title: Late effect of dopamine D1/5receptor activation on stimulus-induced BOLD responses in the hippocampus and its target regions depends on the history of previous stimulations.
abstract: fMRI was used to study late effects of dopamine D1/5receptor activation on hippocampal signal processing and signal propagation to several target regions. The dopamine D1/5receptor agonists SKF83959 and SKF38393 were intraperitoneally applied without, immediately before or 7 days after electrical stimulation of the right perforant pathway with bursts of high-frequency pulses. Control animals received a 0.9% NaCl solution. One day after D1/5receptor activation, the perforant pathway was stimulated and the induced BOLD responses in the right hippocampus and its target regions, left hippocampus (l-HC) and medial prefrontal cortex (mPFC), were measured. Depending on the temporal relation between dopamine receptor activation and the first perforant pathway stimulation the induced BOLD response pattern differed. When applied without concurrent perforant pathway stimulation, the agonists caused region-selective increases in the induced BOLD responses: the effect of SKF83959 was evident in the mPFC whereas that of SKF38393 was confined to the l-HC. When applied in conjunction with perforant pathway stimulation, either agonist caused increased BOLD responses in both regions. In contrast, when applied 7 days after perforant pathway stimulation, neither SKF83959 nor SKF38393 modified the BOLD responses in the mPFC or l-HC 1day later. These findings suggest that (i) activation of dopamine D1/5receptors alone is sufficient to modify stimulus-induced BOLD responses in target regions of the right hippocampus 24h later, and (ii), the history of previous stimulations crucially affects the impact of dopamine receptor activation on stimulus-induced BOLD responses.
authors.affiliation: Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Helbing
authors.affiliation: Leibniz Institute for Neurobiology, Magdeburg, Germany; Center for Behavioral Brain Sciences, Magdeburg, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Tischmeyer
authors.affiliation: Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany; Leibniz Institute for Neurobiology, Magdeburg, Germany; Center for Behavioral Brain Sciences, Magdeburg, Germany. Electronic address: frank.angenstein@dzne.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Angenstein
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000008:administration & dosage / Q000031:analogs & derivatives; D000818:Animals; D001931:Brain Mapping; D018491:Dopamine Agonists / Q000008:administration & dosage; D004558:Electric Stimulation; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D019580:Perforant Pathway / Q000502:physiology; D017397:Prefrontal Cortex / Q000187:drug effects / Q000502:physiology; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000819:agonists / Q000502:physiology*; D050641:Receptors, Dopamine D5 / Q000819:agonists / Q000502:physiology*
chemical_list: D018491:Dopamine Agonists; D017447:Receptors, Dopamine D1; D050641:Receptors, Dopamine D5; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; C080703:SK&F 83959