Experimental models for the investigation of female sexual function and dysfunction

Changes of Apomorphine-Induced Vaginal Hemodynamics in an Ovariectomized Rat Model Using Near-Infrared Spectroscopic Probe

INTRODUCTION

Female sexual arousal disorder (FSAD) can be caused by the change in vaginal structure due to the decline of estrogen and one of the main symptoms is vaginal dryness. FSAD is a prevalent problem afflicting women all over the world and thus the interest is growing on the matter, but related studies of monitoring FSAD using a non-invasive optical method barely have been carried out.

AIM

This study aims to investigate the longitudinal changes in female sexual arousal response induced by apomorphine (APO) administration in the ovariectomized rat using near-infrared spectroscopy (NIRS) probe.

METHODS

To elicit sexual arousal, APO was administered subcutaneously to animals (n = 6) before and after ovariectomy, and the changes in oxyhemoglobin (OHb), deoxyhemoglobin (RHb), total hemoglobin (THb) concentration, and temperature on the vaginal wall after APO administration were monitored bi-weekly for 8 weeks. Furthermore, estradiol hormone, vaginal secretion, and body weight have been measured for comparison with the results from vaginal hemodynamics.

RESULTS

APO administration caused the increase of vaginal OHb and RHb concentration but a decrease in temperature. The amplitude of OHb, RHb, and THb increase induced by APO gradually decreased over 8 weeks after ovariectomy while the decrease in vaginal temperature became profound. The level of estradiol and vaginal secretions also decreased over 8 weeks after ovariectomy, but bodyweight showed an increasing trend.

CONCLUSIONS

A comparison between the parameters measured from the NIRS probe and the others (estradiol level, amount of vaginal secretion, and body weight) proved that the NIRS has the potential as a monitoring tool to evaluate female sexual arousal response. Jeong H, Lee HS, Seong M, et al. Changes of Apomorphine-Induced Vaginal Hemodynamics in an Ovariectomized Rat Model Using Near-Infrared Spectroscopic Probe. J Sex Med 2021;18:1328-1336.

Sexual dysfunction and central obesity in patients with first episode psychosis

Background

In recent years the association between sexual dysfunction (SD) and obesity in the general population has drawn major attention. Although sexual dysfunction is common in psychosis, its relationship with weight gain and obesity remains unclear.

Aims

To investigate the association between sexual dysfunction and obesity in a cohort of patients with first episode psychosis.

Method

Sexual function was assessed in a cohort of patients with first episode psychosis using the Sexual Function Questionnaire (SFQ). Anthropometric measures, including weight, BMI, waist, waist–hip ratio were investigated. Additionally, leptin and testosterone were investigated in male patients.

Results

A total of 116 patients (61 males and 55 females) were included. Of these 59% of males and 67.3% of females showed sexual dysfunction (SD) according to the SFQ. In males, higher SFQ scores were significantly correlated with higher BMI (Std. β = 0.36, P = 0.01), higher leptin levels (Std. β = 0.34, P = 0.02), higher waist–hip ratio (Std. β = 0.32, P = 0.04) and lower testosterone levels (Std. β = −0.44, P = 0.002). In contrast, in females, SFQ scores were not associated with any of these factors.

Conclusions

While sexual dysfunction is present in both female and male patients with their first episode of psychosis, only in males is sexual dysfunction associated with increased BMI and waist–hip ratio. The association between SD, BMI, low levels of testosterone and high levels of leptin suggest that policies that lead to healthier diets and more active lifestyles can be beneficial at least, to male patients.

[Sexual disorders in the renal patient]

Quality of Life Related to Health is currently considered one of the primary therapeutic objectives in renal failure patients who need substitution treatment as life prolonging therapy. Sexual health is a basic right that positively affects the quality of life. Although a significant percentage of chronic patients have some type of sexual dysfunction, this is not openly discussed, making it important for doctors to address these issues in the clinic. A review is presented on the pathophysiology of sexual dysfunctions in both male and female chronic renal patients. The effects of dialysis and transplantation on sexual function will be addressed, as well as presenting the main sexual dysfunctions and their treatment.

