Endogenous opioids and hypogonadism in human obesity

Consumption of Sugar-Sweetened or Artificially Sweetened Beverages and Semen Quality in Young Men: A Cross-Sectional Study

BACKGROUND

Existing literature suggests that frequent consumption of sugar-sweetened drinks may be associated with lower semen quality. Studies performed in mice suggest a dose-response relationship between intake of saccharin or aspartame, two artificial sweeteners, and sperm and testis function.

METHODS

A cross-sectional study based on data from The Fetal Programming of Semen Quality (FEPOS) Cohort, including 1047 young men (mean age = 19 years) was performed. Each male participant completed an online questionnaire on health, health behavior and diet, and provided a semen sample. The associations between consumption of sugar-sweetened or artificially sweetened beverages (moderate ≥ 3 days/week; infrequent < 3 days/week) and semen quality were analyzed using a multivariable, negative, binomial regression model.

RESULTS

Sugar-sweetened or artificially sweetened beverage consumption was not strongly associated with either semen volume, sperm concentration, total sperm count or total motility in young men. The proportion of morphologically normal sperm was 11% lower (0.89 (95% CI 0.76, 1.04)) for moderate (≥3 days/week) consumption of artificially sweetened beverages relative to infrequent (<3 days/week).

CONCLUSION

Consumption of sugar-sweetened or artificially sweetened beverages, at the levels present in this study had limited effect on the measured markers of semen quality in young men.

Vitamin D and Obesity: Two Interacting Players in the Field of Infertility

Obesity plays an important role in human fertility in both genders. The same is true for vitamin D, for which accumulating evidence from observational human studies suggests a key role for both male and female fertility. In the latter case, however, robust data from relevant interventional studies are currently lacking. It is also not clear whether obesity and vitamin D deficiency, besides their independent effect on human infertility, act in synergy. Several pathogenetic mechanisms may be proposed as a linkage between vitamin D deficiency and obesity, with respect to infertility. In any case, the independent contribution of vitamin D deficiency in obese infertile states needs to be proven in interventional studies focusing on either vitamin D supplementation in obese or weight loss strategies in vitamin D-deficient infertile patients.

Effects of apelin on reproductive functions: relationship with feeding behavior and energy metabolism

Apelin is an adipose tissue derived peptidergic hormone. In this study, 40 male Sprague-Dawley rats were used (four groups; n = 10). Apelin-13 at three different dosages (1, 5 and 50 μg/kg) was given intraperitoneally while the control group received vehicle the same route for a period of 14 days. In results, apelin-13 caused significant decreases in serum testosterone, luteinizing hormone and follicle-stimulating hormone levels (p < 0.05). Administration of apelin-13 significantly increased body weights, food intake, serum low-density lipoprotein and total cholesterol levels (p < 0.05), but caused significant decreases in high-density lipoprotein levels (p < 0.05). Serum glucose and triglyceride levels were not significantly altered by apelin-13 administration. Significant decreases in both uncoupling protein (UCP)-1 levels in the white and brown adipose tissues and UCP-3 levels in the biceps muscle (p < 0.05) were noted. The findings of the study suggest that apelin-13 may not only lead to obesity by increasing body weight but also cause infertility by suppressing reproductive hormones.

Male infertility: lifestyle factors and holistic, complementary, and alternative therapies

While we may be comfortable with an allopathic approach to male infertility, we are also responsible for knowledge about lifestyle modifications and holistic, complementary, and alternative therapies that are used by many of our patients. This paper provides an evidence-based review separating fact from fiction for several of these therapies. There is sufficient literature to support weight reduction by diet and exercise, smoking cessation, and alcohol moderation. Supplements that have demonstrated positive effects on male fertility on small randomized controlled trial (RCT) include aescin, coenzyme Q 10 , glutathione, Korean red ginseng, L-carnitine, nigella sativa, omega-3, selenium, a combination of zinc and folate, and the Menevit antioxidant. There is no support for the use of Vitamin C, Vitamin E, or saffron. The data for Chinese herbal medications, acupuncture, mind-body practice, scrotal cooling, and faith-based healing are sparse or inconclusive.

