Hyaluronan-estradiol nanogels as potential drug carriers to target ER+ breast cancer cell line.

An innovative hyaluronan-based nano-delivery system is proposed for the active targeting towards ER+ breast cancer. Hyaluronic acid (HA), an endogenous and bioactive anionic polysaccharide, is functionalized with estradiol (ES), a sexual hormone involved in the development of some hormone-dependent tumors, to give an amphiphilic derivative (HA-ES) able to spontaneously self-assemble in water to form soft nanoparticles or nanogels (NHs). The synthetic strategy used to obtain the polymer derivatives and the physico-chemical properties of the obtained nanogels (ES-NHs) are reported. ES-NHs ability to entrap hydrophobic molecules has also been investigated, by loading curcumin (CUR) and docetaxel (DTX), both able to inhibit the growth of ER+ breast cancer. The formulations are studied for their capability to inhibit the growth of the MCF-7 cell line, thus evaluating their efficacy and potential as a selective drug delivery systems. Our results demonstrate that ES-NHs have not toxic effects on the cell line, and that both ES-NHs/CUR and ES-NHs/DTX treatments inhibit MCF-7 cell growth, with ES-NHs/DTX effect higher than that of free DTX. Our findings support the use of ES-NHs to deliver drugs to ER+ breast cancer cells, assuming a receptor-dependent targeting.

A semi-automated protocol for NGS metabarcoding and fungal analysis in forensic.

Metabarcoding through Next Generation Sequencing (NGS) has revolutionized environmental biological studies. The availability of this technical approach has opened the opportunity for a systematic implementation of fungal metabarcoding analysis in forensics, where standardized, sensitive and reproducible protocols are highly desirable. In the present paper, a pipeline including a semi-automated molecular protocol and user-friendly bioinformatics tools are applied to several kinds of environmental samples and forensic caseworks. The identification of fungi that characterize specific environments (like Aspergillus for indoor walls, or Penicillium, Debaryomices and Wickerhamomyces for food storage) can be informative for the provenance of samples. In some situations, fungal analysis cannot allow the identification of a defined environment but seems useful to cluster samples with similar provenance. Based on these considerations, fungal analysis can be included in a wider process of non-human DNA identification in order to provide clues on sample provenance.

Dipeptidyl peptidase 4 (DPP-4) inhibitors and their role in Type 2 diabetes management.

Dipeptidyl peptidase 4 (DPP-4) inhibitors are a new pharmacological class of drugs for treating Type 2 diabetes. They improve the capacity of the organism to control glycemia by increasing the levels of active incretins. Their mechanism of action is thus radically different from those of other anti-diabetic drugs currently available. DDP-4 inhibitors use a physiological mechanism to control hyperglycemia, by stimulating the secretion of insulin from beta-cells, decreasing the secretion of glucagon from pancreatic alpha-cells, and at the same time reducing the production of glucose by the liver. DDP-4 inhibitors have shown significant efficacy in maintaining reduced levels of glycosylated hemoglobin for up to 1 year. In vitro and animal studies have shown that they can inhibit apoptosis of beta-cells and favor their regeneration and differentiation. The oral DPP-4 inhibitors vildagliptin, sitagliptin, and saxagliptin are efficacious both alone and in association with other oral anti-diabetic agents and may be administered in a single daily dose. Lastly, they have substantial advantages with respect to other anti-diabetic drugs, since they involve a low risk of hypoglycemia and do not affect body weight.

Usefulness of ambulatory blood pressure monitoring in predicting the presence of autonomic neuropathy in type I diabetic patients.

This study investigated whether nondipping (defined as a day-night change in blood pressure (BP)

Immunity to extracellular matrix antigens is associated with ultrastructural alterations of the stroma and stratified epithelium basement membrane in the skin of Hashimotos thyroiditis patients.

