Use of naltrexone in postmenopausal women with exaggerated insulin secretion: a pilot study

Oral sensory and cephalic hormonal responses to fat and non-fat liquids in bulimia nervosa

Sensory evaluation of food involves endogenous opioid mechanisms. Bulimics typically limit their food choices to low-fat "safe foods" and intermittently lose control and binge on high-fat "risk foods". The aim of this study was to determine whether the oral sensory effects of a fat versus a non-fat milk product (i.e., traditional versus non-fat half-and-half) resulted in different subjective and hormonal responses in bulimic women (n=10) compared with healthy women (n=11). Naltrexone (50mg PO) or placebo was administered 1h before, and blood sampling began 30 min prior to and 29 min after, a 3 min portion controlled modified sham-feeding trial. Following an overnight fast, three morning trials (fat, naltrexone; fat, placebo; and non-fat, placebo) were administered in a random double-blind fashion separated by at least 3 days. Overall, there were no differences between Fat and Non-Fat trials. Hunger ratings (p<0.001) and pancreatic polypeptide levels (p<0.05) were higher for bulimics at baseline. Bulimics also had overall higher ratings for nausea (p<0.05), fatty taste (p<0.01), and fear of swallowing (p<0.005). Bulimics had approximately 40% higher total ghrelin levels at all time points (p<0.001). Hormones and glucose levels were not altered by the modified sham-feeding paradigm. Naltrexone, however, resulted in an overall increase in blood glucose and decrease in ghrelin levels in both groups (p<0.05, for both). These data suggest that bulimic women have different orosensory responses that are not influenced by opioid receptor antagonism, evident in hormonal responses, or dependent on the fat content of a similarly textured liquid.

Normalization of hyperinsulinemia by chronic opioid receptor blockade in hyperandrogenemic women

OBJECTIVE

Evaluation of the effects of naltrexone on hyperinsulinemia and hyperandrogenemia in hyperandrogenemic, hyperinsulinemic women.

DESIGN

Controlled clinical study.

SETTING

Department of Gynecologic Endocrinology and Reproductive Medicine, Center of Obstetrics and Gynecology, Medical University of Innsbruck, Austria.

PATIENT(S)

Thirty-nine hyperandrogenemic, hyperinsulinemic women were studied.

INTERVENTION(S)

Women were treated with naltrexone (50 mg/d) for >or=3 weeks.

MAIN OUTCOME MEASURE(S)

Body mass index (BMI), gonadotropin (LH, FSH) and androgen (T, free T, DHEAS) levels, and plasma levels of glucose, insulin, and C-peptide, during a standard 75-g oral glucose tolerance test (OGTT), were determined before and during chronic opiate receptor blockade.

RESULT(S)

The BMI did not change during therapy. When OGTT was repeated after treatment with naltrexone, glucose levels were not different from those before treatment. Insulin response, however, had dramatically declined. We also observed a significant decrease in the levels of serum androgens.

CONCLUSION(S)

Hyperinsulinemia associated with hyperandrogenemia can be improved or completely abolished by chronic opiate receptor blockade. This observation suggests that endogenous opiates play a critical role in the process leading to hyperinsulinemia in hyperandrogenemia.

Endogenous opiates and behavior: 2004

This paper is the 27th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over 30 years of research. It summarizes papers published during 2004 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.