Multiple hormonal responses to morphine: relationship to diagnosis and dexamethasone suppression

Opioid-induced endocrinopathies

The use of opioids is becoming a global epidemic, leading to a rise in the occurrence and recognition of the effects of opioid drugs on the endocrine system. Nonetheless, opioid-induced endocrinopathies still remain underdiagnosed, mainly because of symptom under-reporting by patients and poor clinician awareness. Hypogonadism is the most well recognised consequence of opioid use, but the inhibitory effects of opioid drugs on the hypothalamo-pituitary-adrenal axis and their negative effects on bone health also require attention. Hyperprolactinaemia might be detected in opioid users, but clinically relevant thyroid dysfunction has not been identified. The effects of opioids on other hormones have not been clearly defined. Assessment of gonadal and adrenal function (particularly if high index of clinical suspicion of hypogonadism or hypoadrenalism) and evaluation of bone health are advised in people that use opiods. Discontinuation or reduction of opioid dose and appropriate hormone replacement are the management approaches that should be considered for hypogonadism and hypoadrenalism. Further research is needed to facilitate the development of evidence-based guidelines on the diagnosis and optimal management of opioid-induced endocrinopathies.

Real-time surveillance of illicit drug overdoses using poison center data

BACKGROUND

In early 2006, government and media sources reported that crime syndicates were mixing fentanyl with heroin. This was followed by an increase in heroin overdoses and opiate-related deaths. The most recent fentanyl outbreak illustrated the need for identifying and establishing effective and responsive real-time surveillance tools to monitor drug overdoses in the United States.

OBJECTIVE

In this study, poison call center data from Illinois were evaluated to determine whether the data could have detected the outbreak that occurred in Illinois in early 2006 and whether it could be used for real-time surveillance.

METHODS

For this analysis, a two-step approach was used to analyze potential heroin-related calls. First, the data were analyzed retrospectively to identify whether any significant temporal shifts occurred, then a prospective analysis was conducted to simulate real-time surveillance.

RESULTS

Between 2002 and 2007, there were a total of 1,565 potential heroin-related calls, and the calls increased by 63.6% in 2006 compared to 2005. In the prospective analysis, the principal model would have identified the outbreak in March 2006.

CONCLUSIONS

If there had been a real-time surveillance program using poison center data, the outbreak would have been identified 1 month before the initial postmortem reports to the Centers for Disease Control and Prevention at the end of April 2006. Poison center data provide the potential for an earlier warning system than postmortem data sources, because the reports are usually made within hours of the exposure. Poison center data can be effectively used to monitor heroin-related exposures.

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.

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.

Effect of naloxone therapy on depersonalization: a pilot study

To test the hypothesis of the role for the opioid system in the pathogenesis of depersonalization, the effect of naloxone (an opioid receptor blocker) on the symptoms and corticosteroids secretion was studied in patients with depersonalization syndrome. Fourteen depersonalization patients were treated with naloxone: 11 patients received single doses (1.6 or 4 mg i.v.) and three others received multiple infusions, with the maximal dosage being 10 mg, and the effect of naloxone on symptom severity was determined. In eight patients, the cortisol, cortisone and corticosterone content in the blood plasma was determined prior to and after the 4 mg naloxone infusion. A reversed-phase microcolumn high-performance liquid chromatography with ultraviolet detection was applied for assessment of glucocorticoids. In three of 14 patients, depersonalization symptoms disappeared entirely and seven patients showed a marked improvement. The therapeutic effect of naloxone provides evidence for the role of the endogenous opioid system in the pathogenesis of depersonalization.

Circadian variations in the amplitude of corticotropin-releasing hormone 41 (CRH41) episodic release measured in vivo in male rats: correlations with diurnal fluctuations in hypothalamic and median eminence CRH41 contents

The possible correlation between the circadian and episodic release of corticotropin-releasing hormone 41 (CRH41) in male rats was explored in a comparative study, including the measurement at 0700 hr and 1700 hr of (1) the quantitative parameters of the episodic release pattern of CRH41 into the push-pull-cannulated median eminence (ME); (2) CRH41 content measured by radioimmunoassay in the hypothalamus, and immunocytochemically in the ME; and (3) plasma adrenocorticotropic hormone (ACTH). The data showed that in early evening, the 3.4-fold rise in plasma ACTH coincided with a doubling of CRH41 content in the hypothalamus and in the ME, and of the CRH41 release from the perfused ME. The immunocytochemical data further indicated that the ME area labeled with CRH41 immunoreactivity, rather than the labeling intensity of CRH41-stained neurons, increased in the evening, which may point to an evening recruitment of additional CRH41-producing neurons as the origin of the evening increment in CRH41 and ACTH releases. Finally, the computerized analysis of the CRH41-releasing pattern with three different algorithms (Pulsar, Ultra, and the Santen and Bardin algorithm) showed for the first time that the evening rise in CRH41 output was associated with correlative increases of three parameters of the episodic pattern--peak amplitude (+55% to +80%), peak duration (+20%), and mean absolute peak values (+73%)--while the pulse frequency remained at the baseline level of 3 cycles.hr-1. The data suggest the occurrence of a connection between the circadian pacemaker and the machinery generating the episodic release of CRH41.

