Opioid control of gonadotrophin secretion in humans

Long-term opioid treatment and endocrine measures in chronic non-cancer pain patients

BACKGROUND

The prevalence of chronic non-cancer pain (CNCP) has increased dramatically the past decades, which combined with indiscriminate use of prescribed opioids has become a public health problem. Endocrine dysfunction may be a complication of long-term opioid treatment (L-TOT), but the evidence is limited. This study aimed at investigating the associations between L-TOT and endocrine measures in CNCP patients.

METHODS

Cortisol (spot and after stimulation), thyrotropin (TSH), thyroxin (T4), insulin-like growth factor 1 (IGF-1), prolactin (PRL), 17-hydroxyprogesterone, androstenedione, dehydroepiandrosterone (DHEAS), sex hormone-binding globulin (SHBG), total testosterone (TT) and free testosterone (fT) were measured. Group comparisons were done between CNCP patients in L-TOT and controls as well as between patients on high- or low-dose morphine equivalents.

RESULTS

Eighty-two CNCP patients (38 in L-TOT and 44 controls not receiving opioids) were included. Low TT (p = 0.004) and fT concentrations (p < 0.001), high SHBG (p = 0.042), low DEAS (p = 0.017) and low IGF-1 (p = 0.003) in men were found when comparing those in L-TOT to controls and high PRL (p = 0.018), low IGF-1 standard deviation score (SDS) (p = 0.006) along with a lesser, but normal cortisol response to stimulation (p = 0.016; p = 0.012) were found when comparing L-TOT to controls. Finally, a correlation between low IGF-1 levels and high opioid dose was observed (p < 0.001).

CONCLUSIONS

Our study not only supports previous findings but even more interestingly disclosed new associations. We recommend future studies to investigate endocrine effects of opioids in larger, longitudinal studies. In the meanwhile, we recommend monitoring endocrine function in CNCP patients when prescribing L-TOT.

SIGNIFICANCE

This clinical study found associations between L-TOT, androgens, growth hormone and prolactin in patients with CNCP compared to controls. The results support previous studies as well as add new knowledge to the field, including an association between high opioid dose and low growth hormone levels. Compared to existing research this study has strict inclusion/exclusion criteria, a fixed time period for blood sample collection, and adjustments for potential confounders, which has not been done before.

Decreased cerebral opioid receptors availability related to hormonal and psychometric profile in restrictive-type anorexia nervosa

PURPOSE

The opioid system role in anorexia nervosa (AN) pathophysiology is still unclear since conflicting results were reported on peripheral and cerebrospinal fluid opioids levels. The study main aim was to evaluate cerebral AN opiate receptor availability by using [¹¹C] diprenorphine, a ligand with non-selective binding.

METHODS

In vivo [¹¹C]diprenorphine cerebral non-displaceable binding potential (BP_ND) evaluated by PET imaging was compared between three groups : 17 undernourished restrictive-type AN patients (LeanAN), 15 AN patients having regained normal weight (RecAN) and 15 controls. A lower BP_ND may account for an increased opioid tone and vice versa. Serum hormones and endogenous opioids levels, eating-related and unspecific psychological traits were also evaluated.

RESULTS

Compared to controls, LeanAN and RecAN patients had decreased [¹¹C]diprenorphine BP_ND in middle frontal gyrus, temporo-parietal cortices, anterior cingulate cortex and in left accumbens nucleus. Hypothalamo-pituitary (H-P), left amygdala and insula BP_ND was found decreased only in LeanAN and that of putamen only in RecAN. LeanAN presented higher dynorphin A and enkephalin serum levels than in controls or RecAN. Inverse correlations were found in total group between : 24 h mean serum cortisol levels and anterior cingulate gyrus or insula BP_ND; eating concern score and left amygdala BP_ND. Positive correlation were found between leptin and hypothamus BP_ND; LH and pituitary BP_ND.

CONCLUSIONS

Low opiate receptor availability may be interpreted as an increased opioid tone in areas associated with both reward/aversive system in both AN groups. The relationship between the opioid receptors activity and hypercorticism or specific psychometric scores in some of these regions suggests adaptive mechanisms facing anxiety but also may play a role in the disease perpetuation.

Hormone Replacement Therapy and Opioid Tapering for Opioid-Induced Hypogonadism Among Patients with Chronic Noncancer Pain: A Systematic Review

OBJECTIVE

To systematically review evidence addressing the efficacy of testosterone replacement therapy (TRT) and opioid tapering for opioid-induced hypogonadism among patients with chronic noncancer pain.

STUDY DESIGN

Systematic review of randomized controlled trials (RCTs) and observational studies.

