Penile growth receptors

We investigated the effects of androgens on penile androgen receptor expression. At necropsy we compared penile size and androgen receptor expression of.
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Finally, men with below average penises fared significantly worse than other men on three measures of psychosocial adjustment. Though most men felt their penis size was average, many fell outside this "norm. Further, size played a significant role in sexual positioning and psychosocial adjustment. These data highlight the need to better understand the real individual-level consequences of living in a penis-centered society. Feb Arch Sex Behav. Men and women living in New Zealand and California completed five studies regarding human physique and sexual attractiveness.

In Studies , women rated images of male stimuli and, in Studies , men rated female stimuli.

Enhanced Growth of the Adult Penis With Vitamin D 3

In Study 1, women in both countries rated mesomorphic muscular and average male somatotypes as most attractive, followed by ectomorphic slim and endomorphic heavily built figures. In Study 2, amount and distribution of masculine trunk hair chest and abdominal was altered progressively in a series of front-posed male figures. In both countries, the image lacking any trunk hair was rated as the most attractive, with a steady decline in attractiveness as hirsutism became more pronounced.

Study 3 assessed attractiveness of front-posed male figures that varied only in the length of the non-erect penis. Five lengths were presented: The smallest penile size was rated as less attractive than three intermediate sizes. The largest penile size was not the most attractive, but received higher scores than the unaltered and smallest penile size. In Study 4, men rated the attractiveness of back-posed female images varying in waist-to-hip ratio WHR from 0.

The 0. Study 5 measured the attractiveness of female skin color; men expressed preferences for lighter skinned female figures in New Zealand and California. Results indicate very similar preferences for sexually dimorphic physical traits among men and women of European extraction, living in two culturally and geographically different environments. Beyond Muscles: Unexplored Parts of Men's Body Image. Thus far the study of men's body image has been largely restricted to the dimensions of adiposity and muscularity.

The aim of this study was to investigate in a systematic way multiple aspects of men's body images, in particular, head hair, body hair, height and penis size, in addition to body weight and muscularity. Questionnaires were completed online by heterosexual men. It was found that men were dissatisfied with all six aspects of their bodies, and worried primarily about body weight, penis size and height. In addition, aspects of weight, muscularity, height and penis size, but not head or body hair, were related to overall appearance self-esteem.


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It was concluded that men's body image is both multi-faceted and complex. Surgical Techniques, Success, and Complications. Most men who request surgical penile enhancement have a normal-sized and fully functional penis but visualize their penises as small psychological dysmorphism.

The aim of this review is to describe the various reported techniques and to provide the available scientific data on the success and complication rates of penile enhancement procedures. The following key words were used: Only English-language articles that were related to penile surgery and dysmorphobia were sought. We excluded articles in which fewer than five cases were described and articles in which the type of surgical treatment and the outcome were not clear.

Of the papers found, 34 were selected and critically analyzed. We found only a small number of well-designed and comprehensive studies, and most of the published articles reported data that were obtained from small cohorts of patients. The more recently published studies presented better methodologies and descriptions of the surgical techniques than did the older publications. In general, penile enhancement surgery can cause a cm increase in penile length and a 2.

The effect of testosterone on androgen receptors and human penile growth. - Semantic Scholar

Unwanted outcomes and complications, namely penile deformity, paradoxical penile shortening, disagreeable scarring, granuloma formation, migration of injected material, and sexual dysfunction were reported frequently in these studies. Disappointing short- and long-term patient satisfaction rates following these procedures were also reported in most studies.

To date, the use of cosmetic surgery to enlarge the penis remains highly controversial. There is a lack of any standardization of all described procedures. Indications and outcome measures are poorly defined, and the reported complications are unacceptably high. In our opinion, until new, reliable, and more objective and reproducible data are available, these procedures should be regarded as investigational and patients should be discouraged from undergoing these invasive treatments.

Penile size and growth in children and adolescents with isolated gonadotrophin defiency IGnD. Penile length and circumference were measured in twenty boys with isolated gonadotrophin deficiency, before and during the administration of androgen therapy.

Their age ranged between 3 and 20 years. Considering as normal, measurements above the tenth centile, in all the patients but four the penile length was below normal, and in two it was borderline. Penis circumference was normal in two, borderline in four and subnormal in sixteen. Regular administration of androgen therapy increased penile length in eleven out of fourteen patients with achievement of normal length in four. It is concluded that congenital lack of LH and testicular androgen activation causes small sized penises, even in the prepubertal period.

