Biomedical subjects

Jens M Langosch

Publications and source records attributed to Jens M Langosch.

4 recordsLinked to original sources

PubMed2005

Effects of substance P and its antagonist L-733060 on long term potentiation in guinea pig hippocampal slices.

The neuropeptide substance P (SP) has been suggested to be involved in several physiological and pathological conditions including learning and memory and the processing of pain. This study investigated for the first time acute effects of SP and the neurokinin-1 (NK-1) receptor antagonist L-733060 on long term potentiation (LTP) in the hippocampus. Electrically evoked fEPSP was tested under the influence of SP in the CA1 region of the guinea pig hippocampus. Concentrations of 1 and 10 microM SP increased fEPSP slopes to 114.3+/-4.5% and 115.8+/-2.7%, respectively. A threshold concentration was found at 0.1 microM SP. The SP-specific NK-1 receptor antagonist L-733060 did not influence fEPSP in a concentration of 1 microM. In experiments with LTP, a significant increase of potentiations after 60 min was seen with 1 microM SP. Even if the initial baseline increase due to SP (1 microM) was subtracted, potentiations were bigger compared to controls. L-733060 (1 microM) suppressed the excitatory effects of 1 microM SP nearly complete and subsequent induced LTP was not increased. In conclusion, SP has excitatory effects in the hippocampus and is able to facilitate LTP via activation of the NK-1 receptor.

Animals↗

PubMed2002

Effects of the atypical antidepressant trimipramine on neuronal excitability and long-term potentiation in guinea pig hippocampal slices.

Acute effects of the atypical tricyclic antidepressant (TCA) trimipramine on long-term potentiation (LTP) were investigated in this study. Electrically evoked population spikes (PS) were tested under the influence of trimipramine in the CA1 region of the hippocampus. A concentration of 10 microM trimipramine reduced PS amplitudes to 85.1 +/- 8.8%. They were reduced to 12.2 +/- 8.5% with 50 microM trimipramine. In experiments with LTP, trimipramine 10 microM was applied. Only 8 of 10 tested slices showed LTP. These potentiations were smaller than in the control experiments. LTP could not be induced with 50 microM trimipramine. In conclusion, the influence of trimipramine on LTP is similar to other TCA. It is contended that this contributes to the antidepressant effect of the drug.

Animals↗

PubMed2002

St John's wort (Hypericum perforatum) modulates evoked potentials in guinea pig hippocampal slices via AMPA and GABA receptors.

The effects of an ethanolic extract of the plant Hypericum perforatum L. (St John's wort) (HYP) and its hydrosoluble fraction (HYPWS) on electrically evoked population spikes and fEPSP were investigated in this study. Concentration dependent (10(-6) to 10(-4) g/l) excitatory effects were found. Above concentrations of 10(-3) g/l, HYP reduced the evoked responses, whereas HYPWS further increased them. Paired pulse facilitation was unaffected with HYPWS (10(-4) to 10(-2) g/l). The excitatory effects of HYPWS were amplified by the GABA(A) and GABA(B) receptor antagonists bicuculline and phaclofen, respectively. These excitations were antagonised by the AMPA receptor antagonist CNQX. Excitations caused by hypericum were not antagonised by the NMDA receptor antagonists D-APV and MK801, the metabotropic glutamate receptor (type I and II) antagonist MCPG, or the L-type calcium channel blocker verapamil. Hypericin and hyperforin, two components of H. perforatum, were found not to be responsible for the excitatory effects of the extract.

Animals↗

PubMed2002

Assessing cerebral dysfunction with probe-evoked potentials in a CNV task -- a study in alcoholics.

OBJECTIVES: Contrary to event-related potential (ERP) components N1, N2 and P3, slow ERPs have rarely been used in assessing cerebral dysfunction in mental disorders. Focussing on slow waves (SWs) and on patients with mild cerebral dysfunction, we recorded ERPs in alcoholics using a dual task design. METHODS: ERPs to auditory probes presented either 1s before the warning or 1s before the imperative stimulus of a visual contingent negative variation (CNV) paradigm were recorded from 33 scalp electrodes in 27 alcoholics following detoxification and 12 healthy controls. Independent component analysis (ICA) was used to separate potentially overlapping spatial components. RESULTS: In alcoholics compared to controls, probe ERPs showed increased N2, decreased P3 and increased negative SWs of two types appearing pre- and post-P3, respectively. Both negative SWs significantly correlated with neuropsychological indices reflecting verbal intelligence and memory functions. The increase in probe-evoked N1 and P3 potentials during CNV, putatively associated with enhanced cortical excitability, significantly correlated with clinical features of protracted alcohol withdrawal syndrome in alcoholics. CONCLUSIONS: Our experimental approach revealed two types of negative SWs which strongly correlated with neuropsychological deficits of mildly impaired patients. It is suggested that our methods might enhance diagnostic efficiency of ERPs. An electrophysiological measure of protracted alcohol withdrawal might be useful for managing central nervous system dysfunction in alcoholics.

Adult↗