Hydrogen Gas: A Novel Type of Antioxidant in Modulating Sexual Organs Homeostasis

Sex is a science of cutting edge but bathed in mystery. Coitus or sexual intercourse, which is at the core of sexual activities, requires healthy and functioning vessels to supply the pelvic region, thus contributing to clitoris erection and vaginal lubrication in female and penile erection in male. It is well known that nitric oxide (NO) is the main gas mediator of penile and clitoris erection. In addition, the lightest and diffusible gas molecule hydrogen (H2) has been shown to improve erectile dysfunction (ED), testis injuries, sperm motility in male, preserve ovarian function, protect against uterine inflammation, preeclampsia, and breast cancer in female. Mechanistically, H2 has strong abilities to attenuate excessive oxidative stress by selectively reducing cytotoxic oxygen radicals, modulate immunity and inflammation, and inhibit injuries-induced cell death. Therefore, H2 is a novel bioactive gas molecule involved in modulating sexual organs homeostasis.

Androgen and estrogen receptor expression in the developing human penis and clitoris

To better understand how the human fetal penis and clitoris grows and remodels, we undertook an investigation to define active areas of cellular proliferation and programmed cell death spatially and temporally during development of human fetal external genitalia from the indifferent stage (8 weeks) to 18 weeks of gestation. Fifty normal human fetal penile and clitoral specimens were examined using macroscopic imaging, scanning electron microscopy and immunohistochemical localization for the cellular proliferation and apoptotic markers, Ki67 and Caspase-3. A number of hot spots of cellular proliferation characterized by Ki67 localization are present in the penis and clitoris especially early in development, most notably in the corporal body, glans, remodeling glanular urethra, the urethral plate, the roof of the urethral groove and the fully formed penile urethra. The 12-fold increase in penile length over 10 weeks of growth from 8 to 18 weeks of gestation based on Ki67 labelling appears to be driven by cellular proliferation in the corporal body and glans. Throughout all ages in both the developing penis and clitoris Ki67 labeling was consistently elevated in the ventral epidermis and ventral mesenchyme relative to the dorsal counterparts. This finding is consistent with the intense morphogenetic activity/remodeling in the ventral half of the genital tubercle in both sexes involving formation of the urethral/vestibular plates, canalization of the urethral/vestibular plates and fusion of the urethral folds to form the penile urethra. Areas of reduced or absent Ki67 staining include the urethral fold epithelium that fuses to form the penile tubular urethra. In contrast, the urethral fold mesenchyme is positive for Ki67. Apoptosis was rarely noted in the developing penis and clitoris; the only area of minimal Caspase-3 localization was in the epithelium of the ventral epithelial glanular channel remodeling.

Immunohistochemical expression analysis of the human fetal lower urogenital tract

We have studied the ontogeny of the developing human male and female urogenital tracts from 9 weeks (indifferent stage) to 16 weeks (advanced sex differentiation) of gestation by immunohistochemistry on mid-sagittal sections. Sixteen human fetal pelvises were serial sectioned in the sagittal plane and stained with antibodies to epithelial, muscle, nerve, proliferation and hormone receptor markers. Key findings are: (1) The corpus cavernosum in males and females extends into the glans penis and clitoris, respectively, during the ambisexual stage (9 weeks) and thus appears to be an androgen-independent event. (2) The entire human male (and female) urethra is endodermal in origin based on the presence of FOXA1, KRT 7, uroplakin, and the absence of KRT10 staining. The endoderm of the urethra interfaces with ectodermal epidermis at the site of the urethral meatus. (3) The surface epithelium of the verumontanum is endodermal in origin (FOXA1-positive) with a possible contribution of Pax2-positive epithelial cells implying additional input from the Wolffian duct epithelium. (4) Prostatic ducts arise from the endodermal (FOXA1-positive) urogenital sinus epithelium near the verumontanum. (5) Immunohistochemical staining of mid-sagittal and para-sagittal sections revealed the external anal sphincter, levator ani, bulbospongiosus muscle and the anatomic relationships between these developing skeletal muscles and organs of the male and female reproductive tracts. Future studies of normal human developmental anatomy will lay the foundation for understanding congenital anomalies of the lower urogenital tract.

