Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.

There has been a global rise in obesity in the last three decades, and at present one in five women are obese at antenatal booking. Maternal obesity is associated with an increased risk of adverse pregnancy outcomes, including increased fetal size and prolonged pregnancy. In the longer-term, offspring of obese are at increased risk of premature death from a cardiovascular event in their adulthood. One mechanism that has been linked to these outcomes is fetal exposure to glucocorticoids in utero. During normal pregnancy, the maternal hypothalamic pituitary adrenal (HPA) axis undergoes major changes, resulting in exponentially increasing levels of the major circulating glucocorticoid cortisol, and other HPA axis hormones, such as corticotrophin releasing hormone (CRH). Cortisol and CRH are vital for normal fetal growth and length of gestation, but in excess they are associated with fetal growth restriction and preterm labour. In non-pregnant obesity, it is thought that the HPA axis is dysregulated, although evidence is inconclusive. Little is known about the effects of maternal obesity in pregnancy on the HPA axis. The work in this Thesis used clinical studies to test the hypothesis that the HPA axis is dysregulated in obese pregnant women with altered release, clearance and placental metabolism of cortisol. Associations with clinical outcomes related to fetal size and length of gestation were also studied. The HPA axis activity during pregnancy was investigated in a prospective case-control study cohort. Fasting serum cortisol levels were measured at 16, 28 and 36 weeks of gestation (obese n=276, lean n=135). In a subset (obese n=20, lean n=20), corticosteroid binding globulin (CBG), CRH, estrogens and progesterone were measured. Salivary cortisol was measured in samples collected at bedtime, waking and 30 minutes after waking at 16 weeks. Urinary glucocorticoid metabolites were measured at 19 weeks and 36 weeks (obese n=6, lean n=5) and non-pregnant (obese n=7, lean n=7) subjects. All circulating hormone levels rose similarly in obese and lean during pregnancy, but were significantly lower in obese women. The diurnal rhythm of cortisol was maintained. Urinary glucocorticoids increased with gestation in lean, but not in obese, indicating a lesser activation of the HPA axis in obese compared with lean pregnancy. These findings associated with increased birthweight and longer gestation in obese pregnancy, suggesting that decreased HPA axis activity may underlie these obese related adverse pregnancy outcomes. Whether or not lower glucocorticoids in obese pregnancies are maintained at delivery was investigated by measuring active glucocorticoids (cortisol and corticosterone) and their inactive versions (cortisone and 11- dehydrocorticosterone, respectively) from matched maternal and cord plasma samples (n=259, BMI 18 – 55 kg/m2). Active glucocorticoids were significantly higher in maternal than cord blood, and inactive versions were significantly higher in cord than maternal blood. Increased maternal BMI associated with lower maternal cortisol, corticosterone and 11-dehydrocorticosterone. Despite significant correlations between maternal and cord blood glucocorticoid levels, increased maternal BMI did not associate with lower cord blood glucocorticoids. This suggests that conditions at delivery may overcome any potential negative effects of low maternal glucocorticoids on the fetus in the short-term. However, it may not preclude the longer-term effects of fetal exposure to lower glucocorticoid levels during obese pregnancy, and offspring follow-up studies are required. Potential mechanisms leading to altered HPA axis activity in obese pregnancy were explored by studying the pulsatile release and placental metabolism of glucocorticoid hormones. Glucocorticoid pulsatility is thought to be important for transcriptional regulation of glucocorticoid responsive genes, and disruptions to pulsatility have been reported in some disease processes. Glucocorticoids were measured in 10-minute serum sampling between 08.00h-11.00h and 16.00h- 19.00h. Peripheral tissue cortisol was measured from 20-minute sampling of interstitial fluid, over 24-hours, at 16-24 weeks and 30-36 weeks (obese n=7, lean n=8), and non-pregnant controls (obese n=4, lean n=3). Total circulating serum cortisol levels were higher in pregnancy than non-pregnancy in lean and obese, and increased significantly with advancing gestation in lean but not in obese. Pulsatility of cortisol was demonstrated in interstitial fluid in both non-pregnancy and pregnancy. In obese pregnancy, interstitial fluid pulse frequency was lower with advancing gestation. This may be a novel mechanism underlying the observed decreased HPA axis activity in obese pregnancy. Placental cortisol metabolism and transport was studied using an ex vivo placental perfusion model, perfused with a deuterium-labelled cortisol tracer combined with computational modeling. The findings challenge the concept that maternal cortisol diffuses freely across the placenta, but confirmed that 11β- HSD2 acts as major ‘barrier’ to cortisol transfer to the fetus, protecting the fetus from the high maternal circulating cortisol levels. In addition we showed preliminary evidence of local cortisol production within the placenta. The model is able to predict maternal-fetal cortisol transfer and can now be used in future experimental design. In conclusion, in obese pregnancy, lower maternal cortisol and urinary clearance suggested reduced HPA axis activity. Altered glucocorticoid pulsatility may underlie this change. Future studies of placental cortisol metabolism in maternal obesity could be conducted using an ex vivo perfusion model. The lower HPA axis activity in obese pregnancy represents a novel pathway underlying increased fetal growth.

