Abstract
Backgroundβ-adrenoceptor activation in the hippocampus is sufficient to induce heterosynaptic long-term potentiation of perforant path input to the dentate gyrus. However, in vitro and in vivo studies suggest the plasticity effects of β-adrenoceptor activation may vary depending on the level of receptor activation.MethodsThe present experiments use an in vivo model concurrently infusing differing concentrations of the β-adrenoceptor agonist, isoproterenol (ISO; 0, 0.1, 1, 10, and 100 μmol/L in aCSF; 1 μL over 12.5 min) in the dentate gyrus, while monitoring changes in the perforant path-evoked potential at the same site.ResultsLong-term depression (LTD) of fEPSP slope was elicited by 0.1 μmol/L ISO. Higher doses did not alter fEPSP slope. Maximal long-term potentiation of the perforant path-evoked population spike (183% >3 h) occurred at 10 μmol/L ISO. Transient depression of spike amplitude occurred at 0.1 μmol/L ISO.ConclusionsThese data demonstrate concentration-dependent effects of β-adrenoceptor activation on the perforant path-evoked potential. Long-term depression and long-term potentiation of perforant path-evoked responses are variably elicited as a function of the degree of receptor activation.
Highlights
The electrophysiological effects of b-adrenergic activation on perforant path-evoked potentials in the dentate gyrus have been studied extensively in vitro using the badrenergic receptor agonist isoproterenol (ISO) (Lacaille and Harley 1985; Dahl and Sarvey 1990; Dahl and Li 1994a), but to date no in vivo recordings with infused ISO have been attempted
The electrode placement was localized to the granule cell layer by monitoring the response to 0.2 ms test pulses delivered to the perforant path and by maximizing the positive-going fEPSP and negative-going population spike
The within-group analysis of the evoked fEPSP slope measurements revealed that only a single concentration of ISO produced long-term effects on the perforant pathevoked fEPSP response
Summary
The electrophysiological effects of b-adrenergic activation on perforant path-evoked potentials in the dentate gyrus have been studied extensively in vitro using the badrenergic receptor agonist isoproterenol (ISO) (Lacaille and Harley 1985; Dahl and Sarvey 1990; Dahl and Li 1994a), but to date no in vivo recordings with infused ISO have been attempted. This study addresses this issue and characterizes a spectrum of dose–response effects of ISO on both the dentate gyrus—perforant path-evoked field excitatory postsynaptic field potential (fEPSP) slope and population spike.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