Increased squalene concentrations in the clitoral gland during the estrous cycle in rats: an estrus-indicating scent mark?

Squalene in the rat clitoral gland is reported to be semi-volatile and may serve as a chemo-signal. The objective was to determine squalene concentrations in the clitoral gland throughout the reproductive cycle. Clitoral glands were extracted with dichloromethane; 23 compounds were identified with Gas Chromatography linked Mass Spectrometry (GC-MS). Since squalene concentrations were significantly higher during proestrus and estrus, and remarkably reduced during metestrus and diestrus, we inferred that it could be an ovulation-indicating chemosignal in the female rat, acting as a scent mark for the male. This hypothesis was tested by investigating its efficacy to attract males, including studying the role of the olfactory-vomeronasal system of the male in perceiving squalene. For detection of squalene, males used their conventional olfactory system when at a distance from the female, whereas the vomeronasal organ was used when they were in close proximity to the female. We concluded that squalene was a female-specific chemosignal that attracted males, and furthermore, that the olfactory-vomeronasal system had an important role in the perception of squalene.

Expression of messenger ribonucleic acid encoding for phosphodiesterase isoenzymes in human female genital tissues

OBJECTIVES

The use of inhibitors of phosphodiesterase 5 (PDE5) has been suggested to treat symptoms of female sexual dysfunction (FSD). Nonetheless, there has been a relatively low success rate of PDE5 inhibitors in FSD in comparison with male erectile dysfunction. The elevated expression of PDE5 in the human penile erectile tissue is considered the reason for the high clinical efficacy of PDE5 inhibitors in the pharmacotherapy of male erectile dysfunction.

AIM

To evaluate by means of molecular biology the expression of messenger ribonucleic acid expression (mRNA) encoding for cyclic AMP and cyclic GMP PDE isoenzymes in female genital tissues.

MAIN OUTCOME MEASURES

The amount of mRNA transcripts specifically encoding for cyclic AMP- and/or cyclic GMP-degrading PDE isoenzymes was determined.

METHODS

Human clitoral, labial, and vaginal tissue was obtained from four female cadavers (age at death: 18-42 years). The expression of mRNA specifically encoding for PDE1A, 1B, 1C, 2A, 4A, 5A, 10A, and 11A was elucidated by means of real-time polymerase chain reaction (PCR) analysis (TaqMan). Human penile erectile tissue (corpus cavernosum [HCC]) was used as a reference tissue.

RESULTS

mRNA encoding for all PDE isoforms mentioned above is expressed in the female genital tissues. Different magnitudes of mRNA expression were observed: a predominant expression of mRNA encoding for PDE1A but only insignificant amounts of PDE1B, 1C, 4A, 10, and 11A mRNA were registered. With PDE1A being the only exception, the mRNA expression was always higher in the HCC than in the female genital tissues. Especially, the expression of mRNA encoding for PDE5 was several-fold higher in the HCC.

CONCLUSION

On the mRNA level, various PDE isoforms are expressed in the clitoris, labia, and vagina. It remains to be established as to whether the low expression of PDE5 in female genital tissue might be a negative predictor for the success of PDE5 inhibitors in the treatment of FSD.

Expression of cAMP and cGMP-phosphodiesterase isoenzymes 3, 4, and 5 in the human clitoris: immunohistochemical and molecular biology study

OBJECTIVES

Only a little research has focused on the evaluation of female sexual function. With sexual stimulation, the clitoris becomes engorged with blood and tumescent. Nevertheless, only little is known about the significance of the cyclic nucleotide-mediated signal transduction in the control of this process. We sought to elucidate the presence of the phosphodiesterase (PDE) isoenzymes 3, 4, and 5 in the human clitoris using immunohistochemical and molecular biology methods.

