Browsing by Author "Miettinen, Ville"

Pedunculopontine tegmental nucleus (PPTg) has been connected to many different brain functions. Lesions in this region have been demonstrated to have effects on drug related behavior, learning and locomotion. Furthermore, glutamatergic projections to VTA have been found in earlier studies. VTA is one of the most important brain regions related to feeling of reward. Thus, it is plausible that glutamatergic cells are the ones that are responsible for these alterations in drug related behaviour. Additionally, there are efferents to basal ganglia and regions related to them, which indicates that PPTg is likely to possess some functions related to locomotion. The aim of this study was to explore what kind of differences in food consumption, spontaneous locomotion, morphine induced locomotion and morphine induced conditioned place preference result from modulation of activity of the glutamatergic neurons of the PPTg in mice. In this study DREADD-method was used. This method allowed for both excitation and inhibition of the neurons. This method involves injection viral vector stereotactically to the desired brain region, which leads to expression of artificial receptor in specific type of neurons. These receptors can then be activated by injecting clozapine-Noxide(CNO) intraperitoneally. There were two test groups, one got receptor that activates the neuron when activated, other got one that inhibits the neuron. Control group got receptor that does not react to CNO. In the tests conducted, there was no difference in the amount of food consumed or distance moved spontaneously. In the conditioned place preference experiment, there was no significant difference in distance moved between groups. However, both of the test groups expressed weaker preference to the morphine-paired environment when compared to the control group. This could be explained by reinforcing effects of morphine being mediated through glutamatergic neurons of the PPTg.