2 decades (overall prolactin greater than 20 ng./ml. in 1.86% of 1,821 patients, prolactinomas in 7, 0.38%). Bromocriptine was definitely effective in cases with prolactin greater than 35 ng./ml. (8 of 12 compared to only 9 of 22 cases with prolactin between 20 and 35 ng./ml.). Testosterone was low in less than 50% of cases with prolactin greater than 35 ng./ml.

CONCLUSIONS

Low prevalences and effects of low testosterone and high prolactin in erectile dysfunction cannot justify their routine determination. However, cost-effective screening strategies recommended so far missed 40 to 50% of cases improved with endocrine therapy and the pituitary tumors. We now advocate that before age 50 years testosterone be determined only in cases of low sexual desire and abnormal physical examination but that it be measured in all men older than 50 years. Prolactin should be determined only in cases of low sexual desire, gynecomastia and/or testosterone less than 4 ng./ml.

A prolactin-secreting tumor in a patient with Klinefelter's syndrome: a case report

We report the case of a patient with Klinefelter's syndrome who developed a prolactin (PRL)-secreting tumor. The patient developed headaches, visual alterations and also symptoms of hypogonadism despite appropriate testosterone (T) replacement therapy. The diagnosis of hyperprolactinemia was then suspected. The laboratory findings confirmed the hypothesis, showing high levels of serum PRL. The patient was initially treated with oral bromocriptine, and afterwards with the injectable form. There was a marked decrease in PRL levels and in tumor size. Although some neoplasms, like breast carcinoma and germ cell tumors, are known to occur more frequently in patients with Klinefelter's syndrome, an association with PRL-secreting tumor has not been reported yet. In conclusion, symptoms of hypogonadism in patients with Klinefelter's syndrome receiving appropriate T replacement therapy can suggest the presence of hyperprolactinemia.

Prolactin and testosterone: their role in male sexual function

The role of androgens in the sexuality of men is still not completely clear. Men with severe hyperprolactinaemia frequently show mild hypogonadism, and many complain of loss of libido and penile erectile dysfunction (ED). We studied the night-sleep related erections and the penile response to visual erotic stimuli (VES) in 44 men: 13 with severe hypogonadism (Group 1; serum testosterone < 1.4 ng/ml), 10 with mild hypogonadism (Group 2; serum testosterone 2-3.5 ng/ml), nine with severe hyperprolactinaemia and mild hypogonadism (Group 3) and 12 control men (Group 4). All of the patients complained of loss of libido and ED. Group 1 showed significantly impaired night erections when compared with any of the other three groups, but no differences were detected between Groups 2, 3 and 4. The penile response to VES did not show any significant difference between the four groups, but was lower in Group 1 than in Group 4. These data confirm that night erections are androgen-dependent, but also suggest that there are two thresholds for serum testosterone: one below which sexual behaviour is impaired with normal night erections, and a lower threshold below which night erections are also impaired. The penile response to VES was confirmed as being only partially androgen-independent. Furthermore, hyperprolactinaemia does not affect night erections or the penile response to VES, suggesting that its effect on libido and sexual behaviour is due mainly to modulation of the psychological pattern of the patient.

Routine prolactin measurement is not necessary in the initial evaluation of male impotence

The authors determined the prevalence of hyperprolactinemia in impotent men in a community setting and assessed the cost of case detection with routine estimation of serum prolactin. They recruited 299 consecutive patients with impotence and determined the hormonal levels (prolactin, luteinizing hormone, follicle-stimulating hormone, and testosterone). Pituitary gland imaging was done when the prolactin level was elevated. Simultaneous prolactin and testosterone levels were available for 212 patients. Three patients (1.4%) had elevated prolactin levels but none had pituitary tumor. Two of these had low testosterone levels. Overall, 51 patients (24.1%) had low testosterone levels. Cost of selective prolactin estimation in patients with low testosterone levels resulted in a net saving of $2,574 per case detected. The authors conclude that the prevalence of hyperprolactinemia in impotence is low. Routine measurement of prolactin levels in impotence is not indicated. Selective determination in patients with low testosterone reduces the cost of diagnostic evaluation.