METHODS

Thin sections of clitoral specimens were incubated with primary antibodies directed against PDE isoenzymes 3, 4, and 5. Next, the sections were incubated with either Texas red or fluorescein isothiocyanate-labeled secondary antibodies, and visualization was done using laser microscopy. The expression of mRNA encoding for various PDE isoenzymes was evaluated using reverse transcriptase polymerase chain reaction.

RESULTS

Immunofluorescence indicating the presence of PDE4 (cyclic adenosine monophosphate-PDE) was observed in the nonvascular smooth musculature of the corpus cavernosum clitoris, sinusoidal endothelial and subendothelial layers, and nerve fibers innervating the tissue. Immunoreactivity specific for PDE5 (cyclic guanosine monophosphate-PDE) was limited to the smooth muscle of the clitoral erectile tissue. The fluorescein isothiocyanate reaction indicating the expression of PDE3 (cyclic adenosine monophosphate-PDE) was registered to a certain degree only in the clitoral epidermis. In the reverse transcriptase polymerase chain reaction studies, a predominant expression of mRNA encoding for PDE1A was registered, but only small amounts of mRNA encoding for PDE4 and PDE5 were detected.

CONCLUSIONS

Our results have demonstrated the presence of cyclic adenosine monophosphate-PDE and cyclic guanosine monophosphate-PDE in the human clitoris and may indicate a regulatory function of these enzymes in the cyclic nucleotide-mediated control of smooth muscle tone.

ANATOMY OF THE CLITORIS

PURPOSE

We present a comprehensive account of clitoral anatomy, including its component structures, neurovascular supply, relationship to adjacent structures (the urethra, vagina and vestibular glands, and connective tissue supports), histology and immunohistochemistry. We related recent anatomical findings to the historical literature to determine when data on accurate anatomy became available.

MATERIALS AND METHODS

An extensive review of the current and historical literature was done. The studies reviewed included dissection and microdissection, magnetic resonance imaging (MRI), 3-dimensional sectional anatomy reconstruction, histology and immunohistochemical studies.

RESULTS

The clitoris is a multiplanar structure with a broad attachment to the pubic arch and via extensive supporting tissue to the mons pubis and labia. Centrally it is attached to the urethra and vagina. Its components include the erectile bodies (paired bulbs and paired corpora, which are continuous with the crura) and the glans clitoris. The glans is a midline, densely neural, non-erectile structure that is the only external manifestation of the clitoris. All other components are composed of erectile tissue with the composition of the bulbar erectile tissue differing from that of the corpora. The clitoral and perineal neurovascular bundles are large, paired terminations of the pudendal neurovascular bundles. The clitoral neurovascular bundles ascend along the ischiopubic rami to meet each other and pass along the superior surface of the clitoral body supplying the clitoris. The neural trunks pass largely intact into the glans. These nerves are at least 2 mm in diameter even in infancy. The cavernous or autonomic neural anatomy is microscopic and difficult to define consistently. MRI complements dissection studies and clarifies the anatomy. Clitoral pharmacology and histology appears to parallel those of penile tissue, although the clinical impact is vastly different.

CONCLUSIONS

Typical textbook descriptions of the clitoris lack detail and include inaccuracies. It is impossible to convey clitoral anatomy in a single diagram showing only 1 plane, as is typically provided in textbooks, which reveal it as a flat structure. MRI provides a multiplanar representation of clitoral anatomy in the live state, which is a major advantage, and complements dissection materials. The work of Kobelt in the early 19th century provides a most comprehensive and accurate description of clitoral anatomy, and modern study provides objective images and few novel findings. The bulbs appear to be part of the clitoris. They are spongy in character and in continuity with the other parts of the clitoris. The distal urethra and vagina are intimately related structures, although they are not erectile in character. They form a tissue cluster with the clitoris. This cluster appears to be the locus of female sexual function and orgasm.