[Physiology and physiopathology of sexuality]

From desire to orgasm, sexuality, in women and men, is underpinned by a complex organic, psychological and emotional function. Sexual dysfunction encompasses diverse aetiologies, including chronic diseases and iatrogenesis resulting from medication or surgery. The effects of a chronic disease can have an impact on all phases of the sexual response.

Effect of estrogen on molecular and functional characteristics of the rodent vaginal muscularis

INTRODUCTION

Vaginal atrophy is a consequence of menopause; however, little is known concerning the effect of a decrease in systemic estrogen on vaginal smooth muscle structure and function. As the incidence of pelvic floor disorders increases with age, it is important to determine if estrogen regulates the molecular composition and contractility of the vaginal muscularis.

AIM

The goal of this study was to determine the effect of estrogen on molecular and functional characteristics of the vaginal muscularis utilizing a rodent model of surgical menopause.

METHODS

Three- to 4-month old Sprague-Dawley rats underwent sham laparotomy (Sham, N = 18) or ovariectomy (Ovx, N = 39). Two weeks following surgery, animals received a subcutaneous osmotic pump containing vehicle (Sham, Ovx) or 17β-estradiol (Ovx). Animals were euthanized 1 week later, and the proximal vagina was collected for analysis of contractile protein expression and in vitro studies of contractility. Measurements were analyzed using a one-way analysis of variance followed by Tukey's post hoc analysis (α = 0.05).

MAIN OUTCOME MEASURES

Protein and mRNA transcript expression levels of contractile proteins, in vitro measurements of vaginal contractility.

RESULTS

Ovariectomy decreased the expression of carboxyl-terminal myosin heavy chain isoform (SM1) and h-caldesmon and reduced the amplitude of contraction of the vaginal muscularis in response to KCl. Estradiol replacement reversed these changes. No differences were detected in the % vaginal muscularis, mRNA transcript expression of amino-terminal MHC isoforms, l-caldesmon expression, and maximal velocity of shortening.

CONCLUSION

Systemic estrogen replacement restores functional and molecular characteristics of the vaginal muscularis of ovariectomized rats. Our results indicate that menopause is associated with changes in the vaginal muscularis, which may contribute to the increased incidence of pelvic floor disorders with age.

Inhibition of phosphodiesterase 4 enhances clitoral and vaginal blood flow responses to dorsal clitoral nerve stimulation or PGE1 in anesthetized female rats

INTRODUCTION.: Cyclic adenosine 3'5' monophosphate (cAMP) is produced by adenylate cyclase after activation by, e.g., vasoactive intestinal polypeptide or prostaglandin E1 (PGE1). The cAMP-degrading phosphodiesterase 4 (PDE4) is expressed in the vagina and clitoris, but no information is available on the functional role for PDE4-related signals in the female neurovascular genital response. AIM.: The aim of this study is to study the effect of inhibition of PDE4 with rolipram on nerve- and PGE1-induced vaginal and clitoral blood flow responses of rat. METHODS.: Measure of clitoral and vaginal blood flow and blood pressure in anesthetized rats during activation of the dorsal clitoral nerve (DCN) before and after intraperitoneal administration of rolipram or sildenafil (phosphodiesterase type 5 inhibitors [PDE5]) and nitro-L-arginine (L-NNA) (nitric oxide synthase inhibitor). Effect by topical administration of PGE1 on genital blood flow was also evaluated. MAIN OUTCOME MEASURE.: Blood flow was recorded as tissue perfusion units (TPU) by a Laser Doppler Flowmeter. Mean arterial blood pressure (MAP) was recorded (cmH2 O) in the carotid artery. Blood flow responses are expressed as TPU/MAP. Unpaired t-test and an analysis of variance were used. RESULTS.: Compared with control stimulations, rolipram (0.3 mg/kg) caused a twofold increase in peak blood flow (P < 0.05) and fourfold increase of the rate of clitoral blood flow during activation of the DCN (P < 0.05). Simultaneously, a twofold increase in peak blood flow and threefold increase in rate of blood flow were noted in the vagina (P < 0.05). Similar effects were noted for sildenafil (0.2 mg/kg) (P < 0.05). Inhibitory effects by L-NNA (60 mg/kg) on blood flow responses to DCN activation were significantly lower for rats treated with rolipram than with sildenafil (P < 0.05). PGE1-induced (10 μg) blood flow responses were significantly higher (P < 0.05) in rats treated with rolipram than with sildenafil. CONCLUSIONS.: These findings suggest that the cAMP/PDE4 system may be of similar functional importance as the nitric oxide/cyclic guanosine monophosphate/PDE5 pathway for neurovascular genital responses of the female rat.

