Luteinizing hormone and cortisol responses to naloxone in normal weight women with bulimia

A new biomarker of hedonic eating? A preliminary investigation of cortisol and nausea responses to acute opioid blockade

Overweight and obese individuals differ in their degree of hedonic eating. This may reflect adaptations in reward-related neural circuits, regulated in part by opioidergic activity. We examined an indirect, functional measure of central opioidergic activity by assessing cortisol and nausea responses to acute opioid blockade using the opioid antagonist naltrexone in overweight/obese women (mean BMI=31.1±4.8) prior to the start of a mindfulness-based intervention to reduce stress eating. In addition, we assessed indices of hedonic-related eating, including eating behaviors (binge eating, emotional eating, external eating, restraint) and intake of sweets/desserts and carbohydrates (Block Food Frequency); interoceptive awareness (which is associated with dysregulated eating behavior); and level of adiposity at baseline. Naltrexone-induced increases in cortisol were associated with greater emotional and restrained eating and lower interoceptive awareness. Naltrexone-induced nausea was associated with binge eating and higher adiposity. Furthermore, in a small exploratory analysis, naltrexone-induced nausea predicted treatment response to the mindfulness intervention, as participants with more severe nausea at baseline maintained weight whereas those with little or no nausea responses tended to gain weight. These preliminary data suggest that naltrexone-induced cortisol release and nausea may help identify individuals who have greater underlying food reward dependence, which leads to an excessive drive to eat. Future research is needed to confirm this finding and to test if these markers of opioidergic tone might help predict success in certain types of weight management programs.

Drugs and HPA axis

This paper outlines the interferences of the most widely used drugs with hypothalamo-pituitary-adrenal function and the related laboratory parameters, with the purpose of providing practical help to clinicians during testing for hypo- or hypercortisolemic states.

Naloxone does not influence cardiovascular responses to mild mental stress in postmenopausal women

The interaction between central opioid activity, sex hormones, and the cardiovascular reactivity to stress is unknown. Twenty-eight healthy postmenopausal women, 16 without, and 12 with hormone replacement therapy (HRT) participated in this randomized, double-blind, cross-over study. The opioid receptor antagonist naloxone or placebo was administered intravenously on 2 different days and mild mental stress was induced by the Stroop Color-Word Test. Cardiovascular responses were assessed noninvasively by impedance cardiography. Stress significantly increased stroke volume, cardiac output, blood pressure, and heart rate, which was not influenced by opioid receptor blockade. Whereas naloxone increased cortisol plasma concentrations irrespective of HRT status, luteinizing hormone concentrations, which were higher in non-HRT compared with HRT women, were increased by naloxone in women with HRT only. These data suggest that the opioidergic tone of the hypothalamus-pituitary-adrenal axis persists in postmenopausal women, irrespective of HRT use, while the opioidergic tone on the hypothalamus-pituitary-gonadal axis seems to depend on an estrogenic milieu. Naloxone does not alter cardiovascular mental stress reactions in postmenopausal women independent of their hormone substitution status.

Pituitary LH reserve suggests high risk of bulimia in amenorrheic women

The present study was aimed at investigating a) the risk of having bulimia in a heterogeneous population of secondary amenorrhea; b) the LH and FSH secretion under basal and stimulated conditions (GnRH challenge) according to the presence of bulimic risk in our study population; c) the clinical and endocrine factors predictive of the bulimic risk in amenorrheic women. Amenorrheic women (n=73; age: 23.1+/-4.8 yrs; BMI:20.2+/-2.2 kg/m2) filled in a self rating scale for bulimia (BITE) and were classified accordingly, as being at low risk (score <10), at medium risk (score between 10 and 24), and at high risk (score > or =25) of having bulimia. In each subject basal mean plasma LH levels were calculated over one hour, sampling every 10 minutes, while in a subgroup of 45 patients the area under the curve (AUC) of plasma LH and FSH levels following a challenge with two doses of GnRH (10+10 microg, every two hours), sampling every 15 minutes, was also evaluated. High risk of bulimia was present in 12.3% of the population whereas 45.2% showed a low risk and 42.5% were at medium risk of developing the disorder. Mann-Whitney U test revealed that basal LH values were differently distributed with significantly lower levels (P<0.046) in amenorrheic women at high risk of bulimia in comparison with amenorrheic women at low risk. The AUC of LH secretion following the first challenge of GnRH was significantly higher in amenorrheic women with a high risk of bulimia in respect with both groups of women at low (P<0.034) and medium (P<0.009) risk. A similar result was found with FSH AUC following the first GnRH challenge (P<0.04 high risk vs low risk and P<0.014 high risk vs medium risk). In a multiple regression analysis, the best model predicting the risk of bulimia (BITE total score) included both the LH response to GnRH challenge and BMI. In conclusion, when facing secondary amenorrhea at first consultation, long before a precise pathophysiologic diagnosis of the disease, low basal plasma LH levels and LH response to GnRH challenge may allow one to suspect the presence of abnormal eating pattern of bulimic type.

Endogenous opiates: 1991

This paper is the fourteenth installment of our annual review of research concerning the opiate system. It includes papers published during 1991 involving the behavioral, nonanalgesic, effects of the endogenous opiate peptides. The specific topics this year include stress; tolerance and dependence; eating; drinking; gastrointestinal and renal function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.