Brain opiates and neuroendocrine function

New developments and concepts in the diagnosis and management of diabetes insipidus (AVP-deficiency and resistance)

Diabetes insipidus (DI) is a disorder characterised by the excretion of large amounts of hypotonic urine, with a prevalence of 1 per 25,000 population. Central DI (CDI), better now referred to as arginine vasopressin (AVP)-deficiency, is the most common form of DI resulting from deficiency of the hormone AVP from the pituitary. The less common nephrogenic DI (NDI) or AVP-resistance develops secondary to AVP resistance in the kidneys. The majority of causes of DI are acquired, with CDI developing when more than 80% of AVP-secreting neurons are damaged. Inherited/familial CDI causes account for approximately 1% of cases. Although the pathogenesis of NDI is unclear, more than 280 disease-causing mutations affecting the AVP2 protein or AVP V2 receptor, as well as in aquaporin 2 (AQP2), have been described. Although the cAMP/protein kinase A pathway remains the major regulatory pathway of AVP/AQP2 action, in vitro data have also revealed additional cAMP independent pathways of NDI pathogenesis. Diagnosing partial forms of DI, and distinguishing them from primary polydipsia, can be challenging, previously necessitating the use of the water deprivation test. However, measurements of circulating copeptin levels, especially after stimulation, are increasingly replacing the classical tests in clinical practice because of their ease of use and high sensitivity and specificity. The treatment of CDI relies on desmopressin administration, whereas NDI requires the management of any underlying diseases, removal of offending drugs and, in some cases, administration of diuretics. A better understanding of the pathophysiology of DI has led to novel evolving therapeutic agents that are under clinical trial.

Central diabetes insipidus and pain medications - a risky combination

Background

Central Diabetes Insipidus (CDI) results from decreased production of antidiuretic hormone (ADH) leading to an inability to concentrate urine. CDI is treated with desmopressin (DDAVP). Rarely reported in the literature, opioids and non-steroidal anti-inflammatories (NSAIDs) can induce hyponatremia in individuals treated for CDI.

Case presentation

A 10-year-old boy with septo-optic dysplasia and CDI was treated with DDAVP 1.6 mg orally TID maintaining normal sodium levels. Post admission for a femur fracture, he was discharged on ibuprofen and hydromorphone. Sodium was 136 mmol/l two days before discharge.

He returned to the ED after having a seizure at home. He was euvolemic and mildly lethargic. Sodium was low at 108 mmol/l. DDAVP and hydromorphone were held and he was fluid restricted, but the sodium remained low. Sodium began to rise when Ibuprofen was stopped. Intermittent small doses of DDAVP were given to facilitate gradual correction of hyponatremia. At discharge, sodium had normalized.

Conclusion

Hyponatremia has occasionally been described as a side effect of opioids and rarely of NSAIDs in patients with CDI. Stimulation of the thirst centre may play a role with opioids while a decrease in urine output may be the mechanism with NSAIDs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40842-021-00124-9.

Nonthyroidal illness in critically ill children

PURPOSE OF REVIEW

This review summarizes recent literature on nonthyroidal illness syndrome (NTI) and outcome of pediatric critical illness, to provide insight in pathophysiology and therapeutic implications.

RECENT FINDINGS

NTI is typically characterized by lowered triiodothyronine levels without compensatory TSH rise. Although NTI severity is associated with poor outcome of pediatric critical illness, it remains unclear whether this association reflects an adaptive protective response or contributes to poor outcome. Recently, two metabolic interventions that improved outcome also altered NTI in critically ill children. These studies shed new light on the topic, as the results suggested that the peripheral NTI component, with inactivation of thyroid hormone, may represent a beneficial adaptation, whereas the central component, with suppressed TSH-driven thyroid hormone secretion, may be maladaptive. There is currently insufficient evidence for treatment of NTI in children. However, the recent findings raised the hypothesis that reactivation of the central NTI component could offer benefit, which should be tested in RCTs.

SUMMARY

NTI in critically ill children can be modified by metabolic interventions. The peripheral, but not the central, component of NTI may be a beneficial adaptive response. These findings open perspectives for the development of novel strategies to improve outcome of critical illness in children.

Post-marketing surveillance study of the safety and efficacy of nalfurafine hydrochloride (Remitch® capsules 2.5 μg) in 3,762 hemodialysis patients with intractable pruritus

Background

Intractable pruritus in hemodialysis patients can significantly decrease their quality of life and is also associated with poor vital prognosis. Although combined multiple causes of intractable pruritus in these patients have been identified, no existing treatments are proven to be sufficiently effective. We conducted a post-marketing surveillance to follow-up and assess the safety and efficacy of nalfurafine, a selective κ-opioid receptor agonist, for the treatment of intractable pruritus in patients undergoing hemodialysis.

Patients and methods

Hemodialysis patients with intractable pruritus from institutions in Japan who received oral nalfurafine hydrochloride between January 2010 and December 2013 were enrolled in the surveillance. Surveillance was completed in July 2015. Safety data during 1 year after nalfurafine treatment onset, and efficacy data of nalfurafine evaluating the first 12-week treatment period and the following period until 1 year after the initial dose of nalfurafine (using global assessment of the itch improvement by the physician, Visual Analog Scale, and the Shiratori's severity scores) were collected and analyzed.

Results

In total, 3,762 patients were analyzed for safety. Adverse drug reactions were experienced by 402/3,762 (10.69%) patients. The most frequent adverse drug reactions were insomnia (127/3,762 [3.38%] patients), constipation (34 [0.90%]), somnolence (32 [0.85%]), dizziness (23 [0.61%]), nausea (13 [0.35%]), and malaise (9 [0.24%]). No patients developed dependence on nalfurafine. Nalfurafine was effective in 82.50% (2,880/3,491) of patients during the first 12 weeks and in 84.95% (2,167/2,551) on treatment during the subsequent period until 1 year after nalfurafine treatment initiation. Statistically significant decreases were reported in the Visual Analog Scale and the Shiratori's severity scores (p<0.001).

Conclusion

Oral nalfurafine hydrochloride (from 2.5 μg/day to a maximum of 5.0 μg/day) continues to be safe and effective for the treatment of intractable pruritus in hemodialysis patients in real-world clinical settings.

