Thyroid hormone receptors and ligand, tissue distribution and sexual behavior

The thyroid hormones (THs) triiodothyronine (T3) and tetraiodothyronine, or thyroxine (T4), not only dramatically impact on development and differentiation, but also on the sexual and reproductive function. There is large body of literature, in fact, on the effects of THs on the reproductive function in both humans (Poppe and Velkeniers, 2004; Wajner et al., 2009) and animals (Hapon et al., 2010; Nelson et al., 2011). For a long time the gonads were thought to be unresponsive to THs, but TH receptors (TR) were discovered in rat (Jannini et al., 1990; Palmero et al., 1988) and then in human testis (Jannini et al., 2000). In women, the association of menstrual disturbance with thyroid disease was described as early as 1840 by von Basedow, but the discovery of TRs in the ovary was carried out at the end of last century (Wakim et al., 1994b). Therefore, the link between thyroid and reproductive function was well established. Since then, research has shown that thyroid dysfunction is associated with an adverse effect on fertility, both in men (Wagner et al., 2009) and women (Dittrich et al., 2011). There is also evidence that THs can affect the sex steroid hormone axis (Bagamasbad and Denver, 2011), consequently sexual hormones and the pituitary gland can mediate the action of THs on the reproductive physiology. While the effects of THs on fertility have been widely studied, little is known about their influence on sexual function. In the last few years, an increasing number of evidences have shown the influence of THs on male sexual function, particularly on ejaculation control as well on desire and erectile function (Carani et al., 2005; Corona et al., 2012b; Di Sante et al., 2016). The female sexual function and the relationship with thyroid function is still less studied. Furthermore, studies conducted on animals have shown the presence of TRs in the male (Carosa et al., 2010) and female genitalia (Rodriguez-Castelan et al., 2017). Moreover, knockout mice for TRs showed alterations in sexual behavior (Dellovade et al., 2000). The purpose of this review is to summarize and discuss the available data on the influence of THs on male and female sexual function to understand the molecular mechanisms of the influence of the thyroid gland on sexual behavior and function

The psychosexual profile of sexual assistants: an internet-based explorative study

Sexual assistance may have some aspects that resemble prostitution and others that might lead one to think of sexual assistants as similar to a group of subjects whose sexual object is disability (devotees). In this study, we investigate whether a rigorous selection and training process on the part of specialised organisations may reduce the risk of training subjects with an atypical sexual interest and behaviours resembling prostitution

Type V phosphodiesterase inhibitor treatments for erectile dysfunction increase testosterone levels.

OBJECTIVE Lack of sexual activity due to erectile dysfunction (ED) decreases testosterone (T) levels through a central effect on the hypothalamic-pituitary axis. In this paper we studied the effect of different type V phosphodiesterase (PDE5) inhibitor treatments for ED on the reversibility of this endocrine pattern. DESIGN Open-label, retrospective study. PATIENTS Seventy-four consecutive patients were treated on demand with sildenafil (Sild) (50 mg) and tadalafil (Tad) 20 mg. MEASUREMENTS The success in sexual intercourse was recorded and total (tT) and free testosterone (fT) levels were studied before and after 3 months of treatment. RESULTS Basal level of tT and fT were at the bottom of the normal range and LH levels were at the top of the high normal range. After treatments, this endocrine pattern was reversed in both groups. However, the T increase in Sild-treated patients was significantly lower than in those treated with Tad (4.7 +/- 2.7 vs. 5.1 +/- 0.9, P < 0.001). fT levels followed a directly proportional pattern, while the inverse was found when LH production was studied. The intercourse rate reflected this effect: in fact, the Sild group showed a 4.9 +/- 2.9/month full sexual intercourse rate while in the Tad group a significantly higher rate of sexual intercourse was found (6.9 +/- 4.6/month, P = 0.04). However, drug consumption was comparable between the groups (Sild 4.9 +/- 2.9 vs. Tad 4.4 +/- 2.8 pills/month, P = 0.72). CONCLUSIONS As it is unlikely that the two drugs have a different direct effect on the pituitary-testis axis, this effect is probably due to the higher frequency of full sexual intercourse in the Tad-treated group, because of the drug's longer half-life

Measurement of the thickness of the urethrovaginal space in women with or without vaginal orgasm