Employing purified extracellular matrix (ECM) proteins, i.e. type I, III, IV and V collagens (CI, CIII, CIV, CV), laminin (LM) and fibronectin (FN), as antigen sources we detected autoantibodies to conformational and/or denatured ECM antigens among 34 of 50 sera obtained from Hashimotos thyroiditis (HT) patients and 6 of 51 control sera obtained from non-autoimmune thyroid disease patients and healthy donors (HT sera vs. control sera p=4 x 10-9). Reactivity to conformational antigens, mostly due to autoantibodies of the IgG isotype, was observed in 30/50 HT sera and in 6/51 control sera (p=3.5 x 10-7) and was not always concomitant with that to linear antigens, found in 23/50 HT and in 6/51 control sera (p=1.6 x 10-4). Ultrastructural analysis of skin biopsies obtained from 18 HT patients without symptomatic cutaneous diseases revealed defects of the stratified squamous epithelium basement membrane in 11/18, alterations of the stroma in 13/18 and both basement membrane and stromal defects in 9/18. Interestingly, 13/13 (p=0.012) and 9/11 (p=0.012) patients with stromal and basement membrane defects respectively, exhibited serum antibodies to at least one ECM antigen involved in the organization of the altered tissue compartment. Lastly, 10/18 skin biopsies presented immunoglobulin (Ig) and/or complement (C3) deposits along the cutaneous basement membrane zone (BMZ) or in the papillary dermis and 9/10 sera from the same patients simultaneously showed antibodies to at least one ECM antigen involved in the organization of these two skin compartments. Besides, 8/11 HT patients with basement membrane defects exhibited Ig or C3 deposits along the BMZ. Our findings suggest that autoantibodies to ECM molecules might contribute to the development of asymptomatic extra-thyroid skin diseases in HT patients.

Identification of a novel mutation in the SRY gene in a 46, XY female patient.

BACKGROUND: The SRY gene encodes for a testis-specific transcription factor (TDF, testis determining factor) that plays a key role in sexual differentiation and development in males. Several SRY mutations have been described in patients with gonadal dysgenesis, accounting for 10-15% of the sex reversal cases. The reported mutations are both point mutations and deletions, mostly involving the high mobility group (HMG) box domain of SRY, which is a conserved region through the evolution, suggesting that SRY function strictly depends on the HMG box. CASE PRESENTATION: Here we describe the clinical, endocrinological and molecular data of a patient with complete 46, XY gonadal dysgenesis caused by SRY mutation located within the conserved HMG box. Using DNA direct sequencing of the SRY coding region, we identified a single nucleotide insertion at codon 89 with subsequent frameshift of the reading frame sequence, which results in a truncated protein as consequence of an introduction of a stop codon at the position 103. CONCLUSION: A novel SRY mutation has been described in a female with a gonadal dysgenesis associated with a 46, XY karyotype. The described case is of importance for genetic counseling.

The epidemiology of partialandrogen deficiency in aging men (PADAM).

The quest for eternal youth has been prevalent in civilised societies in many cultures for many centuries. Preventing or deferring the disabilities and morbidities associated with aging through judicious pharmacotherapy has become a particularly relevant healthcare target with the rapid and relentless global demographic shift towards an increasingly elderly population in the 21th century. Aging men commonly loose muscle, become frail, have impaired sexual and cognitive functions, low mood, develop osteopenia and/or osteoporosis with increased risk for fractures and gain visceral fat which predisposes to diabetes, dyslipidaemia, and ischemic heart disease. These alterations in body function are reminiscent of states of androgen deficiency in younger patients. Indeed, aging is associated with a progressive age-related but variable decline in sex hormones. This condition has been named partial androgen deficiency in aging men (PADAM) and consists in a gradual decline in sex hormone levels over years resulting in physical and psychological changes as depression, impotence, decreased sex drive, loss of muscle tone or strength and lethargy. In this review we have tried to give a real identity to PADAM and quantify its entitiy, using the power of the epidemiology.

