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.
The aim of this study was to evaluate the impact of a three-month continuous administration of oral E2, alone, or combined with 2 different dosages of dydrogesterone, on the glucose tolerance and insulin sensitivity in postmenopausal women. In a prospective placebo-controlled study, 43 normal weight and normoinsulinemic women were randomized to receive either 2 mg of oral 17beta E2 daily (group A), or 2 mg E2 daily plus 5 mg daily oral dydrogesterone, from day 14 to 28, in a sequentially combined regimen (group B), or 2 mg of E2 and 10 mg dydrogesterone in the same sequentially combined regimen (group C) or placebo for 12 weeks. An OGTT and a euglycemic hyperinsulinemic clamp were performed before and after treatment. Serum glucose and insulin concentrations were measured both in fasting conditions and after OGTT. C-peptide pancreatic secretion was tested only in fasting conditions. Total body glucose utilization (M), for insulin sensitivity evaluation, was determined in each subject. Postmenopausal women treated with unopposed 17beta E2 (group A) showed a slight but statistically significant decrease of insulin sensitivity (p<0.05). A more marked deterioration of the same parameter was observed in the 2 groups treated with E2 plus dydrogesterone (group B and group C: p<0.01). Post hoc testing for the percent change from baseline indicated that group A significantly differed from group C (p<0.05) and all treated groups significantly differed from the placebo group (p<0.01). Finally, after treatment in group C, a significant reduction of insulin and an increase of glucose responses to OGTT (p<0.01) were observed. These results indicate that, in a short-term period, the use of 17beta E2 and overall 17beta E2 plus dydrogesterone, even with the reduction of insulin plasma levels, might cause a decrease in insulin sensitivity in normal weight and normoinsulinemic post-menopausal women.
To evaluate the effects of acute lowering of FFAs on glucose-induced insulin secretion and GH response to GHRH in polycystic ovary syndrome (PCOS), 27 PCOS subjects (11 lean and 16 obese) and 17 body mass index-matched controls (8 lean and 9 obese) were investigated. Patients underwent an oral glucose tolerance test and a GHRH test before and after administration of the antilipolytic drug acipimox (250 mg orally 3 h and 1 h before the starting of the tests). Blood samples were collected for 2 h after GHRH bolus and for 4 h after the oral glucose tolerance test. Serum concentrations of GH, insulin, glucose, and c-peptide were assayed in each sample, and the results were expressed as area under the curve (AUC). No significant differences were found as to glucose, insulin, and c-peptide AUC before and after acute FFA plasma reduction in any of the investigated groups. Basally, lower GH-AUC was found in lean PCOS compared with body mass index-matched controls and in obese vs. lean controls; no significant differences were found as to the same variable between the two obese groups. The acipimox induced FFA suppression elicited in the four groups a sustained increase in the GH response to its trophic hormone; indeed, the GH-AUC nearly doubled with respect to basal evaluation in all the studied groups. However, the antilipolytic drug was not able to abolish the differences found between lean groups in basal conditions. In conclusion, the presented data confirm that FFAs have a main role in regulating GH secretion at the pituitary level; however, it does not seem that they could explain the GH as well as insulin dysfunction of PCOS.
In order to evaluate the involvement of endogenous opiates in the insulin disorders of polycystic ovary syndrome (PCOs) a total of 25 PCOs women and 11 normo-ovulatory controls were studied by comparing the effect of a chronic opioid blockade on β-cells responsiveness to oral glucose load and to intravenous glucagon bolus. Each patient, studied on follicular phase, underwent to oral glucose tolerance test (OGTT), and, 2 days later, to a glucagon intravenous bolus (1 mg); these tests were then repeated after 6 weeks of naltrexone treatment (50 mg orally). Naltrexone treatment did not modify the insulin secretory patterns of control subjects, whereas the same therapy significantly reduced, in hyperinsulinemic PCOs women, the β-cell hyperresponsiveness both to oral glucose load and to intravenous glucagon (p < 0.05 and p < 0.01, respectively), even if with different mean percent decrease (32% OGTT vs. 45% glucagon, p < 0.05). Moreover, normoinsulinemic PCOs patients showed a slight, but not significantly increase in the β-cells response to OGTT after opioid blockade, whereas, in the same situation, the insulin release after glucagon bolus was significantly reduced (p < 0.01). Chronic opioid blockade did not modify gonadotropins, steroids and SHBG levels in either group. Our data show that naltrexone treatment is able to reduce the β-cell response to a direct intravenous secretagogue stimulus in all PCOs patients, while only in hyperinsulinemic PCOs subjects the same treatment is effective in reducing the exaggerated insulin secretion after oral glucose load. The reason for such a discrepancy could be ascribed to a different effect of opioids on first- and second-phase insulin secretion, or, alternatively, to an involvement of other secretagogue factors, such as glucoincretins.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.