Introdução: A exposição frequente dos profissionais de enfermagem a estressores relacionados ao trabalho tem sido amplamente descrita na literatura. Entretanto, a magnitude e intensidade do estresse dependem não somente dos estressores, mas também da interação destes com a avaliação cognitiva da situação estressora, com os recursos de enfrentamento e com a reação psiconeuroendócrina do estresse. Embora diversos estudos tenham descrito as reações psicológicas do estresse e seu enfrentamento nos profissionais de enfermagem, pouco se sabe sobre as características da reação neuroendócrina. Isto é particularmente importante, dado que padrões atípicos de secreção diurna de cortisol, principal hormônio do estresse, estão associados ao aumento da susceptibilidade ao desenvolvimento de doenças cardiovasculares, imunológicas e transtornos mentais. Assim, questiona-se a frequência de padrões atípicos de cortisol e sua relação com manifestações psicológicas nestes profissionais. Objetivo: Analisar o padrão diurno de secreção de cortisol dos profissionais de enfermagem de unidades hospitalares. Método: Foram incluídos 56 profissionais de enfermagem randomicamente selecionados, alocados nas unidades ambulatório, clínica médica, clínica cirúrgica, centro cirúrgico, pronto socorro infantil e adulto, unidade de terapia intensiva adulto e pediátrica de um hospital universitário. Para avaliação do padrão diurno de secreção de cortisol foram coletadas amostras de saliva em dois dias úteis consecutivos de trabalho e, para as manifestações psicológicas, foram aplicados os instrumentos escala de estresse percebido (EEP), questionário de sofrimento mental (SRQ-20), inventário de depressão de Beck (IDB) e escala de estresse no trabalho (EET). Os dados foram armazenados e analisados utilizando o programa estatístico SPSS versão 14.0 e o nível de significância adotado foi de 5%. Resultados: Quanto ao padrão de secreção de cortisol, 42,5% dos profissionais de enfermagem apresentaram padrão atípico de secreção de cortisol, sendo que 19,5% eram técnicos de enfermagem. Quanto às variáveis psicológicas, 54,5% perceberam-se com alto nível de estresse (EEP), 51,2% referiram que o estresse estava relacionado ao trabalho (EET), 15,5% apresentaram distmia e depressão (IDB) e 56,8% apresentam sinais de sofrimento mental (SRQ-20). Não houve associação entre padrão de secreção de cortisol e as variáveis psicológicas. Conclusão: Mais de um terço da amostra de profissionais de enfermagem apresentou padrões atípicos de secreção de cortisol, além de relatarem elevados níveis de estresse, estresse relacionado ao trabalho e sofrimento mental. Estes dados sugerem que estes profissionais podem estar expostos a uma sobrecarga não apenas mental, mas biológica, estando expostos ao risco para o adoecimento. / Background: Frequent exposure of nurses to work-related stressors has been widely described in the literature. However, the magnitude and intensity of the stress depends not only on stressors, but also their interaction with the cognitive appraisal of stressful situation, the resources and coping with the psychoneuroendocrine stress response. Although several studies have described the psychological reactions of stress and coping with it in nursing, little is known about the characteristics of the neuroendocrine response of stress. This is particularly important since atypical patterns of diurnal cortisol secretion are associated with increased susceptibility to the development of cardiovascular, immunological diseases and mental disorders. Thus, we arised the question about the frequency of atypical patterns of cortisol and its relationship with psychological manifestations in nursing professionals. Objective: To analyze the diurnal pattern of cortisol secretion of nursing professionals at a hospital setting. Methods: Fifty six (n = 56) nursing professionals were randomly selected allocated to the outpatient clinic, medical clinic, surgical clinic, surgical center, pediatric unit, adult and pediatric emergency department and intensive care unit of a university hospital. To evaluate the diurnal pattern of cortisol secretion, saliva samples were collected on two consecutive working days. For the psychological manifestations of stress the following instruments were applied: the Perceived Stress Scale (PSS), the Self-report Questionnaire (SRQ-20), the Beck Depression Inventory (BDI) and the work-related stress scale (WSS). Data were stored and analyzed using SPSS version 14.0 and the level of significance was 5%. Results: Regarding the pattern of cortisol secretion 42.5% of nurses had atypical