Endothelin-1 induces contraction of female rat internal pudendal and clitoral arteries through ET(A) receptor and rho-kinase activation

INTRODUCTION

Endothelin-1 (ET-1), a potent vasoconstrictor peptide, acts mainly through the Gprotein-coupled ET(A) receptor (ET(A)R). Increased vascular ET-1 production and constrictor sensitivity have been observed in various cardiovascular diseases, including hypertension, as well as erectile dysfunction. The internal pudendal artery (IPA) supplies blood to the vagina and clitoris. Inadequate blood flow through the IPA may lead to insufficient vaginal engorgement and clitoral tumescence.

AIM

Characterize the effects of ET-1 on the IPA and clitoral artery (CA).

METHODS

IPA and CA from female Sprague Dawley rats (225-250 g) were mounted in myograph chambers. Arterial segments were submitted to increasing concentrations of ET-1 (10-10-10-6 M). Segments were incubated with the ET(A)R antagonist, atrasentan (10-8 M) or the Rho-kinase inhibitor, Y-27632 (10-6 M) 30 minutes prior to agonist exposure. All E(max) values are expressed as % KCl-induced maximal contraction. ET(A)R, RhoA, and Rho-kinase expression from IPA was evaluated by Western blot. mRNA of preproET-1, ET(A)R, ET(B)R, RhoA, and Rho-kinase were measured by real time PCR.

MAIN OUTCOME MEASURES

ET-1 constrictor sensitivity in IPA and CA, protein expression and messenger RNA levels of ET-1-mediated constriction components.

RESULTS

ET-1 concentration-dependently contracted IPA (% Contraction and pD2, respectively: 156 ± 18, 8.2 ± 0.1) and CA (163 ± 12, 8.8 ± 0.08), while ET(A)R antagonism reduced ET-1-mediated contraction (IPA: 104 ± 23, 6.4 ± 0.2; CA: 112 ± 17, 6.6 ± 0.08). Pretreatment with Y-27632 significantly shifted ET-1 pD2 in IPA (108 ± 24, 7.9 ± 0.1) and CA (147 ± 58 and 8.0 ± 0.25). Protein expression of ET(A)R, ET(B)R, RhoA, and Rho-kinase were detected in IPA. IPA and CA contained preproET-1, ET(A)R, ET(B)R, RhoA, and Rho-kinase message.

CONCLUSION

We observed that the IPA and CA are sensitive to ET-1, signaling through the ET(A)R and Rho-kinase pathway. These data indicate that ET-1 may play a role in vaginal and clitoral blood flow and may be important in pathologies where ET-1 levels are elevated.

Effects of ACE inhibition and beta-blockade on female genital structures in spontaneously hypertensive rats

INTRODUCTION AND AIM

This study evaluated the possible differences between an angiotensin converting enzyme (ACE) inhibitor and a beta-blocker concerning their potential protective role on female external genitalia in spontaneously hypertensive rats (SHR).

MAIN OUTCOME MEASURES

Morphological changes in the clitoris after antihypertensive treatments.

METHODS

For 6 months, SHR received no treatment; SHR + ramipril (RAM), SHR + atenolol (AT), and control Wistar Kyoto (WKY) rats received no treatment. Clitorises were processed for immunohistochemistry using anti-alpha-smooth muscle actin (alpha-SMA), anti-collagen I and III, anti-transforming growth factor beta(1) (TGFbeta(1)), and anti-endothelial nitric oxide synthase (eNOS) antibodies.

