1.
Berggård, Cecilia, 1975-
(author)
Transcription Factor AP-2 in Relation to Personality and Antidepressant Drugs
2004
Doctoral thesis (other academic/artistic) abstract
The CNS monoaminergic systems are considered as the head engine regulating neuropsychiatric functions and personality. Transcription factor AP-2 is known to be essential for the development of the brainstem including the monoaminergic nuclei, and has the ability to regulate many genes in the monoaminergic systems. The ability of transcription factors to regulate specific gene expression, has lately made them hot candidates as drug targets. In this thesis, results indicating a role of AP-2 in the molecular effects of the antidepressant drugs citalopram and phenelzine, are presented. A polymorphism in the second intron of the gene encoding AP-2ß has previously been associated with anxiety-related personality traits as estimated by the Karolinska Scales of Personality (KSP). In this thesis, results confirming this association, gained by using a larger material and several different personality scales, are presented. Furthermore, data is presented showing an association between the activity of platelet monoamine oxidase, a trait-dependent marker for personality, and the genotype of the AP-2ß intron 2 polymorphism. The functional importance of the AP-2ß intron 2 polymorphism has not yet been elucidated. Included in this thesis are results showing that the AP-2ß intron 2 polymorphism is not in linkage disequilibrium with the only other described polymorphism in the AP-2ß gene, i.e. in the AP-2ß promoter (-67 G/A). Introns have in several studies been shown to include binding sites for regulatory proteins, and thus, to be important in transcriptional regulation. Results are presented demonstrating that one human brain nuclear protein binds only to the long variant of the AP-2ß intron 2 polymorphism. If this protein is involved in the regulation of the AP-2ß gene, it would affect the expression levels of the AP-2ß protein. In general, this thesis further establishes the role of transcription factor AP-2 as a regulatory factor of importance for personality and monoaminergic functions.
2.
Göktürk, Camilla, 1967-
(author)
Semicarbazide-sensitive Amine Oxidase (SSAO) – Regulation and Involvement in Blood Vessel Damage with Special Regard to Diabetes : A Study on Mice Overexpressing Human SSAO
2004
Doctoral thesis (other academic/artistic) abstract
Semicarbazide-sensitive amine oxidase (SSAO, EC 1.4.3.6) belongs to a family of copper-containing amine oxidases. SSAO exists as a membrane bound protein in endothelial-, smooth muscle-, and adipose cells as well as soluble in plasma. SSAO catalyses oxidative deamination of primary monoamines, which results in the production of corresponding aldehydes, hydrogen peroxide and ammonia. These compounds are very reactive and potentially cytotoxic, and are able to induce vascular damage if produced in high levels. Patients with diabetes mellitus, and with diabetic complications in particular, have a higher SSAO activity in plasma compared to healthy controls. It has therefore been speculated that high SSAO activity is involved in the development of vascular complications associated with diabetes. The aim of this thesis is to investigate the importance of SSAO in the development of disorders of a vascular origin. We have studied the transcriptional regulation of the SSAO gene, by inducing diabetes in NMRI and in transgenic mice, overexpressing the human form of SSAO in smooth muscle cells. We found that the increase in SSAO activity in diabetes is accompanied by reduced mRNA levels of the endogenous mouse gene, suggesting a negative feedback on the transcription of the SSAO gene. In addition, the transgenic mice exhibited an abnormal phenotype in the elastic tissue of aorta and renal artery. These mice have a lower mean artery pressure and an elevated pulse pressure. These results indicate that high SSAO activity in smooth muscle cells is associated with a change in the morphology of large arteries. This is likely contributing to the development of vascular complications in diabetes.
3.
Karlsson, Krister, 1972-
(author)
Substance P Endopeptidase : Purification and Characterizataion of Enzyme Activity and Evaluation of its Function during Stressful Condition
2004
Doctoral thesis (other academic/artistic) abstract
The purification and biochemical characterization of the substance P (SP) hydrolyzing enzyme, substance P endopeptidase (SPE), have been carried out; with subsequent orientation in neurobiological fundamental processes involved in opioid dependence, withdrawal, and heat-stress.SPE was purified from rat spinal cord, human spinal cord and cerebrospinal fluid (CSF), rat ventral tegemental area (VTA), and rat hippocampus. The enzyme activity was found to release the biologically active fragments SP(1-7) and SP(1-8) as major products. The purified enzymes were characterized with regard to their biochemical and kinetic properties. The typical SPE is neither inhibited by phosphoramidon nor captopril nor phenylmethanesulfonylflourid (PMSF). In comparison to other known proteases SPE differed in characteristics regarding substrate specificity, inhibition-profile, cleavage pattern, and other kinetic parameters. The technically very delicate approach of micro purification of SPE from the rat ventral tegemental area (VTA) (this is a very small tissue), turned out to be possible with the ÄKTA™-purifier system. Studies revealed a crucial role of SPE in a series of clinically important neuropathological conditions, such as opioid tolerance, and withdrawal (SPE, increased); and heat-stress (SPE, increased). These findings emerged from assessment of enzyme activity in hypothalamus, nucleus accumbens (NAc) periaqueductal gray (PAG), pituitary, striatum, substantia nigra (SN), VTA, spinal cord. Viewing the role of SPE in morphine tolerance, it was possible to note regional differences with a decrease in PAG, and striatum, whereas an increase was seen in SN, and VTA. After heat-stress treatment, SPE was raised in several regions (cerebral cortex, hippocampus, diencephalon, cerebellum, spinal cord), and the most precise observation of this was located to the hippocampus structure.
4.
Norqvist-Sjöberg, Astrid, 1953-
(author)
Amine oxidases in dental pulp : a study with special regard to a semicarbazide-sensitive amine oxidase with catalytic potency towards serotonin
1988
Doctoral thesis (other academic/artistic) abstract
The amine oxidizing capacity of piglet dental pulp tissue has been investigated. At least six separate enzyme activities could be distinguished:- a soluble semicarbazide-sensitive (SSAO) activity towards benzylamine, most likely to be derived from the content of blood plasma within the pulp tissue;- a soluble pulp tissue SSAO activity with most properties in common with the plasma enzyme, however with great efficiency not only regarding benzylamine but also tryptamine;- a tissue bound SSAO activity with activity towards benzylamine, tryptamine, tyramine and ß-phenylethylamine;- a tissue bound semicarbazide-sensitive activity towards serotonin (SSA0-5HT) (a combination of properties never reported before);- a mitochondrially bound and clorgyline-sensitive monoamine oxidase-A (MAO-A) activity with activity towards serotonin;- a mitochondrially bound and deprenyl-sensitive MAO-B activity with activity towards e.g. benzylamine, tryptamine, tyramine and ß-phenylethylamine.The relative importance of the various activities for the metabolism of some monoamines has been investigated.Although the SSAO enzymes had lower K values with most substrates than the MAO, the bulk of ïhe compounds was likely to be metabolized by MAO-B because of higher V values. K values and values with serotonin, howSver,were rather similar for rfle MAO and the SSAO membrane-bound enzyme(s).The thermal sensitivity of membrane-bound SSAO activities was found to be considerably lower than that for MAO-B.The SSAO-5HT activity was found to be localized to the plasma membrane with a greater activity towards the perifery of the pulp tissue than towards the centre.No great difference in the various amine oxidase activities was found when pulp tissues of varying degrees of maturity were compared.The occurrence of membrane-bound SSAO and MAO activities was investigated and compared between pig, ox and human dental pulp. All activities were found to be present in about the same order of magnitude in all three species with the exception of a higher MAO-A activity in the ox pulp and the absence of this enzyme activity in the human dental pulp.