Identification of glandular (preputial and clitoral) proteins in house rat (Rattus rattus) involved in pheromonal communication

Proteins (18-20 kDa) belonging to lipocalin family have been reported to act as carriers for ligands binding to pheromones in mouse urine, pig saliva, hamster vaginal fluid and human sweat, that are involved in pheromonal communication. As the preputial gland is a major pheromonal source, the present study was aimed to detect the specific protein bands (around 18-20 kDa) in the preputial and clitoral glands of the house rat, R. rattus. The amount of protein was higher in preputial gland of the male than that of female (clitoral) gland. A 20 kDa protein was noted in male and female glands; however, the intensity of the band was much higher in male than in female. In addition, 70, 60, 35 kDa bands, identified in male preputial gland, were absent in females. The presence of higher concentration of glandular proteins in the male preputial gland suggests that male rats may depend more on these glandular proteins for the maintenance of reproductive and dominance behaviours. The results further suggest that these glandular proteins (20 kDa) may act as a carrier for ligand binding.

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.

Type 5 phosphodiesterase expression in the human vagina

OBJECTIVES

It has been demonstrated that clitoral and vaginal tissues express nitric oxide synthase isoforms in a way that parallels that of the penile corpus cavernosum. Considering the role of the vagina in the female sexual response and the anatomic connection between the clitoris and the anterosuperior vaginal wall, our aim was to study the distribution of type 5 phosphodiesterase (PDE5) in the anterosuperior wall of the human vagina.

METHODS

Immunohistochemistry was performed on the vaginal tissue of 14 women obtained at autopsy and on exfoliated cells of the vaginal epithelium obtained from 5 healthy female donors. Specific antibodies against PDE5 were tested on both paraffin sections and cytologic smears. Immunoblotting experiments were performed in parallel with the same antibodies.

RESULTS

The histologic analysis of human cadaveric vaginal tissue revealed that PDE5 immunoreactivity was mostly localized in the smooth muscle of vessels, forming a pseudocavernous tissue in the vaginal wall and endothelium. The Skene periurethral glands and vaginal epithelium were also positive for the antibody. The latter finding was confirmed using exfoliated cells of the vaginal epithelium harvested in vivo.

CONCLUSIONS

The presence and tissue distribution of PDE5 in the human vagina suggest that the integrated system of nitric oxide synthase-PDE5 may play a physiologic role not only in the male sexual response but also in female sexual arousal.

The effect of estrogen-replacement therapy on clitoral-cavernosal tissue in oophorectomized rats: a histo-quantitative study by image analyzer

Sexual dysfunction is an important problem for aging females. However, little attention has been paid to female sexual dysfunction. The clitoris is an important organ for physiological sexual function in females. There is a close relationship between the presence of sexual complaints and levels of estrogen. Using the rat as an experimental model, we evaluated the effect of estrogen-replacement therapy and its timing on clitoral-cavernosal collogen fiber content after oophorectomy. Four-month-old female Wistar rats (n = 36) weighing 230-250 g were used. They were categorized into four groups: oophorectomized (Group 1: n = 10); oophorectomized delayed estrogen replacement (group 2: n = 10); oophorectomized + immediate estrogen replacement (group 3: n = 10); and sham operated (group 4: n = 6). The estrogen replacement used was 17-beta-estradiol. All rats were euthanized at the same age. The specimens were stained with Masson's trichome technique, and computerized image analysis was used to quantify the collagen-fiber content of clitoral-cavernous tissue. The clitoral collagen-fiber percentages in the different groups were as follows: group 1: 64.17 +/- 5.01%; group 2: 62.57 +/- 5.37%; group 3: 56.33 +/- 3.85%; group 4: 51.48 +/- 6.37%, respectively. Although there was a tendency in the untreated group for a higher collagen-fiber content, no statistically significant difference was found among groups (P > 0.05). Although the results of this study were not statistically significant, estrogen did appear to decrease clitoral-cavernosal collagen-fiber content. These findings may be important in the pathophysiology of postmenopausal female sexual dysfunction.