Opioid-induced endocrinopathy in cancer patients: an underestimated clinical problem

The impact of both endogenous and exogenous opioids on the endocrine system has been known for many years. With the increased use of opioids in chronic pain treatment, the research focuses mainly on their effects on the endocrine system in patients with chronic non-malignant pain. Despite the wide dissemination of cancer, there has been little research on the possible effects of opioids on the endocrine system in cancer patients. For the growing number of cancer survivors and patients in long-term remission who take opioids, other aspects of endocrine disorders caused or exacerbated by opioids will have practical and clinical importance. Conversely, this problem may be less relevant for patients in active cancer treatment or in the advanced stage of disease. This article presents the available research on the effects of opioids on the endocrine system and the clinical consequences resulting from opioid use in cancer patients. Clinicians who use opioids in clinical practice should be aware of the existence of the endocrine symptoms of opioid therapy. There is still a need for more research in this area to maintain the best possible quality of life for cancer patients treated with opioid analgesics.

Intimate associations between the endogenous opiate systems and the growth hormone-releasing hormone system in the human hypothalamus

Although it is a general consensus that opioids modulate growth, the mechanism of this phenomenon is largely unknown. Since endogenous opiates use the same receptor family as morphine, these peptides may be one of the key regulators of growth in humans by impacting growth hormone (GH) secretion, either directly, or indirectly, via growth hormone-releasing hormone (GHRH) release. However, the exact mechanism of this regulation has not been elucidated yet. In the present study we identified close juxtapositions between the enkephalinergic/endorphinergic/dynorphinergic axonal varicosities and GHRH-immunoreactive (IR) perikarya in the human hypothalamus. Due to the long post mortem period electron microscopy could not be utilized to detect the presence of synapses between the enkephalinergic/endorphinergic/dynorphinergic and GHRH neurons. Therefore, we used light microscopic double-label immunocytochemistry to identify putative juxtapositions between these systems. Our findings revealed that the majority of the GHRH-IR perikarya formed intimate associations with enkephalinergic axonal varicosities in the infundibular nucleus/median eminence, while endorphinergic-GHRH juxtapositions were much less frequent. In contrast, no significant dynorphinergic-GHRH associations were detected. The density of the abutting enkephalinergic fibers on the surface of the GHRH perikarya suggests that these juxtapositions may be functional synapses and may represent the morphological substrate of the impact of enkephalin on growth. The small number of GHRH neurons innervated by the endorphin and dynorphin systems indicates significant differences between the regulatory roles of endogenous opiates on growth in humans.

Alcohol administration attenuates hypothalamic-pituitary-adrenal (HPA) activity in healthy men at low genetic risk for alcoholism, but not in high-risk subjects

Acute alcohol challenge studies in rodents and naturalistic observations in drinking alcoholics suggest that alcohol stimulates the hypothalamic-pituitary-adrenal (HPA) system. The literature on respective studies in healthy volunteers is more inconsistent, suggesting differential alcohol effects depending on dosage, recent drinking history, family history of alcoholism and alcohol-induced side effects. These papers and the putative pharmacologic mechanisms underlying alcohol effects on the HPA system are reviewed here and compared with a new study, in which we investigated how secretion of adrenocorticotrophin (ACTH) and cortisol is affected by ingestion of 0.6 g/kg ethanol in 33 young healthy socially drinking males with a paternal history of alcoholism (PHP) versus 30 family history negative (FHN) males. Alcohol and placebo were administered in a 2-day, double-blind, placebo controlled crossover design with randomized administration sequence. After administration of placebo, ACTH and cortisol decreased steadily over 130 minutes. In FHN subjects, secretion of both hormones was even more attenuated after alcohol, resulting in significantly lower levels compared with placebo. In PHP subjects, no alcohol effect on hormone secretion could be detected. The ratio of cortisol to ACTH secretion, each expressed as area under the secretion curve, was significantly increased by alcohol in FHN and PHP participants. These results argue against HPA stimulation being a mechanism that promotes the transition from moderate to dependent drinking. The fact that alcohol-induced HPA suppression was not detected in PHP males is consistent with the general concept that subjects at high risk for alcoholism exhibit less-pronounced alcohol effects.

Opioid-induced biochemical alterations of the neuroendocrine axis

Exogenous opioids have been used for decades to palliate cancer-related pain and other cancer-related manifestations and, more recently, to treat patients with pain not related to oncologic disease. While the goal of opioid treatment is symptomatic relief and improved quality of life, these patients often suffer from adverse side effects, including endocrine system abnormalities, of which hypogonadism is the best known. Opioids may interact with other hypothalamic-pituitary pathways and endocrine end organs, and in most cases these interactions are subtle and the effects unclear. The long-term effects of these agents on the endocrine system are still largely unknown. This article discusses the various effects of opioid agents on the endocrine system and provides information that allows early recognition of side effects that may alter the quality of life of patients affected by pain, awareness of the potential complications in opioid addicts, and detection and treatment of side effects in participants of an opioid detoxification program.

Naloxone decreases the inhibitory effect of alprazolam on the release of adrenocorticotropin/cortisol induced by physical exercise in man

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Alprazolam (ALP), a benzodiazepine activating GABAergic receptors, is involved in ACTH secretion.

WHAT THIS STUDY ADDS

• This study demonstrates a partial opioid influence in the inhibitory effect of ALP on the release of ACTH/cortisol during physical exercise.

AIMS

To establish the possible involvement of alprazolam (ALP) and/or opiates in the mechanism underlying the ACTH/cortisol response to physical exercise.

METHODS

Tests were carried out under basal conditions (exercise control test), exercise plus ALP (50 µg at time -90 min), naloxone (10 mg at time 0) or ALP plus naloxone. Plasma ACTH and serum cortisol concentrations were evaluated in blood samples taken before, during and after the bicycle ergometer tests.

RESULTS

ACTH and cortisol concentrations rose significantly after physical exercise. Maximum peak at time 15 min (P ≤ 0.01 vs. baseline) for ACTH and at time 30 min (P ≤ 0.01 vs. baseline) for cortisol. In the presence of naloxone, the ACTH and cortisol responses were significantly increased (maximum peak at time 20 min, P ≤ 0.02 vs. control test for ACTH, and at time 30 min (P ≤ 0.01 vs. baseline) for cortisol) whereas they were abolished by ALP. When ALP and naloxone were given together, the inhibitory effect of ALP was partial.

