Effects of midbrain raphe stimulation and lesion on EEG activity in rats.
In order to clarify whether the dorsal raphe (d-R) and medial raphe nuclei (m-R) of the midbrain play a different role in EEG activity, the effects of either electrical stimulation or lesion of each raphe nucleus were examined in rats. After m-R stimulation, EEG activity changed to a marked drowsy pattern. D-R stimulation, however, failed to produce such effects. M-R lesion elicited a significant arousal in EEG. The change in hippocampal EEG was the most characteristic, i.e., synchronized waves with an extreme increase in voltage. D-R lesion did not produce such a change. The hippocampal EEG arousal was easily abolished by L-5-hydroxytryptophan without any change in the cortical EEG or behavior. These results suggest that the m-R plays a more important role than the d-R in regulating the hippocampal EEG activity, especially in inhibiting the appearance of high voltage synchronized waves in the hippocampus.
D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000679:Amygdala / Q000502:physiology; D000818:Animals; D001143:Arousal / Q000502:physiology; D001522:Behavior, Animal / Q000502:physiology; D001933:Brain Stem / Q000502:physiology*; D004558:Electric Stimulation; D004569:Electroencephalography; D005071:Evoked Potentials / Q000187:drug effects; D005625:Frontal Lobe / Q000502:physiology; D006624:Hippocampus / Q000502:physiology; D008297:Male; D008636:Mesencephalon / Q000187:drug effects / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D011903:Raphe Nuclei / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D012686:Septal Nuclei / Q000502:physiology; D012701:Serotonin / Q000378:metabolism
D012701:Serotonin; D006916:5-Hydroxytryptophan