The Disappearing Sperms: Analysis of Reports Published Between 1980 and 2015

Reports regarding the changes in sperm concentration in different counties of the world are inconsistent. Furthermore, the reports that sprung up from specific epidemiological and experimental examinations did not include data of prior studies or geographical variations. The current study, following a previous report of massive fall in semen volume over the past 33 years, attempts to delineate the trend of altering sperm concentrations and factors responsible for this by reviewing article published from 1980 to July 2015 with geographic differences. The current study identified an overall 57% diminution in mean sperm concentration over the past 35 years ( r = -.313, p = .0002), which, when analyzed for each geographical region, identified a significant decline in North America, Europe, Asia, and Africa. An increasing trend of sperm concentration was identified only in Australia. The association of male age with such a trend ( R² = .979) is reported. The authors also correlated male fertility with sperm concentration. Thus, this comprehensive, evidence-based literature review aims to concisely and systematically present the available data on sperm concentration from 1980 to 2015, as well as to statistically analyze the same and correlate male health with the declining pattern of sperm count in a single scientific review to serve the scientific research zone related to reproductive health. It points to the threat of male infertility in times ahead.

Androgen deficiency and metabolic syndrome in men

Metabolic syndrome (MetS) is a growing health concern worldwide. Initially a point of interest in cardiovascular events, the cluster of HTN, obesity, dyslipidemia, and insulin resistance known as MetS has become associated with a variety of other disease processes, including androgen deficiency and late-onset hypogonadism (LOH). Men with MetS are at a higher risk of developing androgen deficiency, and routine screening of testosterone (T) is advised in this population. The pathophysiology of androgen deficiency in MetS is multifactorial, and consists of inflammatory, enzymatic, and endocrine derangements. Many options for the concomitant treatment of both disorders exist. Direct treatment of MetS, whether by diet, exercise, or surgery, may improve T levels. Conversely, testosterone replacement therapy (TRT) has been shown to improve MetS parameters in multiple randomized controlled trials (RTCs).

How does obesity affect fertility in men - and what are the treatment options?

Adiposity is associated with reduced fertility in men. The aetiology is multifactorial, with obese men at greater risk of suffering from impaired spermatogenesis, reduced circulating testosterone levels, erectile dysfunction and poor libido. The diagnosis and treatment of reduced fertility observed in obese men therefore requires insight into the underlying pathology, which has hormonal, mechanical and psychosocial aspects. This article summarises the current epidemiological, experimental and clinical trial evidence from the perspective of a practicing clinician. The following conclusions and recommendations can be drawn: Obesity is associated with low serum testosterone concentrations, but treatment with exogenous testosterone is likely to adversely impact on fertility. It is important to discuss this with men prior to initiation of testosterone therapy. Obesity adversely affects sperm concentration and may affect sperm quality. However, whether or not weight loss will correct these factors remain to be established. Oestrogen receptor modulators (and aromatase inhibitors) are unlicensed in the treatment for male hypogonadism and/or infertility. These treatments should hence be considered experimental approach until ongoing clinical trials report their outcomes.

BMI in relation to sperm count: an updated systematic review and collaborative meta-analysis