New achievement and novel therapeutic applications of PDE5 inhibithors in older males.

Erectile dysfunction (ED) increases in prevalence and severity because of aging processes and related organic, iatrogenic and social problems. Decline of testosterone (T) levels is observed with age and also in illnesses with a common basis of endothelial damage. The T deficiency may lead to decreased energy, mood depression, reduction of sexual desire, but no correlation has been reported between T level and severity of ED, which is mainly a neurovascular disease. In facts, inhibition of phosphodiesterase type 5 (PDE5) isoenzyme with sildenafil, tadalafil and vardenafil enhances vasodilatation in the corpus cavernosum and subsequent penile erection. Absolute pharmacological potency of PDE5 inhibitors is similar and non-selectivity defines the side-effects profile, while their elimination half-life explains not only the different duration of action, but also short and long-term tolerability. Efficacy of PDE5 inhibitors in younger patients is greater in respect to older subjects because of associated pathologies and the decline in hypothalamic-pituitary-gonadal function. T is essential in erectile function, controlling the expression and activity of PDE5 and therefore, androgen supplementation improves therapeutic response to PDE5 inhibitors in hypogonadal subjects. Since sexual behavior is a complex interplay of physical, psychological, and social factors, the possible effect of these drugs on androgen levels and brain function need to be deeply investigated. The ubiquitarious distribution of PDE5 and the availability of selective inhibitory molecules foster newer studies in the treatment of heart failure, pulmonary hypertension, inflammation, and depression. This new progress is certainly contributing to a better medical approach to sexuality and quality of life in aging people.

Androgens and body composition in the aging male.

The relevant age-related changes in male body composition are mainly related to the progressive decrease in the level of circulating anabolic hormones, among which testosterone (T) is rather important. Its decline, between the ages of 35 and 75, is associated to a loss of muscle mass and fibers number, a doubling of fat mass and a decrease in bone mineral density by 0.3% per yr after age 35; thus the relationship between age-related changes in body composition and T bioactivity reflects an important endocrine aspect of the aging male. The assessment of human body composition and in particular the evaluation of fat tissue and its distribution, is currently standardized by the use of dual-energy x-ray absorpiometry (DXA). In the present paper we review the mechanisms through which testosterone may inhibit adipogenesis, restore the myogenic programme enhancing the protein turnover at muscle level and maintain bone mineral density in elderly men.

Phosphodiesterase type 5 inhibithors in older males.

Although erectile dysfunction (ED) in older subjects needs a holistic approach, the pathophysiology consists mainly in chronic ischemia with deterioration of cavernous smooth muscles followed by development of corporeal fibrosis. Therefore, phosphodiesterase type 5 (PDE5) inhibition, enhancing vasodilatation in corpora cavernosa, represents a first-line therapy for ED. PDE5 is in fact the major cGMP hydrolizing enzyme in penile corpus cavernosum. The mechanisms of action, the pharmacokinetics and the contraindications of selective PDE5 inhibitors, are described in details. Furthermore, attention is focused on the interaction of PDE5 inhibitors on hypothalamus-pituitary gonadol (HPG) function. Finally, considering that androgens may influence sexual behavior by modifying the central nervous system neurotransmitter targeted system, the potentiation of PDE5 inhibitors with testosterone supplementation may be considered to improve erectile function and quality of life in older males.

Dynamic testing in the evaluation of male gonadal function.

The maturation and physiologic functions of male sexual apparatus are under the control of the hypothalamic-pituitary-gonadal (HPG) axis. The determination of gonadotropins and testosterone as secretory products of pituitary and gonads, respectively, represents the first step in the evaluation of male sexual function and the diagnosis of disorders in male reproductive axis. However, there are several clinical situations that require a dynamic evaluation of this system and the measurement of basal gonadotropins and testosterone must be combined with specific dynamic tests. These mainly consist in GnRH stimulation, which evaluates the endocrine reserve capacity of the pituitary, and human chorionic gonadotropin (hCG) stimulation, which is used in the assessment of Leydig cells activity. The paper illustrates the technical aspects, the normal/pathological responses and the role of these two tests in assessing the male HPG axis in respect to different clinical diagnostic queries.