CONCLUSIONS

These data demonstrate an inhibitory effect of ALP in the regulation of the ACTH/cortisol response to physical exercise in man and suggest that GABAergic receptor activating benzodiazepines and opioids interact in the neuroendocrine secretion of ACTH/cortisol.

Hypoprolactinaemic galactorrhoea in long-term methadone treatment

Although hyperprolactinaemia is associated with galactorrhoea, galactorrhoea often occurs without any hyperprolactinaemia. This has been well established, and it has been documented in women prescribed/using methadone and other opiates. One case series described amenorrhoea and galactorrhoea in 'female heroin addicts', but it has not before been described in a patient with hypoprolactinaemia. We report a case of a 30 year old non-pregnant, non-puerperal, opioid-dependent, HIV positive woman on long-term methadone maintenance programme, who presented with bilateral, milky nipple discharge, associated with painful breast lumps, but with serum prolactin levels below the normal range. She was not prescribed any other medications likely to have effect on the endocrine system. This case highlights the need for prescribers to be alert to the implications of long-term use of opioids.

Hypothalamic opioid-melanocortin appetitive balance and addictive craving

Whilst the parallels between drug and food craving are receiving increasing attention, the recently elucidated complex physiology of the hypothalamic appetite regulatory centres has been largely overlooked in the efforts to understand drug craving which is one of the most refractory and problematic aspects of drug and behavioural addictions. Important conceptual gains could be made by researchers from both appetite and addiction neuroscience if they were to have an improved understanding of each others' disciplines. It is well known in addiction medicine that the use of many substances is elevated in opiate dependency. There is voluminous evidence of very high rates of drug use in opiate agonist maintained patients, and the real possibility exists that opiate agonist therapy therefore increases drug craving. Conversely, opiate antagonist therapy with naloxone or naltrexone has been shown to reduce most chemical and behavioural addictions, and naltrexone is now being developed together with bupropion as the anti-obesity drug "Contrave". Hypothalamic melanocortins, particularly α-MSH, are known to constitute the main brake to consumptive behaviour of food. There is a well described antagonism between melanocortins and opioids at many loci including the hypothalamus. Administration of exogenous opiates is known to both suppress α-MSH and to stimulate hedonic food consumption. Opiate maintenance programs are associated with weight gain. As monoamines, opioids and cannabinoids are known to be involved in appetite regulation, and as endorphin opioids are known to be perturbed in other addictions, further exploration of the hypothalamic appetite regulatory centre would appear to be an obvious, albeit presently largely overlooked, locus in which to study drug and other craving mechanisms.

Naloxone decreases the inhibitory effect of somatostatin on GH release induced by cigarette smoking in man

To establish whether somatostatin (SRIH) exerts its inhibitory effect on the nicotine-induced release of GH by interacting with an opioid pathway, normal volunteers were treated with naloxone during (2 no-filter) cigarettes smoking and with SRIH. Nicotine significantly increased serum GH levels about 3.5 fold. Naloxone alone did not change GH rise induced by cigarette smoking. The stimulatory effect of GH by nicotine was completely blocked by SRIH. In the presence of both SRIH and naloxone, GH levels rose 1.5 fold in response to nicotine. Since naloxone only partially reversed the inhibiting action of SRIH, only a partial involvement of opioid peptides in SRIH action might be supposed. Alternatively, SRIH and naloxone-sensitive opiates might produce this inhibiting effect on GH rise in response to cigarette smoking through independent pathways.

The effects of opioids and opioid analogs on animal and human endocrine systems

Opioid abuse has increased in the last decade, primarily as a result of increased access to prescription opioids. Physicians are also increasingly administering opioid analgesics for noncancer chronic pain. Thus, knowledge of the long-term consequences of opioid use/abuse has important implications for fully evaluating the clinical usefulness of opioid medications. Many studies have examined the effect of opioids on the endocrine system; however, a systematic review of the endocrine actions of opioids in both humans and animals has, to our knowledge, not been published since 1984. Thus, we reviewed the literature on the effect of opioids on the endocrine system. We included both acute and chronic effects of opioids, with the majority of the studies done on the acute effects although chronic effects are more physiologically relevant. In humans and laboratory animals, opioids generally increase GH and prolactin and decrease LH, testosterone, estradiol, and oxytocin. In humans, opioids increase TSH, whereas in rodents, TSH is decreased. In both rodents and humans, the reports of effects of opioids on arginine vasopressin and ACTH are conflicting. Opioids act preferentially at different receptor sites leading to stimulatory or inhibitory effects on hormone release. Increasing opioid abuse primarily leads to hypogonadism but may also affect the secretion of other pituitary hormones. The potential consequences of hypogonadism include decreased libido and erectile dysfunction in men, oligomenorrhea or amenorrhea in women, and bone loss or infertility in both sexes. Opioids may increase or decrease food intake, depending on the type of opioid and the duration of action. Additionally, opioids may act through the sympathetic nervous system to cause hyperglycemia and impaired insulin secretion. In this review, recent information regarding endocrine disorders among opioid abusers is presented.

Opioid and cocaine combined effect on cocaine-induced changes in HPA and HPG axes hormones in men

Nalbuphine, a mixed micro-/kappa-opioid analgesic, may have potential as a new medication for the treatment of cocaine abuse. Kappa-opioid agonists functionally antagonize some abuse-related and locomotor effects of cocaine, and both kappa-selective and mixed micro-/kappa-opioids reduce cocaine self-administration by rhesus monkeys. Because cocaine's interactions with the hypothalamic-pituitary-adrenal and (HPA) hypothalamic-pituitary-gonadal (HPG) axes may contribute to its reinforcing properties, we examined the effects of cocaine alone and in combination with nalbuphine. Neuroendocrine effects of a single dose of cocaine alone (0.2 mg/kg, IV), with nalbuphine (5 mg/70 kg, IV)+cocaine (0.2 mg/kg, IV) in combination were compared in seven adult men (ages 18-35) who met DSM-IV criteria for current cocaine abuse. Cocaine alone, and in combination with nalbuphine was administered on separate test days under placebo-controlled, double blind conditions. Cocaine stimulated ACTH, cortisol, and LH, whereas cocaine+nalbuphine in combination produced a smaller increase in ACTH, and decreased cortisol and LH. Thus it appears that nalbuphine attenuated cocaine's effects on ACTH, cortisol, and LH. These data are consistent with our earlier report that nalbuphine modestly attenuated cocaine's positive subjective effects, and that the subjective and cardiovascular effects of cocaine+nalbuphine in combination were not additive.

