Browsing by Subject "ethanol stimulation"

Histamine is an important neurotransmitter in peripheral as well as in central nervous system. Histaminergic neurons modulate various functions such as sleep-wake cycle, energy metabolism, memory and pain. In addition the brain histaminergic system has been shown to play a role in reinforcement, addiction and addiction related behaviors. After finding the H3 receptor in 1980s it was realised how essential the neuronal histamine is in modulating several central nervous system (CNS) disorders. H3 receptor modulates the synthesis and release of histamine. Furthermore it modulates the release of various other neurotransmitters, such as serotonin, noradrenalin, dopamine, glutamate, γ-aminobutyric acid (GABA) and acethylcoline. The H3 receptor is predominantly expressed in the brain and therefore it is an attractive target for various CNS indications. For more than a decade H3 receptor has gained the interest of many pharmaceutical companies. Several H3 receptor ligands, mainly antagonists or inverse agonists, have been assessed in preclinical as well as in clinical studies. So far there are not enough clinical data on the safety and efficacy of H3 receptor ligands, but there is a strong possibility that H3 receptor antagonists will be used in the treatment of various important disorders, including narcolepsy, schizophrenia and cognitive disorders. Earlier in our research group it was shown that H3 receptor ligands play a major role in ethanol related behaviors. These observations were confirmed in the practical part of this Master's thesis. H3 receptor modulates ethanol stimulation as well as ethanol reinforcement. Both H3 receptor antagonists, ciproxifan and JNJ-10181457 were able to inhibit ethanol-evoked conditioned place preference (CPP). This means they were able to inhibit ethanol reward and reinforcement. Ciproxifan also increased ethanol stimulation. Immepip on the other hand did not alter ethanol-evoked CPP, but it totally inhibited the stimulation of locomotor activity by ethanol. The dopaminergic system regulates both reward and motor functions. The postsynaptic H3 receptors have been shown to be able to heteromerize with both dopamine D1- and D2- receptors in striatum. The formed heteromers modulate dopaminergic neurotransmission in vitro, which may lead to alterations in behavior in vivo. It is therefore possible that the responses we have seen on a behavioral level in this Master's thesis project are due to interactions between histaminergic and dopaminergic systems in striatal areas. The H3 receptor is an interesting target in the drug development of various CNS disorders. The responses seen in this Master's thesis project also indicate that the blockade of H3 receptor inhibit ethanol reward and reinforcement. In conclusion, these findings indicate that H3 receptor antagonists could possibly have therapeutic potential in treating ethanol addiction.