Hypothalamo-pituitary surveillance imaging in hypopituitary patients receiving long-term GH replacement therapy.

Most cases of adult-onset (AO) GH deficiency (GHD) result from the presence of hypothalamo-pituitary tumors or their treatment. GH replacement is now widely used in adults with hypopituitarism, but its effect on hypothalamo-pituitary tumor growth or recurrence is unknown. Anecdotal evidence from early experience of GH replacement in adults documented occasional tumor recurrence, but any relationship of this to the use of GH was unclear. We have now prospectively imaged the pituitary glands of 100 consecutive patients (60 females, 40 males; mean age, 46 yr; range, 18-69 yr) who had AO-GHD after appropriate treatment for a pituitary or peripituitary tumor. External radiotherapy had been given to 91 patients. All patients were treated with a dose titration regimen to maintain serum IGF-I between the median and upper end of the age-related reference range. Pituitary imaging was performed before the commencement of GH and after 6 and 12 months of treatment in all patients, again at 2 yr in 92 patients, at 3 yr in 63 patients, and after 4 yr in 23 patients. In only one patient was there evidence of slight intrasellar tissue enlargement at 6 months; GH replacement was continued, and there was no further change between 6 and 12 months. In all other patients, either the appearances were unchanged or the amount of tissue was reduced during long-term follow-up on GH. We have shown that hypothalamo-pituitary tumor recurrence was thus very rare over this time period in this group of GH-treated patients, and this is reassuring. Similar prospective longitudinal observation of patients who have not received postoperative irradiation and comparison with rates of tumor recurrence in control series are desirable.

Platelet-derived growth factor (PDGF) and PDGF receptors in rat corpus cavernosum: changes in expression after transient in vivo hypoxia.

Platelet-derived growth factor (PDGF) overactivity has been implicated in atherosclerosis and several fibrotic conditions including lung and kidney fibrosis, liver cirrhosis and myelofibrosis. Low oxygen tension (hypoxia) is a known stimulus for transcriptional induction of PDGF ligand and receptor genes in different tissues. We studied the expression and localization of PDGF-A, PDGF-B, and PDGF receptor (PDGFR)-alpha and -beta subunits in adult rat isolated corpus cavernosum (CC) under generalized transient hypoxia (pO(2) 10%) in comparison with normoxic conditions. Semi-quantitative RT-PCR analysis of mRNA extracted from rat penis showed higher amounts of PDGF-A, PDGF-B and PDGFR-beta mRNA transcripts in hypoxic versus normoxic animals. The immunohistochemical analysis showed that the localization of PDGF subunits and PDGFR-beta was confined to the cytoplasm of the perivascular smooth muscle cells, endothelium and trabecular fibroblasts. Our findings indicate that transient low oxygen tension induces PDGF overexpression in rat CC, which in the long term may lead to an increase of connective tissue production. We suggest that a local impairment of the PDGF/PDGFR system may contribute to CC fibrosis, which is an established cause of erectile dysfunction in man.

Re-dosing of prostaglandin-E1 versus prostaglandin-E1 plus phentolamine in male erectile dysfunction: a dynamic color power Doppler study.