METHODS

We searched MEDLINE, CINAHL, AMED, CENTRAL, CINAHL, DARE, EMBASE, and PsycINFO through August 2017. Eligible studies enrolled ≥10 patients with chronic noncancer pain and opioid-induced hypogonadism and reported the effect of TRT or opioid tapering on a patient-important outcome collected ≥14 days after treatment. Pairs of reviewers independently screened for eligible studies, assessed risk of bias, and extracted data. We used the GRADE approach to rate quality of evidence.

RESULTS

Of 666 abstracts reviewed, five studies including one RCT (N = 84) and four observational studies (N = 157) were eligible. No studies explored the effect of opioid tapering for opioid-induced hypogonadism. Very low-quality evidence found that TRT was associated with improvements in pain (median reduction of 2 points on the 11-point numerical rating scale for pain; 95% confidence interval [CI] = -1.4 to -2.6; minimally important difference [MID] = 2 points), and emotional functioning (mean increase of 9 points on the 100-point SF-36 Mental Component Summary score; 95% CI = 4.40 to 13.60; MID = 5 points). Low-quality evidence suggested that TRT had no effect on sleep quality, sexual function, physical functioning, role functioning, or social functioning; very low-quality evidence suggested no association with depressive symptoms.

CONCLUSIONS

Low-quality to very low-quality evidence suggests that TRT may improve pain and emotional functioning, but not other outcomes, in chronic noncancer pain patients with opioid-induced hypogonadism.

Estrogenic influences in pain processing

Gonadal hormones not only play a pivotal role in reproductive behavior and sexual differentiation, they also contribute to thermoregulation, feeding, memory, neuronal survival, and the perception of somatosensory stimuli. Numerous studies on both animals and human subjects have also demonstrated the potential effects of gonadal hormones, such as estrogens, on pain transmission. These effects most likely involve multiple neuroanatomical circuits as well as diverse neurochemical systems and they therefore need to be evaluated specifically to determine the localization and intrinsic characteristics of the neurons engaged. The aim of this review is to summarize the morphological as well as biochemical evidence in support for gonadal hormone modulation of nociceptive processing, with particular focus on estrogens and spinal cord mechanisms.

Hypogonadism and low bone mineral density in patients on long-term intrathecal opioid delivery therapy

OBJECTIVES

This study aimed to investigate the hypothalamic-pituitary-gonadal axis in a sample of male patients undertaking intrathecal opioid delivery for the management of chronic non-malignant pain and the presence of osteopaenia and/or osteoporosis in those diagnosed with hypogonadism.

DESIGN

Observational study using health data routinely collected for non-research purposes.

SETTING

Department of Pain Management, Russells Hall Hospital, Dudley, UK.

PATIENTS

Twenty consecutive male patients attending follow-up clinics for intrathecal opioid therapy had the gonadal axis evaluated by measuring their serum luteinising hormone, follicle stimulating hormone, total testosterone, sex hormone binding globulin and calculating the free testosterone level. Bone mineral density was measured by DEXA scanning in those patients diagnosed with hypogonadism.

RESULTS

Based on the calculated free testosterone concentrations, 17 (85%) patients had biochemical hypogonadism with 15 patients (75%) having free testosterone <180 pmol/L and 2 patients (10%) between 180 and 250 pmol/L. Bone mineral density was assessed in 14 of the 17 patients after the exclusion of 3 patients. Osteoporosis (defined as a T score ≤-2.5 SD) was detected in three patients (21.4%) and osteopaenia (defined as a T score between -1.0 and -2.5 SD) was observed in seven patients (50%). Five of the 14 patients (35.7%) were at or above the intervention threshold for hip fracture.

CONCLUSIONS

This study suggests an association between hypogonadism and low bone mass density in patients undertaking intrathecal opioid delivery for the management of chronic non-malignant pain. Surveillance of hypogonadism and the bone mineral density levels followed by appropriate treatment may be of paramount importance to reduce the risk of osteoporosis development and prevention of fractures in this group of patients.

Hypogonadism in an opioid dependent man

We describe here the case of a 45-year-old man with a chronic history of heroin abuse who has received methadone maintenance therapy for 12 years. At admission, on this occasion, for stabilisation on methadone, he reported a two-year history of painful gynaecomastia and testicular atrophy. Investigations revealed abnormal sex hormone levels. Liver function tests, thyroid function tests, Brain (pituitary) MRI and viral screens were normal. Following assessment and abnormality in two morning total testosterone level measurements he was diagnosed with hypogonadism secondary to opioid use. Although he had a previous history of alcohol abuse, he was abstinent from alcohol use for five years at time of assessment. He was commenced on parenteral testosterone replacement with therapeutic benefit. In light of the increased use of opioids, it is important to recognise and manage the endocrine complications of opioid use. The need for an empathic and adequate sexual history, physical examination and investigation is essential in patients who use opioids to ensure that cases of hormonal dysfunction are detected early and managed appropriately.