pattern of cortisol secretion and 19.2% were from nursing technical professional category. Regarding psychological variables, 54.5% perceived themselves at high stress level, 51.2% reported that stress were work-related 15.5% had depression and dysthymia and 56.8% showed signs of mental distress. There was no association between pattern of cortisol secretion and the psycological variables. Conclusion: More than one third of the sample exhibited atypical pattern of cortisol secretion as well as high levels of stress, work-related stress and mental distress. These data suggest that these workers may be exposed not just to psychological overload, but also to biological burden and could be exposed to a risk for the illness.

Orientador: Ilma Aparecida Paschoal / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-07-27T12:41:27Z (GMT). No. of bitstreams: 1 Poleti_RosanaGalli_M.pdf: 11378631 bytes, checksum: 23fc2e98ea23383dfc4dfba5668a99a2 (MD5) Previous issue date: 2001 / Resumo: A asma brônquica é largamente conhecida como uma doença inflamatória crônica das vias aéreas e os corticosteróide são as drogas mais efetivas no seu tratamento, pois bloqueiam muitos dos mecanismos inflamatórios e têm ação profilática. Nas últimas décadas, com a introdução da corticoterapia via inalatória, houve redução nos cursos de corticosteróide oral. Porém, existe muita preocupação em relação aos seus efeitos colaterais sistêmicos de impacto clínico, que são: supressão das glândulas supra-renais, osteoporose, catarata, glaucoma, distúrbios metabólicos e, em crianças, retardo do crescimento. O objetivo deste estudo foi avaliar o efeito de dois corticosteróide inalatórios - o dipropionato de beclometasona e o propionato de fluticasona - em doses equivalentes, sobre a resposta das glândulas supra-renais. Vinte pacientes asmáticos participaram do protocolo e foram divididos em dois grupos: o grupo I com o corticosteróide beclometasona na dose de 500 mcg, duas vezes ao dia, e o grupo II com o corticosteróide fluticasona na dose de 250 mcg, duas vezes ao dia. O grupo I foi formado por oito pacientes do sexo feminino e dois pacientes do sexo masculino, com idades entre 18 a 73 anos, todos portadores de asma brônquica de grau leve. O grupo 1 / Abstract: Bronchial asthma is widely known as a chronic inflammatory disease of the airways and corticosteroids are the most effective drugs for asthma treatment since they block many of the inflammatory mechanisms of the disease and they have prophylactic action. In the last decades, with the introduction of inhaled corticotherapy, there was a reduction in the periods of use of oral corticosteroids; although there is concern about its systemic side effects of clinical impact that are: adrenal suppression, osteoporosis, cataracts, glaucoma, metabolic disturbances, in adults; and also growth retard in children. The purpose os this study was the comparison of the effects of two different inhaled corticosteroids - beclomethasone dipropionate and fluticasone propionate ¿ in equivalent doses, over the function of adrenal gland. Twenty asthmatic patients have been divided in two groups: group I treated with beclomethasone in doses of 500 microgram twice a day and group II treated with fluticasone in doses of 250 microgram twice a day. The group I was formed byeight female and two male patients, age varying trom 18 to 73 years, with mild bronchial asthma. Group 11was constituted of six female and four male patients, age varying trom 19 to 67 years; six patients had mild bronchial asthma and four patients had moderate bronchial asthma. After the patients were admitted in the protocol, there was the register of the clinical history and the pulmonary function test, with pre and post bronchodilator studies. After the first dosage of basal cortisol (8:00 am), intravenous injection of cortrosyn was made and new blood samples were collected, 30 and 60 minutes afier the stimulation of adrenal glands. After six months of medication, new blood samples were collected for cortisol dosage at basal conditions, 30 and 60 minutes after stimulation with cortrosyn. The cortisol was measured by the method of chemiluminescence. In relation to the symptoms at the beginning of the protocol, the groups did not show significant differences between them, with the great safeguard that the symptoms have not had graduation of intensity. After six months of medication, the groups also presented similar behaviour; when the comparisonis done in the same group, the patients using fluticasone presented a significant improvement of the dyspnea (p = 0,0233), since seven (70%) of