Figure 9.
Estrogen increases the whole-cell T-type calcium current in arcuate neurons. a, The peak current was obtained by applying conditioning pulses, 1 s in duration, ranging from −120 to −65 mV in 5 mV increments and then a test pulse to −60 mV (inset), and the T-type calcium current in the arcuate neuron was completely blocked by 100 μm nickel chloride. b, The current amplitudes were normalized to the cell capacitance in all cases to calculate current density. Bar graphs summarize the density of T-type calcium current in arcuate neurons from oil-treated and E2-treated animals. The mean density was significantly greater in E2-treated (0.97 ± 0.17 pA/pF; n = 25) than in oil-treated (0.48 ± 0.10 pA/pF; n = 23) ovariectomized females. Error bars represent the mean ± SEM tested per group. *p < 0.05 versus vehicle. c, Double labeling of arcuate dopamine and POMC neuron that expressed a T-type current. Top, Biocytin-streptavidin-Cy2 labeling of arcuate neurons after whole-cell recording. Labeled fibers are extending toward medial (third ventricle, 3V), lateral, and ventral regions in both cells. Bottom, Immunocytochemical staining of TH and β-endorphin in the respective cells (arrows). Scale bar, 50 μm (in all panels). d, Expression of Cav3.1 α1 mRNA in arcuate neurons. Representative gel illustrating that single arcuate neurons expressed Cav3.1 α1 mRNA including TH, POMC, and unidentified neurons. One cell contained no RT as a negative control (-RT). In addition, the following controls were included: aCSF from the dispersed cellular milieu and a water blank, both of which were negative after RT-PCR (data not shown). The expected size of the PCR products is as follows (in bp): Cav3.1, 228; TH, 223; POMC, 206.