Estrogen signaling in hypothalamic circuits controlling reproduction

It is well known that many of the actions of 17β-estradiol (E2) in the central nervous system are mediated via intracellular receptor/transcription factors that interact with steroid response elements on target genes. However, there is compelling evidence for membrane steroid receptors for estrogen in hypothalamic and other brain neurons. Yet, it is not well understood how estrogen signals via membrane receptors and how these signals impact not only membrane excitability but also gene transcription in neurons that modulate GnRH neuronal excitability. Indeed, it has been known for some time that E2 can rapidly alter neuronal activity within seconds, indicating that some cellular effects can occur via membrane delimited events. In addition, E2 can affect second messenger systems including calcium mobilization and a plethora of kinases to alter cell signaling. Therefore, this review will consider our current knowledge of rapid membrane-initiated and intracellular signaling by E2 in hypothalamic neurons critical for reproductive function.

The role of opioid system and its interaction with sympathetic nervous system in the processing of polycystic ovary syndrome modeling in rat

BACKGROUND

This study was conducted to evaluate the effect of interaction of sympathetic and opioid systems in the processing of polycystic ovary syndrome modeling in rat.

METHODS

Ninety adult female rats (7-8 weeks of age) were treated with EV for 60 days for induction of follicular cysts (PCO modeling). Clonidine and yohimbine were used for sympathic agonist and antagonist and nalterxone was used for opioid system inhibition. Interactions of two systems were studied.

RESULTS

Our results indicate that both systems and interaction of two systems are effective in processing modeling of PCOS in rat. Interaction of two system drugs decreased estradiol (P < 0.05). Qualitative analysis showed that the bulk of cysts and corpus lutea and dominant follicles were increased in PCO rats in comparison with control group.

CONCLUSION

Therefore there could been an alternative in the treatment of the polycystic ovary syndrome in the rat by using adrenergic agonist and antagonists in combination with naltrexone.

Characterization of the potent gonadotropin-releasing activity of RF9, a selective antagonist of RF-amide-related peptides and neuropeptide FF receptors: physiological and pharmacological implications

Identification of RF-amide-related peptides (RFRP), as putative mammalian orthologs of the avian gonadotropin-inhibitory hormone, has drawn considerable interest on its potential effects and mechanisms of action in the control of gonadotropin secretion in higher vertebrates. Yet, these analyses have so far relied mostly on indirect approaches, while direct assessment of their physiological roles has been hampered by the lack of suitable antagonists. RF9 was recently reported as a selective and potent antagonist of the receptors for RFRP (RFRPR) and the related neuropeptides, neuropeptide FF (NPFF) and neuropeptide AF (NPFF receptor). We show here that RF9 possesses very strong gonadotropin-releasing activities in vivo. Central administration of RF9 evoked a dose-dependent increase of LH and FSH levels in adult male and female rats. Similarly, male and female mice responded to intracerebroventricular injection of RF9 with robust LH secretory bursts. In rats, administration of RF9 further augmented the gonadotropin-releasing effects of kisspeptin, and its stimulatory effects were detected despite the prevailing suppression of gonadotropin secretion by testosterone or estradiol. In fact, blockade of estrogen receptor-alpha partially attenuated gonadotropin responses to RF9. Finally, systemic administration of RF9 modestly stimulated LH secretion in vivo, although no direct effects in terms of gonadotropin secretion were detected at the pituitary in vitro. Altogether, these data are the first to disclose the potent gonadotropin-releasing activity of RF9, a selective antagonist of RFRP (and NPFF) receptors. Our findings support a putative role of the RFRP/gonadotropin-inhibitory hormone system in the central control of gonadotropin secretion in mammals and have interesting implications concerning the potential therapeutic indications and pharmacological effects of RF9.

The impact of opioids on the endocrine system

OBJECTIVES

Opioids have been used for medicinal and analgesic purposes for centuries. However, their negative effects on the endocrine system, which have been known for some times, are barely discussed in modern medicine. Therefore, we conducted a systematic review of the impact of opioids on the endocrine system.

METHODS

A review of the English language literature on preclinical and clinical studies of any type on the influence of opioids on the endocrine system was conducted. Preliminary recommendations for monitoring and managing these problems were provided.

