Figure 10.

E2 increases rebound burst firing in arcuate neurons. Representative traces recorded in whole-cell voltage and current clamp from arcuate neurons in oil-treated (a, b) and E2-treated (c, d) animals. a, In voltage-clamp mode in an arcuate neuron from oil-treated animal, depolarizing voltage commands stepped from −120 mV elicited a peak amplitude T-type current of 20 pA. b, In the current-clamp mode, the cell exhibited an LTS, which triggered a single Na⁺ action potential after a hyperpolarizing current pulse to −100 mV. c, Similar protocols in current-clamp and voltage-clamp modes were applied to another arcuate neuron from an E2-treated animal. In voltage-clamp mode, the voltage command evoked a peak amplitude T-type current of 44 pA. d, The rebound from a hyperpolarization current pulse evoked a burst of Na⁺ action potentials on the crest of a LTS in this arcuate neuron. NiCl₂ (100 μm) abolished the LTS and accompanying Na⁺ spikes (bottom trace). e, Left, Box plot of the peak amplitudes of T-type current used for Na⁺ spike analysis in cells from oil-treated (n = 9) and E2-treated (n = 7) groups. [The median is the center line in the box. The edges of the box represent the 75th and the 25th percentiles of the distribution. The vertical lines extending from the box represent the upper (90th percentile) and lower (10th percentile) limits of the distribution.] Right, Summary histograms of cells from oil-treated (n = 9) and E2-treated (n = 7) groups showing a significant increase in the number of rebound Na⁺ spikes within the time course of the LTS (500 ms). Error bars represent the mean ± SEM tested per group. ***p < 0.005 versus vehicle.