Electrophysiology of Arcuate Neurokinin B Neurons in Female Tac2-EGFP Transgenic Mice

Neurons in the arcuate nucleus that coexpress kisspeptin, neurokinin B (NKB), and dynorphin (KNDy neurons) play an important role in the modulation of reproduction by estrogens. Here, we study the anatomical and electrophysiological properties of arcuate NKB neurons in heterozygous female transgenic...

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Bibliographic Details
Published in:Endocrinology (Philadelphia) 2014-07, Vol.155 (7), p.2555-2565
Main Authors: Cholanian, Marina, Krajewski-Hall, Sally J, Levine, Richard B, McMullen, Nathaniel T, Rance, Naomi E
Format: Article
Language:English
Subjects:
Action Potentials - drug effects
Action Potentials - physiology
Animals
Arcuate Nucleus of Hypothalamus - cytology
Arcuate Nucleus of Hypothalamus - metabolism
Estradiol - blood
Estradiol - pharmacology
Estrogens - blood
Estrogens - pharmacology
Female
Green Fluorescent Proteins - genetics
Green Fluorescent Proteins - metabolism
Image Processing, Computer-Assisted
Immunohistochemistry
Luteinizing Hormone - blood
Membrane Potentials - drug effects
Membrane Potentials - physiology
Mice
Mice, Transgenic
Microscopy, Fluorescence
Neuroendocrinology
Neurokinin B - genetics
Neurokinin B - metabolism
Neurons - metabolism
Neurons - physiology
Ovariectomy
Patch-Clamp Techniques
Promoter Regions, Genetic - genetics
Protein Precursors - genetics
Protein Precursors - metabolism
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Summary:Neurons in the arcuate nucleus that coexpress kisspeptin, neurokinin B (NKB), and dynorphin (KNDy neurons) play an important role in the modulation of reproduction by estrogens. Here, we study the anatomical and electrophysiological properties of arcuate NKB neurons in heterozygous female transgenic mice with enhanced green fluorescent protein (EGFP) under the control of the Tac2 (NKB) promoter (Tac2-EGFP mice). The onset of puberty, estrous cyclicity, and serum LH were comparable between Tac2-EGFP and wild-type mice. The location of EGFP-immunoreactive neurons was consistent with previous descriptions of Tac2 mRNA-expressing neurons in the rodent. In the arcuate nucleus, nearly 80% of EGFP neurons expressed pro-NKB-immunoreactivity. Moreover, EGFP fluorescent intensity in arcuate neurons was increased by ovariectomy and reduced by 17β-estradiol (E2) treatment. Electrophysiology of single cells in tissue slices was used to examine the effects of chronic E2 treatment on Tac2-EGFP neurons in the arcuate nucleus of ovariectomized mice. Whole-cell recordings revealed arcuate NKB neurons to be either spontaneously active or silent in both groups. E2 had no significant effect on the basic electrophysiological properties or spontaneous firing frequencies. Arcuate NKB neurons exhibited either tonic or phasic firing patterns in response to a series of square-pulse current injections. Notably, E2 reduced the number of action potentials evoked by depolarizing current injections. This study demonstrates the utility of the Tac2-EGFP mouse for electrophysiological and morphological studies of KNDy neurons in tissue slices. In parallel to E2 negative feedback on LH secretion, E2 decreased the intensity of the EGFP signal and reduced the excitability of NKB neurons in the arcuate nucleus of ovariectomized Tac2-EGFP mice.
ISSN:0013-7227
1945-7170
DOI:10.1210/en.2014-1065