RESULTS

Long-term opioid therapy for either addiction or chronic pain often induces hypogonadism owing to central suppression of hypothalamic secretion of gonadotropin-releasing hormone. Symptoms of opioid-induced hypogonadism include loss of libido, infertility, fatigue, depression, anxiety, loss of muscle strength and mass, osteoporosis, and compression fractures in both men and women; impotence in men; and menstrual irregularities and galactorrhea in women. In view of the increased use of opioids for chronic pain, it has become increasingly important to monitor patients taking opioids and manage endocrine complications. Therefore, patients on opioid therapy should be routinely screened for such symptoms and for laboratory abnormalities in sex hormones.

CONCLUSIONS

Opioid-induced hypogonadism seems to be a common complication of therapeutic or illicit opioid use. Patients on long-term opioid therapy should be prospectively monitored, and in cases of opioid-induced hypogonadism, we recommend nonopioid pain management, opioid rotation, or sex hormone supplementation after careful consideration of the risks and benefits.

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.

Buprenorphine and methadone treatment of opiate dependence during pregnancy: comparison of fetal growth and neonatal outcomes in two consecutive case series

AIM

To compare the effects of fetal buprenorphine and methadone exposure during maintenance treatment of pregnant heroin dependent subjects.

DESIGN AND SETTING

A population based comparison of consecutive, prospectively followed buprenorphine-exposed pregnancies in Stockholm County, Sweden, to retrospectively analyzed consecutive methadone-exposed pregnancies.

PARTICIPANTS

All 47 pregnancies in 39 women with opiate dependence and buprenorphine maintenance treatment 2001-2006, and all 35 methadone-exposed pregnancies (26 women) 1982-2006 in Stockholm County.

MEASUREMENTS

Intrauterine growth, birth outcome, malformations, neonatal adaptation, withdrawal syndrome and infant mortality.

FINDINGS

Buprenorphine-exposed pregnancies resulted in 47 uneventful live births (2 twin pairs), 1 stillbirth (for which no explanation was found) and 1 miscarriage. The birth weight of the infants was normal. Neonatal abstinence syndrome (NAS) occurred in 19 cases (40.4%), the majority mild in nature and only 7 (14.9%) needing withdrawal treatment. Compared to 35 infants born after intrauterine methadone exposure at the same hospital since 1982 (77.8% of them exhibiting NAS and 52.8% needing withdrawal treatment), there were significant advantages with buprenorphine treatment: birth weight was higher, due to longer gestation. Incidence of NAS of any intensity, as well as incidence of NAS that required pharmacological treatment was lower, while length of hospital stay was shorter. When buprenorphine treatment started pre-conception, NAS at any level was significantly less frequent than in subjects with post-conception initiated treatment (7/27, 26%; 12/20, 60%, respectively).

CONCLUSIONS

Data from this non-randomized comparison suggest that buprenorphine may offer advantages for treatment of opiate dependence during pregnancy.

A red clover (Trifolium pratense) phase II clinical extract possesses opiate activity

Trifolium pratense (TP) is one of the most common herbs for the relief of menopausal symptoms. Little is known about its mechanisms of action. In this study, we investigated the affinity of TP at the mu- and delta-opiate receptors. We found that a clinically used TP extract bound to the mu-opiate receptor with a high affinity (K(i)=9.7+/-1.6microg/ml). The same extract was also found to have affinity at the delta-opiate receptor with K(i) of 15.9+/-2.4microg/ml. These results for the first time suggest a potential new mechanism of action of TP at the opiate receptors. Given the essential role of the opioid system in regulating temperature, mood, and hormonal levels and actions, this may explain in part the beneficial effect of TP in alleviating menopausal symptoms.

Age of menopause and menopausal symptoms in HIV-infected women

The objective of this study was to examine the median age of menopause, factors associated with postmenopausal status, and the prevalence of menopausal symptoms in HIV-infected women. We surveyed 120 HIV-infected women between 40 and 57 years old who attended an inner city infectious diseases clinic. Ninety-five percent of the women surveyed were African American and almost half of the women (44%) had used methadone, heroin, cocaine, marijuana, or a combination of these drugs within the past 6 months. Eighty-seven percent had smoked cigarettes at least some time during their life and 45% drank alcohol between the ages of 40 and 49 years old. Thirty women were postmenopausal (having no menstrual periods in the previous 12 consecutive months), 31 were perimenopausal (having 1-11 periods within the previous 12 months), and 59 were premenopausal (having 12 or more periods within the previous 12 months). The median age of menopause was 50 years old (95% confidence interval = 49, 53). In a multivariate model, methadone use within the past 6 months was associated with postmenopausal status. We did not find an association between postmenopausal status and body mass index, number of pregnancies, CD4 cell counts, HIV viral load, individual and grouped antiretroviral therapies, cigarette smoking, and current or past oral contraceptive use. In multivariate analysis, postmenopausal status was associated with hot flashes and cocaine use was associated with vaginal dryness.

