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Browsing by Subject "ruokahalun säätely"

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  • Etuaivojen pohjan kolinergiset projektiot mantelitumakkeeseen ruokahalun säätelyssä 
    Hautala, Jonna (2018)
    Appetite regulation is a complex process involving regulation of energy homeostasis and the rewarding nature of food. Abnormalities in appetite regulation lead to obesity and eating disorders which are challenging to treat with medicines. Especially obesity is an increasing public health problem and drug development against it is a current subject in research. Hypothalamus is the most important brain area related to appetite regulation. Also, the basal forebrain and the amygdala which are part of the reward system in the brain, contribute to the appetite regulation. There is cholinergic innervation from the basal forebrain to the amygdala and most of the cholinergic activity in the amygdala is originating from the basal forebrain. It is known that the cholinergic system inhibits appetite but there is still no research about impact of cholinergic projections between these two brain areas. Aim of this study was to find out if the cholinergic projections from the basal forebrain to the amygdala effect on appetite regulation. The study included two stereotactic surgery. In the first surgery the mice (n=14) received injections to the basal forebrain that contained genetic materials for DREADDs in AAV. DREADDs appeared in the cholinergic cells of the basal forebrain and emanated within their axons to the amygdala. In the second surgery cannulas were placed to the amygdala. CNO was injected through the cannulas to the amygdala to cause the DREADDs activate or inhibit the cholinergic cells. As a control, mice received vehicle. The feeding experiments were performed in normal conditions or after food restriction and there were either food or sugar pellets available. The pellet dispenser monitored how many pellets mice ate during the six hours after the CNO or vehicle treatment. The success of virus injections was checked after the feeding experiments by antibody dyeing. In any conditions there was no significant differences in the results due to DREADDs and treatment. Because of the small group sizes and dispersion of the results no final conclusions can be made but the additional research about this topic is needed.
  • 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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