Journal:

Article Title: Long-term plasticity in interneurons of the dentate gyrus

doi: 10.1073/pnas.141042398

Figure Lengend Snippet: Mechanisms underlying the maintenance of the iLTDep. (A–C) When current pulses were delivered before and after tetanic stimulation of the perforant path leading to iLTDep (A; time points of the input resistance measurements at −60 mV are indicated as “RN”), no changes in RN could be observed either with small (an example is shown in B) or larger current pulses (C). The plot of iLTDep in A and the traces in B are from the same interneuron. The summary plot in C is from n = 6 cells similar to that shown in A and B. The inset in C shows Vm values of interneurons before tetanus (filled bar), 20 min after tetanus (blank bar), and an additional 10 min after switching to ACSF containing APV, CNQX, MCPG, bicuculline, and TTX (hatched bar). (D) There was no sustained increase in extracellular K+ after tetanic stimulation of the perforant path (n = 3 slices). (Inset) Tetanic stimulation evoked only transient changes in [K+]o. (E–F) I–V curves of interneurons from sham-stimulated (E) (n = 4 cells) and stimulated (F) (n = 5 cells) slices, before (“pre-strophanthidin”) and in the presence of strophanthidin. The I–V curves were measured in APV, CNQX, bicuculline, TTX, and ZD-7288, in voltage clamp at zero current potential (note that strophanthidin caused a smaller shift in the I–V curve after tetanus at all membrane potentials). The Insets show examples of I-V curves from individual cells from sham-stimulated and stimulated slices, before and in the presence of strophanthidin. (G) Decreased pump current in interneurons from slices that were tetanized, compared with sham treated controls, from the experiments shown in E–F. (H) Summary plot (n = 4) showing that intracellular application of vanadate (a broad-spectrum blocker of phosphatases) abolished iLTDep. (I) Inclusion of ATP in the recording pipette also prevented the development of iLTDep (n = 3 cells; note that iLTDep could be evoked with gramicidin perforated patch recordings, as well as without recording from the interneurons during induction). (J) Pump current did not change when compounds that enhance pump rate (Na+, ATP, and EGTA) were included in the pipette (n = 3 interneurons in both control and tetanized slices).

Article Snippet: Individual slices were transferred to a recording chamber perfused with oxygenated ACSF at 34°C, which, depending on the experiment, contained some of the following drugs: 1 μM tetrodotoxin (TTX) (Calbiochem), 10 μM 2-amino-5-phosphonovaleric acid (APV), 5 μM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), 100 μM ZD-7288, 500 μM ( RS )-α-methyl-4-carboxyphenylglycine (MCPG), 5 μM N-(4-hydroxyphenylpropanyl)spermine (NHPP-SP) (all from Tocris Neuramin, Bristol, U.K.), 10 μM bicuculline methiodide, or 30–100 μM strophanthidin (Sigma).

Techniques: Transferring