Seit Beginn des 20. Jahrhunderts ist Relaxin bekannt als Schwangerschaftshormon, das unter anderem zur pränatalen Weitung des Geburtskanals beiträgt. Erst in den letzten Jahren wurden weitere Wirkungen des Peptidhormons beschrieben. So beeinflusst Relaxin den Gefäßtonus, die Nierenfunktion sowie die Kollagenbilanz des Bindegewebes. Als Angriffsstelle des Peptidhormons wurden im Jahre 2002 zwei membranständige Rezeptoren, LGR7 und LGR8, identifiziert. Im Rahmen dieser Arbeit an HeLa- und THP-1-Zellen konnte nun erstmals gezeigt werden, dass Relaxin als Agonist mit dem Glukokortikoidrezeptor interagiert. Zunächst konnte mit Hilfe von Koimmunpräzipitationen eine Bindung von Relaxin an den Rezeptor nachgewiesen werden. 30 Minuten nach Behandlung mit Relaxin kam es zu einer Translokation von Relaxin und Glukokortikoidrezeptoren in den Zellkern. Eine transiente Transfektion mit einem GRE-Luziferase-Konstrukt zeigte eine Aktivierung von „glucocorticoid response elements“ (GRE) nach Inkubation mit Relaxin. Funktionell führte Relaxin zu einer verminderten TNFalpha-Sekretion von Makrophagen nach Stimulation mit bakteriellem Endotoxin. Mittels PCR, Western Blots sowie 3H-Dexamethason-Inkorporation konnte eine Zunahme funktionell aktiver Glukokortikoidrezeptoren nach Behandlung mit Relaxin gezeigt werden. Alle beschriebenen Effekte des Relaxins ließen sich durch Koinkubation mit dem Glukokortikoidrezeptor-Antagonisten RU-486 aufheben. / Relaxin has been known as a central hormone of pregnancy responsible for the dilatation of the birth canal since the beginning of the 20th century. Recent studies elucidated several new effects of relaxin such as regulation of vasotonus, renal function, and collagen turnover. In 2002, two G-protein-coupled receptors, LGR7 and LGR8, were identified as relaxin receptors. The present study shows for the first time that relaxin interacts as an agonist with glucocorticoid receptors (GR) in HeLa- and THP-1-cells. Initially, co-immunoprecipitation experiments revealed binding of relaxin to glucocorticoid receptors. Treatment with relaxin led to translocation of relaxin and glucocorticoid receptors into the nucleus within 30 minutes. After stimulation with relaxin, cells transiently transfected with GRE-luciferase constructs demonstrated activation of glucocorticoid receptors. At the functional level, relaxin reduced – in GR-dependent manner - TNFalpha-secretion of macrophages after stimulation with bacterial endotoxin. An increase of functionally active glucocorticoid receptors after incubation with relaxin was shown by PCR, western blots, and incorporation of 3H-labeled dexamethasone. All investigated effects of relaxin were abolished by co-treatment with the glucocorticoid receptor antagonist RU-486.

<p>In the present studies, aspects of some disease activity measures in rheumatoid arthritis (RA) have been investigated, including the effect of glucocorticoids on this activity. In RA, serum interleukin(IL)-6 levels were elevated and were shown to have a circadian rhythm, with peak levels in the morning, declining towards low or normal levels in the afternoon and evening. In contrast, serum levels of tumour necrosis factor(TNF) alpha were low and stable. In other connective tissue diseases, serum TNF alpha levels were elevated but without circadian variation, while IL-6 levels were low and stable. Nocturnal administration (at 2:00 a.m.) of low-dose prednisolone a few hours before the early morning peak of IL-6 was shown to be significantly more effective in reducing clinical symptoms of disease activity and serum IL-6 levels than the traditional morning administration (at 7:30 a.m.) of the same dose of prednisolone. Circulating monocytes are activated in RA, expressing receptors related to adhesion and phagocytosis. Treatment with glucocorticoids suppressed the expression of these receptors on monocytes, and this may be one mechanism of the beneficial effect of glucocorticoids in RA. Endogenous levels of cortisol seem to play a minor role in expression of monocyte receptors. The different acute phase markers used to assess disease activity in RA showed good corrrelations with each other and with serum IL-6 levels. There were especially strong corrrelations between C-reactive protein (CRP) and Serum amyloid protein A (SAA), and between fibrinogen and erythrocyte sedimentation rate (ESR). Fibrinogen and CRP showed stronger correlation than ESR with the Modified Health Assessment Questionnaire (MHAQ) score and with the neutrophil count. Four simple objective function tests were each compared with the HAQ score a with a radiological joint damage score (Larsen score). The objective function tests correlated with the MHAQ score, and each of these two methods of assessing physical disability correlated with pain, CRP and ESR. In addition, most of the objective function tests correlated significantly with radiological joint damage, while the MHAQ score did not.</p>

