Browsing by Author "Lehto, Anna"

The histamine system in the brain has many important functions, including regulating the sleep-wake cycle, locomotor activity, cognition and memory. Gamma-Aminobutyric acid (GABA) on the other hand is the most important inhibitory transmitter in the brain, thus important for example in inducing sleep. Disturbances in these systems are present in various neurological diseases. Of the various histamine receptors, the histamine receptor 3 (HRH3) has a unique role in restricting the synthesis and release of both histamine and other transmitters, including glutamate, acetylcholine, dopamine and noradrenaline. GABA is synthesized from glutamic acid by glutamic acid decarboxylase (GAD), which has two different isoforms, GAD65 and GAD67. NKCC1 and KCC2 are ion transporter molecules essential for the development of the GABA system. The aim of this study was to examine the effect the HRH3 has on four essential genes regarding the GABAergic system GAD65, GAD67, KCC2, and NKCC1. This was accomplished using a HRH3 knockout zebrafish strain. The expression patterns of the genes were visualized by whole-mount in situ hybridization. The GAD67 and KCC2 gene expression patterns were also visualized in zebrafish brains treated with HRH3 antagonists ciproxifan and thioperamide. The results of the study showed that knocking out of the HRH3 did not seem to have an effect on the expression of the studied GABAergic genes. Samples treated with thioperamide or ciproxifan on the other hand showed diminished gene expression. This indicates that these pharmaceutical agents decrease the expression of KCC2, revealing new information about their effect on brain function. This result still needs to be confirmed using quantitative methods. New information about the genes was also acquired regarding their expression in the wild type zebrafish. For GAD65 and GAD67 new information was gained about the changes in expression during the zebrafish development. For KCC2 and NKCC1 the expression patterns in the zebrafish brain are completely new, previously unpublished information.