Absence of an opioid stimulatory tone on growth hormone secretion in women with microprolactinoma

INTRODUCTION

Literature data suggest that prolactinoma is a tumor with a complex pathogenesis and that its growth is the result of changes at the pituitary and/or hypothalamic level. Abnormal release of hypothalamic factors (including endogenous opioid peptides) may contribute to prolactinoma development. An increased endogenous opioid tone (EOT) occurs in patients with prolactinoma, and seems to play an important role in pituitary secretion, as suggested by the ability of the opiate receptor antagonist naloxone to stimulate luteinizing hormone pulsatile secretion in these patients.

OBJECTIVE

To investigate the effect of the EOT on growth hormone (GH) secretion in women with prolactinoma.

DESIGN

Eleven women aged 30.4+/-6.7 years (range 20-41), with an established diagnosis of microprolactinoma, were studied. GH-releasing hormone (GHRH), 100 microg as an intravenous (i.v.) bolus, was administered with and without preadministration of i.v. naloxone, an opioid receptor antagonist, 2 mg as a bolus followed by a constant infusion of 1.6 mg/h. Blood samples were taken for 120 min after GHRH administration.

RESULTS

Naloxone did not affect the GH response to GHRH, measured as single times, mean peak values, or as integrated concentrations.

CONCLUSION

Our data suggest that an opioid stimulatory tone on GH secretion in women with prolactinoma is absent.

Effects of nalbuphine on anterior pituitary and adrenal hormones and subjective responses in male cocaine abusers

Nalbuphine (Nubain) is a mixed action mu-kappa agonist used clinically for the management of pain. Nalbuphine and other mu-kappa agonists decreased cocaine self-administration in preclinical models. Cocaine stimulates the hypothalamic-pituitary-adrenal (HPA) axis, but the effects of nalbuphine on the HPA axis are unknown. Analgesic doses (5 and 10 mg/70 kg) of IV nalbuphine were administered to healthy male cocaine abusers, and plasma levels of PRL, ACTH and cortisol were measured before and at 10, 17, 19, 23, 27, 31, 35, 40, 45, 60, 75, 105, and 135 min after nalbuphine administration. Subjective effects were measured on a Visual Analog Scale (VAS). Prolactin (PRL) increased significantly within 17 min (P=.04) and reached peak levels of 22.1+/-7.1 ng/ml and 54.1+/-11.3 at 60 min after low and high dose nalbuphine administration, respectively. VAS reports of "Sick," "Bad" and "Dizzy" were significantly higher after 10 mg/70 kg than after 5 mg/70 kg nalbuphine (P=.05-.0001), and were significantly correlated with increases in PRL (P=.05-.0003). However, sedation and emesis were observed only after a 10 mg/70 kg dose of nalbuphine. Interestingly, ACTH and cortisol levels did not change significantly after administration of either dose of nalbuphine. Taken together, these data suggest that nalbuphine had both mu- and kappa-like effects on PRL (PRL increase) but did not increase ACTH and cortisol.

An overview of the genetics of substance use disorders

Twin, family, and adoption studies show that genetic factors play a significant role in vulnerability to becoming addicted to drugs. Through a combination of genetic approaches, the variant alleles responsible for interindividual differences in susceptibility to addiction are being uncovered.

Suppression of thyrotropin by morphine in a severely stressed patient

Opiates suppress TSH in experimental animals but are reported to increase TSH in human subjects. We describe a patient in severe pain treated with morphine, whose previously normal TSH fell to a level usually associated with hyperthyroidism. After returning to a normal concentration, TSH again decreased with morphine administration. This suggests that, in contrast to the stimulation of TSH secretion that has been reported in unstressed experimental subjects, morphine can inhibit TSH secretion during stress in man as it does in experimental animals. This observation is consistent with the known sensitization of opiate receptors by stress. Consideration should be given to the possibility that severe suppression of TSH by opiates in stressed patients may induce clinically significant central hypothyroidism.

Links between the appetite regulating systems and the neuroendocrine hypothalamus: lessons from the sheep

The hypothalamus is integral to the regulation of energy homeostasis and the secretion of hormones from the pituitary gland. Consequently, hypothalamic systems may have a dual purpose in regulating both neuroendocrine function and appetite. To date, most studies investigating the interface between appetite and hormone secretion have been performed in rats or mice that have been acutely fasted or baring a genetic abnormality causing either obesity or aphagia. By contrast, various physiological models, including chronic food-restriction or photoperiodically driven changes in voluntary food intake, add further perspective to the issue. In this regard, sheep provide an innovative model whereby long-term changes in body weight or extended feeding rhythms can be investigated. This review compares and contrasts data obtained in different species with regard to the neuroendocrinology of appetite, and discusses the benefits and knowledge gained from using various nonrodent models with a particular emphasis on a ruminant species.

Morphine decreases the levels of the gene transcripts of growth hormone receptor and growth hormone binding protein in the male rat hippocampus and spinal cord

In this study we have characterized the nucleotide sequence of the cDNA for the growth hormone receptor (GHR) and examined the effects of morphine on the gene transcripts for GHR as well as GH binding protein (GHBP) in the male rat hippocampus and spinal cord. Using reverse transcription-polymerase chain reaction followed by cloning and sequencing, we found that the entire coding region of the GHR mRNA in the spinal cord is identical to that previously described in liver. A similar observation was made for the partially sequenced GHR cDNA from hippocampus. Northern blot analysis showed that in both tissues the levels of the transcripts for both GHR and GHBP were significantly decreased 4 h after a single dose of morphine. After 24 h the level of both transcripts did not significantly differ from that of control animals. This result indicates that the opiate does not only affect the receptor protein as shown earlier by binding studies, but also reduces the expression or turnover of the GHR as well as GHBP at the transcription level.