In the present studies, aspects of some disease activity measures in rheumatoid arthritis (RA) have been investigated, including the effect of glucocorticoids on this activity. In RA, serum interleukin(IL)-6 levels were elevated and were shown to have a circadian rhythm, with peak levels in the morning, declining towards low or normal levels in the afternoon and evening. In contrast, serum levels of tumour necrosis factor(TNF) alpha were low and stable. In other connective tissue diseases, serum TNF alpha levels were elevated but without circadian variation, while IL-6 levels were low and stable. Nocturnal administration (at 2:00 a.m.) of low-dose prednisolone a few hours before the early morning peak of IL-6 was shown to be significantly more effective in reducing clinical symptoms of disease activity and serum IL-6 levels than the traditional morning administration (at 7:30 a.m.) of the same dose of prednisolone. Circulating monocytes are activated in RA, expressing receptors related to adhesion and phagocytosis. Treatment with glucocorticoids suppressed the expression of these receptors on monocytes, and this may be one mechanism of the beneficial effect of glucocorticoids in RA. Endogenous levels of cortisol seem to play a minor role in expression of monocyte receptors. The different acute phase markers used to assess disease activity in RA showed good corrrelations with each other and with serum IL-6 levels. There were especially strong corrrelations between C-reactive protein (CRP) and Serum amyloid protein A (SAA), and between fibrinogen and erythrocyte sedimentation rate (ESR). Fibrinogen and CRP showed stronger correlation than ESR with the Modified Health Assessment Questionnaire (MHAQ) score and with the neutrophil count. Four simple objective function tests were each compared with the HAQ score a with a radiological joint damage score (Larsen score). The objective function tests correlated with the MHAQ score, and each of these two methods of assessing physical disability correlated with pain, CRP and ESR. In addition, most of the objective function tests correlated significantly with radiological joint damage, while the MHAQ score did not.

Obesity and specifically central obesity is related to insulin resistance, type 2 diabetes and other components of the so-called metabolic syndrome. The aim of this study was to elucidate the interplay between hormones, nutrients and adipose depots in normal and insulin-resistant fat cell metabolism. High levels of free fatty acids (FFAs) induce insulin resistance in muscle and liver in vivo. In the present study, rat adipocytes were treated with high physiological levels of oleic or palmitic acid in vitro for 4-24 h. This treatment had no effect on basal or insulin-stimulated glucose uptake capacity in these cells, neither did it affect the levels of the insulin signalling proteins; insulin receptor substrate (IRS)-1 or –2, phosphatidylinositol 3-kinase (PI3-K), protein kinase B (PKB) or glucose transporter (GLUT) 4, or the regulation of lipolysis rate. Visceral adiposity is considered to be more harmful than peripheral adiposity with respect to metabolic and cardiovascular complications. In adipose biopsies from subjects undergoing abdominal surgery, we found that glucose uptake capacity was elevated in omental as compared to subcutaneous adipocytes. The sensitivity (EC50) or maximum relative response to insulin, measured as % of basal, did however not differ between the depots. In women, subcutaneous adipocytes displayed a higher lipolysis rate following cAMP-stimulation than omental adipocytes, whereas there was a tendency towards the opposite in adipocytes from men. No differences were found between depots or sexes in the ability of insulin to inhibit lipolysis or in the levels of the lipolysis regulating proteins, i.e. protein kinase A (PKA), hormone sensitive lipase (HSL) and perilipin. Glucocorticoids, e.g. cortisol, exert pronounced insulin-antagonistic effects and are associated with redistribution of fat from peripheral to central fat depots in humans. Treatment of human subcutaneous and omental adipocytes in vitro, with the cortisol analogue dexamethasone, resulted in a dose dependent down-regulation of basal and insulin-stimulated glucose uptake capacity in omental, but not in subcutaneous cells. Concomitantly, the levels of IRS-1 and PKB were decreased only in omental adipocytes after dexamethasone treatment. The relative effect of insulin to stimulate glucose uptake was however not altered by dexamethasone treatment. The cAMP-stimulated lipolysis rate was elevated by dexamethasone treatment in cells from the subcutaneous depot in women and tended to be elevated in omental cells from men. No alterations however, were seen in the levels of the assessed lipolysis regulating proteins. Subcutaneous as well as omental fat cell size correlated negatively to insulin action in subcutaneous fat cells in vitro after adjusting for age, sex and body fat parameters in non-diabetic, but not in type 2 diabetic, subjects. Large subcutaneous fat cell size was strongly related to plasma leptin levels in non-diabetic and in type 2 diabetic subjects. We conclude that 1) adipocytes seem to be less vulnerable to elevated levels of fatty acids than muscle and liver cells, 2) the interactions between glucocorticoids and insulin in the regulation of glucose uptake differ between adipose depots, 3) depot specific hormonal lipolysis regulation differs between sexes and 4) fat cell size is related to insulin action in subcutaneous fat cells and to circulating levels of leptin.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 114-146).