Neuroendocrine mechanism of onset of puberty. Sequential reduction in activity of inhibitory and facilitatory N-methyl-D-aspartate receptors

In humans and in several animal species, puberty results from changes in pulsatile gonadotropin-releasing hormone (GnRH) secretion in the hypothalamus. In particular, the frequency of pulsatile GnRH secretion increases at the onset of puberty, as can be shown by using hypothalamic explants of male rats of 15 and 25 d. Previous observations from us and others suggested that the initiation of puberty could involve a facilitatory effect of excitatory amino acids mediated through N-methyl-D-aspartate (NMDA) receptors. We found that GnRH secretion could be activated through NMDA receptors only around the time of onset of puberty (25 d). The aim of this study was to clarify why this activation did not occur earlier (at 15 d) and could no longer be observed by the end of puberty (at 50 d). We studied GnRH secretion in the presence of MK-801, a noncompetitive antagonist of NMDA receptors or AP-5, a competitive antagonist. We showed that, in the hypothalamus of immature male rats (15 d), a highly potent inhibitory control of pulsatile GnRH secretion in vitro was mediated through NMDA receptors. These data were confirmed in vivo because administration of the antagonist MK-801 (0.001 mg/kg) to immature male rats resulted in early pubertal development. Onset of puberty (25 d) was characterized by the disappearance of that NMDA receptor-mediated inhibition, thus unmasking a facilitatory effect also mediated through NMDA receptors. During puberty, there was a reduction in activity of this facilitatory control which was no longer opposed by its inhibitory counterpart. We conclude that a sequential reduction in activity of inhibitory and facilitatory NMDA receptors provides a developmental basis for the neuroendocrine mechanism of onset of puberty.

Effect of luteinizing hormone releasing hormone pulse characteristics on comparative luteinizing hormone and follicle stimulating hormone secretion from superfused rat anterior pituitary cell cultures

We have shown that 4 ng luteinizing hormone releasing hormone (LHRH) pulses induced significantly greater luteinizing hormone (LH) release from proestrous rat superfused anterior pituitary cells with no cycle related differences in follicle stimulating hormone (FSH). Current studies gave 8 ng LHRH in various pulse regimens to study amplitude, duration and frequency effects on LH and FSH secretion from estrous 0800, proestrous 1500 and proestrous 1900 cells. Regimen 1 gave 8 ng LHRH as a single bolus once/h; regimen 2 divided the 8 ng into 3 equal 'minipulses' given at 4 min intervals to extend duration; regimen 3 gave the 3 'minipulses' at 10 min intervals, thereby further extending duration: regimen 4 was the same as regimen 2, except that the 3 'minipulses' were given at a pulse frequency of 2 h rather than 1 h. In experiment 1, all four regimens were employed at proestrus 1900. FSH was significantly elevated by all 8 ng regimens as compared to 4 ng pulses; further, 8 ng divided into 3 equal 'minipulses' separated by 4 min at 1 and 3 h frequencies (regimens 2 and 4) resulted in FSH secretion that was significantly greater than with either a single 8 ng bolus (regimen 1) or when the 'minipulses' were separated by 10 min (regimen 3). In experiment 2, at proestrus 1500, FSH response to the second pulse of regimen 4 was significantly greater than in regimen 2; LH release was significantly suppressed at pulse 2 compared to regimen 2 accentuating divergent FSH secretion. At estrus 0800, FSH response to the second pulse of regimen 4 was significantly stimulated FSH at proestrus 1900, 1500 and estrus 0800, FSH divergence was most marked at proestrus 1500. These data indicate a potential role for hypothalamic LHRH secretory pattern in inducing divergent gonadotropin secretion in the rat.

Cycle-related LHRH responsiveness of superfused pituitary cells in a Phenol red free medium

Anterior pituitary cell cultures are frequently used in studying the control of gonadotropin secretion. Historically, many (if not most) of these studies have been performed in the presence of Phenol red as a pH indicator. Phenol red preparations, because of their potential estrogenic activity, may have influenced the results of previous studies defining the relative luteinizing hormone releasing hormone responsiveness of rat anterior pituitary-cells derived from various stages of the estrous cycle. We therefore felt it of interest to investigate this possibility by repeating our previous cycle-related superfusion studies [(1988) Life Sci. 42, 61-72] in the absence of these Phenol red preparations. Comparisons of data obtained in the presence or absence of Phenol red revealed cells derived from late proestrous (19.00) and cultured in the absence of Phenol red continued to evidence the highest LH responsiveness. However, diestrous 1 08.00 cells cultured in the absence of Phenol red were lower in responsiveness than previously observed in the presence of the substance and the responsiveness of proestrous 08.00 and 15.00 in the presence was lower in comparison to the same stages in the absence of Phenol red. The results suggest that Phenol red preparations are capable of modulating LHRH responsiveness in superfusion and that the effect is more pronounced at certain cycle stages than at others.