Gonadotrophin deficiency should be looked for in patients with measurements below the tenth centile. Early diagnosis and institution of androgen therapy between 11 and 12 years is likely to increase penile size and prevent the psychological side effects of undersized genitals and delayed puberty. Show more. Welcome back! Please log in. Most researchers use their institutional email address as their ResearchGate login. Password Forgot password? Keep me logged in. Log in. No account? Sign up. Similar observations were made in the animal model [ 36 ].

Several reports have suggested that little or no evidence exists to support the relationship between androgens and erectile function. The authors concluded that the use of testosterone supplementation in this population for the treatment of ED is questionable. However, only limited medical risk factors for ED smoking, hypertension, depression were considered, and other risk factors such as diabetes, hyperlipidemia, obesity, and coronary artery disease were not evaluated in this study.

Total and bioavailable testosterone were also determined and showed significant negative correlation with age. The authors concluded that a low total of bioavailable testosterone is only relevant in severe ED. Ojumo and Dobs [ 79 ] have suggested that in men with hypogonadism, ED is a frequent finding and testosterone treatment improved sexual response.

The symptomatic threshold was significantly lower in men with secondary hypogonadism compared with men with primary or mixed hypogonadism, but was not affected by the underlying cause of hypogonadism or by specific symptoms of any severity. The FTI and calculated bioavailable testosterone were greater in the testosterone treatment group as compared with the placebo group.

The authors concluded that oral TU preserves mood and erectile function, particularly in men with the lowest testosterone levels. Testosterone replacement therapy for hypogonadal ED is effective in restoring sexual desire and erectile function, especially in younger and healthier men. At the Second International Consultation on Erectile and Sexual Dysfunction Paris, , it was recommended that the assessment of testosterone levels in all cases of ED be made and, in the case of testosterone deficiency, the treatment of hypogonadism before using medication for ED was recommended [ 17 ].

Although this is not yet a common clinical practice, a strong rationale for this recommendation is supported by the literature. It is suggested that no significant correlation exists between plasma total testosterone level and the severity of ED, although patients reporting hypoactive sexual desire showed significantly lower testosterone levels, especially when free or bioavailable testosterone is measured [ 86 ].

More recently, Lazarou and Morgentaler [ 21 ] suggested that hypogonadism is commonly associated with ED and many urologists lack appreciation for the relative merits of treating hypogonadism with androgens compared with oral PDE5 inhibitors for the management of ED. The authors noted that concerns regarding prostatic and cardiovascular risks of testosterone treatment are not well supported by the scientific literature.

Hematocrit or hemoglobin also should be obtained regularly due to the risk of erythrocytosis. These observations suggest that improvement in selected patients can occur with androgen therapy. The authors noted that a decrease in NPT was observed in all patients treated with antiandrogens, with a concomitant decrease in testosterone and estradiol levels. Bioavailable testosterone correlated significantly with NPT measurements while total testosterone, estradiol, luteinizing hormone LH , and prolactin were mostly unrelated to NPT.

Both duration and maximum level of rigidity were increased.


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    • Testosterone treatment normalized NPT as well as visually stimulated erection with the restoration of a normal response to pharmacological stimulation with the centrally active drug, apomorphine, as well as the peripherally active drug, sildenafil. The authors concluded that testosterone plays a key role in the central as well as the peripheral modulation of erectile function, even in the absence of a defined threshold level of testosterone.

    This subject has, recently, been thoroughly reviewed by Montorsi and Oettel [ 92 ]. They noted a direct correlation between corporeal resistive index values and free testosterone, a relationship that was maintained after adjusting for age, SHBG, and estradiol. They concluded that men with ED and low free testosterone may have an impaired relaxation of the penile smooth muscle, thus providing clinical evidence for the importance of androgen in regulating erectile function.

    One month after treatment with transdermal testosterone and sildenafil on demand, they found significantly increased scores in the EF domain of the IIEF. These clinical observations suggest a critical role for testosterone in human erectile function. More important, in all patients there was a strong direct correlation between resistive index values and free testosterone levels. This relationship was maintained also when adjusted for age, SHBG, and estradiol.

    These results indicate that in men with ED, low free testosterone may correlate independently of age with the impaired relaxation of the cavernous smooth muscle cells. These findings give clinical support to the experimental knowledge of the importance of androgens in regulating smooth muscle function.