Not available / text

Post-traumatic stress disorder (PTSD), an anxiety disorder, may develop after experiencing or witnessing a severe traumatic event. Characteristic symptoms include hyper arousal and amnesic symptoms, while volume reductions in the hippocampus of these patients appear correlated with illness severity and the degree of cognitive deficit. Stress-induced increases in plasma cortisol have been implicated in this apparent atrophy of the hippocampus, although, clinical studies have described a marked suppression of plasma cortisol in PTSD. Given this hypocortisolemia, the basis for hippocampal neuro degeneration and cognitive decline remains unclear. While stress-related hippocampal structural changes have been linked to the neurotoxic effects of glucocorticoids and glutamate. NMDA-NO pathways have been found to play a causal role in anxiety-related behaviours. Prior exposure to trauma is an important risk factor for PTSD. In most instances the disorder becomes progressively worse over time, possibly with a delayed onset, suggesting a role for sensitization. In this study a time-dependent sensitization (TDS) model was used to induce PTSD-like sequelae in male Spraque-Dawley rats. The TDS-model is based on exposure to acute stressors, with a reminder of the trauma, in the form of re-exposure to one of the acute stressor, seven days later. NOS-activity, NMDA receptor parameters (Bmax and Kd) and GABA levels in the hippocampus of rats, as well as plasma corticosterone levels were determined 21 days after exposure to the TDS-model. Increased levels of corticosterone were measured after exposure to acute stress, but these levels were found to decrease below basal levels 21 days after the re-exposure, thus mimicking glucocorticoid levels in patients with PTSD. These findings may also imply that the increase in glucocorticoid levels after stress exposure is only the initial step in a cascade of events leading to neuronal damage in the hippocampus. This study also found that stress-restress evoked a long-lasting increase in hippocampal NOS activity that was accompanied by a reactive down-regulation of hippocampal NMDA receptors and dysregulation of inhibitory GABA pathways. Subsequently, animals were chronically treated with certain pharmacological agents prior to exposure to the TDS-model to determine possible approaches for inhibiting the induction of PTSD. Pre-treatment with fluoxetine, currently indicated in the treatment of PTSD. and the nNOS inhibitor, 7-nitroindazole, had no effect on the increased NOS activity measured 21 days afler exposure to the TDS-model. Pre-treatment with the iNOS inhibitor, aminoguanidine, however, resulted in inhibition of the observed increase in hippocampal NOS-activity, implicating a possible role for the iNOS isoform in the etiology of PTSD. Treatment with ketoconazole, an inhibitor of glucoccfticoid synthesis, resulted in inhibition of the increase in NOS-activity observed after exposure to TDS-stress, thus indicating a possible link between stress glucocorticoid-release and NO synthesis. These perturbations may have importance in explaining the increasing evidence for stress-related hippocampal degenerative pathology and cognitive deficits seen in patients with PTSD. Uncovering and understanding the role of NO in PTSD will hopefully lead to the development of selective therapeutic agents in disorders like PTSD. as well as providing a better understanding of basic processes underlying normal and pathological neuronal functions in PTSD. / Thesis (Ph.D. (Pharmacology))--North-West University, Potchefstroom Campus, 2004.