Effect of morphine on cortisol and prolactin secretion in anorexia nervosa and depression

Endogenous opioid peptides are involved in feeding regulation, and alterations in opioidergic regulation have been implicated in the pathophysiology of eating disorders. To investigate further this hypothesis, we conducted a placebo-controlled study of the effect of the opiate alkaloid morphine on cortisol and prolactin secretion in six patients with anorexia nervosa and six age-matched healthy volunteers, and compared the results with those obtained in nine depressed patients. Basal cortisol but not basal prolactin levels were elevated in patients with anorexia nervosa and patients with depression. Following the administration of morphine plasma concentrations of cortisol levels declined progressively and at a similar rate in all three groups. The prolactin response to morphine was attenuated significantly in patients with depression. Neither the cortisol and prolactin response to morphine in the anorectic patients nor the cortisol response in the depressed patients we observed in this study suggests altered opiate receptor sensitivity. However, the decreased prolactin response to morphine in depressed patients remains compatible with this hypothesis.

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.

Opioid influences on pituitary function in sheep under basal conditions and during psychological stress

The effects of intravenous injections of naloxone (2 mg/kg), morphine (0.3 mg/kg) and saline vehicle on plasma concentrations of cortisol, prolactin, vasopressin and oxytocin were assessed in sheep (N = 10) when in their social groups (basal conditions) and during a period of isolation (psychological stress). Blood samples were collected by jugular venipuncture before and during the 60-min period following drug administration. Plasma hormone concentrations were determined by radioimmunoassay. Under basal conditions, cortisol levels were increased after naloxone (36-48%), but not after morphine or saline, and concentrations of prolactin, vasopressin and oxytocin did not change. Under stress conditions, (1) cortisol concentrations were elevated throughout the 60-min sampling period after naloxone or saline but for only 20 min after morphine; maximum increases observed were 161% (naloxone), 150% (saline) and 112% (morphine); (2) prolactin levels were raised after saline (85-129%) and morphine (55-61%) but were unchanged after naloxone; (3) vasopressin concentrations decreased transiently (43%) after saline but not following naloxone or morphine; and (4) oxytocin levels did not change after any treatment. These results indicate that endogenous and exogenous opioids modulate cortisol release in nonstressed sheep, and cortisol and prolactin secretion in sheep subjected to psychological stress. The nature of the anterior pituitary responses induced, together with the absence of a discernible effect on posterior pituitary function, suggest that the central opioid systems involved are similar in sheep and primates but different from those in the rat.

Effect of chronic administration of progesterone on the naloxone-induced LHRH release from hypothalami of ovariectomized, estradiol-primed prepubertal rats

To test the hypothesis that progesterone (P) administered in a high dose and for a long duration would influence in vitro LHRH release by naloxone, silastic capsules containing P (50 mg/ml) or vehicle were implanted sc in ovariectomized, estradiol-primed (OVX+E) prepubertal rats. Following a 48 hr exposure to P, rats were sacrificed and mediobasal hypothalamic (MBH) fragments were obtained. In addition, in other OVX+E primed rats, a single injection of P (1 mg) was given sc 6 hr prior to decapitation. Naloxone or control medium were infused into superfusion chambers containing MBH fragments derived from these animals for 2 hr following a 1 hr control period. Infusion of naloxone (1 x 10(-4) M) markedly stimulated in vitro LHRH release from MBH from rats pre-exposed to P for 48 hr, whereas it was unable to do so in other groups examined. These data clearly indicate that the ability of naloxone (1 x 10(-4) M) to stimulate LHRH release is dependent on the duration of P administration.

Influence of the menstrual cycle on neuroendocrine and behavioral responses to an opiate agonist in humans: preliminary results

Growth hormone (GH), prolactin (PRL), cortisol, noradrenaline (NA) and euphoric responses to the mu opiate receptor agonist Fentanyl (FE) (0.2 mg/70 kg intravenously) were investigated in five healthy, drug-free, female volunteers at menstruation and at ovulation. The plasma GH response to FE was blunted at menstruation relative to the GH response at ovulation. Basal and maximal PRL concentrations were about 1.5 times higher at ovulation than at menstruation. Cortisol and NA concentrations as well as mood and behavioral responses were not influenced by the menstrual cycle. These results confirm earlier reports of a reduced GH response at menstruation to other pharmacological agents. They also demonstrate that the menstrual cycle is an important influence on neuroendocrine responses to opiate challenge.