During penile pharmacotesting, anxiety may overcome complete smooth muscle relaxation and lead to false positive diagnosis of organic male erectile dysfunction (ED). We tested the efficacy and safety of re-dosing of PGE1 alone versus combination of PGE, and the alpha1,2-blocker phentolamine (PHE) to improve an incomplete pharmaco-induced erection during color-power-Doppler (CPD) sonography. 116 consecutive impotent patients were submitted to CPD and injected with 10 microg PGE, plus audiovisual sexual stimulation. Clinical evaluation of rigidity and CPD parameters were normal in 26 patients while in the remaining they were upgraded in 15% and 35% after redosing of 10 microg PGE1 alone and 10 microg PGE1 plus 1 mg PHE, respectively (P < 0.05); furthermore, in these latter patients CPD studies showed increased visualisation of distal ramifications of helicine arterioles. The final diagnosis was changed in those patients who responded to re-dosing with no differences in the occurrence of prolonged erections between the two treatments. We conclude that re-dosing of PGE1/PHE mixture is a safe and effective procedure to maximize erectile response during dynamic CPD sonography and has a better diagnostic sensitivity than re-dosing of PGE1 alone.

Androgens and penile erection: evidence for a direct relationship between free testosterone and cavernous vasodilation in men with erectile dysfunction.

OBJECTIVE: Androgens are essential in the maintenance of nitric oxide-mediated erectile activity in the rat. The objective of the present study was to investigate the role of androgens in regulating trabecular smooth muscle relaxation in the corpus cavernosum in response to vasoactive challenge in men with erectile dysfunction (ED). DESIGN: Retrospective, double-blind correlation analyses. PATIENTS: Fifty-two impotent patients without confounding risk factors for ED were obtained from a total of 250 undergoing diagnostic evaluation. MEASUREMENTS: All patients had dynamic colour duplex ultrasound (D-CDU) and hormonal evaluation for LH, total and free testosterone, SHBG and oestradiol. RESULTS: Based upon D-CDU results patients were diagnosed as having arteriogenic (AR, n = 18; mean age 51) or corporeal venocclusive (CVO, n = 13; mean age 49) ED; in other patients (n = 21, mean age 43) a diagnosis of psychogenic (P)-ED was made by comprehensive psychogenic testing and confirmed by normal D-CDU results. AR and CVO patients had altered compliance of cavernous arteries recorded by D-CDU [20-25% lower resistive index (RI) than patients with psychogenic ED], and lower free testosterone (FT) levels than psychogenic patients [42.3 +/-3.5 SE and 49.3+/-5.2 vs. 75.2+/-7.6 pmol/l, respectively; P<0.01]. More important, in all patients there was a strong direct correlation between resistive index values and FT levels (r = 0.47, P = 0.002); the relationship was maintained also when adjusted for age, SHBG and oestradiol (r = 0.37, P = 0.02). CONCLUSIONS: These results indicate that in men with erectile dysfunction low free testosterone may correlate independently of age with the impaired relaxation of cavernous endothelial and corporeal smooth muscle cells to a vasoactive challenge. These findings give clinical support to the experimental knowledge of the importance of androgens in regulating smooth muscle function in the penis.

Novel point mutation in the splice donor site of exon-intron junction 6 of the androgen receptor gene in a patient with partial androgen insensitivity syndrome.

Androgen receptor (AR) gene mutations have been shown to cause androgen insensitivity syndrome with altered sexual differentiation in XY individuals, ranging from a partial insensitivity with male phenotype and azoospermia to a complete insensitivity with female phenotype and the absence of pubic and axillary sexual hair after puberty. In this study we present an 11-yr-old XY girl, with clinical manifestations peculiar for impaired androgen biological action, including female phenotype, blind-ending vagina, small degree of posterior labial fusion, and absence of uterus, fallopian tubes, and ovaries. At the time of the diagnosis the patient had a FSH/LH ratio according to the puberal stage, undetectable 17beta-estradiol, and high levels of testosterone (80.1 ng/mL). After bilateral gonadectomy, performed at the age of 11 yr, histological examination showed small embryonic seminiferous tubules containing prevalently Sertoli cells and occasional spermatogonia together with abundant fibrous tissue. Molecular study of the patient showed a guanine to thymine transversion in position +5 of the donor splice site in the junction between exon 6 and intron 6 of the AR gene. The result of RT-PCR amplification of the AR messenger ribonucleic acid from cultured genital skin fibroblasts of the patient suggests that splicing is defective, and intron 6 is retained in most of the receptor messenger ribonucleic acid molecules. We show by immunoblotting that most of the expressed protein lacks part of the C-terminal hormone-binding domain, and a small amount of normal receptor is observed. This is probably responsible for the reduced binding capacity in genital skin fibroblasts of the patient. The molecular basis of the alteration in this case is a novel, uncommon mutation, leading to a phenotype indicative of a partial androgen insensitivity syndrome, Quigley's grade 5.