    The corollary has been shown that decreasing testosterone levels progressively restrict the effectiveness of PDE5 inhibitor treatment [ 94 ]. Androgens may directly control the expression and activity of PDE5 in human corpus cavernosum. Androgen deficiency or hypogonadism reduced the cavernosal expression of PDE5 mRNA, protein and enzyme activity, and testosterone supplementation restored PDE5 expression and activity [ 4 , 95 ].

    The authors suggested that testosterone gel taken with sildenafil may be beneficial in improving erectile function in hypogonadal men with ED who are unresponsive to sildenafil alone [ 42 , 97 ].

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    The Massachusetts Male Aging Study reported a marked increase in the incidence of ED with aging [ 98 ]; however, the prevalence and the severity of ED with advancing age may also be attributed to a multitude of different etiological factors, such as hypertension, cardiovascular disease, diabetes, and low circulating androgens. This is in part attributed to changes in function of the hypothalamus, the pituitary gland, and the Leydig cells of the testicles [ ].

    Various factors influence the levels of total and bioavailable testosterone, the most important being advancing age [ 98 , , ]. Other common clinical conditions found in men with complaints of ED include diabetes mellitus, hypertension, hyperlipidemia, and atherosclerotic cardiovascular disease [ 98 ]. The authors pointed out that both ED and estradiol levels appear to increase with age. It was suggested that erectile function and sexual activity are improved with relatively low testosterone levels.

    In a recent study, this same group investigated the relationships between testosterone dose and its effects on sexual function, mood, and visual—spatial cognition in older men [ 9 ]. Sexual function was evaluated by questionnaires, and their scores were calculated for overall sexual function, as well as its subcomponents of libido, sexual activity, and erectile function.

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    The authors noted that changes in overall sexual function and waking erections differed by dose. An interaction between libido and sexual activity was observed, showing that libido was changed by testosterone only among those men who reported sexual activity at the beginning of the study. It is suggested that different aspects of male sexual behavior may be responsive to different testosterone threshold levels.

    Testosterone biosynthesis and bioavailability decline with age as a result of changes in the hypothalamic—pituitary—testicular axis. This further leads to increased SHBG levels probably due to an imbalance between androgens and estrogens, resulting in reduced free testosterone.

    In addition, the AR function may be attenuated in aging. The combination of reduced androgen levels and potential reduction in receptor function may require higher testosterone threshold levels for erectile function in aging men. The paucity of the clinical data in the field of androgens and erectile function provides a reasonable argument for discounting the critical role of androgens in this physiological process. In a study that included men, of whom In more than 1, patients with ED, the prevalence of hypogonadism was It is possible that hypogonadism is associated with type II diabetes, and increases sexual dysfunction by reducing libido and mood, and by compromising penile vascular reactivity.

    There is evidence to suggest that testosterone is an important regulator of insulin sensitivity in men. Observational studies have shown that testosterone levels are low in men with diabetes, visceral obesity which is strongly associated with insulin resistance , coronary artery disease, and metabolic syndrome.

    However, limited data are available on the role of androgens in maintaining nerve fiber structure and the regulation of the synthesis and distribution of neurotransmitters in the corpus cavernosum. The authors put forth arguments that the site of androgen action is located on the neurons rather than the penile erectile tissue. They concluded that proerectile postganglionic parasympathetic neurons seem to be the exact site of androgen action. Many nonmyelinated nerve fibers became indistinct and smaller with a concomitant increase in the number of nucleated Schwann cells.

    Testosterone treatment of castrated animals restored the nerve fibers and myelin sheath structure similar to that observed in the sham control group, suggesting that androgens are important in maintaining the peripheral autonomic and sensory nerve structure and function in the penis. This may explain the lag of clinical response with androgen therapy in men.

    Several studies have reported that androgens regulate the expression of nitric oxide synthase NOS isoforms in the corpus cavernosum of animal models [ 22 , 23 , 25 , 31 - 35 , 39 , - ]. Using NADPH—diaphorase staining as a marker of neural nitric oxide synthase nNOS expression, several studies have shown that orchiectomy results in a rapid decrease in serum testosterone and decrease in intracavernous pressure ICP in response to cavernous nerve stimulation and marked decreases in NADPH—diaphorase staining.

    This was associated with a reduced penile erectile response to electrical stimulation of the cavernosal nerve. These metabolic and physiological changes were restored by androgen administration [ 33 - 35 , , , ]. PDE5 is the predominant enzyme responsible for cGMP hydrolysis in vascular and trabecular smooth muscle. In clinical studies, these agents were proven to be safe and effective in the management of ED.

