Gaetano Frajese

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

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).

Serum cholesterol and impulsivity in a large sample of healthy young men

Studies that have investigated the association between cholesterol levels and impulsivity are relatively few in number and have yielded equivocal results. In this study, we investigated the relationship between impulsivity, depression and serum lipids [total cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides] in a large sample (N=2051) of healthy young men who were remarkably homogeneous in terms of age, educational level, and socioeconomic conditions. Depression was assessed using the depression scale of the Minnesota Multiphasic Personality Inventory-2, and impulsivity was measured using the impulse control scale of the Big Five Questionnaire (BFQ). We found that subjects with a low serum cholesterol, defined as the lowest tenth of the total cholesterol distribution (< or =3.7 mmol/l), scored significantly lower on the impulse control scale of the BFQ. There was no significant association between depression and cholesterol concentrations. In addition, in a multiple regression model, both lower levels of total cholesterol and higher levels of HDL cholesterol emerged as significant predictors of impulsivity. However, since the regression model accounted for only 0.6% of the variance in the score on the impulse control scale of the BFQ, the biological significance of these correlations was negligible. Taken together, these findings suggest that, in healthy young men, a relationship between cholesterol and impulsivity emerges only when the statistical analysis focuses on subjects with very low levels of cholesterol.

Growth hormone-releasing hormone and pituitary adenylate cyclase-activating polypeptide in the reproductive system

Growth hormone-releasing hormone (GHRH) and pituitary adenylate cyclase-activating polypeptide (PACAP) are both members of the glucagon superfamily that, with gonadotropins, act at central and peripheral levels as paracrine and autocrine coregulators of reproductive function. GHRH and PACAP are ancient peptides. Their original forms (both 27 amino acids long) were encoded by a single ancestral gene, several duplications of which led to the genes that encode the neuropeptides of the glucagon superfamily. In the male and female reproductive tracts, GHRH and PACAP interact with a subset of G protein-coupled receptors that are structurally similar to the PACAP receptor and variants of the vasoactive intestinal peptide receptor, and share several biological actions. These are related mainly to the modulation of cAMP-dependent and other signal transduction pathways in several cells of the pituitary-gonadal axis. The recent discovery that antagonists of GHRH and PACAP suppress the growth of human cancer cell lines that are derived from reproductive tissues indicates the potential importance of these peptides as local regulators of cell division, cell cycle arrest, differentiation and cell death.

Body-fat distribution and responsiveness of the pituitary-adrenal axis to corticotropin-releasing-hormone stimulation in sedentary and exercising women

Excess upper-body (android) fat is considered an health hazard. Exercise training is known to have the potential to modify body composition and to induce a preferential loss of abdominal fat. We studied and compared the composition of whole body and major body regions using dual-energy X-ray absorptiometry (DEXA) in 21 exercising (3–4 hours of intense physical activity/day) and 21 sedentary eumen-orrhoic women of similar ages, body mass index (BMI), waist-to-hip ratio (WHR) and age of menar-che. In a small number of women in each group (6 out of 21), the ACTH and cortisol response to CRH test and the 24-h urinary cortisol excretion was evaluated. Exercising women had 10% higher total and leg lean mass (p<0.05), and 38% lower total fat mass (p<0.01) than sedentary women. Furthermore, the proportion of android fat was 22% lower in exercising than sedentary women (p<0.01), while the proportion of lower-body (gynoid fat) was unchanged. BMI and WHR were not different between the two groups, while the android/gynoid fat ratios were 16% lower in exercising than in sedentary women (p<0.01). In the exercising women, ACTH and cortisol plasma levels, as well as the 24-h urinary cortisol excretion, were significantly (p<0.01) higher than in the sedentary women studied. In these subjects, a direct relationship between the peak Δ percentage increases of ACTH and cortisol after the CRH test and the proportion of android fat was found (r=0.60, p<0.05 and r=0.69, p<0.02, respectively). These results demonstrate that in women who practise intense exercise there are significant differences in body fat distribution in comparison to sedentary women, with a marked less amount of android fat, and suggest that this difference may be related to a reduced response of the pituitary-adrenal axis to CRH.

Regulation of the Cyclic Nucleotide-Dependent Pathway in Seminiferous Tubule Cells

It is well established that the development and maturation of the male gamete is dependent on germ cell interaction with somatic cells (1–3). Thus, in the protected environment of the seminiferous tubules, germ cells and somatic cells are continuously exchanging the signals necessary to integrate their functions. In the last 15 years, there has been a major effort to elucidate the biochemical nature of the signals mediating these cell-to-cell interactions (3–5). One concept that has emerged from these studies is that the mechanisms of signal transduction must be operating in seminiferous tubule cells. These mechanisms are necessary for somatic and germ cells to receive and elaborate extracellular signals (6) and to translate them into changes in cell function. Activation of signal transduction pathways must also play an important role in mediating another cell-cell interaction, that between the spermatozoon and the oocyte (7, 8).