the patients presented dyspnea at the beginning and did not have it in the post medication moment. Nevertheless, it was not the objective of the protocol the evaluation of improvement of the symptoms and the number of patients in each group was too small. The analysis of the pulmonary function tests in the pre and post medication periods shows no significant differences between the groups. It was observed significant improvement of the response to bronchodilator after six months of treatment with both inhaled corticosteroids. The concentration of cortisol, before and after six months of the use of both drugs, did not show alterations in any of the groups. The results of this study show that beclomethasone and fluticasone, at the doses described, used with a spacer attachment, do not cause any detectable adrenal suppression / Mestrado / Clinica Medica / Mestre em Clinica Medica

The multiple functions of the pineal gland have been collectively interpreted as constituting a general anti-stressogenic role. The adrenal glands play a central role in maintaining homeostasis. The major neuroendocrine consequence of long-term stress is elevated circulating glucocorticoid levels. In this study, the effect of chronic, oral hydrocortisone treatment on pineal biochemistry was investigated in male Wi star rats of the albino strain. The results show that seven days of oral hydrocortisone treatment endows the pineal gland with the ability to increase melatonin synthesis in organ culture. The increase is accompanied by a rise in NAT activity, cyclic AMP levels and enhanced specific binding to the pineal B-adrenergic receptors. It appears that hydrocortisone sensitizes the pineal gland to stimulation by B-adrenergic agonists. thus rendering the pineal more responsive to B-adrenergic agonists. Further studies were directed at demonstrating an anti-stressogenic function for the pineal gland by investigating whether the principal pineal indole, melatonin. could protect against the deleterious effects of elevated. circulating drocortisone levels. The results show that chronic, oral hydrocortisone treatment significantly increases liver tryptophan pyrrolase activity. The catabolism of tryptophan by tryptophan pyrrolase is an important determinant of tryptophan availability to the brain, and therefore, brain serotonin levels. The findings show that melatonin inhibits basal and hydrocortisone-stimulated liver tryptophan pyrrolase apoenzyme activity in a dose-dependent manner. This inhibition suggests that melatonin may protect against excessive loss of tryptophan from circulation and against deficiencies in the cerebral serotinergic system which are associated with mood and behavioural disorders. It was shown that another deleterious effect of chronic hydrocortisone treatment is a significant increase in the number of glutamate receptors in the forebrain of male Wistar rats. The increase in receptor number observed in this study is probably due to an increase in the synthesis of glutamate receptors and is associated with a marked reduction in the affinity of the glutamate receptors for glutamate. possible to demonstrate an receptor number or the For practical reasons, it was not effect of melatonin on either glutamate affinity of glutamate receptors for glutamate in rat forebrain membranes. In view of the neurotoxic effect of glutamate in the eNS, the functional significance of recently described glutamate receptors in the pineal gland was investigated. The results show that 10-4 M glutamate significantly inhibits the isoprenaline-stimulated synthesis of N-acetylserotonin and melatonin in organ culture when the pineal glands were pre-incubated with glutamate for 4 hours prior to stimulation with isoprenalin and when glutamate and isoprenaline were administered together in vitro. GABA, a glutamate metabolite could not mimic the decrease in isoprenalinestimulated melatonin, and it is likely that the observed effects were directly attributed to glutamate. Incubation of the pineal gland with 10-4 M glutamate in organ culture did not affect HIOMT activity in pineal homogenates, but significantly elevated both basal and isoprenaline-stimulated NAT activity. It was concluded that glutamate only inhibits melatonin synthesis in intact pineal glands and not in pineal homogenates. The present study has provided further support for an interaction between the pineal and the adrenal glands. There is an ever increasing likelihood that melatonin is an anti-stressogenic hormone and that the pineal gland may have a protective role to play in the pathology of stress-related diseases.