Thesis (PhD)--Stellenbosch University, 2012. / Bibliography / ENGLISH ABSTRACT: Most individuals latently infected with Mycobacterium tuberculosis (Mtb) contain the infection by a balance of effector and regulatory immune responses. However, this balance can be influenced by steroid hormones such as glucocorticoids (GCs), which are known to increase the risk of reactivation of TB. The contraceptive medroxyprogesterone acetate (MPA), which also possesses selective glucocorticoid activity, is widely used in developing countries with approximately 60% of women on contraceptives using MPA in our study cohort. Therefore, our aim was to investigate the effect of this hormone on protective immune responses to BCG in HIV negative household contacts of active TB patients. When PBMCs of TB household contacts were stimulated with BCG in the presence of 10 μM MPA; this hormone displayed both glucocorticoid as well as progestogenic properties. Similarly to cortisol, MPA suppressed antigen specific expression of a range of cytokines including IL-1α, IL-1ra, IL- 17, TNFα, IL-5 and IFNγ. Dose response curves showed that MPA can also alter expression of some cytokines at lower contraceptive doses (in the nano molar range). To assess whether this effect of MPA in vitro also occurs in women using this hormone as contraceptive the PBMCs of MPA users and controls were stimulated with BCG and the levels of up to 29 different cytokines measured by luminex analysis. PBMCs of MPA users produced significantly lower levels of cytokines involved in immune responses against Mtb such as IL-12p40, IL-1α, IL-10, IL-13 and G-CSF, which corresponds with lower numbers of circulating monocytes observed in these women. These findings warrant further investigation and clinical trials should investigate the risk of progression from latent to active TB disease in women using this contraceptive. These trials, however, require a large number of participants and are prohibitively expensive; therefore it was decided to setup an Mtb/MPA mouse model to determine the effect of MPA on the disease outcome. BALB/c and C57BL/6 mice were injected with a weekly dose of one mg MPA or PBS and infected with 30 colony forming units of Mtb H37Rv one week after commencing the hormonal treatment. Both strains were included to establish which strain best represents the human model. Three and eight weeks post infection the MPA treated C57BL/6 mice had a significantly higher bacterial load in their lungs compared to untreated mice, whereas no difference was found in the bacterial loads of the BALB/c mice. MPA treated C57BL/6 mice had significantly lower serum levels of IL-10 and G-CSF and MPA treated BALB/c mice lower serum levels of IFNγ, when compared to untreated mice. Furthermore, cells isolated from the MLNs of MPA treated C57BL/6 mice, produced significantly less TNFα, significantly more IP-10 and less IL-10 in response to PPD, while MLN cells of MPA treated BALB/c mice produced significantly less IFNγ, IL-2, IL-17, GM-CSF and MCP-1. Data of the C57BL/6 mouse strain correlated with our human data and can it therefore be said that the C57BL/6 mouse strain, together with the serum concentration of MPA used in these experiments, is a good model to determine the effect of MPA in the context of a low dose Mtb infection. To conclude MPA use could therefore alter susceptibility to TB, TB disease severity as well as change the efficacy of new BCG-based vaccines, especially prime-boost vaccine strategies which may be administered to adult of adolescent women in the future. / AFRIKAANSE OPSOMMING: Die meeste mense wat latent met Mycobacterium tuberculosis (Mtb) geïnfekteer is, hou die infeksie onder beheer