Effects of estrogen on nitric oxide synthase and histological composition in the rabbit clitoris and vagina

We investigated the functional and histological changes after oophorectomy in the rabbit clitoris and vagina to determine the mechanism responsible for the development of arousal disorder in postmenopausal women. Twenty mature female New Zealand white rabbits were randomly divided into three groups: control; oophorectomy; and estrogen replacement after oophorectomy. We compared the nitric oxide synthase (NOS) activity and the degree of expression of neuronal (nNOS) and endothelial NOS (eNOS) using biochemical and Western blot analysis in clitoral and vaginal tissues. Histological change of smooth muscle and collagen contents in those tissues were also compared using Masson's trichrome staining. NOS activity and the expression of nNOS and eNOS were significantly increased in the oophorectomized group while there was a decrease to the level of the control group in the estrogen replacement group. Histological examination showed that oophorectomy induced a significant increase in collagen and decrease in muscle content in both clitoris and vagina, while the ratio of smooth muscle content was increased significantly after the estrogen replacement. Our results clearly demonstrate that estrogen deficiency induces compensatory NOS production which may be related to decreases in muscle to collagen ratio in female rabbit genital organs.

Sry gene detection in gonads of intersex patients using FISH

A candidate gene for sex determination was localized within a 35 kb region of the Y chromosome immediately adjacent to the pseudoautosomal boundary. Here, we describe a study of Sry detection in the gonads of intersex patients including 5 male pseudohermaphrodite (MPH), 4 XX true hermaphrodite (TH) and each 1 mixed gonadal dysgenesis (MGD) and XX sex reversal, and in the clitoris of 3 female pseudohermaphrodite (FPH) by fluorescent in situ hybridization (FISH). Sry gene was observed in all cases of MPH and each case of MGD and sex reversal in contrast to bare expression in all cases of FPH and most of TH. To our knowledge, the Sry gene itself functions testicular determination in almost all intersex cases except true hermaphrodite, a distinguished type of intersex in a different pathogenesis. In addition, FISH might be useful to detect the translocated Sry gene and localize the signal with ease.

Specific 5alpha-dihydrotestosterone binding in labial skin fibroblasts cultured from patients.with male pseudohermaphroditism

The cytoplasm of skin fibroblasts serially subcultured from the labium majus of normal human females binds 5alpha-dihydrotestosterone (5alpha-DHT) with high affinity and low capacity. Such binding was absent from the strains of two male pseudohermaphrodites with unambiguous female external genitalia: one of these was from a patient with the clinical features and a family history typical of complete testicular feminization; the other merited the same diagnosis on anatomic and endocrine grounds, but had an XYY karyotype in multiple tissues, including the testes. Normal cytoplasmic binding was found in strains from two prepubertal male pseudohermaphrodites with bilateral inguinal testes: one had unambiguous female external genitalia, the other had clitoromegaly; the former had normal specific nuclear binding of 5alpha-DHT, and thereby the target cell capacity for pubertal masculinization. Measurement of specific 5alpha-DHT binding by cultured labial skin fibroblasts should be an early step in the investigation of male pseudohermaphroditism with female external genitalia.

54Mn uptake by the ovaries and reproductive tract of cycling and anestrous ewes

The uptake of 54Mn by the ovaries and reproductive tract of cycling and anestrous ewes has been investigated following intravenous injection of a single dose of 54MnCl2 and sacrifice of the ewes 6 h later. The uptake of 54Mn was greater in the Graafian follicle and the corpus luteum (CL) of the cycle than in the other components of the ovary. An increased uptake of radioactivity was recorded in the CL of the 11th day of the cycle when compared with that of the 4th day. The uptake of 54Mn was lower in the corpus albicans and follicles. A low uptake of radiomanganese was found also in the various tissues of the reproductive tract. These findings indicate that manganese may play a role in the normal functioning of ovarian activity in the ewe.