RESULTS

SHR + RAM and SHR + AT presented significantly lower blood pressure in both groups vs. untreated SHR. Compared with WKY, alpha-SMA was increased in the arteries and in the cavernous spaces of the clitoris together with a marked increase in wall/lumen ratio in clitoral vessels in untreated SHR. All these alterations were diminished in SHR + AT (P < 0.01). SHR + RAM presented differences with respect to SHR + AT in the reduction of these variables. TGFbeta(1) expression in the vessel wall from the clitoris and collagen I and III deposition in the interstitium from the clitoris in untreated SHR were significantly more (P < 0.01) than in WKY. While SHR + AT showed a mild decrease in these variables, SHR + RAM presented a significant reduction (P < 0.01) in TGFbeta(1) expression interstitial fibrosis and in both types of collagens. Positive immunostaining of eNOS in the sinusoidal endothelium from the clitoris was less (P < 0.01) in untreated SHR (3.4 +/- 1.3%) and SHR + AT (5.1 +/- 1.2%) than in SHR + RAM (17.2 +/- 1.6%) and WKY (15.9 +/- 1.7%). Untreated SHR and SHR + AT presented more surrounding connective tissue at the perineurium in the clitoris (P < 0.01) than SHR + RAM.

CONCLUSION

ACE inhibition provided a considerable protective role on the female external genitalia structures in SHR by a mechanism that may be, at least in part, independent of the degree of blood pressure lowering.

Changes in clitoral blood flow in premenopausal women affected by type 1 diabetes after single 100-mg administration of sildenafil

OBJECTIVES

To verify whether sildenafil is effective in modifying clitoral blood flow in premenopausal women affected by type 1 diabetes.

METHODS

The setting was a diabetes outpatient clinic in which 30 premenopausal women affected by type 1 diabetes treated with insulin therapy and 39 healthy premenopausal women participated in our prospective open-label clinical study. Each diabetic woman received a single oral dose of 100 mg sildenafil. Translabial color Doppler ultrasonography was used to measure the resistance index, pulsatility index, peak systolic velocity, and end-diastolic velocity of the clitoral arteries 1 and 4 hours after sildenafil intake.

RESULTS

One hour after the administration of sildenafil, the mean resistance index was significantly lower and the mean pulsatility index, mean peak systolic velocity, and mean end-diastolic velocity of the clitoral arteries were significantly greater compared with baseline and 4 hours after sildenafil (P <0.05). The baseline clitoral blood flow of the diabetic women was lower compared with that of the control group (P <0.001).

CONCLUSIONS

Sildenafil seems to improve the clitoral blood flow of premenopausal women with type 1 diabetes.

Sildenafil improves sexual functioning in premenopausal women with type 1 diabetes who are affected by sexual arousal disorder: a double-blind, crossover, placebo-controlled pilot study

OBJECTIVE

To verify whether sildenafil is effective in type 1 premenopausal women affected by sexual arousal disorder (SAD).

DESIGN

Double-blind, crossover, placebo-controlled study.

SETTING

Gynecological diabetic outpatient clinic and sexual clinic.

PATIENT(S)

Thirty-six type 1 premenopausal diabetic women affected by SAD.

INTERVENTION(S)

Two 8-week periods of sildenafil 100 mg, washout, and placebo, by two possible sequences.

MAIN OUTCOMES MEASURE(S)

Each woman submitted blood samples to measure HbA(1c), and T, free T (FT), and PRL. Efficacy was assessed [1] subjectively by the Personal Experiences Questionnaire based on the 5-point Likert scale, quantifying arousal, desire, orgasm, enjoyment of sexual activities, and frequency of sexual relationships; and [2] objectively by translabial color Doppler ultrasound to measure the resistance index (RI), pulsatility index (PI), peak systolic velocity (PSV), and end diastolic velocity of clitoral arteries.

RESULT(S)

Thirty-two women completed the study. The mean HbA(1c) value was 8.0% +/- 1.8%, and plasma concentrations of T, FT, and PRL were normal. Sildenafil seems to improve arousal, orgasm and sexual enjoyment, and dyspareunia in women affected by type 1 diabetes. However, by flowmetric measurements, the mean RI was significantly lower and both the mean PI and PSV of the clitoral arteries were significantly higher compared with baseline and placebo.

CONCLUSION(S)

Sildenafil seems to improve subjective sexual aspects and can be used to treat objectively genital arousal disorder of premenopausal women with type 1 diabetes.

Physiology of female sexual function: animal models

INTRODUCTION

Data concerning the physiology of desire, arousal, and orgasm in women are limited because of ethical constraints. Aim. To gain knowledge of physiology of female sexual function through animal models.