Proopiomelanocortin gene expression and β-endorphin localization in the pituitary, testis, and epididymis of stallion

Proopiomelanocortin (POMC) is a precursor protein that contains the sequences of several bioactive peptides including adrenocorticotropin (ACTH), beta-endorphin (beta-EP), and melanocyte-stimulating-hormone (MSH). POMC is synthesized in the pituitary gland, brain, and many peripheral tissues. Immunoreactive POMC-derived peptides as well as POMC-like mRNA have been evidenced in several nonpituitary tissues, thus suggesting that POMC is actively synthesized by these tissues. The present study was aimed at evaluating if also in the case of stallion POMC-derived peptide, beta-EP, is produced locally in the testis, thus playing effects in a paracrine/autocrine fashion. To investigate this hypothesis the POMC gene expression was analyzed using 3' RACE-PCR and Northern Blot approaches in the testis and epididimys of stallion; moreover, immunocytochemical localization for beta-EP was also performed through confocal laser microscopy. The immunofluorescence results showed a positive beta-EP reaction not only in cellular nest of pituitary but also in the testis and genital tract of stallion, which function could be related with sperm mobility. Such role seem not to be no dependent on the peptide synthesized locally, because the molecular biology approach demonstrated the presence of POMC transcript in the pituitary only. In fact the Northern Blot analysis showed the presence of a single POMC transcript in the pituitary while no signal was detected in the testis and epididimys. The same results were obtained by applied 3' RACE-PCR analysis. In conclusion, opioid-derived peptide beta-EP is present in the genital tract of stallion, but is not locally produced as in other mammalian, and nonmammalian models; its possible biological function at testicular level could be linked to a long-loop feed-back mechanisms.

Immunity and β-Endorphin Concentrations in Hypothalamus and Plasma in Rats with Steroid-Induced Polycystic Ovaries: Effect of Low-Frequency Electroacupuncture1

The human endocrinological disorder polycystic ovary syndrome (PCOS) is a common cause of reproductive failure. Even though the cause of PCOS is unknown, hormone and immune disturbances as well as hyperactivity in the sympathetic nervous system are likely to be involved in the pathogenesis of the disease. The present study was undertaken to elucidate if rats with estradiol valerate (EV)-induced polycystic ovaries (PCO) have altered beta-endorphin concentrations in the hypothalamus and in plasma and if they have alterations in circulating immune cell populations and the activity. Repeated low-frequency (2 Hz) electroacupuncture (EA) treatments are known to modulate the release of beta-endorphin, immune responses, and the activity in the autonomic nervous system. We therefore also investigated the effect of EA treatments on the beta-endorphin and the immune systems. Low-frequency EA was given 12 times, 25 min each, over 30 days starting 2-3 days after i.m. injection of EV. The beta-endorphin concentrations in the hypothalamus and in plasma as well as the frequencies of CD4+ T cells and CD8+ T cells were significantly lower in EV-injected control rats as compared to oil-injected control rats. Repeated EA treatments in EV-injected rats significantly increased beta-endorphin concentrations in the hypothalamus. In conclusion, these findings show that both the beta-endorphinergic and the immune system are significantly impaired in rats with steroid-induced PCO and that repeated EA treatments can restore some of these disturbances.

Symptomatic hypogonadism in male survivors of cancer with chronic exposure to opioids

BACKGROUND

Profound hypogonadism has been noted in patients receiving intrathecal opioids. The purpose of the current study was to determine whether chronic consumption of oral opioids by male survivors of cancer also would lead to central hypogonadism and whether this hypogonadism was associated with symptoms of sexual dysfunction, fatigue, anxiety, and depression.

METHODS

A case-control study was conducted at The University of Texas M. D. Anderson Cancer Center (Houston, TX), in which 20 patients who were chronically consuming opioids were compared with 20 matched controls. Patients completed the Sexual Desire Inventory (SDI), the Hospital Anxiety and Depression Scale (HADS), the Functional Assessment of Chronic Illness Therapy with general and fatigue subscales (FACT-G/FACIT-F), and the Edmonton Symptom Assessment System (ESAS) questionnaires. Serum samples were collected for testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH).

