0000000000319665
AUTHOR
Gerd Boehmer
The superoxide anion is involved in the induction of long-term potentiation in the rat somatosensory cortex in vitro.
Abstract The involvement of the superoxide anion (O2−) in the induction of neocortical long-term potentiation (LTP) was examined in rat brain slices containing the primary somatosensory cortex. Field potentials evoked by stimulation in cortical layer IV were recorded from layer II/III. In control experiments, tetanic high-frequency stimulation (HFS) resulted in essentially input-specific, NMDA receptor-dependent LTP (20.2±3.0% increase in field potential amplitude). When the availability of intracellular O2− was reduced by application of the cell membrane-permeable O2− scavengers MnTBAP or CP-H (spin trap), HFS-induced LTP was attenuated to 12.0±1.7% and 8.7±3.1% increase, respectively. In …
A repetitive intracortical microstimulation pattern induces long-lasting synaptic depression in brain slices of the rat primary somatosensory cortex.
Repetitive intracortical microstimulation (ICMS) applied to the rat primary somatosensory cortex (SI) in vivo was reported to induce reorganization of receptive fields and cortical maps. The present study was designed to exam- ine the effect of such an ICMS pattern applied to layer IV of brain slices containing SI on the efficacy of synaptic in- put to layer II/III. Effects of ICMS on the synaptic strength was quantified for the first synaptic component ( s1) of cor- tical field potentials (FPs) recorded from layer II/III of SI. FPs were evoked by stimulation in layer IV. The pattern of ICMS was identical to that used in vivo. However, stimula- tion intensity had to be raised to induce an a…
Subthreshold oscillation of the membrane potential in magnocellular neurones of the rat supraoptic nucleus
The hypothalamic supraoptic nucleus (SON) contains two major populations of magnocellular neurosecretory neurones, producing and secreting vasopressin and oxytocin, respectively (for review see Poulain & Wakerley 1982). Neurones of a subpopulation of supraoptic neurosecretory cells share the capability of generating phasic bursts of action potentials. In these neurones, action potentials are succeeded by a depolarizing afterpotential (DAP; Andrew, 1987; Armstrong et al. 1994; Li et al. 1995). Depending on the discharge frequency, DAPs summate, eventually resulting in the generation of a plateau potential that gives rise to the discharge of a long-lasting train of action potentials. Thus, DA…
Components of after-hyperpolarization in magnocellular neurones of the rat supraoptic nucleusin vitro
1. The pharmacological sensitivity of hyperpolarizing components of spike train after-potentials was examined in sixty-one magnocellular neurones of the rat supraoptic nucleus using intracellular recording techniques in a brain slice preparation. 2. In 26 % of all neurones a slow after-hyperpolarization (AHP) was observed in addition to a fast AHP. In 31 % of all neurones a depolarizing after-potential (DAP) was observed. 3. The fast AHP was blocked by apamin whereas the slow AHP was blocked by charybdotoxin (ChTX). The DAP was enhanced by ChTX or a DAP was unmasked if not present during the control period. 4. Low concentrations of TEA (0.15-1.5 mM) induced effects on the slow AHP and the D…
Platelet-activating factor contributes to the induction of long-term potentiation in the rat somatosensory cortex in vitro
The contribution of platelet-activating factor (PAF) to the induction of neocortical LTP was examined in rat brain slices containing the primary somatosensory cortex (SI). Field potentials evoked by single pulse stimulation in cortical layer IV were recorded from layer II/III. In control experiments, tetanic high frequency stimulation (HFS) resulted in input-specific, NMDA receptor-dependent LTP (21.1+/-3.2%; mean+/-SEM; n=15; P0.001). BN-52021 (5 microM), an antagonist at the extracellular PAF receptor, weakened the HFS-induced LTP to 12.4+/-2.7% (n=11; P0.05). In contrast, HFS-induced LTP was significantly enhanced to 29.4+/-2.3% (n=11; P0.05) when brain slices were superfused with ACSF c…