title: Corticosterone and corticotropin-releasing factor acutely facilitate gamma oscillations in the hippocampus in vitro.
abstract: Stressful experiences do not only cause peripheral changes in stress hormone levels, but also affect central structures such as the hippocampus, implicated in spatial orientation, stress evaluation, and learning and memory. It has been suggested that formation of memory traces is dependent on hippocampal gamma oscillations observed during alert behaviour and rapid eye movement sleep. Furthermore, during quiescent behaviour, sharp wave-ripple (SW-R) activity emerges. These events provide a temporal window during which reactivation of memory ensembles occur. We hypothesized that stress-responsive modulators, such as corticosterone (CORT), corticotropin-releasing factor (CRF) and the neurosteroid 3α, 21-dihydroxy-5α-pregnan-20-one (THDOC) are able to modulate gamma oscillations and SW-Rs. Using in vitro hippocampal slices, we studied acute and subacute (2 h) impact of these agents on gamma oscillations in area cornu ammonis 3 of the ventral hippocampus induced by acetylcholine (10 μm) combined with physostigmine (2 μm). CORT increased the gamma oscillations in a dose-dependent fashion. This effect was mediated by glucocorticoid receptors. Likewise, CRF augmented gamma oscillations via CRF type 1 receptor. Lastly, THDOC was found to diminish cholinergic gamma oscillations in a dose-dependent manner. Neither CORT, CRF nor THDOC modulated gamma power when pre-applied for 1 h, 2 h before the induction of gamma oscillations. Interestingly, stress-related neuromodulators had rather mild effects on spontaneous SW-R compared with their effects on gamma oscillations. These data suggest that the alteration of hippocampal gamma oscillation strength in vitro by stress-related agents is an acute process, permitting fast adaptation to new attention-requiring situations in vivo.
authors.affiliation: Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Charitéplatz 1, D-10117, Berlin, Germany.
authors.forename: Gürsel
authors.initials: G
authors.lastname: Çalışkan
authors.forename: Steffen B
authors.initials: SB
authors.lastname: Schulz
authors.forename: David
authors.initials: D
authors.lastname: Gruber
authors.forename: Joachim
authors.initials: J
authors.lastname: Behr
authors.forename: Uwe
authors.initials: U
authors.lastname: Heinemann
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Gerevich
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D003345:Corticosterone / Q000378:metabolism*; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D003900:Desoxycorticosterone / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D065818:Gamma Rhythm / Q000187:drug effects / Q000502:physiology*; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D018377:Neurotransmitter Agents / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology; D017208:Rats, Wistar; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D013997:Time Factors; D046509:Tissue Culture Techniques; D000099052:CRF Receptor, Type 1
chemical_list: D002800:Cholinesterase Inhibitors; D018377:Neurotransmitter Agents; D018019:Receptors, Corticotropin-Releasing Hormone; D011965:Receptors, Glucocorticoid; D003900:Desoxycorticosterone; C009413:tetrahydrodeoxycorticosterone; D000099052:CRF Receptor, Type 1; D003346:Corticotropin-Releasing Hormone; D010830:Physostigmine; D000109:Acetylcholine; D003345:Corticosterone
keywords: corticosterone; corticotropin-releasing factor; gamma oscillations; hippocampus; neurosteroid