BACKGROUND The global obesity epidemic has paralleled a decrease in semen quality. Yet, the association between obesity and sperm parameters remains controversial. The purpose of this report was to update the evidence on the association between BMI and sperm count through a systematic review with meta-analysis. METHODS A systematic review of available literature (with no language restriction) was performed to investigate the impact of BMI on sperm count. Relevant studies published until June 2012 were identified from a Pubmed and EMBASE search. We also included unpublished data (n = 717 men) obtained from the Infertility Center of Bondy, France. Abstracts of relevant articles were examined and studies that could be included in this review were retrieved. Authors of relevant studies for the meta-analysis were contacted by email and asked to provide standardized data. RESULTS A total of 21 studies were included in the meta-analysis, resulting in a sample of 13 077 men from the general population and attending fertility clinics. Data were stratified according to the total sperm count as normozoospermia, oligozoospermia and azoospermia. Standardized weighted mean differences in sperm concentration did not differ significantly across BMI categories. There was a J-shaped relationship between BMI categories and risk of oligozoospermia or azoospermia. Compared with men of normal weight, the odds ratio (95% confidence interval) for oligozoospermia or azoospermia was 1.15 (0.93-1.43) for underweight, 1.11 (1.01-1.21) for overweight, 1.28 (1.06-1.55) for obese and 2.04 (1.59-2.62) for morbidly obese men. CONCLUSIONS Overweight and obesity were associated with an increased prevalence of azoospermia or oligozoospermia. The main limitation of this report is that studied populations varied, with men recruited from both the general population and infertile couples. Whether weight normalization could improve sperm parameters should be evaluated further.

Male fertility, obesity, and bariatric surgery

Obesity has become a new worldwide health problem with significant impact not only on cardiovascular diseases but also on many other related disorders, highlighting infertility. Obesity may adversely affect male reproduction by endocrinologic, thermal, genetic, and sexual mechanisms. There is good evidence that obesity can be associated with reduced sperm concentrations, but studies about sperm motility, morphology, and DNA fragmentation have been less numerous and more conflicting. Although weight loss is the cornerstone of the treatment of obesity-related infertility, with promising results in restoring fertility and normal hormonal profiles, bariatric surgery impact on male fertility is still unclear and until now there is not enough data to support the informed consent in this scenario. Physicians are encouraged to highlight possible positive and/or negative impacts concerning male capacity of fertilization when informing patients. A balanced judgment and a personalized case-by-case management with patient involvement in decisions are fundamental in this setting and indication of cryopreservation of semen samples should be considered in selected circumstances. Well-structured trials controlled for confounders including female factors and based on solid outcomes (ie, birth rates) must urgently come up to clarify this emerging scenario.

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.

Impact of male obesity on infertility: a critical review of the current literature

OBJECTIVE

To evaluate the current understanding of the effects and potential mechanisms of obesity on male fertility.

DESIGN

Literature review of articles pertaining to obesity and male infertility.

RESULT(S)

Recent population-based studies suggest an elevated risk for subfertility among couples in which the male partner is obese and an increased likelihood of abnormal semen parameters among heavier men. Male factor infertility is associated with a higher incidence of obesity in the male partner. Obese men exhibit reduced androgen and SHBG levels accompanied by elevated estrogen levels. Reduced inhibin B levels correlate with degree of obesity and are not accompanied by compensatory increases in FSH. This complexly altered reproductive hormonal profile suggests that endocrine dysregulation in obese men may explain the increased risk of altered semen parameters and infertility. Additional features of male obesity that may contribute to an increased risk for infertility are altered retention and metabolism of environmental toxins, altered lifestyle factors, and increased risks for sexual dysfunction. Neither reversibility of obesity-associated male infertility with weight loss nor effective therapeutic interventions have been studied yet.

CONCLUSION(S)

The increasing prevalence of obesity calls for greater clinician awareness of its effects on fertility, better understanding of underlying mechanisms, and eventually avenues for mitigation or treatment.