Leptin and aging: correlation with endocrine changes in male and female healthy adult populations of different body weights.

Aging is associated with changes in plasma levels of several hormones. There are conflicting reports on whether circulating leptin levels change during aging, the possible explanation for which is that alterations in adiposity and body mass index (BMI) also occur. In this study we measured plasma leptin and other hormonal parameters known to influence leptin in 150 men and 320 women of a wide age (18-77 yr) and BMI (18.5-61.1 kg/m2) range. Subjects of each gender were separated into 2 groups of similar BMI, i.e. nonobese (BMI, <30) and obese (BMI, >30), and treated separately. Statistical analysis was performed, treating each group of subjects as a whole population or divided into age groups (<30, 30-50, and >50 yr). BMI-adjusted leptin levels were progressively lower with increasing age in women, with a consistent fall after menopause (-21%; P < 0.001); in men, leptin levels also tended to be lower in subjects more than 50 yr of age, but the reduction was not significant. Multiple linear regression analysis, performed on subjects treated either as a whole population or divided into obese and nonobese, showed that in both genders BMI and age were independent contributors of leptin levels, and there was an inverse relationship between leptin and age in both obese (standardized coefficient beta = -0.25 in women and -0.23 in men; P < 0.01) and nonobese (-0.22 in women and -0.20 in men; P < 0.05) subjects. The correlation of leptin and age with plasma levels of sex and thyroid hormones, GH, insulin-like growth factor I, PRL, and insulin was also evaluated. The variables that correlated with leptin were included in a multiple regression model that included BMI and age. Testosterone in men (-0.43 in nonobese and -0.19 in obese; P < 0.05) and estradiol in women (0.22 in nonobese and 0.24 in obese; P < 0.05) were important contributors to leptin levels; also, dehydroepiandrosterone sulfate in obese women (-0.16) and sex hormone-binding globulin in obese subjects of both genders (0.15 in women and 0.19 in men) were significant determinants in the model. However, none of the hormonal parameters abolished the negative correlation between leptin and age or the gender difference in leptin levels. In conclusion, our data show that in adult humans of different body weight, serum leptin gradually declines during aging; leptin reduction is higher in women than in men, but it is independent from BMI and other age-related endocrine changes.

Pituitary adenylate cyclase-activating polypeptide (PACAP) and PACAP-receptor type 1 expression in rat and human placenta.