RESULTS

Comparing the opioid group with the control group, 18 of the 20 patients (90%; 95% confidence interval [CI], 65-98%) exhibited hypogonadism, compared with 8 of the 20 control patients (40%; 95% CI, 19-64%). The median testosterone level was 145 ng/dL versus 399.5 ng/dL (5.0 nmol/L vs. 13.9 nmol/L; P < 0.0001), the median FSH level was 2.85 milli-International Units (mIU)/mL versus 5.3 mIU/mL (P = 0.08), the median LH level was 1.8 mIU/mL versus 4.2 mIU/mL (P = 0.0014), the median SDI-dyadic score was 18.5 versus 40 (P = 0.01), the median SDI-solitary score was 0 versus 5 (P = 0.007), the HADS (anxiety) score was 8.5 versus 5.5 (P = 0.053), the HADS (depression) score was 7.5 versus 1.5 (P = 0.0002), the FACT-G score was 64 versus 96.3 (P = 0.0001), and the FACIT-F score was 24 versus 46 (P = 0.0003).

CONCLUSIONS

Survivors of cancer who chronically consumed opioids experienced symptomatic hypogonadism with significantly higher levels of depression, fatigue, and sexual dysfunction. With the increasing use of opioids among patients with cancer, further research in improving quality-of-life outcomes is warranted.

Hypogonadism and sexual dysfunction in male cancer survivors receiving chronic opioid therapy

The purpose of this study was to determine the prevalence of central hypogonadism and sexual dysfunction in male cancer survivors exposed to chronic high-dose oral opioid therapy. We studied 20 male patients with cancer-related chronic pain who were disease-free for at least one year. All patients consumed at least 200 mg-equivalent of morphine on a daily basis for at least one year. Participants completed the Sexual Desire Inventory questionnaire and serum levels of testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were assessed. Serum testosterone levels were reduced in these patients. The median value was 140 ng/dL (normal 241-827). There was no compensatory increase in FSH and LH. The median FSH level was 3.5 mIU/mL (normal 1.4-18.1). The median LH level was 2.1 mIU/mL (normal 1.5-9.3). The mean dyadic sexual desire score was 23.9+/-15.7 (normal value, 42.8+/-8.9). The mean solitary sexual desire score was 1.3+/-1.9 (normal value, 10.6+/-1.9). Our data suggest that chronic exposure to high-dose oral opioid therapy may result in marked central hypogonadism and sexual dysfunction. Given the increasing use of long-term opioid therapy for chronic pain syndromes, further investigation into these findings is warranted.

Biochemical and functional aspects of gonadotrophin-releasing hormone and gonadotrophins

Reproductive function in mammals is governed by the hypothalamic-pituitary-gonadal axis, which conforms a functional unit. Sexual maturation and the subsequent development of reproductive competence depend on the precise and coordinated function of this axis. The components of the reproductive axis communicate each other through endocrine signals. The hypothalamus synthesizes gonadotrophin-releasing hormone or GnRH, which in turn stimulates synthesis and secretion of the pituitary gonadotrophins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The ovarian follicles and the interstitial and Sertoli cells of the testis are the targets for these pituitary signals. Under gonadotrophic stimulation, the gonads produce and secrete several steroid and non-steroid (polypeptide) factors, which in turn regulate in different ways the function of the hypothalamic-pituitary axis. An episodic and pulsatile mode of secretion of hormonal signals characterize (as in other endocrine systems) the function of the reproductive axis, particularly that of the hypothalamic-pituitary unit. The target cell response, and consequently the harmonic function of the corresponding gland, will depend on the adequate dynamics of this pulsatile secretion. The function of each component of the reproductive axis is strongly influenced by locally-produced signals acting either in a paracrine or autocrine manner; these particular signals represent fine-tuning regulation systems that eventually amplify or restrain the magnitude of response to a particular endocrine signal, providing additional mechanisms for tissue homeostasis and a better functional plasticity of the target gland. The design and rational use of novel therapeutic strategies for an optimal exogenously-controlled reproductive function largely depend on the detailed knowledge of the hypothalamic-pituitary-gonadal axis function and the structure and mechanism of action of those factors and signals involved in its regulation.

Sex hormone suppression by intrathecal opioids: a prospective study

OBJECTIVE

Sexual dysfunction and low testosterone levels have been observed previously in males with chronic noncancer pain treated with intrathecal opioids. To investigate the hypothesis that intrathecal opioids suppress the hypothalamic-pituitary-gonadal axis, a prospective nonrandomized investigation of the function of this axis was undertaken.

DESIGN

Ten males with chronic noncancer pain were evaluated for clinical and biochemical evidence of hypogonadism at baseline and during the first twelve weeks of intrathecal opioid therapy.

