Biomedical subjects

Antonio Lanzone

Publications and source records attributed to Antonio Lanzone.

21 records · Page 2Linked to original sources

PubMed2002

Estrogen treatment and body fat distribution are involved in corticotropin and cortisol response to corticotropin-releasing hormone in postmenopausal women.

To assess the effect of transdermal estrogen substitution on the hypothalamic-pituitary-adrenal (HPA) axis responsiveness/sensitivity and the impact of the antrophometric characteristics on these parameters, 20 postmenopausal women seeking treatment for the relief of postemenopausal symptoms were studied. They received transdermal 50 microg/d estradiol for 12 weeks (estrogen replacement therapy [ERT]). Patients were classified as low waist-to-hip ratio (WHR) (peripheral fat distribution women; n = 12) and high WHR (central fat distribution women; n = 8) according to the cut-off value of 0.85. Plasma hormone and lipid concentration were assessed at baseline and after 12 weeks of treatment. Results were compared with a group of 8 placebo-treated patients who served as controls. Corticotropin (ACTH) and cortisol (F) were expressed as fasting values, area under the curve (AUC), and time course over 90 minutes after corticotropin-releasing hormone (CRH) intravenous (IV) bolus (1 microg/kg body weight [BW]). Adrenal sensitivity to CRH stimulus was expressed as time course over 90 minutes and AUC of the F/ACTH molar ratio. The plasma F levels in response to ACTH stimulation did not change after ERT; however, a highly significant improvement of adrenal sensitivity was observed (P <.01). In fact, estrogen treatment significantly decreased the amount of ACTH produced after CRH stimulation, both as absolute time course and AUC (P <.01). No significant change was observed in controls. Considering body fat distribution, the high WHR group showed higher ACTH (P <.01), lower F/ACTH values, and superimposable F plasma values compared with the low WHR group. Estrogen treatment induced a significant ACTH reduction after CRH (P <.01) only in the high WHR group, whereas cortisol response was similar in both groups both before and after treatment. A significant negative correlation was found between WHR and adrenal sensitivity before treatment. ERT significantly improved adrenal sensitivity only in the low WHR group (P <.01). These data suggest that different mechanisms can prevail in the control of the HPA axis in menopause. Estrogens could exert different effects on the hypothalamic-pituitary axis, as well as on adrenal function, and these changes seem to be partially dependent on the pattern of body fat distribution.

Adipose Tissue↗

PubMed2002

Pituitary adenylate cyclase-activating polypeptide modulates plasminogen activator expression in rat granulosa cell.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a bioactive peptide isolated from ovine hypothalamus. It has been demonstrated to be transiently expressed in preovulatory follicles and to positively affect several parameters correlated with the ovulatory process. The aim of the present study was to investigate whether PACAP influences the plasminogen/plasmin system in rat ovary. Plasminogen activators (PAs) are serine proteases, modulated by gonadotropins and several peptides in preovulatory follicles, that appear to be involved in ovulation. Granulosa cells obtained from immature eCG-treated rats were cultured for 24 h in the presence of increasing concentrations of PACAP and vasoactive intestinal peptide (VIP). A significant, dose-dependent increase in tissue-type PA (tPA) activity and decrease in urokinase-type (uPA) PA activity were observed in PACAP-treated cells. These effects were exerted at the mRNA level. The use of cycloheximide, a protein synthesis inhibitor, suggested that PACAP requires an intermediary protein to decrease uPA-mRNA, but not to induce tPA-mRNA. However, no significant modulation of PAs was observed in the presence of VIP. When granulosa cells were stimulated within the intact follicle (i.e., maintaining the three-dimensional structure and in the presence of the theca cell layers), both PACAP and VIP dose-dependently stimulated tPA. These data suggest that, in addition to the PACAP type I receptor present on granulosa cells, different subtypes of PACAP receptors are present in the different ovarian compartments.

Animals↗

PubMed2002

The effect of raloxifene on glyco-insulinemic homeostasis in healthy postmenopausal women: a randomized placebo-controlled study.

The effect of raloxifene, a selective estrogen receptor modulator recently approved as a therapeutic agent for menopause, on glyco-insulinemic metabolism was investigated in 40 healthy postmenopausal women. At the baseline and after 12 wk of raloxifene (60 mg/d) or placebo administration, all aspects of glucose metabolism were evaluated in each subject using both an oral glucose tolerance test (OGTT; 75 g) and a hyperinsulinemic euglycemic clamp to assess peripheral insulin sensitivity. Glucose, insulin, and C-peptide, measured in fasting conditions, as well as glucose and insulin responses to OGTT [expressed as area under curve (AUC)] were not modified by raloxifene, whereas C-peptide-AUC increased significantly (P < 0.05). Furthermore, a trend toward an improvement of peripheral insulin sensitivity and hepatic clearance of the hormone (fractional hepatic insulin extraction) was observed in the raloxifene-treated women with respect to the control patients. When the subjects were studied in relation to their insulin secretion in response to the glucose load, the patients, classified as hyperinsulinemic, showed the most significant response to the raloxifene treatment. In these women, the selective estrogen receptor modulator was able to induce a significant reduction of insulin circulating plasma values (P < 0.01) through both an increase of fractional hepatic insulin extraction (P < 0.01) and an improvement of the peripheral insulin sensitivity (P < 0.05). On the contrary, no net change of insulin dynamics was observed in normoinsulinemic and placebo-treated women. The present data indicate that raloxifene does not negatively influence glyco-insulinemic metabolism in unselected postmenopausal women and may indeed improve the excessive insulin responsiveness to OGTT in a selected population of hyperinsulinemic postmenopausal women.

Androgens↗