Endocrine consequences of long-term intrathecal administration of opioids

Intrathecal administration of opioids is a very efficient tool in the long-term control of intractable nonmalignant pain. However, despite the well known role of opioids in endocrine regulation, few data are available about possible effects on hypothalamic-pituitary function during this treatment. Seventy-three patients (29 men and 44 women; mean age, 49.2 +/- 11.7 yr) receiving opioids intrathecally for nonmalignant pain were enrolled for extensive endocrine investigation. At the time of hormonal determination, the mean duration of opioid treatment was 26.6 +/- 16.3 months; the mean daily dose of morphine was 4.8 +/- 3.2 mg. The control group consisted of 20 patients (11 men and 9 women; mean age, 54.2 +/- 14.0 yr) with a comparable pain syndrome but not treated with opioids. Decreased libido or impotency was present in 23 of 24 men receiving opioids. The serum testosterone level was below 9 nmol/L in 25 of 29 men and was significantly lower than that in the control group (P < 0.001). The free androgen index was below normal in 18 of 29 men and was significantly lower than that in the control group (P < 0.001). The serum LH level was less than 2 U/L in 20 of 29 men and was significantly lower than that in the control group (P < 0.001). Serum FSH was comparable in both groups. Decreased libido was present in 22 of 32 women receiving opioids. All 21 premenopausal females developed either amenorrhea or an irregular menstrual cycle, with ovulation in only 1. Serum LH, estradiol, and progesterone levels were lower in the opioid group. In all 18 postmenopausal females significantly decreased serum LH (P < 0.001) and FSH (P = 0.012) levels were found. The 24-h urinary free cortisol excretion was below 20 microg/day in 14 of 71 opioid patients and was significantly lower than that in the control group (P = 0.003). The peak cortisol response to insulin-induced hypoglycemia was below 180 microg/L in 9 of 61 opioid patients and was significantly lower than that in the nonopioid group (P = 0.002). The insulin-like growth factor I SD score was below -2 SD in 12 of 73 opioid patients and was significantly lower than that in the control group (P = 0.002). The peak GH response to hypoglycemia was below 3 microg/L in 9 of 62 subjects and was significantly lower than that in the control group (P = 0.010). Thyroid function tests and PRL levels were considered normal. No metabolic disturbances were recorded, apart from significantly decreased high density lipoprotein cholesterol levels (P = 0.041) and elevated total/high density lipoprotein cholesterol ratio (P = 0.008) in the opioid group compared to the control group. Supplementation with gonadal steroids improved sexual function in most patients. In conclusion, of all patients receiving intrathecal opioids, the large majority of men and all women developed hypogonadotropic hypogonadism, about 15% developed central hypocorticism, and about 15% developed GH deficiency. These findings suggest that further investigations are required to determine the need for systematic endocrine work-up in these patients and the necessity for substitutive therapy.

Expression of mu, kappa, and delta opioid receptor messenger RNA in the human CNS: a 33P in situ hybridization study

The existence of at least three opioid receptor types, referred to as mu, kappa, and delta, is well established. Complementary DNAs corresponding to the pharmacologically defined mu, kappa, and delta opioid receptors have been isolated in various species including man. The expression patterns of opioid receptor transcripts in human brain has not been established with a cellular resolution, in part because of the low apparent abundance of opioid receptor messenger RNAs in human brain. To visualize opioid receptor messenger RNAs we developed a sensitive in situ hybridization histochemistry method using 33P-labelled RNA probes. In the present study we report the regional and cellular expression of mu, kappa, and delta opioid receptor messenger RNAs in selected areas of the human brain. Hybridization of the different opioid receptor probes resulted in distinct labelling patterns. For the mu and kappa opioid receptor probes, the most intense regional signals were observed in striatum, thalamus, hypothalamus, cerebral cortex, cerebellum and certain brainstem areas as well as the spinal cord. The most intense signals for the delta opioid receptor probe were found in cerebral cortex. Expression of opioid receptor transcripts was restricted to subpopulations of neurons within most regions studied demonstrating differences in the cellular expression patterns of mu, kappa, and delta opioid receptor messenger RNAs in numerous brain regions. The messenger RNA distribution patterns for each opioid receptor corresponded in general to the distribution of opioid receptor binding sites as visualized by receptor autoradiography. However, some mismatches, for instance between mu opioid receptor receptor binding and mu opioid receptor messenger RNA expression in the anterior striatum, were observed. A comparison of the distribution patterns of opioid receptor messenger RNAs in the human brain and that reported for the rat suggests a homologous expression pattern in many regions. However, in the human brain, kappa opioid receptor messenger RNA expression was more widely distributed than in rodents. The differential and region specific expression of opioid receptors may help to identify targets for receptor specific compounds in neuronal circuits involved in a variety of physiological functions including pain perception, neuroendocrine regulation, motor control and reward.

The impact of sleep on gonadotropin secretion

Comparable to the period of pubertal transition, sleep also exerts profound effects on episodic gonadotropin secretion in adult women. During the early follicular phase of the menstrual cycle, a sleep-induced slowing of luteinizing hormone (LH) secretion occurs concurrently with a rise in LH pulse amplitude. A selective increase in opioidergic, but not in dopaminergic or serotoninergic activity may account for this decline in LH pulsatility. In addition, sleep-reversal studies have confirmed that the presence of sleep is essential for the expression of this neuroendocrine function. Since pituitary gonadotropin responsiveness to gonadotropin-releasing hormone (GnRH) is virtually unchanged during sleep, the reasons for the enhanced LH pulse amplitude remain unresolved. This sleep-associated increase in opioidergic activity may be restricted to a hypothalamic site, since opiate blockade does not modify the gonadotropin response to GnRH stimulation. In addition, circadian variability is shown in terms of gonadotropin secretion in regularly cycling women; this may again represent sleep-associated effects on gonadotropin release. Although the physiological importance of sleep-associated neuroendocrine phenomena remains basically unexplained, the observed changes in LH secretory profiles during sleep in adult women suggest close functional links between the endocrine secretion and the rest-activity cycle of the brain.

