Monoamines block kainate‐ and carbachol‐induced γ‐oscillations but augment stimulus‐induced γ‐oscillations in rat hippocampus in vitro

Abstract

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.

Oscillations and Neuronal Dynamics in Schizophrenia: The Search for Basic Symptoms and Translational Opportunities

“…In addition to inhibitory and excitatory neurotransmission, there is also evidence for the potential contribution of monoamines, such as DA, to the modulation of high-frequency oscillations [44][45][46] [47]. However, further research is required to systematically address this relationship.…”

IgG accumulates in inhibitory hippocampal neurons of experimental antiphospholipid syndrome

“…Extracellular recordings in hippocampal slices were performed as previously described [16,17]. Briefly, mice were rapidly decapitated, and 400 mm horizontal hippocampal slices were used.…”

Sustained Modafinil Treatment Effects on Control-Related Gamma Oscillatory Power in Schizophrenia

“…Bath-applied DA selectively, dose-dependently increases stimulation-induced gamma oscillations in hippocampal slices (Wojtowicz et al, 2009), which is modulated by D4 receptors (Andersson et al, 2012b). In addition, haloperidol suppresses the increased gamma oscillations observed in DAT knockout mice (relative to wild-type mice) exposed to a novel environment; haloperidol and clozapine both inhibit hippocampal gamma via a D3 receptor-mediated mechanism (Schulz et al, 2012); and awake mice with DA depletion (by α-methyl-p-tyrosine) also show impaired hippocampal gamma (Dzirasa et al, 2006).…”

“…Findings from other experimental paradigms, while conducted in vitro, support this notion. The 40-Hz firing of reticular thalamic cells is abolished by local prazosin infusion or bilateral LC lesions (Pinault and Deschenes, 1992); bathapplied NE induces in olfactory bulb slices a long-lasting increase in 30−70 Hz activity of cortical responses to patterned olfactory nerve stimulation that mimics the breathing cycle (Gire and Schoppa, 2008); and NE selectively and dose-dependently increases stimulation-induced gamma oscillations in hippocampal slices (Wojtowicz et al, 2009). It remains unknown whether these LC-mediated effects exist in awake, behaving animals.…”