Hypogonadotrophic hypogonadism in type 2 diabetes

Recent work shows a high prevalence of low testosterone and inappropriately low luteinizing hormone (LH) and follicle stimulating hormone (FSH) concentrations in type 2 diabetes. This syndrome of hypogonadotrophic hypogonadism (HH) is associated with obesity in patients with type 2 diabetes. However, the duration of diabetes or HbA1c are not related to HH. Furthermore, recent data show that HH is not associated with type 1 diabetes. C-reactive protein concentrations have been shown to be elevated in patients with HH and are inversely related to plasma testosterone concentrations. This inverse relationship between plasma free testosterone and C- reactive protein concentrations in patients with type 2 diabetes suggests that inflammation may play an important role in the pathogenesis of this syndrome. This is of interest since inflammatory mechanisms may have a cardinal role in the pathogenesis of insulin resistance. It is also relevant that in the mouse, deletion of the insulin receptor in neurons leads to HH in addition to a state of systemic insulin resistance. It has also been shown that insulin facilitates the secretion of gonadotrophin releasing hormone (GnRH) from neuronal cell cultures. Thus, HH may be the result of insulin resistance at the level of the GnRH secreting neuron. Low testosterone concentrations are also related to an increase in total and regional adiposity. This review discusses these issues and attempts to make the syndrome relevant as a clinical entity. Clinical trials are required to determine whether testosterone replacement alleviates insulin resistance and inflammation. In addition, low testosterone levels are associated with an increase in cardiovascular events. Testosterone therapy may therefore, reduce cardiovascular risk. This important aspect requires further investigation.

Systemic naloxone infusion may trigger spasticity in patients with spinal cord injury: case series

BACKGROUND/OBJECTIVE

Three patients with spinal cord injury (SCI) and 3 able-bodied (AB) patients were infused with naloxone during a study to examine their neuroendocrine function. An unanticipated side effect occurred during the naloxone infusion. All 3 patients with SCI, but none of the AB patients, experienced profoundly increased spasticity during the naloxone infusion. Our report describes this side effect, which has potential implications for the clinical treatment or scientific evaluation of individuals with SCI.

METHODS

All patients were in good general health and medication free for 11 days or longer before the study. Each patient was placed on a 30-hour protocol to analyze pulsatile release of gonadotropins. Physiologic saline was intravenously infused on day 1 to serve as a control period for naloxone infusion on day 2.

RESULTS

AB patients experienced no muscle spasm activity or any other side effects at any time during the study. In contrast, all 3 patients with SCI experienced a profoundly increased frequency and duration of spasticity in muscles innervated by the nerve roots caudal to their level of injury. In all 3 patients with SCI, spasticity increased only during the period of naloxone infusion. Within 1 hour of stopping naloxone, spasticity returned to baseline levels.

CONCLUSIONS

Naloxone infusion produced a differential effect on the muscle activity of men with SCI compared to AB men with intact spinal circuits. Consistent with previous studies, the results of this study indicate a relationship between opioid neuromodulation and spasticity after SCI.

Reduced fertility among overweight and obese men

BACKGROUND

Overweight and obese men have been reported to have lower sperm counts and hormonal changes, but data are lacking regarding effects on couple fertility.

METHODS

We examined the relationship between male body mass index (BMI) and infertility in couples enrolled in the Agricultural Health Study in the United States. The analysis sample was limited to couples (wife <40 years old) with an attempt at pregnancy in the last 4 years based on pregnancy and fertility data provided by wives. Infertility was defined as not conceiving a pregnancy after at least 12 months of unprotected intercourse regardless of whether or not a pregnancy ultimately occurred. Self-reported weight and height were used to calculate BMI (kg/m). Adjusted odds ratios (aORs) for infertility associated with increases in male BMI were calculated with logistic regression.

RESULTS

Adjusting for potential confounders, a 3-unit increase in male BMI was associated with infertility (aOR = 1.12; 95% confidence interval = 1.01-1.25; n = 1329). There was a dose-response relationship, and the BMI effect was stronger when the data were limited to couples with the highest-quality infertility data. The association between BMI and infertility was similar for older and younger men, suggesting that erectile dysfunction in older men does not explain the association.

CONCLUSIONS

This report of lower fertility in overweight and obese men needs replication. If the findings are robust, programs to prevent obesity may improve men's reproductive health and save medical costs for infertility treatment.