METHODS

To provide state-of-the-art knowledge concerning female sexual function in animal models, representing the opinions of seven experts from five countries developed in a consensus process over a 2-year period.

MAIN OUTCOME MEASURE

Expert opinion was based on the grading of evidence-based medical literature, widespread internal committee discussion, public presentation, and debate.

RESULTS

Sexual desire may be considered as the presence of desire for, and fantasy about, sexual activity. Desire in animals can be inferred from certain appetitive behaviors that occur during copulation and from certain unconditioned copulatory measures. Proceptive behaviors are dependent in part on estrogen, progesterone, and drugs that bind to D1 dopamine receptors, adrenergic receptors, oxytocin receptors, opioid receptors, or gamma-amino butyric acid receptors. Peripheral arousal states are dependent on regulation of genital smooth muscle tone. Multiple neurotransmitters/mediators are involved including adrenergic, and nonadrenergic, noncholinergic agents such as vasoactive intestinal polypeptide, nitric oxide, neuropeptide Y, calcitonin gene-related peptide, and substance P. Sex steroid hormones, estrogens and androgens, are critical for structure and function of genital tissues including modulation of genital blood flow, lubrication, neurotransmitter function, smooth muscle contractility, mucification, and sex steroid receptor expression in genital tissues. Orgasm may be investigated by urethrogenital (UG) reflex, in which genital stimulation results in rhythmic contractions of striated perineal muscles and contractions of vagina, anus, and uterine smooth muscle. The UG reflex is generated by a multisegmental spinal pattern generator involving the coordination of sympathetic, parasympathetic, and somatic efferents innervating the genital organs. Serotonin and dopamine may modulate UG reflex activity.

CONCLUSIONS

More research is needed in animal models in the physiology of female sexual function.

Progress in Female Sexual Dysfunction

INTRODUCTION

Female sexual dysfunction (FSD) is a significant age-related, progressive and highly prevalent problem that affects a substantial number of women that causes personal distress and has negative effects on quality of life and interpersonal relationships.

DEFINITIONS

The female sexual response cycle consists of three phases: desire, arousal, and orgasm, and is initiated by non-adrenergic/non-cholinergic, e.g. vasoactive intestinal polypeptide and nitric oxide, neurotransmitters that maintain vascular and non-vascular smooth muscle relaxation resulting in increased pelvic blood flow, vaginal lubrication, and clitoral and labial engorgement. Furthermore, hormonal status may influence female sexual function. For the diagnosis of FSD, a detailed history should be taken initially, followed by a physical examination and laboratory studies.

CONCLUSION

Due to the fact that there has been little research and attention on FSD, our knowledge in this field is quite limited and there is still no approved therapy. Future advances in evaluation and treatment of female sexual problems are forthcoming.

In vitro functional responses of isolated human vaginal tissue to selective phosphodiesterase inhibitors

Only little is known as to the significance of the cyclic nucleotide-mediated signal transduction in the control of the function of human vaginal smooth musculature. Recently, the presence of the phosphodiesterase (PDE) isoenzymes 4 (cAMP-PDE) and 5 (cGMP-PDE) in the human vagina was reported. Thus, it was the aim of the study to elucidate the effects of some PDE inhibitors on the tension induced by endothelin 1 (ET-1), as well as on levels of cGMP and cAMP in isolated human vaginal wall tissue. Using the organ bath technique, the ability of norepinephrine (NE), carbachol, serotonin (5-HT), oxytocin and ET-1 to contract isolated vaginal wall muscle strips was evaluated. In another set-up, the effects of the PDE4 inhibitor rolipram and PDE5 inhibitors sildenafil and vardenafil (1 nM-10 microM) on the tension induced by 0.1 microM ET-1 of human vaginal wall tissue strips were investigated. In order to measure drug effects on tissue levels of cGMP and cAMP, vaginal tissue was exposed to different concentrations (0.1, 1 and 10 microM) of the compounds and the accumulation of cyclic nucleotides was determined. The adenylyl cyclase stimulating agents forskolin and nitric oxide donor sodium nitroprusside (SNP) (0.01, 0.1 and 1 microM) were used as reference compounds. While NE, carbachol and oxytocin failed to contract the vaginal tissue, ET-1 and, to a certain degree, 5-HT elicited contractile responses of the isolated strip preparations. The tension induced by 0.1 microM ET-1 was dose-dependently reversed by the drugs. The rank order of efficacy was sildenafil > forskolin > rolipram >or= vardenafil > SNP. Rmax values ranged from 24% (SNP) to 50% (sildenafil). With sildenafil being the only exception, none of the compounds reached an EC50 value. The relaxing effects of the drugs were paralleled by a fourfold to tenfold increase in tissue levels of cGMP and/or cAMP. Our results demonstrate that PDE inhibitors can relax human vaginal tissue and increase levels of cyclic nucleoside monophosphates. The findings with regard to the PDE5 inhibitors may indicate that the NO-cGMP pathway is, to a certain degree, involved in the control of vaginal smooth muscle tone. This might be of significance with regard to the pharmacological treatment of disorders connected with female sexual arousal and the ability to achieve orgasm.