RESULTS

Intrathecal opioid administration resulted in a significant (p <0.0001) reduction in serum testosterone, from 7.7 +/- 1.1 (mean +/- SEM) nmol/L at baseline to 2.0 +/- 0.7, 2.8 +/- 0.5, and 4.0 +/- 0.9 nmol/L at 1, 4, and 12 weeks, respectively. This was associated with a reduction in libido and potency. Luteinizing hormone and follicle-stimulating hormone levels remained within reference ranges, indicating central rather than peripheral suppression.

CONCLUSIONS

Administration of intrathecal opioids may result in hypogonadotrophic hypogonadism. As part of the consent for therapy process, patients should be informed about this effect and its management. With long-term intrathecal opioid administration, the hypothalamic-pituitary-gonadal axis should be monitored. Where indicated, testosterone replacement should be undertaken to improve sexual function and prevent the potential metabolic effects of hypogonadism, in particular, osteoporosis.

Update on endocrine disturbances in anorexia nervosa

The marked endocrine changes that occur in anorexia nervosa have aroused a great deal of interest, and over the last decade much research has been conducted in this field. The endocrine disturbances are not specific to this disorder, as they also occur in starvation states secondary to other causes, and they return to normal upon weight restoration. However, emaciation may have profound effects on psychological processes, establishing an intricate circular interaction whereby somatic and psychological manifestations of starvation may continue to act. The purpose of this paper is to provide an overview of the large body of literature concerning endocrine aspects of anorexia nervosa with the main focus on the latest results, which provide leads for potential etiological theories.

Hypogonadism in patients treated with intrathecal morphine

OBJECTIVE

The objective of this study was to investigate the hypothalamic-pituitary-gonadal response to intrathecal opioids.

PATIENTS

Thirty patients receiving intrathecal morphine for chronic nonmalignant pain were studied for clinical and biochemical evidence of hypogonadism. Ten men and 10 postmenopausal women with chronic pain of similar duration but who were not receiving any form of opioid therapy acted as control subjects.

RESULTS

Men and both premenopausal and postmenopausal women had evidence of hypogonadism with low levels of serum testosterone or estrogen coupled with low levels of pituitary gonadotrophins. Control subjects had hormone levels in the expected range for their sex and age. Two men demonstrated recovery after ceasing intrathecal opioid therapy.

CONCLUSIONS

Hypogonadotrophic hypogonadism is a common complication of intrathecal opioid therapy in both men and women.

A review of endocrine changes in anorexia nervosa

Anorexia nervosa is a syndrome of unknown etiology. It is associated with multiple endocrine abnormalities. Hypothalamic monoamines (especially serotonin), neuropeptides (especially neuropeptide Y and cholecystokinin) and leptin are involved in the regulation of human appetite, and in several ways they are changed in anorexia nervosa. However, it remains to be clarified whether the altered appetite regulation is secondary or etiologic. Increased secretion of corticotropin-releasing hormone and proopiomelanocortin seems to be secondary to starvation, however, there is evidence that it may maintain and intensify anorexia, excessive physical activity and amenorrhea. Hypothalamic amenorrhea, which is a diagnostic criterion in anorexia nervosa, is not solely related to the low body weight and exercise. Growth hormone resistance with low production of insulin-like growth factor I and high growth hormone secretion reflect the nutritional deprivation. The nutritional therapy of patients with anorexia nervosa might be improved by administering an anabolic agent such as growth hormone or insulin-like growth factor I. So far none of the endocrine abnormalities have proved to be primary, however, there is increasing evidence that some of these might participate in a vicious circle.

