Localization of Estrogen Receptor 1 in Kisspeptin Neurons during Maturation of the Reproductive Neuroendocrine Axis in Ewe Lambs

Abstract

The maturation of the reproductive neuroendocrine axis is associated with a decrease in the sensitivity to estradiol negative feedback and an increase in the frequency of secretion of luteinizing hormone (LH). It is proposed that inhibition of LH release is mediated by estradiol actions in kisspeptin neurons. Therefore, the objective of this study was to develop a dual-label immunocytochemical procedure to detect estrogen receptor 1 (ESR1) in kisspeptin neurons and investigate whether changes in ESR1 immunoreactivity occur during maturation of the reproductive neuroendocrine axis in ewe lambs. Histological sections used for this study were produced from brain tissue collected from 30-wk-old ewe lambs. Initially, an immunocytochemical procedure was used to test an antibody for detecting ESR1. The optimal dilution of the ESR1 antibody was determined using an immunofluorescent procedure. Then, a procedure to detect ESR1 and kisspeptin immunoreactivity in the same sections was tested using fluorophore-conjugated secondary antibodies. A dual-label immunofluorescent procedure was developed successfully and revealed the presence of ESR1 in kisspeptin neurons in the lamb hypothalamus. This procedure was used in the proposed project to test the hypothesis that decreased sensitivity to estradiol negative feedback during pubertal transition is associated with alterations in ESR1 immunoreactivity in kisspeptin neurons. Dual-labeled cells were detected throughout the preoptic area (POA) and hypothalamus of the processed tissue sections. However, further analysis must be conducted to better compare the means of the proportion of dual-labeled cells between groups.