The role of the central nervous system in the psychoneuroendocrine disturbances of anorexia and bulimia nervosa

It has been well-recognized that starvation in anorexia and bulimia nervosa causes endocrine disturbances. Such disturbances may help understand why many people with eating disorders cannot easily reverse their illness since people with eating disorders often enter a downward spiraling circle with malnutrition sustaining and perpetuating the desire for more weight loss and dieting. Symptoms, such as obsessions and dysphoric mood, and altered appetitive behavior, may be exaggerated by neuropeptide alterations and thus contribute to this downward spiral. While neuropeptide disturbances do not appear to be a permanent feature or cause or anorexia nervosa, these disturbances are strongly entrenched, and are not easily corrected by improved nutrition or short-term weight normalization. This suggests that therapy should be sustained for months after nutritional normalization.

A clinical review of the adaptive role of vasopressin in migraine

Vasopressin is a naturally available neuropeptide that subserves important vasomotor, antinociceptive, behavior control, fluid and electrolyte balance, platelet aggregation and blood coagulation functions. This review focuses on the clinical phenomena of migraine that are likely to influence vasopressin bioavailability or efficacy as well as the modulating influence of vasopressin itself. As part of a complex homeostatic adjustment to stress and pain, the intricacies of vasopressin metabolism may have particular relevance to the pathophysiology of migraine.

Neuropeptide abnormalities in anorexia nervosa

Starvation-induced alterations of neuropeptide activity probably contribute to neuroendocrine dysfunctions in anorexia nervosa. For example, CRH alterations contribute to hypercortisolemia and NPY alterations may contribute to amenorrhea. Alterations of these peptides as well as opioids, vasopressin, and oxytocin activity could contribute to other characteristic psychophysiological disturbances, such as reduced feeding, in acutely ill anorexics. Such neuropeptide disturbances could contribute to the vicious cycle that has been hypothesized to occur in anorexia nervosa. That is, the consequences of malnutrition perpetuate pathological behavior.

Alcohol stimulates ACTH secretion in the rat: mechanisms of action and interactions with other stimuli

This review discusses some of the mechanisms through which alcohol (EtOH) alters the activity of the hypothalamic-pituitary-adrenal (HPA) axis. In adult rats, acute EtOH treatment increases plasma ACTH and corticosteroids levels primarily by stimulating the release of corticotropin-releasing factor (CRF) and possibly vasopressin (VP) from nerve terminals in the median eminence. Increased CRF gene transcription in the hypothalamus may also be important. The HPA axis remains activated during chronic EtOH exposure, although habituation may take place. Changes in the responsiveness of hypothalamic neurons, a phenomenon itself dependent in part on a number of intermediate secretagogues, as well as decreased pituitary responsiveness to VP, all play a role. Finally, the activity of the HPA axis is influenced by exposure to EtOH during embryonic development, with mature offspring showing hyporesponsiveness to many stimuli. These altered responses appear to be caused in part by changes in the synthesis/release CRF, possibly under the influence of nitric oxide. CRF, VP, ACTH, and corticosteroids are important regulators of the immune system, behavior, metabolic pathways, and reproductive parameters. Alcohol therefore may influence such functions through the pathological secretion of these hormones. A better understanding of the mechanisms through which the drug alters their release thus may permit the development of therapies designed to alleviate some of the consequences of alcoholism.

Spontaneous periodic hypothermia

Spontaneous periodic hypothermia is a rare syndrome of recurrent, centrally mediated hypothermia without an identifiable systemic cause or brain lesion. Most patients defend a temporarily lowered temperature "set point" during episodes of hypothermia, despite manifesting many well-known systemic consequences of core temperature hypothermia. No case of death directly attributable to an episode of spontaneous periodic hypothermia has been reported, although many of the serious systemic effects of hypothermia have been documented in these cases, so it is not unlikely that death may occur. The syndrome's cause, and that of Shapiro syndrome, remains unknown. Pharmacologic trials to date have been only modestly successful. Anticonvulsant agents, clonidine, and cyproheptadine appear the most likely to succeed, with cyproheptadine being a reasonable first choice. Given that the term "spontaneous periodic hypothermia" describes a syndrome, and not a pathophysiologic mechanism, it is likely to encompass a common eventuality, arrived at via several different pathways. One can postulate mechanisms such as structural abnormalities, trauma, infection, irritation, and degeneration involving strategic locations which create a focus for epileptic or other periodic dysfunction whose scope involves the centers for thermoregulation. The existence of 2 distinct, oppositional thermoregulatory centers would allow for speculation of similar mechanisms accounting for cases of both periodic hypo- and hyperthermia (61). Postmortem data regarding the hypothalamic and surrounding areas from future cases of Shapiro syndrome and spontaneous periodic hypothermia would be of great interest. Further, more sensitive in vivo testing methods are clearly needed. The role of PET or single photon emission computed tomography (SPECT) with technetium 99m-labeled hexamethylpropylene amine oxime (Tc 99m HMPAO) performed acutely during an episode remains to be characterized (64, 103, 105). The term "diencephalic epilepsy" may in fact be accurate, given the periodic episodes of the case presented here and similar cases resulting from non-generalized seizure activity, with or without an underlying predisposing lesion. The label diencephalic epilepsy has been merely speculative so far, however, as definitive evidence of seizure activity has not been documented. Further, it is expected that the descriptive terms "spontaneous periodic hypothermia" and "episodic spontaneous hypothermia with hyperhidrosis" will outlive their usefulness as researchers gain greater understanding of this syndrome, and be replaced with a more pathophysiologically meaningful nomenclature.

Role of GABA and opioids in the regulation of the vasopressin response to physical exercise in normal men

The present study was undertaken in order to establish the possible involvement of GABAergic and/or opioid pathways in the mechanism underlying the arginine-vasopressin (AVP) response to physical exercise. After fasting overnight, seven subjects were tested on four mornings at least 1 week apart. Exercise was performed on a bicycle ergometer. The workload was gradually increased at 3 min intervals until exhaustion and lasted about 15 min in all subjects. Tests were carried out under administration of placebo, the opioid antagonist naloxone (10 mg as an i.v. bolus injection), the GABAergic agonist sodium valproate (600 mg in three divided doses orally) or naloxone plus sodium valproate. Plasma AVP levels rose 4-fold during exercise. The administration of naloxone did not modify, whereas sodium valproate completely abolished the plasma AVP rise during exercise. When naloxone was given together with sodium valproate, AVP rose 3-fold in response to exercise. These data suggest the involvement of a GABAergic mechanism in regulation of the AVP response to physical exercise in men. Furthermore, the data argue against a role of naloxone sensitive endogenous opioids in the control of AVP during exercise, whereas they suggest a partial opioid mediation of the GABAergic inhibitory action.