Role of arginase in the male and female sexual arousal response

The NO-cGMP pathway plays a key role in the male and female genital sexual arousal response. Nitric oxide synthase (NOS) utilizes L-arginine and oxygen as substrates to produce nitric oxide (NO) and citrulline. Arginase is a metalloenzyme that catalyzes the hydrolysis of L-arginine to produce L-ornithine and urea. It is proposed that arginase competes for L-arginine and reduces NOS activity in genital tissues, thus modulating sexual function. Using 2 transition state analogue inhibitors of arginase, 2(S)-Amino-6-boronohexanoic acid (ABH) and S-(2-boronoethyl)-L-cysteine (BEC), we have characterized arginase activity in penile and vaginal tissue. Neither of these inhibitors has activity against NOS. Thus, ABH and BEC are useful compounds for examining the role of arginase in genital tissue physiology, without directly influencing NOS activity. We present data to suggest that arginase may regulate NO production by competing for endogenous pools of L-arginine. In this fashion, arginase is an indirect regulator of penile and vaginal blood flow and specific arginase inhibitors may improve genital blood flow during sexual arousal. As evidenced by the upregulation of arginase in specific disease states, its distribution in the vagina, and its modulation by sex steroid hormones, this enzyme may also participate in numerous other physiological and pathophysiological processes, such as tissue growth, fibrosis, and immune function.

A Double‐Blind Randomized Placebo Control Study Comparing the Objective and Subjective Changes in Female Sexual Response Using Sublingual Apomorphine

INTRODUCTION

Female sexual dysfunction and its therapeutic approach is a growing area.

AIM

We aimed to assess the subjective and objective changes of the female sexual response, in patients with orgasmic sexual dysfunction using 3 mg SL Apomorphine (APO).

METHODS

Twenty-four patients (mean age 32 years old, SD: 9.69) were included in a prospective randomized cross-over protocol. Sexual response was evaluated objectively (duplex ultrasound) and subjectively (self-reported questionnaire) following vibrator stimuli with the addition of 3 mg SL APO or placebo.

MAIN OUTCOME MEASURE

Sexual response objective (PSV, EDV, RI) and subjective (arousal and lubrication degree and orgasm achievement). Adverse events were also recorded.

RESULTS

Clitoral hemodynamical changes, particularly peak systolic velocity (PSV), were significantly higher with APO (P = 0.003), mean increase of PSV poststimulus was 72.50% with placebo (from 9.7 cm/second to 17.0 cm/second) and 139.14% with APO (from 9.7 cm/second to 21.4 cm/second). SUBJECTIVE CHANGES (AROUSAL AND LUBRICATION) WERE ALSO SIGNIFICATIVE WITH APO (P < 0.05).

CONCLUSION

According to our observations, APO seemed to produce more subjective and objective changes in the sexual arousal phase of women with orgasmic sexual dysfunction than placebo. Future research is needed to evaluate the place of this drug in the treatment of the female sexual dysfunction.