    Androgen deprivation reduced the effect of PDE5 inhibitors on neurogenic relaxation in vitro, and this was restored in tissues of castrated animals treated with testosterone. These observations taken together suggest that androgens are critical not only for NOS activity, but also in modulating PDE5 activity. The authors found that both acute and chronic use of an oral PDE5 inhibitor were ineffective in improving the penile erection response in castrated rats, but the erectile response was restored following androgen treatment.

    While these observations may appear counterintuitive to what we have learned about PDE5 expression and activity, they suggest an important physiological control mechanism and homeostasis between NO production and NO signal termination. This suggests that androgens regulate both NO synthesis and PDE5 expression to maintain physiological homeostasis in the corpora cavernosa. The trabecular smooth muscle is an important component of penile detumescence and erection [ , ].

    In preliminary studies using transmission electron microscopy, we have noted marked differences in the penile trabecular smooth muscle from castrated animals compared to that of intact sham animals. In castrated animals, the corpus cavernosum smooth muscle appeared disorganized, with a large number of cytoplasmic vacuoles. In the intact animals, the corpus cavernosum smooth muscle cells exhibited normal morphology and were arranged in clusters [ , ]. PNS, pelvic nerve stimulation. This is in contrast to the observations made using Masson's trichrome staining and histomorphometry [ 4 ].

    However, transmission electron microscopy [ 5 , , ] showed the marked differences in the morphology of the smooth muscle cells and the endothelium. The cytoplasm contained abundant contractile myofilaments and dense bodies and the cell membrane consisted of alternating dense and light bands. The light bands contain numerous pinocytotic vesicles caveolae.

    The intercellular spaces among myocytes were usually quite narrow with many gap junctions connecting individual cells. The nuclei of the endothelial cells were occasionally seen and appeared oval shaped or elongated. These results suggest that androgens have a profound effect on the ultrastructure of the corpus cavernosum and these alterations may be responsible for the loss of physiological function.

    Nevertheless, further investigations are necessary to define the molecular and cellular mechanisms pertaining to changes in penile nerve fibers, trabecular smooth muscle, or connective tissue proteins in response to androgen deficiency and supplementation. In addition to programmed cell death, androgen deficiency may cause changes in smooth muscle shape and orientation, cellular organelles, contacts with connective tissue proteins, and alterations in cellular response to vasoactive substances.

    These data strongly suggest that androgen deficiency may contribute to venous leakage and ED. The extracellular matrix ECM is a dynamic cellular scaffold that plays an important role in modulating tissue physiological function. The ECM regulates cell morphology, movement, growth, differentiation, and survival by regulating cell adhesion, cytoskeletal machinery, and intracellular signaling.

    Changes in the fibroelastic properties of penile tissue may alter penile compliance and hemodynamics, resulting in ED. Histological studies have shown an association between vasculogenic ED and ECM deposition [ - ]. To date, limited studies have investigated the role of androgens in modulating the synthesis, accumulation, and deposition of connective tissue proteins in the penis e. Furthermore, no data are available on the regulation of connective tissue growth factor or metalloproteases by androgens. We have previously shown that androgen deprivation in an animal model produced a significant loss of trabecular smooth muscle, increased deposition of connective tissue, and impairment of erectile function [ 4 , 36 ].

    We attribute the changes in penile vascular erectile physiology in androgen deprivation to: Androgen deprivation produced significant reduction in trabecular smooth muscle content, increased connective tissue deposition, and loss of erectile function. Androgen treatment of castrated animals resulted in a reversible increase in smooth muscle, concomitant decrease in connective tissue, and restoration of erectile function [ 4 ]. The corpus cavernosum ECM consists of a network of fibrillar collagen and elastin that are intimately connected to the trabecular smooth muscle.

    Histological analysis revealed that all specimens were composed of viable penile tissue. Cellular density of the castrate penises was approximately 2 times greater than that of the normal and super testosterone specimens Supraphysiological doses of testosterone did not change the histology compared to controls.

    Immunohistochemical localization revealed androgen receptors expressed throughout the corporeal bodies, surrounding stroma and penile skin with intracellular localization to nucleus. The mean proportion of cells expressing androgen receptors was higher in the castrate However, in regard to growth there was no change in the proportion of androgen receptor positive cells among the groups.

    Testosterone influences penile growth, possibly as a result of extracellular stromal expansion.