Pituitary adenylate cyclase-activating polypeptide (PACAP), the new hypophysiotropic factor member of the vasoactive intestinal peptide (VIP)/secretin/glucagon/GHRH family of neuropeptides, exerts its biological action by interacting with both PACAP-selective type I receptors (PAC1) and type II receptors (VPAC1), which bind both PACAP and VIP. The placenta is a site of production of hypophysiotropic factors that participate in the control of local hormone production, as well as the respective hypothalamic-pituitary neurohormones. In the present study, we show the expression of PACAP gene and irPACAP distribution within rat and human placental tissues, by means of RT-PCR and immunohystochemical experiments. In both rat and human placenta, we evaluated the expression of PAC1 gene by Northern hybridization analysis performed with a 32P-labeled 706 nt complementary DNA probe, derived from the full-length coding region of the rPAC1 complementary DNA. The results of these experiments demonstrate the presence, in both human and rat placenta, of a 7.5-kb transcript similar in size to those detected in the ovary, brain, and hypothalamus. Alternative splicing of two exons occurs in human and rat PAC1 gene generating splice variants with variable tissue-specific expression. To ascertain which of the splice variants were expressed in placental tissue we performed RT-nested PCR using primers flanking the insertion sequence termed hip/hop cassette in rat or SV1/SV2 box in human gene. Electrophoretic analysis of the PCR products showed a different pattern of expression of messenger RNA splicing variants in human and rat placenta. In particular, the rat placenta expresses the short PAC1 receptor (PAC1short), the rPAC1-hip or hop (which are indistinguishable with the primers used), and the rPAC1-hip-hop, whereas the human placenta expresses only the PAC1SV1 (or SV2) variant, structurally homologous to the rat PAC1 hip (or hop). Sequence analysis of the human PCR-amplified PAC1 variant was therefore carried out and revealed that human placenta only expresses the PAC1SV2 isoform. The presence and characterization of PACAP binding sites was then investigated in human placenta by radioligand binding studies performed on crude membrane preparation using [125I]PACAP27 as tracer. Scatchard analysis of the binding results revealed the presence of two binding sites, one with high affinity and low capacity (Kd 0.33+/-0.04 nM; Bmax 36.9+/-12.1 fmol/mg protein) and one with low affinity and high capacity (Kd 24+/-6.9 nM, Bmax 9.3+/-0.19 pmol/mg protein). The relative potencies of PACAP-related peptides for inhibition ofradioligand binding were: PACAP27 > or = PACAP38 > VIP, whereas GHRH and other unrelated peptides, such as CRH and beta-endorphin, did not inhibit [125I]PACAP27 binding. In conclusion, in this study, we provide evidence for the expression of PACAP within rat and human placenta. We also demonstrate that both human and rat placenta express the PAC1 gene and that the human tissue has binding sites for PACAP. These findings may suggest a role for PACAP in the regulation of placental physiology through autocrine and/or paracrine mechanisms.

Leptin and androgens in male obesity: evidence for leptin contribution to reduced androgen levels.

Leptin circulates in plasma at concentrations that parallel the amount of fat reserves. In obese males, androgen levels decline in proportion to the degree of obesity. Recently, we have shown that in rodent Leydig cells leptin inhibits hCG-stimulated testosterone (T) production via a functional leptin receptor isoform; others have found that leptin inhibits basal and hCG-induced T secretion by testis from adult rats. In this study, we further investigated the relationship linking leptin and androgens in men. Basal and hCG-stimulated leptin and sex hormone levels were studied in a large group of men ranging from normal weight to very obese (body mass index, 21.8-55.7). Initial cross-sectional studies showed that circulating leptin and fat mass (FM) were inversely related with total and free T (r = -0.51 and r = -0.38, P < 0.01 and P < 0.05, respectively). Multiple regression analysis indicated that the correlation between leptin or FM and T was not lost after controlling for SHBG and/or LH and/or estradiol (E2) levels and that leptin was the best hormonal predictor of the lower androgen levels in obesity. Dynamic studies showed that in obese men the area under the curve of T and free T to LH/hCG stimulation (5000 IU i.m.) was 30-40% lower than in controls and inversely correlated with leptin levels (r = -0.45 and r = -0.40, P < 0.01 and P < 0.05, respectively). Also, LH/hCG-stimulation caused higher increases in 17-OH-progesterone to T ratio in obese men than in controls, whereas no differences were observed between groups either in stimulated E2 levels or in the E2/T ratio. In all subjects, the percentage increases from baseline in the 17-OH-progesterone to T ratio were directly correlated with leptin levels or FM (r = 0.40 and r = 0.45, P < 0.01), but not with E2 or other hormonal variables. In conclusion, our studies, together with previous in vitro findings, indicate that excess of circulating leptin may be an important contributor to the development of reduced androgens in male obesity.