Diurnal variation in fentanyl-induced hormone responses and side effects

Blunted prolactin response to fentanyl in depression. Normalizing effect of partial sleep deprivation

There is some evidence that sleep deprivation (SD) might exert its antidepressant properties by involving endogenous opioid mechanisms. The authors investigated the effects of mu-receptor agonist administration on prolactin release in depressed patients before and after partial SD. Medication-free female depressed inpatients (N=18) were participating in two fentanyl challenge tests after partial SD and undisturbed sleep, 3 days apart in random order. Healthy volunteer women (N=10) were enrolled after full night sleep as comparison subjects. Five of them had placebo trials. Participants were given an intravenous injection of 0.1 mg/70 kg fentanyl at 9:00 AM. The prolactin secretory response to the opiate agonist was investigated for 1 h with serial blood sampling. After a night of undisturbed sleep, fentanyl administration prompted increases in plasma prolactin concentrations with blunted responses found in the depressed group. Following partial SD, the stimulated prolactin secretion of depressed patients increased significantly and was comparable to the response of comparison subjects. These findings suggest that SD acts via an opioid/dopamine-related mechanism. An alternative explanation, based on serotonin involvement is addressed in the discussion.

The effects of heroin on prolactin levels in male rhesus monkeys: use of cumulative-dosing procedures

There is considerable evidence that mu opioid receptors are involved in the regulation of anterior pituitary function. For example, in nonhuman primates and humans, mu agonists generally increase prolactin (PRL) levels. In contrast, mu antagonists decrease or have no effect on PRL levels. The goal of this study was to assess the potential utility of cumulative-dosing procedures to evaluate the endocrine effects of mu opioid receptor ligands. The effects of single and multiple, cumulative doses of the mu agonist heroin and the mu-selective antagonist quadazocine on PRL levels were investigated in four male rhesus monkeys. Cumulative dose-response curves were determined by infusing increasing drug doses at 60 min intervals over 290 min. Blood samples for PRL analysis were collected at 25 and 50 min after each cumulative infusion. Samples were collected at similar time points following single drug dose administration. Heroin (0.01-0.32 mg/kg, IV) administration dose-dependently increased PRL levels. Maximum levels of heroin-induced PRL levels were equivalent after single and cumulative doses. Quadazocine alone (0.032-1.0 mg/kg, IM) did not alter PRL levels significantly. However, quadazocine (0.1 mg/kg, IM) antagonized heroin-stimulated increases in PRL levels and produced a significant rightward shift in the heroin dose-effect curve. These data suggest that a cumulative-dosing procedure similar to that used in behavioral pharmacology may be useful to study the endocrine pharmacology of mu opioids in rhesus monkeys.

Prolactin response to fentanyl in depression

Ten unmedicated female inpatients with major depression (DSM-III) and 10 healthy volunteer women were given an intravenous injection of 0.1 mg fentanyl at 9:00 AM and 9:00 PM on different days. The prolactin secretory response to this opioid agonist was investigated for 1 h with serial blood sampling. Repeated measures Analysis of Variance yielded a significant effect of fentanyl administration on prolactin secretion (p less than 0.0001), and there were elevated hormone responses in the evening (p less than 0.005). No group difference was seen between healthy volunteers and depressed patients, but four of the depressives showed the most blunted response, and three of these low responders committed suicide within 1 year.