The postnatal period is a critical time for development where external influences can help shape the long-term structure and function of the brain. Adverse experiences or stressors during the postnatal period, such as abuse or neglect, can have huge consequences on the long term function, health and susceptibility to disease. One environmental factor, whose importance is becoming increasingly more recognised for normal development, is light. Abnormal light during the first three weeks of life has been shown to have long term effects on the circadian system of rodents. On the other hand, the effects of abnormal light during the postnatal period on the stress system have yet been relatively unexplored. Therefore the aim of this thesis was to assess if altered postnatal light environment, such as that a preterm baby might be exposed to, has any long-term effects on the stress system. Mice were raised under constant light (LL), constant darkness (DD) or a normal 12:12hr light:dark cycle (LD) for the first three weeks of life from postnatal day (P)1 up until P21. From P21, all mice were then housed in LD conditions and the stress system was assessed by looking at several different levels of the HPA axis including neuropeptide expression in the brain, body and adrenal weight, and plasma corticosterone levels under both basal and stressed conditions. Learning and memory, anxiety-like behaviour and circadian output rhythms were also evaluated. Finally, mother-pup behaviour and maternal HPA axis were assessed to see if maternal care was changed by altered postnatal light. Both LL and DD rearing caused changes in the HPA axis of offspring with LL raised mice showing alterations in neuropeptide and glucocorticoid receptor expression in the brain. Postnatal DD resulted in a blunted corticosterone response to a stressor in females but had no effect in males. In terms of behaviour, LL raised mice had increased depressive-like behaviour. In contrast, postnatal light appears to have no effect on learning and memory or anxiety behaviour. When we looked at circadian output rhythms, we found that LL rearing appears to confer resilience to the rhythm disrupting effects of LL later on in life as seen by the maintenance of locomotor activity, body temperature and plasma corticosterone rhythms in LL. Maternal care and maternal stress systems appeared unaltered under the different postnatal light environments suggesting that the changes we see in the offspring are attributed to mechanisms other than alterations in maternal care.

Prenatal ethanol (E) exposure has marked effects on development of the hypothalamic-pituitary-adrenal (HPA) and -gonadal (HPG) axes. E rats show HPA hyperresponsiveness to stressors and altered reproductive function in adulthood. Importantly, prenatal ethanol differentially alters stress responsiveness in adult males and females, raising the possibility that gonadal hormones play a role in mediating ethanol effects on HPA function. To address this possibility, two studies were conducted to test the hypothesis that the differential alterations in HPA activity observed in E compared to control males are mediated, at least in part, by ethanol-induced changes in HPG effects on HPA regulation. The first study compared the effects of gonadectomy (GDX) on HPA and HPG activity in adult male offspring from prenatal E, pair-fed (PF) and ad libitum-fed control (C) dams. There were no differences among groups in basal testosterone levels under intact conditions. However, E males showed increased adrenocorticotropin but blunted testosterone and luteinizing hormone (LH) responses to restraint stress compared to PF and/or C rats, and no stress-induced elevation in arginine vasopressin (AVP) mRNA levels. GDX eliminated these differences among groups. The second study explored dose-related effects of testosterone on HPA regulation. Testosterone had less of an inhibitory effect on stress-induced CORT and LH increases in E than in PF and C males. Furthermore, testosterone had a reduced effect on central corticotropin-releasing hormone pathways, but an increased effect on central AVP pathways in E compared to PF and/or C males. Importantly, reduced androgen receptor (AR) mRNA levels, possibly reflecting downregulation of AR in key brain areas, may counteract the increased inhibitory AVP signals upstream from the paraventricular nucleus, and thus contribute to the HPA hyperresponsiveness seen in E males. Together these findings suggest that central regulation of both the HPA and HPG axes are altered by prenatal ethanol exposure. The capacity of testosterone to regulate HPA activity is altered in E males, with some effects mediated by the nutritional effects of ethanol. These changes would impair the ability to maintain homeostasis in E animals and have implications for the development of secondary disabilities in children with Fetal Alcohol Spectrum Disorder. / Medicine, Faculty of / Graduate