deur ʼn balans te handhaaf tussen effektor en regulatoriese immuunresponse. Hierdie balans kan egter beïnvloed word deur steroïedhormone soos glukokortikoïede (GCs), wat bewys is om die risiko van die heraktivering van TB te verhoog. Die voorbehoedmiddel medroksiprogesteroon-asetaat (MPA), wat ook selektiewe glukokortikoïed-aktiwiteit toon, word wyd gebruik in ontwikkelende lande en omtrent 60% van die vrouens in ons studie-bevolking wat voorbehoedmiddels gebruik, gebruik MPA. Om dié rede wou ons die effek van hierdie hormoon op die beskermende immuun-response teenoor M.bovis Bacilli Calmette-Guérin (BCG) in HIV negatiewe huishoudelike kontakte (HHKe) van pasiënte met aktiewe TB ondersoek. Ons het gevind dat wanneer perifere bloed mononukleêre selle (PBMSe) met BCG gestimuleer word in die teenwoordigheid van 10 μM MPA, hierdie hormoon beide glukokortikoïede en progesterogeniese eienskappe toon. Soos kortisol het MPA die antigeenspesifieke-uitdrukking van ʼn reeks sitokiene, insluitend IL-1α, IL-1ra, IL-17, TNFα, IL-5 en IFNγ, onderdruk. Respons kurwes wat verskillende konsentrasies van hormoon insluit, het getoon dat MPA ook by laer (nano-molare) dosisse die uitdrukking van sommige sitokiene kon verander. Om te bepaal of hierdie in vitro effek van MPA ook in vrouens wat MPA as voorbehoedmiddel gebruik voorkom, het ons PBMSe van MPA-gebruikers and kontroles met BCG gestimuleer en die vlakke van tot 29 verskillende sitokiene met behulp van Luminexanalise gemeet. PBMSe van MPA-gebruikers produseer beduidende laer vlakke van IL-12p40, IL-1α, IL- 10, IL-13 en G-CSF, wat elk in imuunafweerreaksies teen Mtb betrokke is. Die afname in dié sitokiene het gepaard gegaan met laer hoeveelhede sirkulerende monosiete. Ons resultate regverdig verdere ondersoeke en kliniese proewe behoort die risiko van progressie vanaf latente tot aktiewe TB in vrouens wat hierdie voorbehoedmiddel gebruik te bepaal. Sulke proewe vereis egter groot getalle deelnemers en is skrikwekkend duur, om die rede het ons besluit om ʼn Mtb/MPA muis-model op te stel om sodoende die algehele effek van MPA op die uitkoms van die siekte te bepaal. BALB/c en C57BL/6 muise is met ʼn weeklikse dosis van een mg MPA of sout oplossing ingespuit en een week na die aanvang van die hormoon behandeling met 30 kolonie-vormende eenhede Mtb H37Rv geïnfekteer. Beide muis tipes was ingesluit om sodoende te bepaal watter tipe die mens data die beste verteenwoordig. Drie en agt weke na die infeksie het die MPA-behandelde C57BL/6 muise ‘n beduidende hoër bakteriële lading in hul longe gehad as die onbehandelde muise, maar was daar geen verskil in die bakteriële ladings in die longe van die BALB/c muise nie. MPA-behandelde C57BL/6 muise het beduidende laer serumvlakke van IL-10 en G-CSF gehad, terwyl MPA-behandelde BALB/c muise laer serumvlakke van IFNγ gehad het. Verder het ons gevind dat die geisoleerde limfosiete van MPA-behandelde C57BL/6 muise beduidend minder TNFα, beduidend meer IP-10 en minder IL-10 geproduseer het na stimulasie met PPD, terwyl die limfosiete van MPA-behandelde BALB/c muise beduidend minder IFNγ, IL-2, IL-17, GM-CSF en MCP-1 geproduseer het. Data van die C57BL/6 muise stem ooreen met die van ons mens studie en ons kan dus vermeld dat die C57BL/6 muise, tesame met die spesifieke serumkonsentrasie van MPA wat gebruik is, ʼn goeie model is om die effek van MPA in die konteks van ʼn lae-dosis Mtb-infeksie te bestudeer. MPA gebruik kan dus die vatbaarheid vir TB, asook die erns van die siekte verander en kan ook die effektiwiteit van nuwe BCG-gebaseerde entstowwe, veral prima-hupstoot enstowwe, wat moontlik in die nabye toekoms vir volwasse en adolessente vroue toegedien kan word, verander.