Obesity and androgens: facts and perspectives

OBJECTIVE

This review discusses androgen status in male and female obesity, according to their specific phenotype, and the main mechanisms responsible.

DESIGN

Published data in the literature of the last 20 years represented the basis of most of the data and concepts incorporated in the review.

RESULT(S)

Obesity is associated with profound alterations in androgen secretion, transport, metabolism, and action, according to a dichotomous behavior depending on sex. Obese men are characterized by a progressive decrease of testosterone levels with increasing body weight, whereas obese women, particularly those with the abdominal phenotype, tend to develop a condition of functional hyperandrogenism. Reduced sex hormone-binding globulin synthesis and circulating blood levels represent the sole common mechanism which is responsible in both sexes. Among other still partially undefined factors, mechanisms potentially responsible for the sex dichotomy in androgen levels involve specific alterations of gonadotropin secretion, estrogens, the hypothalamic-pituitary-adrenal axis, leptin, androgen receptors, specific steroidogenic enzymes in the peripheral tissues, and, possibly, ghrelin. In both sexes, androgens play an important role in determining the sex-dependent pattern of body fat distribution. Moreover there are theoretical possibilities that low testosterone in men and high free testosterone fraction in women may play a role in the development of the metabolic syndrome. This is exemplified by the well defined association between obesity and other features of the metabolic syndrome in women with polycystic ovary syndrome and in hypogonadal men. The effects of androgen and antiandrogens in obese men and women also represent arguments in favor of this association.

CONCLUSION(S)

Given the fundamental role of sex hormones in the regulation of body composition, fuel homeostasis, and reproduction in humans, more emphasis should be placed on the potential role of androgen dysregulation in the pathophysiology of different obesity phenotypes and the metabolic syndrome.

Effects of occupational solvent exposure on reproductive hormone concentrations and fecundability in men

BACKGROUND

Little is known about the effects of organic solvents on male reproductive health. To assess fertility and reproductive endocrine function in solvent-exposed men, we investigated time-to-pregnancy using a retrospective cohort design and cross-sectionally measured reproductive hormone concentrations in painters and millwrights compared to a reference group of carpenters.

METHODS

Detailed occupational, exposure, medical, and time-to-pregnancy histories were obtained by telephone interview. Plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone concentrations were determined by immunoassay. Exposure indices, which summarized working life exposure to total solvents, chlorinated solvents, aromatic solvents, and thinners, degreasers, varnishes, and adhesives as a category were calculated from exposure histories.

RESULTS

FSH concentrations increased significantly with increasing exposure indices for all solvents and for chlorinated solvents. There were no significant associations of solvent exposure indices with LH or testosterone levels. LH, FSH, and testosterone concentrations also did not differ by job title. Using Cox regression, time-to-pregnancy was non-significantly longer in the painters and millwrights than the carpenters. There was no significant association between time-to-pregnancy and any of the solvent exposure indices; however, it should be noted that some of the pregnancies occurred more than 20 years previously, potentially reducing the reliability of the retrospectively collected pregnancy and exposure data.

CONCLUSIONS

The significant associations between FSH levels and solvent exposure indices suggest the potential for adverse effects of solvent exposures on reproductive function in men.

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.

Reversal of the hypogonadotropic hypogonadism of obese men by administration of the aromatase inhibitor testolactone