Les glucocorticoïdes sont des substances très utilisées en thérapeutique, mais parfois détournées de leur utilisation première par les sportifs. Si l’effet ergogénique d’une prise de courte durée de glucocorticoïdes chez l’homme a été démontré, les répercussions de cette prise chez la femme et les mécanismes impliqués restent mal connus. Dans une première étude, nous nous sommes intéressés aux effets d’une prise de courte durée de prednisone (50 mg/j/7j) lors de la réalisation d’un exercice submaximal jusqu’à épuisement chez des volontaires sains de sexe féminin pratiquant une activité physique régulière. Nous avons mis en évidence une performance significativement améliorée sous glucocorticoïdes, avec des altérations métaboliques et hormonales vs. placebo comparables à celles mises en évidence chez le sujet de sexe masculin. Il apparaît donc qu’il n’existe pas d’effet « genre », à l’exception toutefois d’une absence d’insulino-résistance sous corticoïdes chez la femme. Dans une deuxième étude effectuée lors d’un exercice de plus longue durée, la prise de prednisone vs. placebo induit en fin d’exercice une augmentation des concentrations d’acides aminés branchés et de la glycémie, pouvant être interprétée comme une augmentation de la néoglycogénèse. Dans une troisième étude, nous avons mis en évidence qu’un traitement d’une semaine de prednisone per os ne semblait altérer l’axe hypothalamo-hypophysosurrénalien que de manière très transitoire, avec un retour à des concentrations basales de cortisol et de DHEA seulement 3 jours après la fin du traitement. Enfin, dans une étude préliminaire effectuée sur modèle animal, grâce au concours du Laboratoire de Neurobiologie, la prednisone semble augmenter la sérotonine et son métabolite chez les souris sédentaires au repos. / Glucocorticoids are widely used as therapeutic substances, but sometimes diverted from their primary use by athletes. The ergogenic effect of short-term glucocorticoid administration was previously demonstrated in men subjects but its effect in women as well as the mechanisms involved remain unknown. In a first study, we investigated the effects of short-term prednisone intake (50 mg/j/7j) during a submaximal exercise until exhaustion in healthy recreationally-trained women. Under glucocorticoid, performance was significantly improved, with comparable hormonal and metabolic alterations vs placebo as in male subjects. It appears therefore that there is no "gender" effect, except an absence of glucocorticoid- induced insulin resistance in women. In a second study realized during a more prolonged exercise, prednisone intake induced vs. placebo, an increase in branched amino acids and in blood glucose concentrations at the end of exercise, which can be interpreted as an increase in gluconeogenesis. In a third study, we have highlighted that 1-week per os prednisone treatment only suppressed hypothalamic-pituitary-adrenal axis in very transient manner, with a return of cortisol and DHEA concentrations to basal values 3 days after the end of treatment. Finally, in a preliminary study on animal model, thanks to the Neurobiology Laboratory, prednisone seemed to increase serotonin and its metabolite in resting sedentary mices.

The purpose of the present study was twofold: (1) to determine if X-irradiation can be considered a direct stress agent, and if so, to what extent it differs from other stressors; and (2) to further elucidate the role of the adrenal cortex in the radiation syndrome by determining the more immediate responses of this system to X-irradiation.

Due to the large volume and often conflicting results reported on postoperative endocrinological changes, the practicing surgeon has difficulty in finding applicable principles. A knowledge of these principles is however necessary for an understanding of the mechanisms responsible for survival of the organism after surgery. The results thus far thus far reported are based upon complicated methodology, and may appear to be more theoretical than of practical value. Studies based upon small laboratory animals are indeed statistically significant, but the interpretation of these results as applied to the patient is difficult. Controlled human studies have been few in number and only very small areas of the total picture have been studied. There are a few studies on surgical patients; however, the variable results make the conclusion questionable. Nevertheless, these studies have lent a realistic significance to the evaluation of the total postoperative state.