Current concepts of beta-endorphin physiology in female reproductive dysfunction

beta-Endorphin has a role in the regulation of the normal menstrual cycle and possibly in the onset of puberty. We have reviewed the evidence pointing to an alteration in this neuropeptide that may contribute to the pathogenesis of various reproductive dysfunctions. Elevated or high levels of beta-endorphin have been associated with exercise-associated amenorrhea, stress-associated amenorrhea, and polycystic ovarian syndrome. Depressed or low levels of beta-endorphin have been associated with PMS and menopause. Alterations in the levels of beta-endorphin may change the pulsatile release of GnRH via noradrenergic and/or dopaminergic pathways. We have primarily focused on beta-endorphin as representative of the endogenous opioid peptides, but other opioid peptides may also contribute to the pathogenesis of various types of reproductive dysfunction. Perhaps it will become possible to characterize and hone our understanding of the function of beta-endorphin and the other substances composing the endogenous opioid peptides. A better understanding of their role in physiological as well as pathophysiological processes may allow for the development of rational approaches to the treatment of specific disorders pertaining to reproduction. Many questions remain unanswered. Among the most relevant are: what is the precise mechanism of action by which beta-endorphin exerts its influence on pulsatile GnRH release? Is there a functional relationship between CNS and peripheral (serum) levels of beta-endorphin? Are the detected changes in beta-endorphin levels merely associated, or are they a cause of a particular disorder? Since it took almost 40 years between the time prostaglandins were first discovered and eventual realization of their clinical application, it may take some time before the beta-endorphin story is complete.

Neuroendocrine control of male reproductive function. The opioid system as a model of control at multiple sites

It is known that the same peptide can be identified in different secretory tissues and in the central nervous system (CNS). We now provide evidence that the same peptides can be found in different organs related to the control of a single function, and speculate on the possibility that this reflects a common neuroendocrine programming. Endogenous opioid peptides (EOP) inhibit the reproductive function acting via the CNS. EOP inhibit gonadotropin secretion in rodents and humans via inhibition of GnRH release and have direct inhibitory actions at the pituitary level via specific binding sites on the gonadotrophs. However, EOP can also be synthesized in the testis and in different compartments of the male genital tract. Several findings indicate that EOP of the reproductive tract have a local, paracrine role. These include: (1) the detection of significant beta-endorphin (beta-EP) production by rat Leydig cells (Lc) in cultures; (2) the hormonal regulation of Lc beta-EP production by positive (gonadotropins) and negative (steroids, glucocorticoids, GnRH) factors; (3) the presence of opioid binding sites (Kd in the nanomolar range) in tubular homogenates and Sertoli cells (Sc) in culture of adult and immature rat testes; (4) the inhibition of basal and FSH-stimulated ABP production by Sc in culture when chronically exposed to beta-EP treatment; (5) the detection of high levels of beta-EP and met-enkephalin in human semen with values 6-12 times higher than in plasma; (6) the evidence for inhibitory functions of seminal opioids on sperm motility, vas deferens muscle contraction and partner immune system. Thus the same peptides, i.e. EOP, may control the reproductive function at multiple sites, operating as a multimessenger system in which the central and peripheral level are unified by the common chemical and inhibitory nature of the message.

The neuropsychiatry of post-traumatic stress disorder

The publication of DSM-III introduced the diagnosis Post-Traumatic Stress Disorder (PTSD), thus providing, for the first time, a framework for studying the consequences of extremely stressful events. Previously, traumatic neuroses had attracted a wide variety of labels - as wide as the experiences that produced them. Competing explanations in psychological and biological terms have characterised the approach to these disorders, and social and legal issues have added to the confusion. In recent years, psychosocial issues have tended to dominate the literature in relation to PTSD. While acknowledging the importance of such phenomenological and psychosocial approaches, this paper seeks to redress the balance by focusing on a biological perspective.

Controversies in plastic surgery: suction-assisted lipectomy (SAL) and the hCG (human chorionic gonadotropin) protocol for obesity treatment

The advent of SAL (suction-assisted lipectomy) has dramatically increased the number of obese patients coming to our consultation offices. Despite several articles suggesting a conservative approach to fat suction, some reports insinuate that SAL might be a useful tool for obesity treatment. This hypothesis is refuted by a vast body of evidence that concludes that the adipose tissue may regenerate in adult humans. Therefore, surgical procedures are not advised as the method of choice to manage the disease. On the other hand, the terms obesity and being overweight may not be interchangeable. Obesity may be a disease whereas being overweight is a sign of the disease. Consequently, proper preoperative selection of candidates for SAL becomes mandatory. The hCG (human chorionic gonadotropin) method for obesity treatment appears to be a complete program for the management of obesity. It contains pharmacologic, dietetic, and behavior modification aspects in a 40-day course of treatment. Some data suggest hCG to be lipolytic, thus explaining former clinical observations regarding body fat redistribution in treated patients. hCG commercial preparations contain beta-endorphin, an opioid peptide linked to mood behavior. This article speculates on the possible actions of the complex hCG beta-endorphin in the neuromodulation of mood and energy metabolism. The method comprises a behavior modification that helps in handling the patient better. There are some correlations between a current behavior modification program and the basic guidelines contained in the hCG protocol. Thus, the hCG method appears to be a reasonable alternative in the management of a long-standing, unsolved problem of human metabolism.