Effects of ovarian surgery on the dopaminergic and opioidergic control of gonadotropin and prolactin secretion in women with polycystic ovarian disease

Ovarian surgery has been demonstrated as an effective means to establish regular menstrual cycles and resumption of ovulation in patients with polycystic ovarian disease (PCO). We questioned whether such reinstitution of menstrual cyclicity may be associated with changes in the opioidergic and dopaminergic activity known to be aberrant in these women. Opioidergic and dopaminergic tone was therefore assessed in patients with PCO before and after ovarian laser vaporization (n = 4) or classical ovarian wedge resection (n = 4). Blood samples for the determination of luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin were frequently obtained following opioidergic and/or dopaminergic antagonism affected by naloxone (4 mg i.v.) or metoclopramide (10 mg i.v.). In response to either surgical approach, circulating LH levels decreased (p < 0.01), while FSH concentrations remained unaltered. Further, LH and FSH concentrations did not noticeably change following challenges with naloxone or metoclopramide: this applied to conditions before and after ovarian surgery. Prolactin release in response to metoclopramide was markedly (p < 0.01) higher following ovarian surgery than before. Thus, both ovarian laser surgery and classical wedge resection can effectively restore normal menstrual cyclicity in PCO patients, although they failed to alter opioidergic and dopaminergic activity. Dopaminergic inhibition of prolactin secretion was further enhanced after ovarian surgery. These observations suggest that different modes of ovarian surgery are effective in influencing central gonadal control, but that the central opioidergic and dopaminergic control of gonadotropin and prolactin secretion remains unaffected by ovarian surgery in PCO women, even when menstrual cyclicity is resumed.

Role of serum prolactin determination in evaluation of impotent patient

Hyperprolactinemia is a recognized cause of impotence. The discovery of elevated prolactin levels in impotent men is very important since pharmacotherapy in this instance is highly successful. We review our experience with prolactin determinations in impotent men, and a population is defined that may benefit from routine prolactin determination. In our experience, the predominant symptom associated with hyperprolactinemia in men is loss of libido.

Neuroleptic binding to human brain receptors: relation to clinical effects

Table 2 summarizes the potential clinical consequences of neurotransmitter receptor blockade by neuroleptics. These pharmacological effects of neuroleptics at receptors in brain and elsewhere in the body are likely responsible for therapeutic and certain adverse effects as well as some drug-drug interactions. Data presented here should allow the physician a rational basis for selecting neuroleptics to minimize these unwanted effects in patients.

Prolactin secretion in polycystic ovary syndrome: circadian rhythmicity and dynamic aspects

The circadian rhythms of plasma prolactin (PRL) and cortisol and of oral temperature were simultaneously studied in 24 women with polycystic ovary syndrome (PCOS). The PRL response to thyrotropin-releasing hormone (TRH) and domperidone was also evaluated in some of these patients. The physiological circadian chrono-organization of prolactin and cortisol secretion and of oral temperature was maintained in PCOS. The PRL responsiveness to the specific stimulations fell within normal limits. These results do not support the hypothesis of an impaired central dopaminergic regulation of prolactin secretion in PCOS.

Erectile failure in the aged: evaluation and treatment

With aging, there are changes in both libido and erectile function. Although the majority of aged men remain interested in sex, less than 15% report continued sexual intercourse. The cause of this "libido-potency gap" is due primarily to erectile failure. Penile erection is dependent upon a complex interaction of the autonomic nervous system, cardiovascular system, and local neurotransmitters such as acetylcholine and vasoactive intestinal polypeptide. Sexual stimulation causes augmented blood flow into the corpora cavernosa, and restricted outflow, resulting in penile rigidity. With aging, there is a decline in gonadal steroids, nerve conduction velocity, and vascular compliance, any of which could interfere with normal erections. When disease is superimposed on the normal changes of aging, erectile function is further impaired. Evaluation of an elderly male with impotence may consist of a detailed drug history and trial of alternate therapy, as in the case of adverse drug reactions. More often, evaluation entails hormonal assays, penile vascular assessment, neurologic assessment, and an evaluation of nocturnal erectile function. Based on the results of these assessments, appropriate treatment alternatives can be chosen. With the availability of multiple treatment options, patients and physicians can now choose from a range of noninvasive or invasive alternatives depending upon the etiology, associated disorders, and preference of the patient.

The anatomy of erection

Erection is due to a neurovascular mechanism: an inflow of arterial blood and an obstruction of venous return. The direction of this mechanism is of neurologic origin: (1) control of the smooth muscle tissue of the corpora cavernosa by the autonomic system controlled by reflex centers in the cord or cortical centers accessible to multiple (visual) stimuli (2) control of the perineal muscles by the somatic system. Tumescence is due to a reduction in the alpha-sympathetic tonus of the cavernous tissue permitting influx of arterial blood, and to decreased venous flow from compression of the subalbugineal venous network against the tunica albuginea of the corpus cavernosum. Once this obstruction to the venous return has been achieved, the arterial flow in the corpora cavernosa decreases but persists; the arterial blood in the corpora cavernosa is renewed and not shut off. Rigidity is due to an increase in intracavernous arterial pressure simultaneous with contraction of the perineal muscles (ischiocavernosus) under the somatic control of the pudendal nerve.