Sepsis claims over 215,000 lives in the US annually. Inducible glucocorticoids (iGC) is produced during sepsis. However, the precise effects of iGC in sepsis remain unclear due to a lack of appropriate animal models. Glucocorticoid (GC) insufficiency is associated with a marked increase in mortality and occurs in 60% of severe septic patients. Yet the conclusion of GC therapy on septic patients is still controversial. Scavenger receptor class B type I (SR-BI) in the adrenal mediates the selective uptake of cholesteryl ester from lipoproteins for GC synthesis. SR-BI-/- mice completely lack iGC during sepsis and are highly susceptible to septic death, which presents SR-BI-/- mice as a GC insufficient model. However, SR-BI-/- mice display multiple defects contributing to septic death, making it difficult to study iGC by using these mice. Therefore, we utilized adrenal-specific SR-BI-/- mice (ADR-T SR-BI-/-) generated by adrenal transplantation. As expected, the ADR-T SR-BI-/- mice failed to generate iGC under cecal ligation and puncture (CLP)-induced sepsis and showed a significantly higher mortality than the control mice, demonstrating that iGC is essential for preventing septic death. High blood urea nitrogen (BUN) was observed in the ADR-T SR-BI-/- mice but not in the control mice in CLP, indicating that iGC protects kidney injury in sepsis. Plasma IL-6 was remarkably higher in the ADR-T SR-BI-/- mice than the control mice, demonstrating an anti-inflammatory effect of iGC in sepsis. The ADR-T SR-BI-/- mice also displayed significantly lower phagocytic activity of monocytes and neutrophils in the blood and lower activation of T cells in the spleen compared to the control mice in CLP, suggesting that iGC is immunomodulatory in sepsis. Low-dose GC supplementation significantly improved the survival of SR-BI-/- mice in CLP, but did not increase the survival rate of SR-BI+/+ mice in CLP, indicating that GC supplementation improves the survival specifically in mice with adrenal insufficiency. Overall, we revealed that iGC is essential for sepsis survival. iGC prevents kidney damage, modulates inflammatory responses and exerts immunomodulatory functions in sepsis. GC supplementation specifically improves survival of individuals with adrenal insufficiency in sepsis.

Post-traumatic stress disorder (PTSD), an anxiety disorder, may develop after experiencing or witnessing a severe traumatic event. Characteristic symptoms include hyper arousal and amnesic symptoms, while volume reductions in the hippocampus of these patients appear correlated with illness severity and the degree of cognitive deficit. Stress-induced increases in plasma cortisol have been implicated in this apparent atrophy of the hippocampus, although, clinical studies have described a marked suppression of plasma cortisol in PTSD. Given this hypocortisolemia, the basis for hippocampal neuro degeneration and cognitive decline remains unclear. While stress-related hippocampal structural changes have been linked to the neurotoxic effects of glucocorticoids and glutamate. NMDA-NO pathways have been found to play a causal role in anxiety-related behaviours. Prior exposure to trauma is an important risk factor for PTSD. In most instances the disorder becomes progressively worse over time, possibly with a delayed onset, suggesting a role for sensitization. In this study a time-dependent sensitization (TDS) model was used to induce PTSD-like sequelae in male Spraque-Dawley rats. The TDS-model is based on exposure to acute stressors, with a reminder of the trauma, in the form of re-exposure to one of the acute stressor, seven days later. NOS-activity, NMDA receptor parameters (Bmax and Kd) and GABA levels in the hippocampus of rats, as well as plasma corticosterone levels were determined 21 days after exposure to the TDS-model. Increased levels of corticosterone were measured after exposure to acute stress, but these levels were found to decrease below basal levels 21 days after the re-exposure, thus mimicking glucocorticoid levels in patients with PTSD. These findings may also imply that the increase in glucocorticoid levels after stress exposure is only the initial step in a cascade of events leading to neuronal damage in the hippocampus. This study also found that stress-restress evoked a long-lasting increase in hippocampal NOS activity that was accompanied by a reactive down-regulation of hippocampal NMDA receptors and dysregulation of inhibitory GABA pathways. Subsequently, animals were chronically treated with certain pharmacological agents prior to exposure to the TDS-model to determine possible approaches for inhibiting the induction of PTSD. Pre-treatment with fluoxetine, currently indicated in the treatment of PTSD. and the nNOS inhibitor, 7-nitroindazole, had no effect on the increased NOS activity measured 21 days afler exposure to the TDS-model. Pre-treatment with the iNOS inhibitor, aminoguanidine, however, resulted in inhibition of the observed increase in hippocampal NOS-activity, implicating a possible role for the iNOS isoform in the etiology of PTSD. Treatment with ketoconazole, an inhibitor of glucoccfticoid synthesis, resulted in inhibition of the increase in NOS-activity observed after exposure to TDS-stress, thus indicating a possible link between stress glucocorticoid-release and NO synthesis. These perturbations may have importance in explaining the increasing evidence for stress-related hippocampal degenerative pathology and cognitive deficits seen in patients with PTSD. Uncovering and understanding the role of NO in PTSD will hopefully lead to the development of selective therapeutic agents in disorders like PTSD. as well as providing a better understanding of basic processes underlying normal and pathological neuronal functions in PTSD. / Thesis (Ph.D. (Pharmacology))--North-West University, Potchefstroom Campus, 2004.