Topical administration of a novel nitric oxide donor, linear polyethylenimine-nitric oxide/nucleophile adduct (DS1), selectively increases vaginal blood flow in anesthetized rats

The aim of the present study was to test the effects of a topical administration of a novel nitric oxide donor, linear polyethylenimine-nitric oxide/nucleophile adduct (DS1), on vaginal blood flow and hemodynamics in rats. Laser Doppler flowmetry was used to measure blood flow changes following topical application of DS1 (0.3 or 1.5 mg in 0.15 ml saline) into the vagina of anesthetized Wistar rats. In vivo hemodynamic parameters were measured with Millar-tip-catheter placed in the left ventricle. DS1 (1.5 mg) increased vaginal blood flow by 191+/-24, 226+/-22 and 166+/-23% of the baseline value (at 5, 15 and 30 min, respectively, after application) without affecting systemic blood pressure, heart rate and cardiac function. The increased vaginal blood flow following DS1 application returned to baseline between 45 and 60 min. Thus, topical application of nitric oxide donors such as DS1 may be useful for the treatment of female sexual dysfunction that develops due to an impairment of local blood flow supply to the vaginal tissue.

The function of sildenafil on female sexual pathways: a double-blind, cross-over, placebo-controlled study

OBJECTIVES

To determine the changes, if any, on female sexual pathways using sildenafil (primary outcome), and to verify the safety of this drug (second outcome).

STUDY DESIGN

Following previous research on symptomatic women, we wanted to study the effects of sildenafil on asymptomatic women. We would like to make it clear from the outset that this study is part of an ongoing line of research and this drug, and others of its type, should be used under strict medical supervision only on symptomatic patients. A randomized double-blind cross-over, placebo-controlled study was conducted at the Family Planning Centre of the Group for Sexological Research, Department of Microbiological and Gynecological Science, School of Medicine, University of Catania, Italy. Sixty-eight healthy volunteer women aged 19-38 years, asymptomatic for sexual disorders, were enrolled. The study consisted of 4 weeks sildenafil, 2 weeks washout, and 4 weeks placebo, by two possible sequences: sildenafil 50 mg, washout, placebo; or placebo, washout, sildenafil 50 mg. Efficacy of sildenafil was assessed by the Personal Experiences Questionnaire (PEQ) based on the 5-point Likert scale. The questionnaire quantified subjective sexual aspects at baseline, during washout, after treatments, and at the follow-ups. Statistical analysis was done with the Wilcoxon's rank-sum test and Student's t-test.

RESULTS

50/68 women completed the study at the first follow-up, and 38 women reached the second follow-up. Six women withdrew because of adverse events. Sildenafil improved arousal (P<0.001), orgasm (P<0.05), and enjoyment (P<0.001) with respect to placebo. Significant differences were noted during sildenafil usage with respect to the baseline for arousal (P<0.01), orgasm (P<0.001), and sexual enjoyment (P<0.001). The adverse events were transient and mild or moderate.

CONCLUSIONS

Our study suggests that sildenafil acts on the different sexual pathways in healthy women, improving their sexual experience. This study could help to understand the physiologic and pathophysiologic aspects of female sexuality. In comparison with current psychosexual therapies, which are long-term, compliance would be improved with use of this drug. Additional studies are required to define the use of sildenafil in a clinical setting.

Morphological modifications in clitoris and vagina in spontaneously hypertensive rats

We evaluated possible morphological alteration in clitoris and vagina from spontaneous hypertensive rats (SHR) and normotensive WKY rats. Clitoris and vagina were processed by Masson's trichrome, anti-alpha-smooth-muscle actin, anticollagen type I (COL I) and type III (COL III), and anti-TGFbeta(1). SHR presented higher amount of clitoral cavernous smooth muscle (CSM), vascular smooth muscle; TGFbeta(1) in clitoral vessel wall; higher wall/lumen ratio in both vaginal and clitoral vessels; and remarkable interstitial fibrosis, expressed by a higher amount in interstitial COL I and III in both clitoris and vagina, compared to WKY rats. Nerve fibers from clitoral and vaginal tissue in SHR showed important fibrosis at perineurium. SHR showed positive correlation between systolic blood pressure (SBP) and clitoral CSM; SBP and fibrosis in clitoris; and SBP and COL I and III in clitoris, respectively. Similar findings were observed between SBP and COL I and III in vagina. In conclusion, SHR present morphologic changes in clitoral vessels as well as in clitoral cavernous space, which have a high positive correlation with the high blood pressure level. Moreover, the increase in extracellular matrix affects not only the clitoral and vaginal interstitium but also the nerve structures from both clitoris and vagina.