EN
Orexins are two neuropeptides appearing to be particularly interesting in terms of hippocampal (HPC) EEG development. Recent studies conducted in our laboratory demonstrated that orexin A induce theta oscillations in HPC slices in certain concentrations. The lack of data concerning the influence of orexins on the changes in the activity of other neurotransmission systems encouraged our research. Thus the aim of the study was to investigate the changes in the activity of monoaminergic neurotransmitter systems in isolated HPC slices, which were used in EEG recordings. Experiments were performed on 50 slices obtained from 6 Wistar rats in accordance to Local Ethical Commission. Slices were subjected to neurochemical analysis immediately after the section, after the 45 min incubation in artificial cerebrospinal fluid (ACSF), and after incubation in ACSF with Orexin A for additional 45 min. Analysis of the concentration of monoamines and their metabolites was determined using high-performance liquid chromatography with electrochemical detection. To determine the changes in the activity of NE, 5-HT and DA systems, we calculated their utilization indexes, i.e. ratio of metabolite to its parent amine. Preliminary results suggest an increase in the particular neurotransmitter systems activity in hippocampal slices in that experimental conditions.