Reduced cerebrospinal fluid levels of immunoreactive pro-opiomelanocortin related peptides (including beta-endorphin) in anorexia nervosa

The discovery that the endogenous opioid peptides contribute to the modulation of appetitive behavior and neuroendocrine function has raised questions as to whether disturbances of opioids contributes to the pathophysiology of eating disorders. To assess central nervous system (CNS) beta-endorphin in patients with anorexia nervosa we measured cerebrospinal fluid (CSF) beta-endorphin concentrations before, and at intervals after weight correction. In addition, we measured three sister peptides (beta-lipotropin, adrenocorticotropic hormone (ACTH), and the N-terminal fragment) derived from the same precursor molecule, pro-opiomelanocortin (POMC) to determine whether possible disturbances might extend to sister peptides. Underweight anorectics (58 +/- 5% of average body weight (ABW), n = 10) had significantly lower CSF concentrations of all 4 peptides compared to healthy controls (102 +/- 10% ABW, n = 11). CSF concentrations of all 4 POMC-related peptides were found to be significantly increased when the same anorectics were restudied 4 to 6 weeks after weight gain (83 +/- 4% ABW). After weight gain, levels of CSF beta-endorphin, beta-lipotropin, and ACTH were similar to controls, whereas levels of CSF N-POMC remained significantly less than controls. Another group of women, previously underweight with anorexia nervosa, but weight-restored (93 +/- 11% ABW, n = 12) for greater than 1 year had CSF concentrations of all 4 POMC-related peptides that were similar to controls. We conclude that underweight anorectics have state-associated disturbances of CNS beta-endorphin as well as other POMC-related peptides. These abnormalities are part of the neurobiological syndrome of anorexia nervosa and may contribute to the characteristic alterations in behavior and neuroendocrine function.

Naloxone has no effect on hormonal responses to ECT in man

Although there is clear evidence in other species that electroconvulsive therapy (ECT) is associated with changes in endogenous opioid activity, there are few data available for such a role in man. Since ECT leads to changes in certain hormones in man, particularly serum prolactin, it was postulated that such changes may represent an increase in endogenous opioids. Six unmedicated patients with major depressive illness were therefore administered either 4 mg i.v. of the opiate antagonist naloxone or a saline control infusion, just before successive treatments with ECT, in a double-blind, randomized crossover design. Blood was sampled at intervals for serum prolactin, growth hormone (GH), and cortisol. ECT led to a clear rise in serum prolactin, with no significant change seen in either serum GH or serum cortisol during the 20-min sampling interval. Naloxone had no significant effect on any of these changes. It is concluded that the rise in serum prolactin in response to ECT is not mediated by changes in endogenous opioid peptide activity.

Prolactin, growth hormone and thyrotropin-thyroid hormone secretion during stress states in man

Changes in hormone secretion and/or metabolism almost constantly accompany stressful events. The hormonal response to stress is directly related to the intensity of the stimulus, and greatly depends on the individual's perception of potentially stressful situations. Hypoglycaemia, surgery and exercise represent physical, metabolic and psychological stressful events where the activation of the endocrine system plays a great role. These endocrine responses also include the secretion of GH and prolactin, but the response pattern varies with the stimulus. Hypoglycaemia, exercise and surgery are potent stimuli to GH and prolactin release, both in men and women. The available data suggest that prolactin is more responsive than GH to surgical stress, whereas physical exercise and hypoglycaemia preferentially stimulate GH secretion. Prolactin levels during hypoglycaemia rise solely when symptomatic neuroglycopenia is achieved. By contrast, prolactin and GH responses to purely psychological stress are rarely seen, although some forms of reproductive stress may potentiate prolactin release in women. A teleologically satisfactory rationale for the acute GH and prolactin rise in response to these stressful stimuli is not clearly apparent in man. No definite metabolic activity of prolactin on intermediate metabolism has been demonstrated, although prolactin is mildly diabetogenic. The known metabolic actions of GH do not appear to be critical during surgery or acute hypoglycaemia, although GH probably participates in the regulation of metabolic homeostasis during chronic hypoglycaemia and chronic exercise. Changes in secretion and/or metabolism of hypothalamic neurotransmitters can increase the secretion of GH by increasing the secretion of GHRH or by decreasing the secretion of somatostatin. The prolactin rise is brought about by either a decrease in dopamine activity, an increased secretion of a hypothetical PRF, or by both mechanisms. Since multiple neuronal pathways converge on the hypothalamus from many other parts of the brain, the pronounced effects of hypoglycaemia, exercise and surgery on the secretion of GH and prolactin also reflect the action of different and complex neural inputs on the activity of the hypothalamic-pituitary axis. However, the morpho-functional mapping of these excitatory pathways still remains incomplete. TSH secretion is tightly regulated by the negative feed-back mechanism exerted by thyroid hormones. The small changes in TSH level observed during surgery and physical exercise seem to reflect mainly alterations in peripheral T4 metabolism.(ABSTRACT TRUNCATED AT 400 WORDS)

Interaction of thyrotrophin releasing hormone and the enkephalin analogue DAMME on pituitary hormone secretion

Because TRH counteracts the inhibitory effect of opiate peptides on LH secretion in cultured cells from normal pituitaries, six normal postmenopausal women were studied to determine whether TRH interacts in vivo with opioid peptides in the regulation of pituitary hormone secretion. At two different times a constant 3 h infusion of either saline or TRH (5 micrograms/min) was initiated. At 60 min a 250 micrograms bolus of the opiate agonist peptide D-Ala2-MePhe4-met-enkephalin-0-ol (DAMME) was injected in one of the two saline and TRH infusion tests. The four treatments, i.e. saline infusion alone, saline infusion with a DAMME bolus, TRH infusion alone; and TRH infusion with DAMME bolus were given at random with an interval of at least 7 d. Blood samples were taken every 15 min during the 3 h study. DAMME induced a significant fall (P less than 0.05) in serum LH (from 35 +/- 8.5 to 18.3 +/- 5.1 mIU/ml) (mean +/- SEM) without significantly affecting FSH levels (from 29 +/- 11.2 to 26.9 +/- 12.4 mIU/ml). These changes were not antagonized by the continuous infusion of TRH. PRL had a monophasic response pattern to continuous isolated TRH infusion; the basal levels increased from 4.2 +/- 1.2 to 24.5 +/- 6.8 ng/ml at 30 min and then slowly decreased with a plateau from 90 min until the end of the study. DAMME administration at 60 min induced a significant second peak of PRL secretion (44 +/- 6.5 ng/ml) 30 min later (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)