Monoamines block kainate- and carbachol-induced gamma-oscillations but augment stimulus-induced gamma-oscillations in rat hippocampus in vitro.
Monoamines are implicated in a cognitive processes in a variety of brain regions, including the hippocampal formation, where storage and retrieval of information are facilitated by synchronous network activities. We have investigated the effects of norepinephrine, serotonin, and dopamine on carbachol-, kainate-, and stimulus-induced hippocampal gamma-oscillations employing combined extra- and intracellular recordings. Monoamines dose-dependently and reversibly suppressed kainate- and carbachol-induced gamma-oscillations while increasing the frequency. The effect of serotonin was mimicked by fenfluramine, which releases serotonin from presynaptic terminals. Forskolin also suppressed kainate- and carbachol-induced gamma-oscillations. This effect was mimicked by 8-Br-cAMP and isoproterenol, an agonist of noradrenergic beta-receptor suggesting that the monoamines-mediated suppression of these oscillations could involve intracellular cyclic adenosine 3',5'-cyclic monophosphate (AMP). By contrast, stimulus-induced gamma-oscillations were dose-dependently augmented in power and duration after monoamines application. Intracellular recordings from pyramidal cells revealed that monoamines prolonged the stimulus-induced depolarization and membrane potential oscillations. Stimulus-induced gamma-oscillations were also suppressed by isoproterenol, the D1 agonist SKF-38393 forskolin, and 8-Br-cAMP. This suggests that the augmentation of stimulus-induced gamma-oscillations by monoamines involves--at least in part-different classes of cells than in case of carbachol- and kainate-induced gamma-oscillations.
Wójtowicz
Anna Maria
AM
Department of Neurobiology, Johannes Müller-Center for Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
van den Boom
Leander
L
Chakrabarty
Arnab
A
Maggio
Nicola
N
Haq
Rizwan Ul
RU
Behrens
Christoph J
CJ
Heinemann
Uwe
U
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D015306:Biogenic Monoamines / Q000494:pharmacology*; D002217:Carbachol / Q000494:pharmacology; D002491:Central Nervous System Agents / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology; D004558:Electric Stimulation; D005277:Fenfluramine / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D007608:Kainic Acid / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000494:pharmacology; D018490:Serotonin Agents / Q000494:pharmacology
D015306:Biogenic Monoamines; D002491:Central Nervous System Agents; D018490:Serotonin Agents; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D005277:Fenfluramine; D012701:Serotonin; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D002217:Carbachol; D007545:Isoproterenol; D007608:Kainic Acid; D004298:Dopamine; D009638:Norepinephrine