Introduction. The physiology and anatomy of female sexual function are poorly understood. The differences in sexual function among women may be partly attributed to anatomical factors. Aim. The purpose of this study was to use ultrasonography to evaluate the anatomical variability of the urethrovaginal space in women with and without vaginal orgasm. Methods. Twenty healthy, neurologically intact volunteers were recruited from a population of women who were a part of a previous published study. All women underwent a complete urodynamic evaluation and those with clinical and urodynamic urinary incontinence, idiopathic detrusor overactivity, or micturition disorders, as well as postmenopausal women and those with sexual dysfunction were excluded. The reported experience of vaginal orgasm was investigated. Main Outcome Measure. The urethrovaginal space thickness as measured by ultrasound was chosen as the indicator of urogenital anatomical variability. Designated evaluators carried out the measurements in a blinded fashion. Results. The urethrovaginal space and distal, middle, and proximal urethrovaginal segments were thinner in women without vaginal orgasm. A direct correlation between the presence of vaginal orgasm and the thickness of urethrovaginal space was found. Women with a thicker urethrovaginal space were more likely to experience vaginal orgasm (r = 0.884; P = 0.015). A direct and significant correlation between the thickness of each urethrovaginal segment and the presence of vaginal orgasm was found, with the best correlation observed for the distal segment (r = 0.863; P < 0.0001). Interobserver agreement between the designated evaluators was excellent (r = 0.87; P < 0.001). Conclusions. The measurement of the space within the anterior vaginal wall by ultrasonography is a simple tool to explore anatomical variability of the human clitoris-urethrovaginal complex, also known as the G-spot, which can be correlated to the ability to experience the vaginally activated orgasm

MANAGEMENT OF ENDOCRINE DISEASE: Female sexual dysfunction for the endocrinologist

Sexual function is an important component of either general health and quality of life in both genders. Many studies have focused on the different risk factors for sexual dysfunctions, proving an association with several medical conditions. Endocrine disorders have been often mentioned in the pathogenesis of female and male sexual dysfunctions; however, particularly in women, sexual function is rarely addressed during clinical, in general, and endocrinological, in particular, consultations. As a thorough diagnosis is required in order to provide an adequately tailored treatment, knowing how each endocrine dysfunction can impair sexual health is of the utmost importance, considering the high prevalence of conditions such as disorders of pituitary, thyroid, adrenal, gonads, as well as metabolic disorders. We performed a thorough review of existing literature on the different mechanisms involved in the pathogenesis of female sexual dysfunctions secondary to endocrine disorders in order to provide an up-to-date reference

Ontogeny and regulation of variant thyroid hormone receptor isoforms in developing rat testis

High affinity-low capacity nuclear triiodothyronine (T 3) receptors (TR(s)), identified as a product of c-erbA(α) proto-oncogene, are expressed in prepubertal rat Sertoli cell. At this age, exogenous T 3 treatment as well as hypothyroidism affects Sertoli cell functions. We examined the ontogenetic expression pattern of TR(s) in the rat testis. Northern analysis confirms that TR(s) are expressed at high level from fetal development until prepubertal period. RNase protection analysis demonstrates that TR(α2), the variant isoform of TR(α1), is constitutively expressed at all ages, while TR(α3) is absent in the adult gonad. While TR(α1) and TR(α2) expression declines during development, Rev-erbA(α) (Rev), the antisense mRNA encoded by the same c-erbA(α) genomic locus, increases beginning 5 days after birth and maximizing in adulthood. TR(α1), TR(α2), and Rev mRNA(s) do not appear to be directly regulated by thyroid hormone in testis; however, short-term neonatal hypothyroidism leads to the expression of TR(α1) and its variant in adult testis, which is absent in control coeval animals. Thus, during development of rat testis, the levels of messages of genes encoded in the c-erbA(α) genomic locus have different ontogenetic control. The ontogenetic profile of TR(α1) and its variant isoforms within the seminiferous epithelium suggests that these receptors are involved in the differentiation of the male gonad. (J. Endocrinol. Invest. 22: 843-848, 1999) (C)1999 Editrice Kurtis

The therapeutic dilemma: How to use tadalafil

Tadalafil, a type 5 phosphodiesterase inhibitor, is a new and effective therapy for erectile dysfunction. It has unique pharmacokinetic proper-ties in its drug class, which also includes sildenafil and vardenafil. It is also well tolerated with few side-effects, and can be used in difficult patients such as neuropaths or diabetics