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Browsing by Subject "kolinerginen"

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  • Kolinergisen viestinvälityksen vaikutukset mantelitumakkeen alueella syömisen säätelyssä 
    Larkiala, Jonna (2018)
    Obesity is a health problem linked to Western lifestyle and it is becoming more general. The complexity of regulation of eating makes it difficult to regulate body weight, when multiple neural networks and regions of brain have overlapping functions regarding to energy gain. Sufficient amount of energy is vital for individuals surviving in their living environment. Cholinergic messaging in brain is wide and for example nicotine is known for its appetite reducing effect. Anorexigenic proopiomelanocortin neurons mediate the effect of nicotine. In nucleus accumbens and central nucleus of amygdala extracellular levels of acetylcholine rise during meal, which promotes satiety. Satiety inhibits eating behavior between meals. Amygdala is a part of limbic system and in earlier knowledge it was associated only to regulation of memory, conditioning and fear. Nowadays importance of amygdala in eating behavior research is rising, but most of the studies focus on the effect of cue in regulation of eating. Cholinergic messaging is vigorous in the amygdala and is received from opposite areas of brain between basolateral and central amygdala and therefore this master’s thesis examined the effect of cholinergic messaging in amygdala on regulation of eating behavior. C57BL/6JRcc male mice were stereotaxically implanted with guide cannulas either in the basolateral complex of amygdala (n=10) or central nucleus (n=13). After recovering and habituation to automated pellet dispenser mice were treated with nicotinic and muscarinic receptor agonists and antagonists and eating behavior was recorded for six hours. Nicotine, administered to central and basolateral part of amygdala, lowered the number of pellets mice ate. In central nucleus effect was dose dependent. Mecamylamine had time related effect on eating behavior in basolateral amygdala, but dose dependent response was seen only in cumulative results. Oxotremorine was the only compound which created statistically significant interaction between time and dose. Result was seen in both groups. Scopolamine reduced eating behavior in central nucleus and dose dependency was seen. In basolateral complex scopolamine had time related effect, similar to mecamylamine. The results suggest that amygdala regulates eating behavior even without cue.
  • Pedunkulopontisen tegmentaalitumakkeen kolinergisten neuronien projektio lateraaliseen hypotalamukseen ruokahalun säätelyssä 
    Helminen, Heidi (2017)
    Obesity is considered one of the major public health challenges. One way to control obesity is to regulate appetite. Because brain is the primary regulative unit responsible for food intake, the research in this field has now been allocated especially to the central nervous system. The aim of this thesis was to clarify the role of cholinergic projections from pedunculopontine tegmentum (PPT) to lateral hypothalamus (LH) in food intake. In this study, DREADD-technology (designed receptors exclusively activated by designer drugs) based on chemogenetics was utilized with a gene manipulated mouse strain. For the experimental part of this work the mice were divided in three separate groups: one transducted with an activating DREADD-receptor (hM3Dq), one transducted with an inhibiting DREADD-receptor (hM4Di) and one transducted only with a fluorescent protein called m-Cherry. The last group was also defined as a control group of this study. In addition, the gene which coded m-Cherry fluorescent protein was transducted together with hM3Dq- and hM4Di-receptor genes for the first two groups to be able to examine the receptor expression later. At the baseline level, no differences were observed in food intake between the three study groups. The food intake did not differ between the groups while clozapine-N-oxide (CNO), a selective DREADD-receptor ligand, was administered straight into the LH area (0,03 µg/injection) with or without fasting of the animals. While administrating CNO to the mice intraperitoneally (1 mg/kg), the hM3Dq-group mice were observed to consume more food compared to the hM4Di-group or the control group. This difference was detected while food consumption was examined cumulatively during total four measuring hours. When the animals were fasted before the intraperitoneal administration test, however no differences were found between the study groups regarding food intake. As a conclusion of this study, cholinergic projections from pedunculopontine tegmentum (PPT) to lateral hypothalamus (LH) were not regulating food intake in mice. However, the cholinergic cells in PPT and some of their axons might be involved in the regulation of food intake while the food consumption is studied continuously and long-term. More studies are required to better define the role of the cholinergic projections from pedunculopontine tegmentum (PPT) to lateral hypothalamus (LH) in food intake.

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