Role of nitric oxide and alcohol on gonadotropin release in vitro and in vivo

Alcohol suppresses reproduction in humans, monkeys, and small rodents by suppressing release of luteinizing hormone (LH). The major action is on the hypothalamus to decrease release of LH-releasing hormone (LHRH). The release of LHRH is controlled by nitric oxide (NO) as determined by in vivo and in vitro experiments. The hypothesized pathway is via norepinephrine (NE)-induced release of NO from NOergic neurons, which activates LHRH release. We have evaluated details of this process in male rats by incubating medial basal hypothalamic (MBH) explants in vitro and examining the release of NO and metabolites generated by NO that control LHRH release. NE increased release of NO as measured by determining the content of the enzyme at the end of the experiment (30 min) by adding [14C]arginine to the homogenate and measuring its conversion to [14C]citrulline since this is formed in equimolar quantities with NO by NO synthase (NOS). Because this increase in content, presumably caused by activation of the enzyme by NE, was blocked by the alpha 1 receptor blocker prazosin, it appears that alpha 1 receptors activate NOS by increasing intracellular free calcium in the NOergic neurons, which combines with calmodulin to activate NOS. The release of LHRH induced by nitroprusside (NP), a donor of NO, is accompanied by an increase in cyclic guanosine monophosphate (cGMP) in the medium supporting the activation of guanylate cyclase by NO. This activation is important in releasing LHRH since addition of 8-monobutyryl cGMP also released the peptide. Ethanol had no effect on the content of NOS or on the increase in content induced by NE, indicating that it did not act on NOS. Earlier experiments indicated that prostaglandin E2 (PGE2) was important in releasing LHRH. PGE2 is produced by activation of cyclooxygenase by NO since this occurred following addition of the NO donor, NP. Not only does NP increase PGE2 release, but it also increases the conversion of [14C]arachidonic acid to its metabolites, particularly PGE2, by activating cyclooxygenase. NP also activated lipoxygenase as indicated by increased release of leukotrienes, which also stimulate LHRH release. Ethanol acts at this step, because it completely blocked the release of PGE2, leukotrienes, and LHRH induced by NP. Therefore, the results support the theory that NE acts to stimulate NO release from NOergic neurons. This NO diffuses to the LHRH terminals, where it activates guanylate cyclase, leading to an increase in cGMP. At the same time, it also activates cyclooxygenase and lipoxygenase. The increase in cGMP increases intracellular free calcium, required for activation of phospholipase A2. Phospholipase A2 converts membrane phospholipids into arachidonic acid, the substrate for conversion by the activated cyclooxygenase and lipoxygenase to PGE2 and leukotrienes that activate the release of LHRH. Because alcohol inhibits conversion of labeled arachidonic acid to PGE2 and leukotrienes, it must act either directly to inhibit cyclooxygenase and lipoxygenase or by some other mechanism which, in turn, inhibits the enzyme. We initially believed that the action of alcohol was exerted directly on the LHRH terminals; however, our recent experiments indicate that alcohol suppresses LHRH release, at least in part, by stimulating beta-endorphinergic neurons that inhibit the release of NE, which drives the NOergic release of LHRH.

Acute dopaminergic blockade augments the naloxone-induced LH rise in estrogen-treated postmenopausal women

OBJECTIVES

To assess the effect of estrogen replacement on the simultaneous blockade of the dopaminergic (DA) and opioidergic neural control of hypothalamic-gonadotropic function in postmenopausal women.

METHODS

Twenty healthy postmenopausal women, 48-55 years old were randomly assigned to receive either a 4-h naloxone infusion at 2 mg/h (group 1, n = 7) or a 10 mg i.v. bolus of metoclopramide (group 2, n = 7) or both drugs, simultaneously (group 3, n = 6) before and after 3 weeks of transdermal estradiol (100 microg/day). Blood samples were obtained at 30-min intervals during 4 h and duplicate determinations of serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2) and prolactin (PRL) were performed in all samples.

RESULTS

In group 1 only a mild but significant LH rise after but not before estrogen replacement was seen. In group 2 PRL had a greater rise after than before estrogen therapy, without other hormonal changes. In group 3 a greater rise in PRL occurred after than before estrogen administration and serum LH had a sustained rise throughout the test only after estrogen replacement (greater than in group 1). No FSH changes were observed. The after-estradiol PRL response was nearly similar in groups 2 and 3.

CONCLUSIONS

Our results indicate that in the untreated postmenopausal women, the dopaminergic system has little and the opioidergic system has no significant input in the control of gonadotropin or prolactin release. However, following estrogen replacement, opioids are involved in the inhibition of LH release and stimulating PRL release, while the dopaminergic system acts to inhibit PRL release and modulates LH release or inhibition, depending on the levels of circulating estrogens.

Acetyl salmon endorphin-like immunoreactivity in the ovary of two teleostean species: changes with environmental conditions

The presence of salmon acetylated endorphin (acetyl sEP) in the ovary of seabream and sea bass was investigated through immunocytochemical and biochemical techniques in order to compare aquatic species with terrestrial ones. Endorphin-like immunoreactivity was found in the cytoplasm of oogonia and similar immunostaining was present in the granulosa layer of mature follicles. In both pituitary and ovarian extracts of the two teleostean species, acetyl sEP-like immunoreactivity was distributed over three main peaks, the second one corresponding to the elution time of the reference synthetic peptide. Serial dilutions of HPLC fraction II of the ovaries of both fishes ran parallel with the standard curve obtained with reference peptide. The ovarian content of acetyl sEP, obtained by calculating the integrated area of the fraction II peak, indicates large and highly significant (p < 0.01) differences in the amount of peptide found in ovarian tissues of wild seabream in comparison with that of farmed fish. Increased peptide values in wild animals with respect to farmed fish were also found in the sea bass. These data indicate that not only the pituitary, but also the ovary is sensitive to environmental cues, and strongly suggest the role of opioid peptides in adaptation.