Studies from this laboratory have shown that obese men have elevated serum estrogen levels and diminished levels of follicle-stimulating hormone (FSH) and free and total testosterone, all in proportion to their degree of obesity. The decreases in testosterone and FSH constitute a state of hypogonadotropic hypogonadism (HHG), and we have hypothesized that it results from feedback suppression of the pituitary by the elevated estrogen levels. We tested this hypothesis by lowering the serum estrogens of 6 health obese men (body mass index [BMI], 38 to 73) by administering the aromatase inhibitor testolactone (1 g daily for 6 weeks). Twenty-four-hour mean serum testosterone rose in every subject, from a mean of 290 +/- 165 ng/dL to a mean of 403 +/- 170 (P <.0003); 24-hour mean serum estradiol decreased in every subject, from a mean of 40 +/- 10.8 pg/mL to a mean of 29 +/- 6.7 (P <.004); and 24-hour mean serum luteinizing hormone (LH) increased in every subject, from a mean of 14.3 +/- 4.1 mIU/mL to a mean of 19.3 +/- 5.1 (P <.004). The rise in mean LH was due to an increase in the amplitude of the individual secretory pulses, especially at night. Twenty-four-hour mean serum estrone decreased nonsignificantly, from 48 +/- 14 pg/mL to 39 +/- 6.4, and 24-hour mean serum FSH increased nonsignificantly, from 13.5 +/- 5.3 mIU/mL to 15.0 +/- 5.4. The results are in accordance with the hypothesis, in that inhibition of estrogen biosynthesis (through administration of the aromatase inhibitor testolactone) results in alleviation of the HHG of our obese male subjects.

Hypogonadism and diabetes

Clinicians have been aware of the increased prevalence of low testosterone levels in patients with type II diabetes for several years, but how these two conditions are associated is difficult to determine. Older age and obesity may be factors, as both are associated with type II diabetes and both decrease testosterone levels. Sex hormone-binding globulin (SHBG), the major serum carrier protein for testosterone, also may have an impact. SHBG levels fall with obesity and increase with aging. Some studies indicate lower SHBG levels in type II diabetes. Most of the differences in testosterone levels between diabetic and nondiabetic patients may be due to reduced SHBG, rather than reduced testosterone production. However, free testosterone levels fall with increasing age and obesity, rendering many type II diabetic patients testosterone deficient. Testosterone replacement may improve insulin sensitivity in hypogonadal, overweight men with type II diabetes by altering body composition, but studies are conflicting.

Reproductive endocrine effects of acute exposure to toluene in men and women

OBJECTIVES

Despite observation of adverse reproductive effects of toluene, including alterations of serum gonadotropins (luteinising hormone (LH) and follicle stimulating hormone (FSH)) in humans, little is known of the mechanism of toxicity. The hypothesis was tested that toluene acutely suppresses pulsatile gonadotropin secretion by measuring LH and FSH at frequent intervals during controlled exposure to toluene.

METHODS

Women in the follicular and luteal phases of the menstrual cycle and men were randomised to inhale filtered air with or without 50 ppm toluene through a mouthpiece for 3 hours (19% of the OSHA permissible exposure limit). Blood was sampled by intravenous catheter at 20 minute intervals for 3 hours before, 3 hours during, and 3 hours after exposure. Plasma LH, FSH, and testosterone were measured. Pulse amplitude, pulse frequency, and mean concentrations of LH and FSH for each of the 3 hour periods before, during and after exposure to toluene versus sham exposure were calculated with the ULTRA pulse detection program and compared by analysis of variance (ANOVA) with repeated measures.

RESULTS

In men mean concentrations of LH showed a significant interaction (p < 0.05) between exposure and sampling period, with a greater LH decline during exposure to toluene than sham exposure. However, there was no concomitant effect on testosterone concentrations. The LH pulse frequency of women in the luteal phase showed a trend towards a significant interaction between exposure and sampling period (p = 0.06), with a greater decline in pulse frequency during exposure to toluene than sham exposure. There were no other significant effects of exposure to toluene.

CONCLUSIONS

Three hour exposure to 50 ppm toluene did not result in abnormal episodic LH or FSH secretion profiles, however, subtle effects on LH secretion in men and women in the luteal phase were found. The clinical relevance of these effects is unclear, indicating the need for further study of reproductive function in exposed workers.

Endogenous opiates: 1994

This article is the 17th installment of our annual review of research concerning the opiate system. It includes papers published during 1994 involving the behavioral, nonanalgesic, effects of the endogenous opiate peptides. The specific topics covered this year include stress; tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.